. GEOLOGICAL SURVEY OF GEORGIA S. W. McCALLIE, State Geologist BULLETIN NO. 26 PRELIMINARY REPORT ON THE GEOLOGY OF THE COASTAL PLAIN OF GEORGIA BY OTTO )TEAT.CH, Assistonf St~te Jeolog:..t of Goorgi?, AND LLOI'"l) WILLIAM STEPHENSON Assistant Geologist, U.S. G. S. PREPARED IN CO-OPERATION WITH THE UNITED STATES GEOLOGICAL SURVEY UNDER THE DIRECTION OF T. WAYLAND VAUGHAN, Geoloe:ist in Charge of Coastal Plain Investigations. ATLANTA, GA. FOOTE & DAVIES CO. 1911 THE ADVISORY BOARD OF THE Geological Survey of Georgia in the Year 1911 (Ex-Officio) H1s ExcELLENCY, HOKE SMITH, Governor of Georgia PRESIDENT OF THE BoARD HoN. PHILIP COOK ________________________ Secretary of State HoN. W. J. SPEER____~--------~----- .. -- ___ ._State Treasurer ,~ ' ' \ j" , .. -' ~ ~ HoN. W. A. WRIGB'f:, ___________________ Co111ptroller-General HoN. THOMAS _FELDER ____________________ Attorney-General HoN. T. G. HU)!SON '. ___________.Comm:ssioner nf Agriculture HoN. M. L. BRJTTAIN _______ Commissioner of Public Schools CONTENTS 5 TABLE Of CONTENTS Page Advisory Board o o o o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 List of Illustrations o o o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Letter of transmittal, Geological Survey of Georgia 3 15-18 20 Letter of transmittal, Uo So Geological Survey Physiography, by Otto Veatch 0 0 0 0 0 0 0 0 22-23 25-50 Other physiographic divisions of the State 25-27 Cumberland Plateau 0 0 25 Appalachian Valley 0 0 26 Appalachian Mountains 26 Piedmont Plateau Coastal Plain 0 o 0 0 0 0 26 . 27-57 Fall Line hills 0 28-30 Dougherty plain 0 30-31 Altamaha upland 0 31-34 Southern lime-sink region 34-35 Okefenokee plain 0 35-36: Satilla coastal lowland or Satilla plain 36-39 Terraces 0 0 0 0 0 39 Drainage o 0 0 0 0 0 0 0 39-41 Lakes and ponds 0 0 0 0 0 0 41-43 Fluviatile and upland swamps Okefenokee Swamp 43-49 44~49V Other swamps o o 0 o 0 o 0 o 0 49 Springs o o 0 0 0 0 0 0 0 0 0 49-50 Elevations, by Otto Veatch 0 0 0 0 0 0 0 0 50-57 General statement of the geology of the Coastal Plain, by Otto Veatch 58-65 Divisions of Coastal Plain strata 59 Thickness 0 0 0 0 0 0 0 0 0 0 0 0 0 0 59-62 Structure 0 o o o . o o o ... 0 0 0 62 Cretaceous, by Lloyd William Stephenson 66-215 Introductory statement 66 Historical review 67-73 Lower Cretaceous 73-111 Definition 73-77 Areal distribution 0 73 Stratigraphic position 73-74 Lithologic characters 0 74-75 Strike, dip, and thickness 0 75-77 Physiographic expression 77 Paleontologic characters 0 77 Detailed sections 0 0 0 0 0 0 78-108 6 CONTENTS Chattahoochee River . . . . . . . . . . 78-83 Region between Chattahoochee and Ocmulgee rivers 83-91 Region between Ocmulgee and Savannah rivers 91-105 Savannah River . . . . . . . . . . . 105-106 Wells south of the belt of outcrop . 106-108 Correlation . . 108-111 Upper Cretaceous . . . 111-215 Eutaw formation . 111-149 Name . . . . . 111-112 Definition . . . 113-117 Areal distribution . 113 Stratigraphic position . . 113 Lithologic characters . . . 113-115 Strike, dip, and thickness . 115-116 Physiographic expression . . 116 Paleontologic. characters . . . 116-117 Detailed sections (Part of formation below the Tombigbee sand member) . . . . . . . . . . . . . . . . . . . . . 117-131 Chattahoochee River . . . . . . . . . . . . . . . 117-123 Region between Chattahoochee a,nd Flint rivers . 123-131 Detailed sections (Tombigbee sand member) . 131-140 Chattahoochee River . . . . . 131-138 East of Chattahoochee River . 138-140 Correlation . . . 140-149 Ripley formation . 149-215 Name . . . . . 149-150 Definition . . . 150-155 Areal distribution . . . 150-151 Stratigraphic position 151 Lithologic characters . . 151-153 Strike, dip, and thickness :153-154 Physiographic expression . 154 Paleontologic characters . 154-155 Detailed sections (Part of formation included within the zone of Exogyra ponderosa) . . . . . . . . . . . . . . . 155-172 Chattahoochee River . . . . . . . . . . . . . . . . . 155-160 Northeast of Chattahoochee River (typical marine beds) 160-161 Region ,between Chattahoochee and Ocmulgee rivers (Cusseta sand member) . . . . . . . . . . 161-172 Detailed sections (Exogyra costata zone) . . . . . . . . . 172-192 Chattahoochee River (typical marine beds) . . . . . . 172-181 Region between Chattahoochee and Ocmulgee rivers (typical marine beds) . . . . . . . . . . . . . . . . 181-192 Region between Chattahoochee and Ocmulgee rivers (Providence sand member) . . . . . . . . . . . . 192-200 Detailed sections (wells south of the belt of outcrop) . . . 200-204 CONTENTS 7 Correlation . . . . . . . . . . . . . . . . . . . . . . ... 204-215 Part of formation included within the zone of Exogyra ponderosa . . . . . . . . . . . . . . . . . . . . . . . 204-210 Exogyra costata zone . . . . . . . . . . . . . . . . . 210-215 Tertiary and Quaternary, by Otto Veatch and Lloyd William Stephen- son . . . . . . . . . . . . 216-456 Eocene . . . . . . . . . . 216-306 Midway formation . . 216-226 Name . . . . . 216 Definition . . . . 2l6-220 Stratigraphic relations . 216-218 Lithologic characters . 218 Thickness . . . . . . . 218 Paleontologic characters 219 Areal distribution . . . . 219 Physiographic expression . 219-220 Structure ..... . 220 Economic geology . 220 Local details. . . . 220-226 Fort Gaines . . . . . 220-221 Hatcher ...... . . 221-223 Greer Cave locality 223 Preston ..... . 223 Ellaville .. . . . . 224 Montezuma ..... . 224-226 Wilcox formation . 226-235 Name ........ . . 226-227 Definition . . . . . . . . 227-231 'Stratigraphic relations . 227-228 Lithologic characters . 228 Thickness ...... . 229 Paleontologic characters . 229-230 Areal distribution . . . . 230 Physiographic expression .. 230 Structure . . . '. . . 231 Economic geology . 231 Local details . . .. . 231-235 Foi-t Gaines . . . 231-234 Cuthbert .. . 234 Weston .... . . 234-235 Plains .... . 235 Ellaville . . . . 235 Andersonville . . . . 235 Claiborne group . . . . 235-296 McBean formation . . 237-284 Name ..... 237 8 OON'I;ENTS Definition . . . . . . . . . . Stratigraphic relations . Lithologic characters .. . Thickness . . . . ... . Paleontologic characters Areal distribution . . . . Physiographic expression Structure . . . . .... Local details (not including Congaree clay member) McBean Creek area, Richmond and Burke counties Savannah River, Burke County Shell Bluff . . . Demeries Ferry . Hancock Landing Blue Bluff ... Griffin Landing . Lime-kiln Bluff . Richmond County . Hephzibah .... Jefferson County .. Louisville . . . . Washington County Sandersville . . Tennille ... . Sunhill .... . Davisboro .. . Twiggs County . Dry Branch .. Gallemore ... Area west of Ocmulgee River Perry, Houston County Flint River . . . ... Chattahoochee River .. Other localities . . . . Congaree clay member of McBean formation Local details . . .. Columbia County Grovetown .. . harlem .... . Jefferson County Wrens ..... Glascock County .. Gibson ..... . Washington County Sandersville . Chalker ..... . 237-241 . 237-238 238 239 . 239-240 . 240-241 241 241 . 242-267 . 242-243 . 243-251 . 243-248 248 . 248-249 . 249-250 250 . 250-251 251 251 . 251-253 . 251-253 . 253-255 253 254 254 255 . 255-257 . 255-256 . 256-257 . 257-267 . 258-260 . 260-262 . 262-266 . 266-267 . 267-284 269 . 269-272 . 269-271 . 271-272 272 272 . 272-274 . 272-274 . 274-276 . 274-275 276 CONTENTS Wilkinson County Gordon . . . Lewiston ... Twiggs County . . Pikes Peak station Jones Comity . . Roberts station . . Griswoldville ... Bibb County .. Economic geology of McBean formation Barnwell sand . Name ..... . Definition . . . . . . . . . . Stratigraphic relations . . . Lithologic characters . . Thickness ........ . Paleontologic characters .. Areal distribution . . . . '. Physiographic expression Structure ... Local details . . . . . . . . Burke County . . . . . . . Storm Branch and Cox Springs Waynesboro .. Midville . . . . Boyd farm .. Stony Bluff .. Richmond County . Hephzibah .... Berzelia . . . . Jefferson County Louisville . . . Wadley .... Wilkinson County . Mcintyre ..... Twiggs County . . Dry Branch clay mines Jeffersonville ... Bibb County . . . . Browns Mountain Jackson formation .. Name ..... . Definition . . . . Stratigraphic relations Lithologic characters and thickness . Paleontologic characters . . . . . . . 9 . 276-278 . 276-277 . 277-278 . 278-279 . 278-279 . 279-283 . 279-282 . 282-283 283 . 283-284 . 285-296 285 . 285-287 . 285-286 286 286 286 287 287 287 . 287-296 . 287-290 . 287-288 . 288-289 289 . 289-290 290 . 290-291 290 . 290-291 . 291-292 . 291-292 292 293 293 . 293-295 . 293-294 . 294-295 . 295-296 296 . 296-306 296 . 296-299 . 296-297 297 . 297-298 10 CONTENTS Areal distribution . . . . Physiographic expression Structure . . . .. Economic geology . Local details . . . . . . Calhoun County . . . Crawford County ... Rich Hill .... Houston County . Bonaire .. Perry ... . Tivola ... . Twiggs County Near Dry Branch Westlake ..... Pulaski County .. Johnson County .. Savamiah River .. Johnsons Landing . Oligocene ....... . Vicksburg formation . Name .... . Definition .. . Stratigraphic relations Lithologic characters . Thickness ...... . Paleontologic characters . Areal distribution . . . . Physiographic expression Structure . . . . . Economic geology . . Local details . . . . . . . Chattahoochee River Between Flint and Chattahoochee rivers .Cuthbert, Randolph County Blakeley, Early County . Hilton, Early County . . . Dawson, Terrell County .. Bronwood, Terrell County . Arlington, Calhoun County Colquitt, Miller County . . Andersonville, Sumter County . Americus, Sumter County . . . Exposures on and near Flint River Near Oakfield, Worth and Lee counties Albany and vicinity . . . . . . . . . Nigger Head Bend, Mitchell County . 298 298 298 . 298-299 . 299-306 299 . 299300 . 299-300 . 300-304 . 300-301 . 301-303 . 303-304 . 304-305 304 . 304-305 305 . 305-306 306 306 . 306-362 . 306-324 . 306-307 . 307-311 . 307-308 . 308309 309 . 309-310 310 310 310 311 . 311-324 31] . 311-314 311 . 311-312 312 312 312 313 313 313 314 . 314-322 . 314-316 . 316-319 319 CONTENTS Dewitt, Mitchell County .. Newton, Baker County . . Bainbridge . . . . . . . . Brinson, Decatur County . Between Flint 'and Ocmulgee Rivers Elko, Houston County . Ocmulgee River .. Hawkinsville ..... . Oconee River . . . . . . Dublin, Laurens County . Exposures on and near Savannah River Girard and Flint Branch, Burke County Johnsons Landing ....... . Hershman Lake, Screven County Millhaven, Screven County Apalachicola group . . . . . . Chattahoochee formation .. Name ..... . Definition . . . . . . . Stratigraphic relations Lithologic characters . Thickness ...... . Paleontologic characters . Areal distribution . . . . Physiographic expression Structure ... Economic geology . Local details . . . . . . Decatur County . . . Bainbridge and vicinity . Faceville ... . Recovery ... . Wylie Landing Grady County .. Whigham ... Ocklockonee River .. Thomas County .... Original Pond and other localities Boston ......... . Other localities . . . . . . Withlacoochee River . . Allapaha River . . . . . . Rock House, Crisp County . Ocmulgee River . . . . . . Millen, Jenkins County .. Jacksonboro, Screven County 11 319 320 . 320322 322 322 322 . 322-323 . 322-323 323 323 . 323-324 323 324 324 324 . 324-362 . 324-342 324 . 325-328 325 326 326 . 326327 327 . 327-328 328 328 . 328-342 . 328334 . 328-333 . 333-334 334 334 . 334-336 . 334-336 336 . 336-339 . 336-338 338 . 339-342 . 339-340 340 340 340 341 . 341342 12 CONTENTS Alum Bluff formation Name ..... . Definition . . . . 'Stratigraphic relations .. Lithologic characters .. . Thickness ....... . Paleontologic characters Areal distribution . . . . Physiographic expression Structure . . . . . Economic geology . . . . Local details . . . . . . . . . Bainbridge, Decatur County Climax, Decatur County . . Attapulgus, Decatur County . . . Whigham and Cairo, Grady County Ocklockonee River . . . . . . . . Thomasville and Boston, Thomas County . Withlacoochee River Allapaha River . . . . Suwanee River . . . . ,St. Mary's River . . . Ocmulgee River . Oconee River . . . . Altamaha River .. Ogeechee River . . Savannah River . Miocene . . . . ... Marks Head marl . Name ..... Definition . . . Stratigraphic relations Lithologic characters and thickness Areal distribution and structure Paleontologic characters . . . . Economic geology . Duplin marl . . Name .... Definition .. Stratigraphic relations . . Lithologic characters and thickness . Areal distribution and structure Paleontologic characters . Economic geology . Undifferentiated Miocene . . . . . . 342-362 . 342-343 . 343-346 343 . 343-344 345 345 . 345-346 346 346 346 . 347-362 . 347-348 . 348-349 . 349-350 . 350-351 351 . 351-352 . 352-353 . 353-354 355 356 . 356-358 . 358-359 . 359-360 360 . 361-362 . 362-379 . 363-366 363 . 363-366 363 363 364 . 364-366 366 . 366-369 366 . 366-369 366 . 366-367. 367 . 367-369 369 369 CONTENTS Local details . . . . . . Savannah River . Hudsons Ferry Marks Head .. Porters Landing and vicinity Mount Pleasant Landing Sisters Ferry . . . . . Frying Pan Landing . . Ebenezer Landing . . . . Purisburg, South Carolina . Altamaha River ...... . Bugs Bluff and Buzzards Roost Bluff . Doctortown . . .. Glynn County . . . . . . Brunswick ..... . Livingston Plantation . Camden County .. Owens Ferry .. Pliocene Historical review . Charlton formation Local details . St. Marys River . Stokes Ferry Hicks Bluff . . Red Bluff ... Schoolhouse Bluff _ Rand Landing . Clay Landing . . Nettles Landing Cow Ford . . . . Sawpit Landing Folkston Chalk Bluff . . Orange Bluff . Altamaha (Lafayette ?) formation . Name ...... . Definition . . . . . . . . . Stratigraphic relations Lithologic characters Thickness ..... . Paleontology and age Areal distribution . . Physiographic expression Structure ....... . Conditions of deposition 13 . 370-379 . 370-376 370-371 371 . 371-373 . 373-374 . 374-375 375 375 . 375-376 . 376-377 376 377 . 377-379 . 377-378 . 378-379 379 379 . 379-423 . 380-392 . 392-400 . 393-400 . 393-400 . 393-394 394 395 395 . 395-396 396 . 396-397 397 398 . 398-399 . 399-400 400 . 400-423 . 400-401 . 401-409 . 401-402 . 402-405 406 . 406-407 407 . 407-408 408 . 408-409 CONTENTS Local details . . . . . . . . . . . . . Altamaha River . . . . . . . . . East and north of Altamaha River . West of Altamaha and Oconee rivers tyestern and southern localities Pleistocene . . . . . . . Columbia group . . . . . . Okefenokee formation . . Coastal terrace deposits Local details . . . . Surficial sands . Deposits beneath the surficial sands Fluviatile terrace deposits Local details . . . . . . . Chattahoochee River Flint River . . . Ocmulgee River . Savannah River Ogeechee River Other rivers Satilla formation . . . . Coastal terrace deposits Local details . . . . Savannah, Chatham County Crescent, Mcintosh County . Glynn County ....... . Camden County, Satilla and St. Marys rivers . Fluviatile terrace deposits . . . . . Ogeechee River . . . . . . . Ocmulgee and Oconee rivers Altamaha River ... Flint River . . . . . Chattahoochee River Other rivers . . . . . Recent. Surficial gray sands of the upland . Local details . . . . . . . Fall Line localities . . "Wire-grass" sand hills . 409-423 . 409-414 . 414-417 . 417-420 . 420-423 . 424-445 . 425;445 . 425-434 . 425-427 . 427-428 . 427-428 428 . 428-430 . 431-434 431 432 . 432-433 433 433 . 433-434 . 434-445 . 434-437 . 437-440 . 437-438 . 438-439 439 . 439-440 . 441-445 443 443 . 443-444 444 444 . 444-445 . 445-447 . 447-456 . 451-456 . 451-454 . 454-456 ILLUSTRATIONS 15 . ILLUSTRATIONS PLATES Opposite Page Plate 1. A.-Pyles Marsh, 11 miles northwest of Brunswick, showing timber killed by the encroachment of salt water upon the land, and old stumps in the foreground B.-Channel of Little Ocmulgee River one mile east of McRae, Telfair County . . . . . . . . . . . . . . . . . . 32 II. A.-Terrace and escarpment bordering St. Marys River (Florida side) opposite Traders Hill, Charlton County, Ga.. B.-Satilla terrace plain immediately west of New Savannah Bluff, Savannah River, Richmond County. . . . 40 III. A.~Sand hill on east side of Little Ocmulgee River, two miles northeast of Helena, Telfair County . . . . . . B.-A lime-sink pond known as Waving Pond, seven miles northwest of Sylvester, Worth County . . . . . . . . 48 IV. A.-Interior of Big Pond, seven miles north of Baxley, Appling County . . . . . . . . . . . . . . . . . . . . . B.-A lime-sink pond in the Chattahoochee formation, on the property of Mrs. Mitchell, six miles west of Boston, Thomas County . . . . . . . . . . . . . . . . . . . . . 56 V. Table showing the lithologic variations of the eastern Gulf Cretaceous deposits, and the age relationships of the Cretaceous deposits of Georgia to those of the remainder of the eastern Gulf region; also the correlation of the eastern Gulf Cretaceous with the Carolina and Middle Atlantic Cretaceous . . . . . . . . . . . 72 VI. A.-Clay pit at plant of the Georgia Kaolin Company, two miles southeast of Dry Branch, in Twiggs County, Ga . B.-Exposure in cut of Columbus-Seale road, four miles southwest of Columbus, Ga., in Russell County, Ala . . 80 VII. A.-Thomas Bluff, Chattahoochee River, one mile below the mouth of Bull Creek, Muscogee County, Ga . . B.-Exposure in cut of Columbus-Macon road, 3% miles northeast of Columbus, Ga . . . . . . . . . . . . . . 88 VIII. A.-Exposure on right bank of Chattahoochee River at Broken Arrow Bend, 101;2 miles below Columbus, Ga . B.-Exposure in cut of Steam Mill road, 7 miles east of Columbus, Ga . . . . . . . . . . . . . . . . . . . . 96 IX. A.-Slick Bluff, Chattahoochee River, right bank, 14 miles below Columbus, Ga. . . . . . . . . . . . . . . . . . . B.-Sandstone dike in clay of Eutaw formation at Slick Bluff . 104 X. A.-Indurated layer of fossiliferous marine sand in bed of Ochillee Creek, at Ochillee, Chattahoochee County, Ga . B.-Exposure in cut of Columbus-Lumpkin road, 13 miles south of Columbus, Ga . . . . . . . . . . . . . . . . . 112 16 ILLUSTRATIONS XI. A.-Bluff below Banks Landing, Chattahoochee River, 26lh miles below Columbus, Ga., left bank . . . . . . . . . B.-Bluff at Snake Shoals, Chattahoochee River, 30 miles below Columbus, Ga., right bank . . . . . . . . . . . . . 120 XII. A.-Bluff at Blufftown, Ga., 311,4 miles below Columbus, Ga. B.-Exposure in cut of Seaboard Air Line Railway, 2lh miles northwest of Cusseta, Chattahoochee County, Ga . . . . 128 XIII. A.-Exposure in cut of Seaboard Air Line Railway, at Manta Station (Hichitee P. 0.) Chattahoochee County, Ga .. B.-Exposure in cut of Seaboard Air Line Railway, three miles east of Cusseta, Chattahoochee County, Ga. . : . 136 XIV. A.-Exposure in gully in Buena Vista-Tazewell road, six miles northeast of Buena Vista, Marion County, Ga.. B.-"Sand stream," one mlle north of Tazewell, Marion County, Ga. . . . . . . . . . . . . . . . . . . . . 160 XV. A.-Exposure on Mercers Mill Creek near Georgetown, in Quitman County, Ga. . . . . . . . . . . . . . . . B.-Bluff on Chattahoochee River at Eufaula, Ala. . . . . 176 XVI. A.-The "Narrows" of Pataula Creek, nine miles north of Fort Gaines, Clay County, Ga. . . . . . . . . . . B.-Waterfall at upper end of the "Narrows" . . . . . . . 184 XVII. A.-Exposure in cut of Southern Railway, about one-third mile north of Zenith Station, Crawford County, Ga.. B.-Cut of Atlanta, Birmingham & Atlantic Railroad, ll/s miles north of Ideal, Macon County, Ga. . . . . . . . . 192 XVIII. A.-Gully lOJh miles northeast of Georgetown, in Stewart County, Ga. . . . . . . . . . . . . . . . . . . . . . B.-Cut of Central of Georgia Railway, one mile southeast of Buena Vista, Marion County, Ga . . . . . . . 208 XIX. A.-Ostrea Georgiana bed at Shell Bluff, Savannah River, Burke County . . . . . . . . . . . . . . . . . . . . . . B.-Layer of pisolitic clay bowlders near the base of the Claiborne group in a pit of the American Clay Company, Eleven Mile Post, Twiggs County . . . . . . . . . 240 XX. A.-Bed of fullers earth in Congaree clay member of McBean formation, pit of General Reduction Company,.12 miles southeast of Macon, near the Macon, Dublin, & Savannah R. R., Twiggs County . . . . . . . . . . . . . . B.-Cut of Macon, Dublin, & Savannah R. R., 12lh miles southeast of Macon, near Pikes Peak Station, Twiggs County, showing Congaree clay member of McBean Formation . . . . . . . . . . . . . . . . . . . . . . . 272, XXI. XXII. A.-Exposure of limestone of the Jackson formation in a quarry near the Georgia, Southern, & Florida Ry., 1lh miles south of Tivola, Houston County . . . . . . . . B.-Exposure of limestone of the Jackson formation in a gully at Rich Hill, five miles southeast of Roberta, Crawford County . . . . . . . . . . . . . . . . . . . . . . . . 296 A.-Masses of flint from the Vicksburg formation in bed of Flint River, eight or nine miles above Bainbridge, Decatur County . . . . . . . . . . . . . . . . . . . . B.-Exposure of flint and limestone of the Vicksburg for- ILLUSTRATIONS 17 mation just above Dewitt Ferry, Flint River, Mitchell County . . . . . . . . . . . . . . . . . . . . . . . . . . 312 XXIII. A.-Sink in Chattahoochee limestone near Recovery, Decatur County . . . . . . . . . . . . . . . . . . . . . . . . B.-Sink in Chattahoochee limestone, known as Original Pond, showing the limestone rock at edge of pond, on property of H. C. Copeland & Co., three miles west of Metcalf, Thomas County . . . . . . . . . . . . . . . 328 XXIV. A.-iExposure of limestone of the Chattahoochee formation at Stony Lake Bluff, Withlacoochee River, seven miles southeast of Quitman, Brooks County . . . . . . . . B.-Exposure of Chattahoochee limestone in bank of With- lacoochee River, New Bridge (or Horn Bridge) three miles below the Valdosta Southern R. R. bridge, Lowndes County . . . . . . . . . . . . . . 336 XXV. A.-Exposure of partially indurated, phosphatic, calcareous sand of the Alum Bluff formation, Allapaha River. Statenville, Echols County . . . . . . . . . . . . . . B.-Lower Sister Bluff, Altamaha River, Appling County, showing strata of the Alum Bluff and Altamaha (Lafayette?) formations . . . . . . . . . . . . . . . . 352 XXVI. A.-Unconformity, probably between the Marks Head marl and the Duplin marl, at a wood landing just above Enochs wood landing, 67%, miles above Savannah, Screven County . . . . . . . . . . . . . . . . . . . . B.-Exposure of Charlton formation, St. Marys River, right bank (Florida side), Stokes' Ferry, 11 miles south of St. George, Charlton County, Ga. . . . . . . . . . . . 376 XXVII. A.-Exposure of Charlton formation, St. Marys River, right bank (Florida side) one mile above Traders Hill, Charlton County, Ga. . . . . . . . . . . . . . . . . B.-Exposure of Charlton formation, St. Marys River, at Atlantic Coast Line R. R. bridge (Florida side), three miles southeast of Folkston, Charlton County, Ga. . . . 392 XXVIII. A.-Cut of Atlantic Coast Line R. R., west of Climax, Decatur County, showing strata of the Altamaha for- mation . . . . . . . . . . . . . . . . . . . . . . . . B.-Characteristic mottling in weathered phase of the Alta- maha formation, cut of Atlantic Coast Line R. R., west of Cairo, Grady County . . . . . . . . . . . . . . 416 XXIX. A.-Deposit of pure white sand used in the manufacture of glass, probably belonging to the Okefenokee formation, two miles northeast of Lumber City, Telfair County . . B.-Beards Bluff, Altamaha River, Tattnall County, showing prominent clay layer in Satilla formation . . . . . . . 440 XXX. A.-Cut of Macon, Dublin & Savannah R. R. through a sand hill on east side of Oconee River, near DU!blin, Laurens County . . . . ........ . B.--Exposure of residual, surficial sand in a sand pit near Howard, Taylor County . . . . . . . 448 18 ILLUSTRATIONS FIGURES Page. Fig. 1. Sketch map showing physiographic divisions of the Coastal Plain . . . . . . . . . . . . . . . . . . . 28 Fig. 2. Profile from Macon southeast to Brunswick . . 37 Fig. "? Profile sketch from Homerville to Cumberland Island . 46 Fig. 4. Profile from Okefenokee Swamp to Kings Ferry, Florida, along line D-E, on map of Okefenolcee Swamp . . . . . . 47 Fig. o). Sketch map of the Coastal Plain of Georgia, showing relation of drainage to geologic structure . . . . . . . . 63 Fig. 6. Sketch map of Chattahoochee River, Columbus, Ga., to Fort Gaines, Ga. . . . . . . . . . . . . . . . . . . 79 Fig. 7. Sketch showing relation of Lower Cretaceous beds to Eutaw formation at bluff below mouth of Upatoi Creek . . . . . 83 Fig. S. Sketch showing J:elation of Cretaceous and Eocene strata at Phinizy Gully, near Grovetown, Ga. . . . . . . . . . . . 102 Fig. 9. Sketch showing the relations of Lower Cretaceous beds and the Eutaw formation to each other and to overlying Pleistocene terrace depo&its . . . . . . . . . . . . . . . 127 Fig. 10. Section constructed from exposures in cuts of Southern Railway, from Zenith, Ga., northward, for about three- quarters of a mile . . . . . . . . . . . . . . . . 167 Fig. 11. Section in cut of Central of Georgia Railway, 11;!! miles northeast of Fort Valley 168 Fig. 12. Section in cut of Central of Georgia Railway, 12 miles northeast of Byron, Ga. 170 Fig. 13. Section in cut of Central of Georgia Railway, six miles southeast of Eufaula, Ala., in Quitman County, Ga. . . . . . . 193 MAPS 1. Map of Okefenokee Swamp and adjacent region 44 ~- Geologic map of the Coastal Plain of Georgia 58 LETTER OF TRANSMITTAL GEoLOGICAL SuRVEY oF GEORGIA, ATLANTA, November 1, 1911. , To Hi& Excellency, HoKE SMITH, Governor and President of the Advisory Board of the Geological Survey of Georgia. Sm: I have the honor to transmit herewith a preliminary report on the Geology of the Coastal Plain of Georgia, to be published as Bulletin No. 26 of this Survey. This report, which is the result of co-operative work between the State Geological Survey of Georgia and the United States Geological Survey, brings together in a systematic form all of the data so far collected by these surveys on the stratigraphic geology of the Coastal Plain of this State. By the aid of the information herein given it is now possible to work out to a greater advantage the various problems of economic geology which present themselves in South Georgia. Very respectfully yours, S. W. McCALLIE, State Geologist. I I LETTER Of TRANSMITTAL \VASHINGTON, June 10, 1911. PRoF. S. W. :McCALLIE, State Geologist of Georgia, Geological Survey of Georgia, Atlanta, Ga. SrR: I ha,e the honor to transmit herewith the mann8cript of a report entitled "The Geology of the Coastal Plain of Georgia with special reference to the stratigraphy, prepared under the direction of Thomas Wayland Vaughan, by Otto Veatch and Lloyd ~William Stephenson," in co-operation between the United States Geological Survey and the Geological Survey of Georgia. This report results from an agreement for the study of the geology and underground 'vater resources of the Coastal Plain of Georgia, entered into by the United States Geological Survey and the Geological Survey of Georgia in 1908. According to this agreement Dr. Vaughan was to have the direction of the investigations, while each co-operating orgainzation was to contribute the services of one geologist until two reports should be completed. One report, on the Stratigraphy of the Coastal Plain of the State, it was agreed, would be published by the Geological Survey of Georgia; while the other report, on the Underground Water Resources of the Coastal Plain of the State, would be published by the United States Geological Survey. The manuscript I am transmitting to you is to be published by the Geological Survey of Georgia. The Geological Survey of Georgia assigned for this ~work :Mr. Otto Veatch, Assistant State Geologist, while the United States Geological Survey assigned Dr. L. W. Stephenson. Dr. Vaughan has had general supervision of the investigations and he has contributed the determinations of the invertebrate fossih of the Tertiary and Quaternary formations and the inferences as to the correlation of the formations of these two systems. He has also contributed the results of his own field work, which has extended over a period from 1900 to 1910. Dr. Stephenson is author of the section on the Cretaceous formations. ln his paleontologic studies he has had aT his disposal, in addition to his own collections, exhaustive collections made h~ Dr. Stanton in 1891 from several localities on Chattahoochee River, and a number of sma!ler collections made by other investigators in Georgia. For purposes of comparison he was alw g-in11 access to the various collections of Cretaceous fossils in the tnitell States N ationa1 ::\luseum. Dr. Stephenson ha,; also bendi tc(1 from the suggestions awl criticisms of Dr. Sta11tcm, \\hose \Yide klw\Yl("ilgt of the Cretaceons fmmas of Xorth ~'unerica amply tit~ him to pa~" judgment 011 the \York of students of lesser experience. ::\Ir. E. \\". Berry, of ,Jolms Hopkins Fnivc.rsity, has contributed lists of fost'il palnts from the Cretaceous formations of Georgia, with annotations, which have been incorporated in the report. :?\Ir. Y catch has supplied numerous unpublished notes on the Cretaceous areas of Georgia, and has also contributed orally much information of value concerning the region. :Mr. Yeatch has >nitten the chapter on the Physiography of the Coastal Plain, has furnished the list of eleYations, has 1vritten the infrodnctory chapter on the geology of the Coastal Plain, and is the senior author of the section describing the Stratigraphy of the Tertiary and Quaternary formations. Dr. Stephenson participated in the field work within this area and has aided in the preparatiou of the manuscript. Although this report constitutes a decided advance in our knowledge of the geology of the Coastal Plain of Georgia, there is still needed a large amount of detailed investigation. This statement particularly applies to the Tertiary and Quaternary formations. The statements in the report are, in the main, conservative, as it is desired not to claim greater definiteness or precision than the available facts warrant. The mode of treatment of the subject should assist in directing the further investigations of problems concerning which the present information is inadequate. Very respectfully, GEo. 0. SMtTH, Director . THE GEOLOGY OF THE COASTAL PLAIN Of GEORGIA PHYSIOGRAPHY BY OTTO VEATCH As an introduction to the study of the physiography of the Coastal Plain the other physiographic divisions of the State will be briefly described. As these other divisions and the Coastal Plain are interrelated in their physiographic history, reference to them will make clearer the account of the geology and topography of the Coastal Plain. OTHER PHYSIOGRAPHIC DIVISIONS OF THE STATE Following Hayes' subdivisions of the Southern Appalachian province of the United States, the subdivisions in Georgia are, beginning on the northwest: (1) Cumberland Plateau; (2) Appalachian Valley; (3) Appalachian Mountains ; (4) Piedmont Plain. The fifth physiographic division is the Coastal Plain, which, however, is within itself a separate province. Cumberland Plateau.-The Cumberland Plateau is made up of flat-ropped mountains or tablelands of Carboniferous strata, and occupies, in Dade and Walker counties, a small area which has an elevation of 1,500 to 2,300 feet above sea level. It is represented in Georgia by Lookout, Pigeon, and Sand or Raccoon mountains. These mountains rise 700 to 1,400 feet above the valleys, and are characterized by comparatively flat tops and have steep, precipikus sides ; they owe their form to the resistant character and synclinal structure of the rock capping them. 2G GEOLOGY 01' THE COASTAL PLAIX Appalachian Yalley.-The Appalachian Y alley lies between the Cumberland Plateau on the west and the Appalachian ::\Iountains on the east. Considered as a whole it is a valley, since it is lower than the regions both to the east and west, but \vithin itself it is a region of parallel ridges and corresponding subordinate valleys. The ''alley is 40 to 50 miles wide, extends from the Tennessee line to the southern part of Polk County and across the State into Alabama. It is limited on the east by an abrupt scarp of semi-crystalline schists of the Appalachian Mountain area, the Cartersville fault line. The province lies within the Paleozoic area and is in a region of intensely folded limestones, sandstones, and shales. The ridg0s have a north-south direction, are generally steep-sided and owe their existence both to the structure and the resistant character of the rock composing them, while the valleys have been eroded from the softer strata. The vallevs have an elevation above sea level of 600 to 900 feet a11cl the ridg;s, 1,000 to 1,800 feet. Appalachian Jiountains.-The Appalachian ::\[ountains area is composed mainly of the Blue Ridge, with lesser mountain groups, both to the east and west. The area occupies the northeastern part of the State; it is roughly delimited on the south by a line from Clarkesville to :Marietta, thence west to Rockmart, Polk County. The Blue Ridge enters the State in Rabun and Towns counties and loses its distinctively mountainous character in Pickens County. As contrasted with the Appalachian Valley and Cumberland Plateau, the region is one of vast1y greater rock complexity, composed of igneous rocks and highly metamorphosed sediments, that have been subjected to great orogenic movements, intense folding and faulting, and erosion since early geological periods. The topography is more rugged, and there is a greater complexity of topographic forms, irregularity of drainage form, and less dependence of ridges upon the strike of the rock. The highest elevation above sea level is about 5,000 feet, while there are a large number of "balds" or knobs which are above 4,000 feet. P1:edmont Plain.-The Piedmont Plain lies between the Appalachian Mountains and the Coastal.Plain. This is a southward sloping plain ranging in elevation from about 1,200 to 300-400 feet above sea level. The region is one of great rock complexity 1ike that of the Appalachian ]\;fountain area, and the beds haYe been snbjected to intense folding and faulting, but the surface has been planatrd hy erosion, and \vith the exception of a few conspicuous elevations the land presents an even sky line. The streams generally conform to the slope of the plain, and have deeply trenched their courses, pro- PHYSIOGRAPHY 27 clueing a broken, or hilly topography, in places approaching moun- tain ruggedness, but the tops of the hills and ridges always present a level. COASTAL PLAIN OF GEORGIA The Georgia Coastal Plain includes that portion of the State lying south of the Piedmont Plain. The contact between these two divisions is known as the Fall Line. This is a somewhat indefinite line which derives its name from the falls or rapids in the rivers at the places where they pass from the Piedmont crystalline rocks to the softer and less resistant rocks of the Coastal Plain. In Georgia this line extends in a northeast-southwest course from Augc1sta through Milledgeville and Macon to Columbus. The "falls" are not precipitous and are indicated by a series of rapids. There is a merging of the topography and the railway traveler in passing from one area to the other rarely recognizes the contact, which is more geological than topographical. That is, no prominent topographic fea hue separates the two regions. The Coastal Plain has an area of about 35,000 square miles if it is considered as con:fip.ed to the area underlain by Cretaceous and later sediments, but considered purely as a physiographic division, it would perhaps include a portion of the crystalline area or represent the original extent of the Coastal Plain beds and would then have an area betv.;een 36,000 and 37,000 square miles. Physiographically, the region is a lqw plain having a gentle southward tilt. In contrast to the other physiographic divisions of the State it has been subjected to the forces of erosion for only a comparatively short time, and its topography over the greater part of the area may be described as youthful. On the whole, the Coastal Plain is level, although there are some hilly and broken areas in the northern part; the plain is dissected in places near the Fall Line, and the topography has a sommYhat more mature aspect. The hills, however, never rise above a general level and their tops always present an even sky line. The rocks are mainly unconsolidated, sands, clays, and marls, and their structure is simple. There is consequently an absence of pronounced topographic features due to resistant varieties of rock and the folding of beds, such as characterize the Appalachian Valley and Appalachian Mountains. The plain reaches a maximum elevation of 650-700 feet between Macon and Columbus, and 500-600 feet between Macon and Augusta, and thence slopes gradually at the rate of about three or four feet per mile to sea level. About one-hal of it has an elevation of less than 300 feet, while a 1 large area near the Atlantic coast, about one-seventh of the total, i~ less than 100 feet above sea level. The streams on the whole have 28 GEOLOGY OF THE COASTAL PLAIN not cut as deep courses as in the older divisions; tributary streams are fewer, and there are large areas, flat and undrained or but poorly drained, particularly in the southeastern part. While the Coastal Plain may be described as a low, level plain, in comparison with the Appalachian Valley, 1\..ppalachian Mountains and Piedmont Plain, it is not entirely featureless and within itself presents topographic contrasts. , The writer has made the following physiographic divisions: (1) Fall Line hills; (2) Dougherty plain; (3) Altamaha upland; (4) Southern lime-sink region; (5) Okefenokee plain; ( 6) Satilla coastal lowland. The location and extent of these divisions may be seen by reference to the map below. 1/i 0 10 2,0 30 jO 50 MOea Fig. 1.-Sketch map showing physiographic divisions of the Coastal Plain of Georgia. FALL LINE HILLS The Fall Line hills division, as the name indicates, occupies the upper portion of the Coastal Plain. The northern extent is that of the Coastal Plain sediments, or approximately the Fall Line, south of which it forms a belt 40 to 50 miles wide, entirely across the State. PHYSIOGRAPHY 29 It can not be sharply Jefined, as on the north the topography merges i11to that of the Piedmont Plain and on the south into the level and less broken land of the Dougherty Plain and the Altamaha Upland. In this region, more than in any of the other divisions, the topogTaphic features are due to surface erosion. Stream erosion is more active on account of the greater altitude and has been in progress for a greater period of time. The region is characterized by flat-topped hills or ridges and deep g11llies or "washes." The larger streams have cut courses 200 t0 350 feet below the level of the upland plain and the northern portion of the belt is as broken as the adjacent Piedmont Plain. The region is underlain mainly by sands and clays of the Cretaceous and Eocene and their softness has been favorable for rapid erosion. In elevation above sea level the higher land west uf the Ocmulgee River varies from approximately 350 to 700 feet; that east of the Ocmulgee, from 300 to 600 feet. The elevations of low water at Columbus, Macon, Milledgeville and Augusta are respectively: 190, 278.6, 241.29, and 98 feet. Two types of hills are commonly recognized, the sand hills and the red hills. The sand hills are best developed in the upper part of the belt and are. conspicuous in Richmond, Crawford, Taylor, Talbot, Marion and other counties, and are really no more than flat ridges which have a notable covering of gray or brownish, superficial sand. The sand is almost pure quartz, incoherent or loose, and ''aries in thickness from three or four to twenty or thirty feet, but the average thickness over the sand hills is perhaps not more than five or six feet. This sand is probably residual from the underlying Cretaceous and Eocene formations. (Seep. 451.) The soil is poorly productive, and the tree growth is mainly stunted oak and scattered long-leaf pine. The lower portion of the Fall Line hills belt is mainly red hills, and the gray superficial sand is less widely distributed. The soil of these hills is a bright red sand or red, sandy loam, which is residual from the underlying geological formations, chiefly the Eocene. The red hills are conspicuous in Wilkinson, Twiggs, Houston, ::\lacon, Sumter, Terrell, Randolph, and Stewart counties. The deep gullies, also known as '~washes" and "ca,-es," which appear in this region, are worthy of note. The softness of the strata together with the high altitudes of the plain above the rivers, timber denudation, and cultivation of the laml, have been especially favoraqle for rapid erosion, and some of the deepest gullies, 100 to 175 feet, are knmvn to have formed since the settlement of the country. Perhaps the largest aml most pictnresqne of the gnlliPs are 1osated 80 GEOLOGY OF THE COASTAL PLAIN 'vest and north of Lumpkin, Stewart County. The gullies at ProYiclence, eight miles west of Lumpkin, are 100 to 175 feet in deptli, and from 200 yards to one-fourth mile in length. The greatest width is at the head, due to the union of a number of tributary gullies, so that a plan of the upper edge would be roughly bottle-shaped or pear-shaped. A transYerse profile would be V-shaped; a longitudinal profile' would be roughly L-shaped, the horizontal line of the letter, of course, greatly exceeding in length the vertical line. That is, the head of the gully is precipitous and the gradient of the floor so low that the water wh~ch flo1vs through the gully is unable to Parry the load of sand which is 'vashecl down, and it is spread out as deltas and "sand streams." 1\n excellent illustration of a "sand stream" is shown in plate XIV, B, opposite page 160. The strata are unconsolidated sand, containing soft clay layers, and are hence, easily eroded. The recession of the gullies has been Yery rapid, and the 11eepest gully is known to have worked back 000 feet in about 30 years, and to have washed out a space of 10 or 15 acres. As much as five or eYen ten feet "cave" or slnmp at one time after very heaYy rain storms. These gullies are the most pictnresque features of the Coastal Plain, presenting cmions erosion forms, pinnacles, "islands," or blocks of strata cut off from the aclj acent land by erosion, and sharp serrated ridges, while the brigbt red and white sands and the dark green pine tops present a vivid color contrast. Similar deep washes or gullies appear in Quitman, \Yebstcr, ::\Iarion, Crawford, Houston, Twiggs, \V.ilkinson, and \Vashington counties. Tlw deep washes on the sonth side of Hich 1I ill, Crawford County, are, next to the Prm'idence gullies, perhaps the most picturesque. The famous Lyell gullies fom miles west of :Milledgeville are properly "ithin this area, although they are cut entirely in residual clay dorin'd from granite, since a few remnants of the Coastal Plain sediments appear at this locali~y. The gullies are about 50 feet deep. They were visited by Sir Charl~s Lyell in 1842, and subsequently described in his "Travels in North America." DOUGHERTY PLAIK This division occupies a large area in the western part of the Coastal Plain. It is characterized by very level tracts, and there are few elevations that may properly be termed hills; it is a region in which there are comparatively few small streams and b1anches and consequently one in which there is little surface erosion, the drainage being in large measure subterranean. It is further characterized by numerous lime-sinks, which form shallow depressions in otherwise level tracts. This division extends from the Chatta- PHYSIOGRAPHY 31 hoochee to a fe11 miles ca,;t of .E'lint HiYcr, aud includes the greater part or all of the counties of Decatur, )[iller, "\Iitchell, Early, Baker, Calhoun, Dougherty, Handolph, Tenell, Lee aucl Sumter. A small strip extends eastward from the .E'lint to the Oconee, including parts of Dooly, Houston, Pula,ki, aud Laurens counties, and includes most of the area underlain by the limestones of the Vicksburg formation. 1t is rather sharply differentiated from the Altamaha Upland on the east and south, but merges into the .E'all Line hills on the north. In elevation above sea le1el it varies from approximately 12:l feet in Decatur County to 50 feet in the southern part of Houston County. Much the greater portion of the area is less than 300 feet. Due to the extensive underground solution of the 8oft underlying limestone, lime-sinks are very numerous and characteristic of the region. These vary in size from small, shallow depressions not more than 100 to 200 feet in diameter to those occupying several hundred acres and to chains of sinks several miles in extent. The sinks usually contain 1v~ter, forming shallow ponds or lakes, and the shallow ponds usually contain a thick growth of cypress and other trees. The amount of water in tho ponds and lakes varieB with the seasons, and during droughts tho smaller ones become dry. The recent desiccation of the sinks is also partly attributed to the removal of timber, thus permitting increased evaporation and oxidation of organie matter. Sinks are aho known to have been suddenly drained through subterranean passages. The absence of nnmerons small tributary creeks and branches is due not so much to the newness of the land surface as to the fact that a large portion of the drainage is through subterranean streams. Most of the largo creeks flow sluggishly through wide, swampy valleys, and rarely have any considerable bluffs along their courses. Chattahoochee, .E'lint and Ocmulgee rivers have cut deep, terraced valleys 75 to 200 feet below the plain, but haYe comparatively few tributary streams. AL'Nc}IAI-IA l:PLAXD This area constitutes the largest physiographic division of the Coastal Plain. Its northern boundary is marked by an irregular line between \Yaynesboro, Tennille, Dublin, Cochran, and Vienna, its western edge thence lying parallel to and a few miles east of Flint River and extending to Decatur County. On the southeast it extends into Effingham, Liberty, Wayne, Pierce, Ware, and Clinch counties, and merges into the sandy pine flats of the Okefenokee Plain. It embraces most of the region popnlarly knom1 as the 32 GEOLOGY OF THE COASTAL PLAIN "wire-grass country," and is underlain mainly by the Altamaha (Lafayette?) and Alum Bluff formations. The geology, topography, and flora of this region are of peculiar scientific interest and have been the subject of a number of papers and articles.1 The region is an upland only in comparison with the low coastal plains on the southeast and the adjacent Dougherty plain on the west, and on the whole is lower than the Fall Line Hills to the north. It varies in elevation above sea-level from about 125 to 470 feet. It reaches the highest elevation on the north and west, thence there is a gradual slope southeast. There is a steep ascent or escarpment on the west, separating it from the Flint River lowland, which is prominent enough, even in this region of low relief, to be distinguished by the observant traveler without the aid of topographic maps. For example, the rise from Camilla to Pelham, Mitchell County, over the Atlantic Coast Line Railroad is 185 feet in a distance of eight miles, and the rise from Bainbridge east to Climax is 175 feet. Arabi, Crisp County, Ashburn, Sylvester, Pelham, and Climax may be considered as marking approximately the crest of the escarpment; thence there is a decrease in elevation to the southeast. A characteristic of the topography is lmY, rolling hills, with smooth or softened outlines, which do not rise except along the large rivers more than 40 or 50 feet above the valleys. There is an absence of any features suggesting ruggedness, yet ~t the same time the region is not a monotonous level or flat. The soil is generally sandy and in places there is a thick mantle of loose gray sand. The area was originally covered with a wonderful forest of long-lea pine. A characteristic growth is wire-grass, Aristida stricta, a long and round-bladed, stiff grass, growing in tufts, six to eight inches high. Streams are much more numerous than in the Dougherty Plain and the coastal flats. The Altamaha, Ocmulgee, and Oconee rivers hm-e cut valleys. 100 to 150 feet b~low the upland, and have made precipitous bluffs in a few places, but with these exceptions the valleys are shallo"w and those of the small streams mav be described "as dish-shaped, or as having low breast-like slopes. The creeks are generally sluggish and flow through broad, swampy bottoms and 1Loughridge, R. H., Tenth Census._ Yol. YI, Georgia, pp. 15 and 49. Dall, W. H., U. S. Geol. Survey, J:mll. 84, p. 81. Harper, R. M., Phytogeographical Sketch of the Altamaha Grit Region of Georgia : Annals N. Y. Acad. Sci., Yo!. XYII, pt. I, 1906. McCallie, S. W., Underground Waters of Georgia: Ga. Geol. Survey, Bull. 15, pp. 31-32. Veatch, Otto, Altamaha Formation of the Coastal Plain of Georgia: Sci., Yo!. XXVII, 1908, pp. 71-74. GEOLOGY OF THE COASTaL PLA lll" OF GEORGI A . A. PYLES MARSH, 11 l\IILES ' OR'rHWE T OF BRUNSWICK, SHOWING TU.!REP. KILLED BY THE ENCROACH:ME T OF ALT WATER UPON THE LAND. OLD STUMPS IN THE FOREGROUND. PHYSIOGRAPHY 33 are char'"acterized by "clear" water, or water free from sediment, in contrast to the muddy water of the Ocmulgee, Oconee, and Altamaha. Many of the creeks and branches have their sources in flat, moist, densely wooded areas locally known as "bays," a name probably suggested by the dense growth of bay trees in these areas. The name "bay" is generally applied to upland, flat, swampy tracts in which water stands, due to imperfect drainage and dense vegetation which conserves the rainfall. These areas are really swamps but are not alluvial in character. Cluffs Bay, about seven miles west of Waycross (see map opposite page 44), is an example. The name is also applied to arms of creek and river swamps which form entrants into the dry land and are characterized by a dense growth of bay trees. The bays contain \Yater, but there is no well defined channel of a stream or "run." The water is furnished directly by rainfall and by seepage from the surrounding higher land. In the southeastern part of the Altamaha upland, the land becomes more level, and finally merges into the moist pine flats of the Okefe-nokee plain. Throughout this part there are numerous small cypress ponds, and the valleys of the small streams become more swampy, and the streams themselves have banks not more than a foot or two high. The ponds appear to be the result of shallow depressions or slight irregularities left in the land surface after the retreat of the last sea which covered this area. (See page 42.) Along the northern and western edges of this division in Screven, wilcox, Crisp, Turner, Worth, and Decatur counties, lime-sinks were noted, due to the underground solution most probably of the Chattahoochee limestone formation. One of the most interesting features of the Altamaha upland is the "sand hills" which border many of the creeks and rivers. These hills slope towards the streams wh~ich they border, but may be only very slightly higher, or not at all higher, than the upland back from the stream. They are made up of gray, yellow, or light brown, unconsolidated, structureless quartz sand, which in places reaches a thickness of' as much as 30 feet. These sand belts may reach a width of as much as two or three miles, parallel to the streams. It has been observed that the sand ridges are generally on the east or left sides of the streams. The only explanation of this which can be offered, and this explanation is merely tentative, is that the prevailing winds might have caused the westward slopes of the ridges to be the steeper, and that the steep slope governed the direction of the present streams by acting as a barrier. These sand deposits appear to be at higher elevations than the accumulations of loose sand on the first and second Pleistocene terraces of the large rivers. The most prominent 34 GEOLOGY OF THE COASTAL PLAIN of the sand hills or sand belts are those on the east side of the Ohoopee River, in Tattnall County, near Reidsville; along the east side of the Cannoochee ; on the Little Ocmulgee near Helena; along Satilla River from waycross, westward; and on the east and north side of Pendleton Creek, in Emanuel and Toombs counties. At the foot of these hills are sometimes densely wooded, moist sandbeds known as "hammocks." There are in some places shallow depressions, so-called "sand hill" ponds, in these sand belts, which contain water during rainy periods. The origin of these sands is not yet well understood. They may have been formed during the Pleistocene. period, and may be of :fluviatile origin; they have doubtless been shifted and in part redeposited by wind. In comparison with the Dougherty plain, the Altamaha upland has a rolling topography, streams are more numerous, and while there are a few lime-sinks along its borders, it is on the whole in contrast to the level lime-sink tracts of the former region. It is not so entirely featureless as the swampy tracts along the coast and is better drained. In contrast to the Fall Line hills, there is an absence of ruggedness, and the valleys are shallower and in addition there is a notable di:ffe:rence in the flora.' SOUTHERN LDIE-sL;U( REGIOX \ The Southern lime-sink region occupies a small area in the southern part of the State. It embraces the southeastern part of Decatur and the southern halves of Grady, Thomas, Brooks and Lowndes <>ounties and extends into Florida. This division is hilly and is characterized by lime-sinks, lakes, and ponds. In elevation above sea level, it varies from 150 to 275 feet and the hills rise 50 to 75 feet above the valleys and in a few places as much as 100 feet. The topography is more rugged than that of the adjacent Altamaha upland and the Dougherty plain. This difference and other characteristics of the division are due mainly to the nature of the underlying geological formations. The lime-sinks are due to the underground solution of an upper Oliogocene limestone, the Chattahoochee formation, but this is not the surfa<;e formation and is over lain by 50 to 100 feet of sand and clay which is soft and easily eroded, and which probably accounts for the topography being more rugged than that in the western lime-sinK: region. The lakes and ponds are due to depressions caused by the underground solution of limestone or are lime-sinks which contain water. Some of the lakes are several hundred acres in area and are free from timber growth, but the smaller and shallower ponds support a thick cypress growth. Ocean 'Flcological "tndies in thi region have bPPn made by Dr. R. 1\L Harper. Annals. New York Academy of Sciences, Vol. XVII. No. 1, and other papers. PHYSIOGRAPHY 35 Pond, in the southern part of Luwndes County, is one of the largest ponds or lakes and has an area of about six square miles. The water- level in these sinks varies with the seasons, and the water has been known suddenly to disappear or to rise, due probably to the opening or stoppage of underground passages. . The drainage, as in the Dougherty plain, is to some extent subter- ranean and hence, small streams are not numerous. The rivers which flow through the region, the Ocklockonee and Withlacoochee; flow canal-like, through broad sand-covered terrace plains. The water of the streams is not muddy, but is dark on account of dissolved and suspended organic matter, while that of the lakes is clear. The soil is in many places red, sandy clay, and loam, and the su- perficial gray sand, characteristic of the Altamaha upland, is not so widely distributed. The tree growth differs somewhat from that of the wire-grass region to the north, in that along with the long-leaf pine there is some o.ak and hiC'kor,y. OKEFE:'iOKEE PLAIN This division forms a narrow north-south strip 20 to 40 miles wide in the southeastern part of the Coastal Plain, and includes parts of Effingham, Bryan, Liberty, Wayne, Pierce, Camden, Ware, Charlton, Clinch, and Echols counties. On the west this division is approximately marked by a line from the northeast corner of Effingham County, southwestward to near Groveland, Bryan County, thence a few miles south of Glenville, to near Jesup, and Waycross, and is continued in the western boundary of Okefenokee Swamp. There is only a poorly defined escarpment separating this plain from the Altamaha upland and the two merge, but on the east it is separated from ll. lower coastal' terrace by an abrupt descent or escarpment, which will be mentioned later. The Okefenokee plain is essentially a featureless, sandy flat, in which there are but few streams. It thus presents a contrast to the rolling topography and dendritic drainage of the Altamaha upland. It is dotted with small cypress and gum ponds and swamps, varying from a few acres or a few miles in extent to the immense Okefenokee Swamp. This swamp is one of the most interesting natural features of the Atlantic Coast and will be described later. The region varies in elevation above sea-level from about 60 toperhaps 125 feet and has an eastward slope of about two f~et per mile. The drainage is poor, at least 25 per cent. of the area being swampy. There are but few branches and creeks and these flow through broad, swampy flats, only slightly lower than the general level. The striking difference in the number of small streams tributary to Satilla, Altamaha, and Cannoo- 36 GEOLOGY OF THE COASTAL PLAIN chee rivers in th~ A~tamaha upland and in the Okefenokee plain may be seen by exammatron o the map o the State. Streams have in only a few places bluffs as much as 30 or, 40 feet high. The flatness o the plain and its sw'ampy condition are due both to the newness o the land surface, since the retreat o the sea took place at a comparatively recent geological time, together with the low altitude and the :fact that the surface has a heavy covering o loose, porous ::,and, whicl1 absorbs the rainfall and hence lessens surface erosion. The streams are sluggish and with the exception o the Altamaha and Savannah, the water in them is black or coffee color rom organic matter. This region is characterized by moist, long-lea pine and saw-palmetto flats, cypress ponds, gallberry flats, and a thick growth o gums and bays in swamps. The acts in favor o considering this plain a wave-built, marine terrace, recently raised above sea level, rather than a plain o alluviation or a plain o denudation by stream erosion are: the trend o the plain parallel to the coast and its parallelism to a lower and younger plain, (the Satilla coastal lowland or Satilla plain) which is surfaced with undisturbed beach sand and muds containing shells and other evidence o near coast deposition; this lower plain is separated rom the higher plain by an escarpment which doubtless represents former coast bluffs and there is a poorly defined escarpment on the west o the Okefenokee plain which is more or less parallel to the lower escarpment. The Okefenokee plain is covered with a uniform or homogenous deposito white incoherent sand, which is uncharacteristic o a fluviatile deposit in its structure and composition. There is no well developed drainage system and there are large undrained areas and swamps, which are most plausibly explained as being due to original, inequal ities in the land surface. SATILLA COASTAL LOWLAND OR SATILLA PLAIN This division is a low marine terrace plain bordering the Atlantic Ocean. It is 20 to 35 miles wide and includes parts or all o the counties o Chatham, Bryan, Liberty, Mcintosh, Glynn, auJ Camden. (See map on page 28.) The western edge o the plain is marked by a rise or escarpment 20 to 40 feet high, which is pl'oJU1~nent at Walthourville, Mount Pleasant, and Waynesville, and a short distance east o Folkston. This escarpment may mark a Pleistoce~o shore line. The greater part o the plain is 15 to 25 feet above sea level, but there are a few places which reach an elevation o about 40 feet. The PHYSIOGRAPHY 37 plain has a slight eastward slope, somewhat difficult to estimate, but probably not more than a foot to the mile. Although it is a low, flat, poorly drained plain, ""0' ' o. <:, ~'1> "0 ' qFall Line Macon it presents several different topographic aspects. It ~ differs from the Okefenokee plain chiefly in its lower N altitude, greater area of swamp and inundated land, and in topographic forms incident to low coast land. The western part is on the whole a sandy flat plain containing an open growth of long-leaf pine. Orig- inally, in the spring and summer, grass and flowers were luxuriant in open areas, termed meadows or "savannas."1 This plain is dotted with small cypress ponds and also contains large swamp areas, in this ~ respect resembling the higher Okefenokee plain. ~ The coast line presents a different aspect. Due to ., c recent submergence, the coast line is irregular and a ~ network of sea-islands, tidal rivers, sounds, estuaries, ~~ and marshes have been formed. The land terminates :~ 1J r )> z 0 as beach on the sea-islands, and in low sand bluffs, ~ ~ not more than 10 or 15 feet above low tide, and as ~"' marshes at the mouths of the rivers flowing into the ~ ocean. The islands are sand-covered, and some of them exhibit sand dunes, but the dunes nowhere reach gj great magnitude. The islands form in the aggregate ~ an area of perhaps 500 to 600 square miles. The 25 1J r -)> z largest are Cumberland, Jekyl, St. Simon, Sapelo, St. ~ Catherine, Skidaway, and Tybee. They are of con- 8" siderable historical interest and some of them are ~ noted as resorts. ~ ~ The tree growth of the coast land is characterized ;1. by the cabbage palmetto and live oaks, which are ~ more abundant than farther west. There are two classes of swamp land, the upland Jesup swamp and the tidal swamp. The first is represented by such swamps .as Buffalo Swamp in the western "~' part of Glynn County which probably represent the :;; sites of former shallow sounds or coastal lagoons and "' marshes which have become land surface through up- lift and the retreat of the sea approximately to its present position. After this movement, however, there was again a subsidence of the coast as is indi- cated by drowned river courses. This subsidence 1An excellent description is given by R. H. Loughridge, Tenth Census, Vol. 6, Cotton Production, Georgia, p. 51. .AT.L.ANTJC OCEAN 38 GEOLOGY OF THE COASTAL PLAIN seems to be going on at present, causing the sea slowly to encroach on the land. The best proof of this is the presence of tree stumps and even dead standing trees in brackish water marshes. (See plate I, A, opposite page 32.) Considerable areas of "tide swamp" occurs along the Savannah, Ogeechee, Altamaha, Satilla, and St. Marys rivers. This lowland bordering the rivers is partly submerged at high tide, and differs from the marsh land chiefly in that it is covered by fresh water and not salt as in the case of the marsh. Tide swamp extends up the above named rivers 10 to 20 miles above the salt marsh, and was at one time utilized in rice-growing and is still so used to a small extent. The salt marsh reaches its greatest extent at the mouths of the rivers, but probably does not aggregate more than 150 or 200 square miles.' The marsh land is probably due in the main to submergence of the coast, although the silting up of water areas, by sediment carried down by streams, has also doubtless been a factor. The plain is poorly drained and there are but few streams owing to the newness of the land surface and its low altitude. The streams are sluggish, and are so-called "clear water streams," except the Savannah and the Altamaha, the waters of which are yellow from suspended sediment. The waters of the other streams, however, are dark or even black from organic matter. The slight eastward slope of the plain has caused the streams to flow directly east to the ocean. An interesting effect of the slight eastward slope of this and the higher Okefenokee plain is observed in the case of the Satilla and Little Satilla rivers in Camden County. The Satilla has no tributaries at all entering from the east, and the head branches of the Little Satilla are extended to within one and one-half miles of the Satilla near Atkinson. Recent submergence has caused a drowning of the streams and in consequence the mouths of the large rivers have been converted into estuaries and rendered navigable by sea-going vessels from 10 to 20 miles from the coast, and small streams which, so far as their lengths are concerned, are really no more than branches or creeks, have been enlarged and are styled rivers. In this latter class are such streams as Crooked River, Turtle River, and Sapelo River. There is also .a network of serpentine water-ways on the sea ishmds which are termed rivers and creeks, but are really no more than natural tidal canals. lNo survey of the marsh land of the State has yet been made, and hence accurate figures can not be given. PHYSIOGRAPHY 39 TERRACES The terraces constitute an interesting physiographic subject in the study of the Coastal Plain. They are intimately connected with the Pleistocene geology and the subject demands further study with the aid of detailed topographic maps, before final conclusions can be offered. Two1 broad terrace plains parallel to the coast are easily recognized, while the large rivers are bordered by fluviatile terraces believed to be equiYalent in age to the two coastal terrace plains. The terraces are illustrated in fig. 2 and Pl. II. The older is designated the Okefenokee plain, and the younger the Satilla plain. For the area of these plains see map on page 4. The river terraces are best developed in the upper part of the Coastal Plain along Chattahoochee, Ocmulgee, and Savannah rivers, and are conspicuous at Columbus, Macon, and Augusta. The lower or younger terrace, also known as "second bottoms," lies 15 to 50 feet above the rivers, and is a smooth plain, varying roughly from one-half to three or four miles in width. The second terrace lies 50 to 100 feet above the rivers; it is in this plain that the lower has been cut, and it has been modified to a greater extent by erosion. The upland plain bordering the rivers is from 125 to 250 or 300 feet above river levels. The terraecs \\ill receive further mention in the chapters on Pleistocene geology. DRAIXAGE OF THE COASTAL PLAIN The drainage of the Coastal Plain discharges into the Atlantic Ocean and the Gulf of :Mexico. The drainage basins, according to a map by B. 1L Hall,' are: (1) Savannah Basin; (2) Ogeechee Basin;. (3) Altamaha Basin; (4) Satilla and St. Marys Basin; (5) Suwanee Basin; (6) Ocklockonee Basin; (7) Apalachicola Basin, drained by the Chattahoochee and the Flint. The first four dis.- lit is not improbable that a third higher terrace plain exists, but sufficient proof of its existence has not been obtained to warrant posiLive statements. water P.owers of Georgia, Geol. Survey Ga., Bull. No. 3-A, p. 16. 40 GEOLOGY 0;;' THE COASTAL PLAD.T charge into the Atlantic and form considerably the larger drainage area; the remaining three discharge into the Gulf of .Mexico. . The rivers of the Coastal Plain fall naturally into two simple classes: ( 1) those originating in the Piedmont Plain and Appalachian Mountains and thence traversing the Coastal Plain; (2) native streams or those having their source within the Coastal plain. To the first class belong Chattahoochee, Flint, Ocmulgee, Oconee, Aitamaha, Savannah, and Ogeechee rivers, although the last throughout the greater part of its course has the aspect of a stream of the second class. The rivers of the second class are much more numerous, and the principal ones are the Little Ocmulgee, Ohoopee, Oannoochee, Satilla, St. Marys Suwanee, Allapaha, Withlacoochee, and Ocklockonee. The rivers of the first class have greater drainage areas, carry a greatBr volume of water, have greater lengths, and have cut deeper and wider valleys. The water of these rivers is always muddy, except that of the Ogeechee, whereas the water of the streams of the second class are clear, and this fact furnishes a popular distinction"clear w.ater"' and "muddy water" streams. Especially the Ocmulgee, Oconee, Altamaha, and Savannah are bordered by broad lowlands or swamps, in which a large part of the sediment is clay, while the smaller Coastal Plain rivers of the second class have sandy banks and the low terraces bordering them are composed almost entirely of sand. The explanation is that in the one case a large amount of sediment is derived from the red clay hills of the Piedmont Plain; while in the other the streams flow through geological formations that are predominantly sand, a region where erosion is not active, many of the smaller streams having not even cut through the superficial sands. The rivers across the Coastal Plain probably assumed their courses on a comparatively level plain, follovving the retreat of the sea from the land and extended their courses across the new land surface, so that, fo; example, the age of the Ocmulgee at the Fall Line is. much greater than the lower 20 or 30 miles of the Altamaha or that part which flows across the later Pleistocene plain. The directions of the streams are due to the initial slope of the new land surface upon which they started their courses. Thus all of the rivers have general south, southeast and east courses, since the tilting of the land surfaces has been in these directions. The rivers have not in all cases formed straight courses to the coast on account of the interposition of certain 'While the native streams of the Coastal Plain are termed "clear," the water is clear only in that it is comparatively free from suspended silt and clay. The water does not possess the transparency of clear mountain streams, but. ts pale brownish or even black from organic matter held in solution and suspension. The water of Suwanee and St. 1\larys rivers. near their source, the Okefenokee Swamp, is of almost inky blackness. GEOLOGY OF 7'HE CO A S1'A L PLAIN Ole ObOR(}lA. PLATE II. A. TERRACE AND E CARPME ,,T BORDERING ST. i\1ARY RIVER (FLORIDA SIDE) OPPO ITE TRADERS HILL, CHARLTON COUNTY, GA . B. SATILLA 'ERRACE PLAIN IM;\fEDIATELY WEST OF NEW SAVANNAH BLUFF, SAVANNAH RIVER , RICHMOND COUNTY. PHYSIOGRAPHY 41 topographic and geologic factors. The direction of a stream might have been deflected by slight irregularities in the new land surface or upraised sea-floor, or by certain geological conditions, which it encountered in cutting down its course. The St. Marys and Satilla rivers present a curious anomaly in the courses they have taken to reach the sea. (See map opposite page 44.) The St. Marys issues from the southern end of Okefenokee Swamp, flows south for about 15 miles, thence east for about eight miles, thence makes a right-angle turn and flows north for a distance of over 30 miles and to within four miles of the Satilla, thence flows to the Atlantic in a course slightly south of east. The Satilla has its source in the Altamaha upland and flows eastward as far as Atkinson in Wayne County, then instead of taking the most direct course to the ocean, which would be the course of the Little Satilla, it flows south for more than 20 miles, thence makes an abrupt turn and Rows east to the Atlantic. These rivers are young, dating probably from the Pleistocene, and are flowing across a newly formed land surface. Their peculiar courses are probably due to the original uneven surface of the upraised sea-floor, caused by low sand ridges or sand heaps such as are incidental to beaches and very shallow seas bordering a low sandy coast-land. The most direct course to the ocean, and the one in conformity with the general slope of the land, which the St. Marys might have taken, is through St. Johns River, Florida, but it was probably deflected to the north by a low sand ridge. There is also a sand ridge separating the St. Marys and the Satilla, which probably prevented their junction. The almost direct south courses of the Allapaha, Withlacoochee, Little, and Ocklockonee rivers are probably due to a low, southwarddipping and flat topped arch in the upper Oligocene strata. A similar flexure probably exists along the Chattahoochee, as is indicated by the unequal drainage divide between the Flint and the Chattahoochee, the great depth to which the latter river has cut its valley, its trench-like channel and the absence of flood plain swamp, in con" trast to the other large rivers. The general southeastward and eastward courses of the Satilla, Altamaha, Ogeechee, Savannah and other streams in the Pastern half of thP OoaRta.l Plain, is in consequence of the initial tilt of the land surfacA on which they originated. The explanation of the general insignificance and shortness of northward and westward flowing tributary streams is hence obvious. LAKES AND PONDS The lakes and ponds of the Coastal Plain are of three types: (1) those due to lime-sinks; (2) those caused by original shallow depres- 42 GEOLOGY OF THE COASTAL PLAIN swns in the land surfaces after the retreat of the sea ; (3) riVer flood-plain lakes. , Lime-sink lakes and ponds are confined mainly to the western and southwestern parts of the Coastal Plain, to the areas described above as Dougherty plain and Southern lime-sink region, but there are also lime-sinks and small ponds in Screven County, in the southern parts of Burke, Jefferson, and Washington counties, and along the western edge of the Altamaha upland. The depressions which lakes and ponds of this type occupy are the result of underground solution of limestone with the formation of subterranean caverns, the roofs of which become weakened and fall in, causing depressions at the surface. The process by which they were formed is in operation at the present time, and sinks have formed since the settlement of these regions. They vary in size from ponds from 100 to 200 feet in diameter to lakes of an area of as much as six square miles. The shallow ponds often become dry and the water level in the larger and deeper ponds varies considerably with the seasons. Some attain considerable depth, and are connected by open passages with underground channels, an example of which is the Lime-sink, Forest Falls, eight miles north of Whigham, Grady County. "\.. small stream flows into this sink, which is about 90 feet deep, and disappears through an opening in the bottom. The most notable of the larger lakes are Ocean Pond and Long Pond in Lowndes County, Original Pond, three miles west of :Met- calf, and Rock Pond, near Camilla, Mitchell County. Tlre second class represent depressions in level sandy plains. These are usually shallow ponds of small area and most of them con- tain a growth of cypress and gum. They are dependent upon seep- age and become dry, with a few exceptions, in times of severe drought. They are numerous in the southeastern part of the Altamaha upland, are typically developed on the Okefenokee plain, and also apl?ear on the Satilla marine terrace plain 20 to 40 feet above sea level. It is probable that these ponds for the most part occupy shallow depressions which were present on the plains when they were first uplifted and became land surface, there, as yet, not having been sufficient subaerial erosion to efface them. There are also a number of untimbered expanses of water in the Okefenokee Swamp which are termed "lakes." (See map opposite page 44.) . The third class represent abandoned channels of rivers and occur in river :flood-plains. This is the type of lake so extensively devel- oped along the lower course of the Mississippi. They are in the form of ox-bows, or are .elongated, rarely circular; their water is usually PHYSIOGRAPHY 43 affected by high water or overflow of the rivers along which they occur and is less clear than that of the lime-sink lakes and ponds. They may be connected with the river or their mouths may be silted up entirely, depending upon how recently they have been formed, but they are all subject to overflow during flood stages of the rivers. Hershman Lake in Screven County and Black Lake in Wilkinson County are the best examples of this type. Other lakes occur along the lower courses of the Oconee and Altamaha. FLUVIATILE AND UPLAND SWAMPS The fresh water swamps of considerable areas are of two types: fluviatile swamps and upland plain swamps. The latter appear along the coastal belt and owe their existence to the flatness and consequent imperfect drainage of the land surface. They are upland in that they lie at a higher level than the river swamps, and also in comparison with the river tide-swamp and the salt marshes although they may not be more than 20 feet above sea level. Okefenokee Swamp is a large upland swamp. Nearly all of the streams of the Coastal Plain, even the small branches, are bordered by swamps. The most extensive are those bordering the large rivers of the first class. The swamp land lies only a few feet above the rivers and the frequent overflows maintain it in a swampy condition. Along the lower part of Savannah River the swamp reaches a width of five or six miles; it is densely wooded with a growth of oak, ash, cypress, gum, and pine. There are also broad swamp areas along the Ogeechee, Altamaha, Oconee, Ocmulgee, . and upper part of the Flint; the Chattahoochee forms an exception since there is scarcely any land along its course in Georgia which could be termed swamp. The small branches, creeks, and rivers flow through broad, densely wooded lowlands, very often spreading out through the trees until it is difficult to determine just where the channel proper is located, and in places necessitating low bridges or a succession of bridges onefourth to one mile in length to effect a safe road crossing. Swamps 'of such character ar~ notable along Ogeechee River, Williamson's Swamp Creek, in Jefferson County; Commissioner's Creek, in Wilkinson County; and along the head waters of Little and Allapaha rivers in Tift, Irwin, and Berrien counties. The amount of fluviatile or river and creek flood-plain swamp amounts to perhaps 1,000 square miles1 in the Georgia Coastal Plain. 1No complete survey of the swamp land of Georgia has been made, and the figures are only a rough estimate based on a knowledge of the approximate widths of the swamp a.long the largest rivers and creeks. 44 GEOLOGY OF THE COASTAL PLAIN This land lies generally form two to eight feet above mean stages of water. THE OKEFENOKEE SWAMP. The Okefenokee Swamp is perhaps the greatest natural wonder in the State. It lies in the southeastern part of the Coastal Plain, em- braces parts of Ware, Charlton, and Clinch counties, and extends to the Florida miles, and line. It an area has a length of of between 700 about and 40 800 msiqleus~rea width miles. of 30 The swamp has been fully explored by hunters and lumbermen, but no very extended descriptions of it have been published. The following excellent short description is that of Dr. R. H. Loughridge," who was one of a party that made a partial survey of the swamp in 1875: This swamp (Okefenokee) has a width of 30 and a length of 40 miles, covering an area of about 500,000 acres. It is in reality an upland swamp, having an altitude of 120 feet above tidewater on .St. Mary's River. A sand rklge (part of the water divide of the State) 30 feet above the swamp extends along its eastern border to the South, becoming lower as it reaches the southern horseshoe bend of St. Mary's River. The swamp is highest on the northeast, and falls irregularly to the south and southwest from 12672 to 11172 feet at Ellicott's mound and on the southwestern corner. The eastern part, 12 miles in width, is an open "prairie" or marsh, largely covered with water, in which are long rushes and water-lillies. Under its surface is a dense body of moss from four to six feet thick, the great mass of which is decayed, forming muck and peat. It is so derise that it will readily bear up a man's weight, merely sinking a little and rising for many feet around; hence the name of Okefenokee-"trembling earth." Small islands, covered with clumps of cypress, bay, and cassino, frequently occur. The western part of the swamp is mostly covered by cypress trees and a dense growth similar to that of the small swamps outside, so tied together by bamboo briers and vines as to be impenetrable except by slow and terious cutting away with bush knives. Small open marshes, and also a number of large islands, are found throughout this region. These islands are quite level, but are slightly elevated above the swamp lands, and have a sandy soil, with an open timber growth of long-leaf pine and a very low undergrowth of sa.wpalmetto, and are similar in every respect to the mainland. Their dimensions are three or four miles by from one to two, and they are bordered by a low hammock land, on which there is a growth of magnolia, oak, etc. Hunters find deer and bear on thes3 islands. The soil or bottom of the swamp proper seems to be but little else than white sand. Dr. R. M. Harper has lately published a description in"which the literature and history of exploration is summarized, the geography,vegetation, etc., of the swamp are briefly set forth, and illustrations from several photographs taken in the swamp are given. Such a phenomenon as the Okefenokee Swamp can not be passed over without offering some explanation of its existence. The following relating to its origin is quoted from Dr. Harper's paper: Immediately east of the Okefinokee is one of the most interesting topographic features of the region, which would scarcely be noticeable but for the 'Tenth Census, Vol. VI, Cotton Production of Georgia, p. 51. 2Pop. Sci. Monthly, June, 1909. F L 0 R I D R I DA N IC:O::ec::E:c5ia:::e:c::Jei:O=:::=:=====':i0:=:=:=:=:=:=:i'2iiif0 MILES MAP OF OKEFENOKEE SWAMP AND ADJACENT REGION. BY OTTO V'EATCH. The map has been compiled from a map of Okefenokee Swamp, by M. T. Singleton; from the map of Georgia, by A. G. Butts, published 1890; from the soil map of the Waycross area, by the U. s. Bureau of Soils; and from notes by the author. The :ligures refer to elevations above sea-level. PHYSIOGRAPHY 45. general flatness of the country. It is a broad low ridge, exactly parallel with the coast and just about forty miles distant from it. This ridge has been traced by the writer from a few miles west of Jesup southward into the great bend of the St. Mary's River, and about thirty miles into Florida, where it is known as the "Trail Ridge," and happens to coincide in part with the Atlantic and Gulf divide and with the eastern boundary of Baker and Bradford Counties, though still maintaining its parellelism with the Atlantic coast. It is not an important divide in Georgia, though no streams intersect it between the St. Mary's and the Altamaha except the Satilla and Little Satilla Rivers. At Camp Cornelia, where the old drainage ditch of the Suwanee Canal Company cuts through it, this remarkable ridge is about two miles wide and only about forty feet high; and it probably keeps practically the same dimension for many miles north and south. Its slopes are so gentle as to be scarcely noticeable to a person passing over it, but when viewed from a point a few miles away on one of the straight railroads which cross it, it stands out quite conspicuous. "Trail Ridge, or Okefinokee Ridge, as the Georgia end of it might be called, does not belong to the class of cuestas or inland-facing escarpments which can be seen in many places in the upper half of the coastal plain, for it slopes equally on both sides and has no stream hugging its inland edge as far as known. Moreover (t is too smooth and too straight to have been formed by erosion. The same reasonable explanation of it would seem to be that it marks a comparatively recent slight flexure of the earth's crust, formed during one of the oscillations which the coastal plain experienced several times during its making. There seems to be a similar though smaller ridge about fifteen miles east of it, but so little is known about that that it could not be mapped at the present time. Mount Pleasant and Waynesville. near the boundary between Wayne and Glynn counties, are located on the latter ridge and along its summit was one of the principal ro:;tds from Savannah to East Florida a century ago, followed by Bartram and other travelers. The internal structure of the Okefinokee Ridge is not its least interesting feature. In the big ditch at Camp Cornelia, as well as at the crossings of four railroads (three of tliem shown on the map and one a little farther north), there occurs beneath a few feet of white sand a chocolate-colored or almost black material of unknown depth known locally as "hardpan." No analysis of the hardpan is available, but when pulverized in the fingers it feels like nothing but sand. Its dark color is doubtless due to vegetable matter, -with a little cement of iron oxide or bog iron ore, which makes it so hard in the mass that dynamite was used in removing it, it is said. No recognizable organic remains were noticed in it, but a faint horizontal stratification could be detected. The aspect of the hardpan is so similar to that of the subsoil of existing salt marshes that its origin is not hard to guess. Although this peculiar formation may not be confined to the Okefinokee Ridge, its extent is evidently limited; for in railroad cuts around Waycross and Folkston and in Camden county and elsewhere the ordinary reddish Pliocene loam can be seen near the surface, without any signs of the black hardpan. The hardpan was doubtless formed in some prehistoric swamp or marsh occupying a somewhat larger area than Okefinokee does now-perhaps the Suwanee Straight of geologists, which is supposed to have separated Florida from the mainland in Miocene times. It seems to have no effect on the vegetation above it, which is just like that of the ordinary flat pine- barrens underlaid by the loam. Assuming the foregoing theories to be true we can now trace the probable development of Okefinokee Swamp. When the ridge was thrown up across the shallow trough which had been suwanee Strait it naturally created a. basin behind it, which must have quickly filled with water, forming a large, shallow lake. This lake then began to fill with vegetation, as many other 46 GEOLOGY OF THE COASTAL PLAIN shallow lakes then began in temperate regions are doing, and gradually took on the aspect it has to-day, which will be described more in detail below, under the head of vegetation. A glance at the map will show how the waters are darned up by the ridge, the straight eastern 'border con- e~ o ~ '"''" ":E 1![11 g' ~~/i!i,; trasting with the very irregular .western iborder of the sw;amp. The notes of the writer on the geology of the region and its physiographic history differ somewhat from the views advanced in the preceding quotation. !,'~I::i;ij' ~<.~"a,,.'l/:i:/:!1~1I,:,1I,1 :~:'1/11 , :1 i"f' It is believed that the swamp lies upon a terrace plain, of probable marine origin, parallel to a lower ~>i ~.i:l !i! surveyorsCreek terrace plain, which lies from 15 to 40 feet above .... ); w 116 sea-level, and extends to the present coast. The @ western edge of the lower plain is marked by an es- ~ 1:::1 lieved that it is a line approximately from Olyo in : Effingham County, southwestward to near Groveland, ~ 1120' thence to Jesup, Offerman, and Waycross and thence ,p :ii St!nd ridge ~: 140' - follows the northern and western borders of Okefeno- kee Swamp. There is a low sand ridge on the east side of the swamp, which has acted, to some extent, as a dam to the drainage from the west. "' ~ Spani..sh Creek- Ltule 0/sef'enokee ~ !![ ~-:,amp ~ ~~ 1:1:r satilla The swamp does not occupy a single large depres- > : to 11l escarpment SarUlalUver sion or basin, since elevations show that the northern I edge is 15 feet higher than the southeastern corner, ~ and there are also differences of elevation of the sur P' face within the swamp. The swamp conforms, in general to the southeastward tilt of the plain upon which it is located. The land now occupied by the swamp was so flat, that the rainfall was not readily removed and hence accumulated as broad sheets of water, which vegetation converted into swamps. The presence of islands in the swamp which are reported to be very similar in soil and tree growth to the dry land adjacent, together with the fact that creek run- ways still exist within the swamp, is v~ry suggestive that the swamp area did not differ materially from the land to the north and west and that the Okefeno- kee was formed by the gradual accumulation of water and consequent aquatic vegetation. The "bays" or entrants of swamp into the dry land, along the 1"'1 Cumberland Island courses of tributary creeks, have produced the ragged PHYSIOGRAPHY 47 or irregular north and west boundaries and indicate the process by which the swamp has increased in area, namely by the enlargement and union of creek swamps and final obliteration of the streani channels. Should there be a period of a number of years with the precipitation even slightly above the present normal the whole area northwest of the swamp to the Atlantic Coast Line Railroad and beyond would be incorporated as a part of the Okefenokee. This area is at present formed of flat, ill-drained islands surrounded by narrow strips of swamp. The swamp then owes its existence to the general flatness of the original land surface which has been lifted above sea level without deformation. The sand ridge on the east, although acting as a dam for a part of the drainage, was a subordinate agent in producing the swamp, as is in a measure proved by the absence of any conspicuous ridge or barriers on the south and southeast, and especially by the differences in elevations of various parts of the surface of the swamp. As for example, the elevation at the point where Cypress Creek issues on the western side is lll2 feet, while at a point half way between this and St. Marys River the elevation is 118lj2 feet, and the point where the St. Marys issues on the southeastern corner is 1111f2 feet. If the existence of the swamp depended entirely upon the barrier ridge on the east the level o:f the western margin of the swamp should be higher than the intermediate levels between the western and eastern margins. This is not true according to known elevations. Fig. 4.-Profile from Okerenokee Swamp to Kings Ferry, Florida, along line D-E, on map of Okefenokee Swamp. The geologic formations adjacent to the swamp are late Tertiary, Pleistocence, and Recent. The Alum Bluff formation (upper Oligo- n cene) consisting of greenish, sandy clays, and overlain by a small thickness of Altamaha (Lafayette and surficial sand, occurs to the north and west, and very probably underlies the swamp. As inferred from the record of a well at Waycross, it is about 300 feet in depth to a limestone formation. The Altamaha (Lafayette'?) formation is typically exposed in cuts and excavations near Waycross, and probably also occurs east of the swamp. This formation is composed of red, argillaceous sand and sandy clay. To the east of the swamp the plain is covered by gray 48 GEOLOGY OF THE COASTAL PLAIN and yellowish or brownish, incoherent quartz sand, varying :from two or three to 15 or 20 :feet in thickness. This sand :foitrns the sand ridge on the east side o:f the swamp. It is considered a Pleistocene deposit. Beneath the surficial sand there is a small thickness, not exceeding 40 or 50 :feet, o:f red, argillaceous sand and bluish clay, Pliocene or Pleistocene in age. Fossiliferous- beds o:f white, argillaceous limestone and greenish or drab laminated clay, probably Pliocene or Pleistocene, and older than the surficial sand, occur in the banks o:f St. Marys and Satilla rivers a :few :feet above sea level. So :far as known, the deposits in the swamp are white sand and recent vegetable or semi-peaty accumulations. White or gray sand occurs on the edges o:f the swamp and only sand is exposed in the old drainage ditch constructed by the Suwanee Canal Company, near Trader's Hill. Fishermen and hunters report white sand in the bottoms o:f some o:f the lakes. Peaty accumulations three or :four :feet thick are reported, and these organic accumulations are known to have been fired :from nearby :forest fires during periods o:f drought. There is no evidence in the many exposures o:f strata examined in Charlton, Ware and Camden counties, that any considerable flexures or :folds exist in this part o:f the State. The escarpment a :few miles east o:f the swamp, which suggests the limb o:f an anticlinal :fold, is believed to be a Pleistocene erosion :feature, as stated above. TABLE OF GEOLOGIC FOR:\IATIONS NEAR OKEFENOKEE S\VAMP Recent: Peaty muck in the Okefenokee Swamp. Pleistocene and Pliocene ( ?) Satilla formation--clay terraces or flatwoods bordering St. Marys and Satilla rivers. Okefenokee formation-surficial white sand, and perhaps some red sand and mud, the latter occupying the sites of ancient estuaries or shallow bays. Altamaha (Lafayette ?)-red, argillaceous sand, typically devel- oped at Waycross. Charlton formation-fossiliferous limestonE) and clay on St. Marys River. Miocene. Probable occurrence at Owens Ferry, Satilla River. Miocene strata are also known' near Jacksonville, Fla. Oligocene (Alum Bluff). Sandy, greenish, and drab clays of the Alum Bluff formation, ov'-rlain by a small thickness of A,tamaha (Lafayette ?') and surficial sand, occur on the north and west sides of the swamp. There are numbers o:f smaller swampy areas in the Okefenokee Plain. Some o:f these are merely broad, undrained flats, due, perhaps, to original ineq~alities in the land sur:face and are Oke:fenokees 'Matson and Clapp. Fla. Geol. Survey, Second Annual Report; 1909, P- 108. GEOLOGY OF 1'HE OOASTAJ~ PLAiN OF' GEORG/.-1.. PLATE Ill. HILL ON EA T IDE OF LITTLE OCMULGEE RIVER, TWO MILES NORTHEAST OF HELENA, TELFAIR COUNTL B. A LilliE l~K POND K:->OW AS WAVI:->G PO:->D. SEVE, Ol~ YLVESTER, WORTH CO NTY . PHYSIOGRAPHY 49 on a small scale. The general slope of the plain eastward is perhap~ not more than two feet per mile, and poor natural drainage is readily inferred. OTHER SWAMPS There are also swamp areas in the lower coastal terrace plain which lie 15 to 25 feet above sea level. These have the appearance of being the sites of ancient lagoons or shallow sounds. Buffalo Swamp in the western part of Glynn County is an example. This swamp extends from Altamaha River southward to Turtle River and has a much greater length than width. It contains clay and is slightly lower than the sandy pine and palmetto land on both sides. Oyster shells in the clay bear evidence of its marine origin. Cabbage palmetto trees occur near Bladen and Everett, and are possibly a survival from the period when this area was a sound or marsh. It is often entirely covered with water during the rainy seasons but becomes almost dry in times of drought. Should the present coast be elevated 20 or 30 feet the waterways and marsh between St. Simon Island and the mainland would probably be the site of such a swamp area as Buffalo Swamp. The Big Pond, located seven miles north of Baxley, Appling County, is worthy of special mention here. Although this tract is locally termed "pond," it is a misnomer, as it is more properly a swamp. The only open water is a small lake in the interior, reported to be not more than 100 yards long, whereas in the area as a whole there is a thick growth of cypress, gum, and pine, with an undergrowth of small trees and bushes. (See plate IV, A.) Big Pond lies upon a flat, sandy, pine-covered plain, at an elevation about 200 feet . above sea level. It has an area, including a small swamp, known as ''Second Pond," of about eight square miles. The two "ponds" are connected by a narrow swamp known as Tiger Bay. On the east side of the swamps there is a low ridge covered with superficial gray sand that reaches a thickness of about 10 feet. Ten-Mile Creek, a small tributary of Altamaha River, flows sluggishly from the southern end of Big Pond. Big Pond belongs to the upland, non-alluvial c]ass of swamps, and is probably somewhat similar in origin to Okefenokee Swamp and to the smaller cypress and gum ponds which are so numerous in the southeastern part of the Coastal Plain. SPRINGS There are a few large springs of physiographic and geologic interest. These springs are in limestone areas and, as they appear to 50 GEOLOGY OF THE COASTAL PLAIN be c~nnected with subter~anean streams, many o them may be descnbed as natural artesian wells. The water is clear and very transparent, usually has a deceptive, faint affected by rains, and evidently comes rom bluish great dceopltohr~. is but The little larg- est o these springs is Blue Spring, 6ur miles south o Albany. The water at this place rises under considerable pressure through a roughly circular opening in limestone, and has an enormous flow. 1 Similar springs are: Blue or Wade Spring, seven miles east o Quit- man; Mcintyre Spring on the \Vithlacoochee near the Florida line; Blue or Russell Spring o Decatur County; Well, Wilkes, and Rock springs o Laurens County, and :Magnolia Spring o Jenkins County. These are all large springs rising through limestone caverns. Small, both permanent and intermittent springs, o only mmor importance, are numerous except along the coastal lowlands. ELEVATIONS BY OTTO VEATCH In the general absence o topographic maps, g1vmg accurate elevations in the Coastal Plain, it is believed that the compilations here given will be o interest and o practical value in working out geologic problems and in the study o underground waters. The following list o elevations has been compiled chiefly rom: Dictionary o Altitudes in the United States, by Henry Gannett, Bulletin No. 274 o the U. S. Geological Survey; rom the list o elevations given in the report on the Water Powers o Georgia, Bulletin No. 3-A o the Geological Survey o Georgia; rom the reports o the U. S. Army Engineers on the surveys o Ocmulgee, Oconee, Altamaha, and Savannah rivers; and rom the Columbus, Talbotton, and Mil~ ledgeville topographic sheets o the U. S. Geological Survey. Several o the elevations given are merely rough estim~tes or guesses based on other elevations and upon knowledge o the topography by the author, in a few instances supported by aneroid barometer readings. In some o the figures given in this compilation there may be errors o even several feet, but, notwithstanding, these elevations are better than none at all, and the errors are not so great but that the data may be useful i"n the study o physiography, geology, and artesian waters. 1Discharge measurements by B. M. and M. R. Hall (U. S. Geological Survey, Water Supply and Irrigation Paper. No. 197, page 236) varied from 26.4 second-feet to 135 second-feet. This is approximately 18,000,000 to 87,000,000 ga\lons per 24 honrs. This is the largest spring in the State. ELEVA.TIONS 51 Tbtl abbreviations used are: A. B. & A.-Atlanta, Birmingham & Atlantic Railroad. A. 0. L.-Atlantic Coast Line Railroad. 0. of Ga.~Oentral of Georgia Railway. Ga. R R.-Georgia Railroad. G. S. & F.-Georgia Southern & Florida Railway. L. & N.-Louisville & Nashville Railroad. M. D. & S.-:J\acon, Dublin & Savannah R.ailroad. S. A. L.-Seaboard Air Line Railway. U.S. A. Eng.-United States Army Engineers. U.S. G. S.-United States Geological Survey. Abbeville . . . . . . . . . . . . . . Rough estimate . 225 ? Abbeville, low water, R. R. bridge . . U. S. A. Eng . . 169.33 Achord ........ . . U.S. G. S . . . . 274 Acree, Dougherty County . A. C. L. R. R .. . 205 Adams Park ..... . . U. S. G. S. . . . 259 Adel . . . . . . . . . . . . G. S. & F. Ry. . 246 Adrian, Emanuel County . Rough estimate . 290 ? Albany ......... . . C. of Ga. Rwy . . 184 Albany, Flint River level A. C. L. R. R . . 127 Allapaha ...... . . A. C. L. R. R . . . 293 Alexanderville . . . . . A. C. L. R. R . . . 153 Allentown ...... . . M. D. & S. R. R . . 411 ? Ambrose, Coffee County . A. B. & A. R. R. . . 395 Americus .. . C. of Ga. Rwy . . 360 Andersonville . C. of Ga. Rwy . . 394 Arabi ... . G. S. & F. Ry. . 460 Argyle . . . . A. C. L. R. R . . . 161 Armena .. . . S. A. L. Ry. . . . 275 ? Ashburn . . . . . . . . G. S. & F. Ry. . . 450 Augusta, Union Station . . City Engineer . . 143 Augusta, River gage . . 'Weather Bureau . 100 Baconton ...... . . A. C. L. R. R . . 160 Bainbridge . . . . . . . A. C. L. R. R . . 110 Bainbridge, river level Rough estimate . 80 Bartow ....... . C. of Ga. Rwy . 237 ? Bath, Richmond County . Rough estimate . 80 Baxley .. . U. S. G. S. . . 206 Belair ... . Ga. R. R. . . . . 295 Berzelia .. . Ga. R. R. . . . 488 Blackshear . A. C. L. R. R. . 106 Bladen . . . S. A. L. Ry. . . 22 Blakely .. Rough estimate . . . . . . 275 Blakely .. . Weather Bureau . . . . . . . 300 Bloomingda]e . C. of Ga. Rwy. . . 24 Bonaire .. . . G. S. & F. Ry. . . 354 Boston . . . . . . A. C. L. R. R. . . 194 Bostwick (Paschal) . C. of Ga. Rwy. . 669 Boulogne, Florida . . A. C. L. R. R. . 70 Box Springs . . . . . U. S. G. S. . 364 Braganza .... . . A. C. L. R. R. . 144 Brentwood . . . . . . . U. S. G. S. . . . 167 Brewer (Tusculum P. 0.) . C. of Ga. Rwy. . 118 Brooklyn ....... . . S. A. L. Ry. . . . 691 52 GEOLOGY OF THE COASTAL PLAIN Brinson Brunswick .. Brunswick (City Hall) Buena Vista . Bullards . . . . Burroughs Bushnell . . . Butler Byromville . . Byron Cairo ... Camak Cameron . Camilla .. Carrs Station . Cecil .. Chauncey Chula . Claxton Clifton Climax Clyo Cochran Coleman Coley Collins Colon Columbus, Union Station . Columbus, river level Cordele Crescent . ... Culverton Cusseta Cuthbert Cutler .. Cl.lyler . . . . Cycloneter . . . . . . . . . . Dakota Darien Dasher Davis Davisboro Dawson . Dearing . Devereux Dewitt Dixie . Dock Junction Doctortown Doctortown, low water level . Donaldsonville Douglas ... Doublerun Dover ... Dry Branch .. Dublin . . .. . A. C. L. R. R. . . Sou. Rwy. U.S. G. S. . Rough estimate U.S. G. S. . . . . A. C. L. R. R. . . A. B. & A. R. R. . C. of Ga. Rwy. . . A. B. & A. R. R. . C. of Ga. Rwy. . . A. C. L. R. R. . . Ga. R. R. . C. of Ga. Rwy. . A. C. L. R. R. . U.S. G. S. . . G. S. & F. Ry. . U.S. G. S. . . . G. S. & F. Ry. . S. A. L. Ry. . . C. of Ga. Rwy. . A. C. L. R. R .. . S. A. L. Ry. . . U.S. G. S. . . . C. of Ga. Rwy. . Sou. Rwy. . S. A. L. Ry. . . G. S. & F. Ry. . C. of Ga. Rwy. . U.S. G. S. . . . G. S. & F. Ry. . Rough estimate . Ga. R. R. . S. A. L. Ry. . . C. of Ga. Rwy. .G. S. & F. Ry. . S. A. L. Ry. . .G. S. & F. Ry. . G. S. & F. Ry. . Rough estimate . G. S. & F. Ry. .A. C. L. R. R. . C. of Ga. Rwy. . C. of Ga. Rwy. . Ga. R. R. . U. S. G. S. B. :\1. . Butt's map ..... . A. C. L. R. R. . U.S. G. S. . A. C. L. R. R: . . U. S. A. Eng. . A. C. L. R. R. . . A. B. & A. R. R. . A. B. & A. R. R. . C. of Ga. Rwy. . . M. D. & S. R. R. . M. D. & S. R. R. . 104 . 13 .11 . 590 . 259 . 19 . 385 ? . 650 . 365 ? . 515 . 237 . 578 . 103 . 167 . 500 250 . 300 . 395 . 194 ? . 22 . 277 . 74 . 342 . 391 . 303 . 23R . 137 . 260 . 200 . 336 . 18 . 549 . 540 . 446 . 78 37 ? . 410 . 410 . 15 . 185 . 238 . 302 . 352 . 464 . 577 . 175 . 130 . 25 . 74 . 31.72 . 139 . 388 ? 363 ? . 104 . 368 ? . 2311 ? 1Elevations on the M. D. & S. R. R. are taken from the Jist given in Water-Powers of Georgia, Geol. Survey of Ga., Bull 3-A, pp, 98-100. Rough corrections were made according to the benchmark established on the Oconee River at Dublin by U. S. Army Engineers. ELEVATIONS Dublin, low water level . U. S. A. Eng. . Dudley . . . . M. D. & S. R. R. Dupont . . . . . . . . . A. C. L. R. R. East Albany . . . . . . A. C. L. R. R. Eastman . . . . . . . . . . U. S. G . S. . . Eden . . . . . . . . . . . . C. of Ga. Rwy. Egypt . . . . . . . . . . . . C. of Ga. Rwy. Eldorado . . . . . . . . . . G. S. & F. Ry. Elko . . . . . . . . . . . . . . . . . . G. S. & F. Ry. Ellabelle . . . . . . . . . . . . S. A. L. Ry. . Ellaville . . . . . . . . . . . . . J. W. Spencer Empire . . . . . . . . . . . . U. S. G. S. . . Esquiline . . . . . . . . . . . U. S. G. S. . Eufaula, Alabama . . . . . . . . C. of Ga. Rwy. Everett City . . . . . . . . . . . . . U. S. G. S. . . . Everett Station, Crawford County . . C. of Ga. Rwy. Everett Station, Flint River, railroad bridge . C. of Ga. Rwy. Exeter . A. C. L. R. R. Exley . . . . . . . S. A. L. Ry. . Faceville . . . A. C. L. R. R. Fargo . . G. S. & F. Ry. Fitzgerald . . . . '. . A. B. & A. R. R. Fitzpatrick . M. D. & S. R. R. Fleming . . . . . . . A. C. L. R. R. Flint . . . . . . . . . A. C. L. R. R. Folkston . . . . . . . . . . . . A. C. L. R. R. Fort Gaines . . . . . . . . . . . C. of Ga. Rwy. Fort Gaines, river level, low water . . . . . . . . . Fort Mudge . . . . A. C. L. R. R. Fort Valley . . . . C. of Ga. Rwy. Fowltown . . A. C. L. R. R. Gallemore (Willis P. 0.) . M. D. & S. R. R. Gardi . . . . . . . U. S. G. S. . . . Geneva (station) . U. S. G. S. . . . Georgetown . . . . . . . . . C. of Ga. Rwy. . Georgetown, low water, Chattahoochee . River . . . . . . . . . . . . . Rough estimate Glenmore . . . . . . . . . . . . . A. C. L. R. R. Godwinville . . . . U. S. G. S. . . Gordon . . . . . . . . C. of Ga. Rwy. Gordon, Alabama . . . . . . . . A. C. L. R. R. Graham . . . . . . . . . . . . . Sou. Rwy. Graves . . . . . . . . . . . C. of Ga. Rwy. Greens Cut . . . . . . . . . . . C. of Ga. Rwy. Griswold . . . . . . . . . . . . C. of Ga. Rwy. Grovania . . . . . . . G. S. & F. Ry. Groveland . . . . . . . S. A. L. Ry. . Grovetown . . . . . . Ga. R. R. . . . Guyton . . . . . . . . C. of Ga. Rwy. Hagan . . . . , . . . . . . S. A. L. Ry. . Hahira . G. S. & F. Ry. Halcyondale . . . . . . . . C. of Ga. Rwy. Halloca . . . . . . . . . . U. S. G. S. Hardaway . . . . . . . . . . A. C. L. R. R. Hardeeville, S. C. . . . . . . A. C. L. R. R. Harlem . . . . . . . . . . . . Ga. R. R. Hatcher . . . . . . . . . . . . C. of Ga. Rwy. . Hawkinsville . . . . . . . . . . Weather Bureau 53 . 160.6 . 325 ? . 180 . 186 . 357 34 . . 132 340 . 443 93 ? . 591 . 382 . 300 . 211 ? 16 . 362 . 337 94 63 . 296 . 116 : . 388 ? . 541 ? 22 . 168 80 . 163 . 100 ? . 134 . 522 . 289 . 394 ? 62 . 581 . 189 . 111 ? . 151 . 312 . 348 . 160 . 240 . 350 . 284 . 447 444 . 162 ? . 495 81 . 186 ? . 230 . 110 . 323 . 183 21 .548 . 289 ? . 235 54 GEOLOGY OF THE COASTAL PLAIN Hawkinsville, low water level . U. S. A. Eng. . . 200.2 Haylow . . . . . . . . . . . G. S. & F. Ry. . 167 Hazlehurst . . . . . . . . . . U. S. G. S. . . 256 Helena . . . . . . . . . . . . U. S. G. S. . . . 247 Hephzibah . . . . . . . . . . .Weather Bureau . 402 Herndon . . . . . . . . . . C. of Ga. Rwy. . 179 Homerville . . . . A. C. L. R. R. . . 176 Howard . . . . . . . . . . . . . . C. of Ga. Rwy. . 666 ? Howell . . . . . . . . . . . . . . . G. S. & F. Ry. . 169 Irwinton . . . . . . . . . . . . . . .Rough estimate 460 ? Isabella (Sylvester) . A. C. L. R. R. . 370 Jasper, Florida . . A. C. L. R. R. . . 152 Jeffersonville . M. D. & S. R. R. . 526 Jennings, Florida . . G. S. & F. Ry. . . 150 Jesup . . . . . . . . . . .. . . . U. S. G. S. . . 100 Johnsonville, Jeff Davis County . Sou. Rwy. . 240 Juniper Station . U. S. G. S. . . . 422 Kathleen . G. S. & F. Ry. . . 330 Kingsland . S. A. L. Ry. . . 41 Kirkland . A. C. L. R. R. . 200 . Knoxville . J ..E. Thomas . 640 Lake Park G. S. & F. Ry. . 160 Lawton . C. of Ga. Rwy. . 225 Leesburg Rough estimate . 300 ? Lenox . . . . G. S. & F. Ry. . 300 Lewiston C. of Ga. Rwy. . 385 Lily . . . . . A. B. & A. R. R. . 364 ? Long~treet . U. S. G. S. . . . . 302 Louisville . . . . . . . Weather Bureau 259 Ludowici . . . . . . . . . A. C. L. R. R. . 71 Lulaton . . . . . . . . . Rough estimate . . 50 Lumber City . . . . . . . . . . . . U. S. G. S. . . . . . . 146 Lumber City, river level, low water . U. S. A. Eng. . . . . . . . . 84.7 Lumpkin (station) Rough estimate . 500 Lumpkin . Weather Bureau . 650 Lyons . . . . . . S. A. L. Ry. . . 254 McBean Station . . C. of Ga. Rwy. . 134 ? McClenny, Florida . S. A. L. Ry. . . 125 McDonald . . . A. C. L. R. R. . 167 McGriff . . . . . . . . U. S. G. S. . . . 259 Mcintosh . . . . . . . . . . A. C. L. R. R. . 22 McRae . . . . . . . . . . . . . . . .U. S. G. S. . . . . 230 Mcintyre . . . . . . . . . . . . C. of Ga. Rwy. . . 261 Macon, Union Station . . . . . . G. S. & F. Ry. . 334 Macon, near Sou. Rwy. Station . . U. S. G. S. . . 311 Macon, low water level . U. S. A. Eng. . . 279.02 Macon Junction C. of .Ga. Rwy. . 350 Manassas S. A. L. Ry. . . 217 Marshallville C. of Ga. Rwy. . 500 Marlow C. of Ga. Rwy. . 72 Mayday . . . G. S. & F. Ry. . 140 Mayfield . . . . . . . . . . Ga. R. R. 417. I> Meigs . . . A. C. L. R. R. 341 Meinhard . S. A. L. Ry. . 19 Meldrim C. of Ga. Rwy. 2!3 Melrose . . G. S. & F. Ry. 154 Metcalf . . . A. C. L. R. R. 170 Midville . . . C. of Ga. Rwy. 186 Milledgeville . . . . . . . . . Ga. R. R. . 276 ELEVATIONS Milledgeville, low water level . . . . U. S. A. Eng. Millen . . . . . . . . . . . . . . . . C. of Ga. Rwy. Millwood . . . . . . . . . . . . . . . A. C. L. R. R. Mineola . . . . . . . . . G. S. & F. Ry. Moniac . . . . . . . . . . . G. S. & F. Ry. Monteith . . . . . . . . . . A. C. L. R. R. Mlontezuma . . . . . . . . . C. of Ga. Rwy. Montrose . . . . . . . . . . M. D. & S. R. R. Morgan . . . . . . . . . . ... Weather Bureau Morris . . . . . . . . . .. . . . . . . C. of Ga. Rwy. Mount Pleasant . . . . . . . . . . . Sou. Rwy. Munnerlyn . . . . . . . . . . . . . . C. of Ga. Rwy. Muscogee . . . . . . . . . U. S. G. S. . . Myers, Effingham County . . . . . . S. A. L. Ry. Naylor . . . . . . . . . . . . . . . A. C. L. R. R. Nicholls . . . . . . . . . . . . . . . A. B. & A. R. R. Norwood . . . . . . . . . . . . . . .Ga. R. R. . . . Ochillee . . . . . . . . . . . . . . U. S. G. S. . . Ocklockonee . . . . . . . . . . . A. C. L. R. R. Ochwalkee, low water Oconee R. . . . U. S. A. Eng. Oconee . . . . C. of Ga. Rwy. Odum . . . . U. S. G. S. . . Offerman . . . . . . . . . . . .. . . A. C. L. R. R. Ogeechee . . . . . . . . . . . . C. of Ga. Rwy. Oglethorpe . . . . C. of Ga. Rwy. Ohoopee . . . . . S. A. L. Ry. Oliver . . . . . . C. of Ga. Rwy. Omaha (station) .Rough estimate Ousley . . . . . A. C. L. R. R. . Paramore Hill . C. of Ga. Rwy. Parrott . S. A. L. Ry. . Paschal . C. of Ga. Rwy. Patterson . A. C. L. R. R. Pearson . . A. C. L. R. R. Pembroke . . S. A. L. Ry. . Pendarvis . . U. S, G. S. . . Pennick . . . . . . U. S. G. S. . . Pikes Peak (station) .. M.D. & S. R. R. Pinegrove . . . . . . . . . . . . . . U. S. G. S. . . Pinehurst . . . . . . . . . . . . . G. S. & F. Ry. Pineora . . . . . . . . . . . . . . C. of Ga. Rwy. Plscola, Brooks County . . . . . . . Weather Bureau Pooler . . . . . . . C. of Ga. Rwy. Poulan . . . . . . . . . . . . . . A. C. L. R. R. . Powersville . . . . . . . . . . C. of Ga. Rwy. . Quitman . . . . . . . . . . . . A .C. L. R. R. . . Racepond . . . . . . . . . . . . . . A. C. L. R. R. . Rebecca . . . . . . . . . . . . . . . . . A. B. & A. R. R. Recovery . . . . . . . . . . . . . A. C. L. R. R. . Register . . . . . . . . . . . . Rough estimate Renfroes . S. A. L. Ry. . Reynolds . . . . . . . . . . . . . C. of Ga. Rwy. Riceboro . . . . . . . . . . . . . Rough estimate Richland . . . . . : . . . . . . . . . S. A. L. Ry. . Richwood . . . . . . . . G. S. & F. Ry. Rincon . . . . . . . . . . . . . S. A. L. Ry. . River Junction, Florida . . . L. & N. R. R. . Roberta . . . . .Rough estimate Roberts Station . . . . . . . . . . Ga. R. R. . . . 55 . 241.29 . 156 . 160 . 220 . 114 . 16 ..3oo' . 391 . 337 . 242 . 59 . 264 ? . 245 . 45 . 192 . 306 ? . 588 . 273 . 263 . 114.4 . 223 . 155 . 106 . 111 . 299 . " 187 . 140 . 240 . 148 . 235 . 482 669 . 104 205 . 101 85 . 18 534 229 . 390 78 . 19() 2:t 345. . 385. 173: 148 373 ?' .189 . 225 '!' 601 ? 43& . 15 . 600 . 358 . 75 . 84 . 620 . 557. 56 GEOLOGY OF THE COASTAL PLAIN Rockyford . . . . . . . . . . . . . . . c. of Ga. Rwy. . 130 Rogers . . . . . . . . . . C. of Ga. Rwy. . 159 Saffold . . . . . . . . . . . . A. C. L. R. R. . 105 Saffold, level of Chatt. R . . . . . . Rough estimate . 65 St. George . . . G. S. & F. Ry. . 78 St. Mary's . . . . . . . . . . Rough estimate . 12 Sandersville . . . . . . . . . . . . . Rough estimate . 470 Satilla . . . . . . . . . . . . . . A. C, L. R. R. . 96 Satilla, river level . . . . . . . . . . A. C. L. R. R. . 71 Savannah . . . . . . . . . . A. C. L. R. R. . . 21 Scarboro . . . . . . . . . . C. of Ga. Rwy. . 147 Schlatterville . . . . . . . . A. C. L. R. R. . 133 Scotland . . . . . . . . . . U. S. G. S. . . . 142 Screven . . . . . . . . . . . A. C. L. R. R. . . . . . . . 124 Shell Bluff Landing, Burke Co. . . U. S. A. Eng. (low water) . . 87 Shell Bluff Landing, Burke Co. . . U. S. A. Eng. (highest point) . 237 Shellman . . . . . . . . . . C. of Ga. Rwy . . . 379 ? Sibley . . . . . . . . '. . . . . . . . G. S. .& F. Ry. . 440 Smithville . . . . . . . . . . . . . . C. of Ga. Rwy. . 332 Sofkee . G. S. & F. Ry. . 370 Soperton . . Rough estimate . 290 Sparks . . . G. S. & F. Ry. . . . . . . 241 Sparta . Ga. R. R. . . . . . . 557 Springfield Rough estimate . . . . . . 100 Statesboro . . . .. Rough estimate . . . . . 175 to 200 Sterling . . . . . . . . . . . . . . .. U. S. G. S. . . . 21 Stillmore (highest land) . Rough estimate . 300 Stillwell, Effingham Co. S. A. L. Ry. . . 69 Stockton . . . . . . . . . . . A. C. L. R. R. . . 187 Sulphur Springs . . . . . . . . . U. S. G. S. . . . 300 Sumner . . . . A. C. L. R. R. . 373 Sunhill . . . . . . . . . . . . . C. of Ga. Rwy. . 362 Surrency . . . . . . . . . . . . U. S. G. S. . . . 187 Swift Creek . . . . . . . . . . M. D. & S. R. R. . 324 ? Sycamore . . . . . . . . . . . . G. S. & F. Ry. . 415 Sylvania ................Rough estimate . 200 Sylvester . . . . A. C. L. R. R. . . 370 ? Talbotton . . . . . . . . . . . . U. S. G. S. . . . 726 Tarrytown . . . . . . . . . . . . . Rough estimate . 290 ? Tennille . . . . . . . . C. of Ga. Rwy. . 469 Thalman . Rough estimate . 20 Thelma . . . G. S. & F. Ry. . . 158 Thomas . . . . . . . . C. of Ga. Rwy. . 285 Thomasville . . . . . . . . . . . . . A. C. L. Rwy. . 250 Thomson . . . . . . . . . . . . . . . Ga. R. R. . . . . . 503 Tifton . . . . . . . . . . . . . . . . A. C. L. R. R. . . 370 Tivola . . . . . G. S. & F. Ry. . 300 Toomsboro . . . . . . . . . . . . C. of Ga. Rwy. Towns . . . . . . . . . . . . . . . U. S. G. S. . . . 227 . 128 Tyty . . . . . . . . . . . . . . A. C. L. R. R. . . 332 Unadilla . . . . . . . . . . . . G. S. & F. Ry. . 412 Upatoi . . . . . . . . . U. S. G. S. . . . 418 Uptonville . . . . . . . . . . . A. C. L. R. R. . . 83 Valambrosa . . . . . . . . . . . M, D. & S. R. R. . 258 ? Valdosta . . . . . . . . . . . . . . .. A. C. L. R. R. . . 215 Valona, Mcintosh County . . Weather Bureau . 10 Vidalia . . . . . . . . . . . . . . . S. A. L. Ry. . . Vienna . . . . . . . . . . . . . . . . G. s. & F. Ry. . . . 257 ? . 350 Wadley . . . . . . . . . . . . . . . C. of Ga. Rwy. . . 234 GEOLOGY OF ~ 'HE OOil.STi!L PLAIN OP GEORGIA. Pl.nl. ~'E IV._ B. A LIME 1:\'K PO:\'D IN THE CH r~'l'TAHOOCHEE FOR:UATION , ON THE PROPERTY OF i\IR . l\IIT HELL. SIX MILE WEST OF BO TON. 'J'HO)lAS COUNTY. ELEVATIONS Wainwright (Uptonville Station) . A. C. L. R. R. Walden . . . . . . . . . C. of Ga. Rwy. Walthourville . . . . . . . . . . . . A. C. L. R. R. Waresboro . . . . . . . . . . . . . . . A. C. L. R. R. Warrenton . . . . . . . . . . . . Ga. R. R. . . . Waverly . . .IS. A. L. Ry. . . Waycross . . A. C. L. R. R. . Waynesboro . C. of Ga. Rwy. Waynesville . A. C. L. R. R. Ways . . . . . . . . . . . . A. C. L. R. R. Wellston . . . . . . . . . . . . . . G. S. & F. Ry. Wenona . . . . . . . . . . . G. S. & F. Ry. .Westlake . . . . . . . . . . . U. S. G. S. . Wheaton, Appling County . . . . U. S. G. S. . Whigham . . . . . . . . . A. C. L. R. R. Whiteoak . . . . . Willis (Gallemore) . . .18. A. L. Ry. . . . . . : M. D. & s. R. R. Weston . . . . . . . . . S. A. L. Ry. . . . Wilcox . . . . . . . ...Southern Rwy. . Willacoochee . . . . . . . A. C. L. R. R. . . Willingham . A. C. L. R. R. . Winchester . . . . . . . . . . C: of Ga. Rwy. . Woodbine . . . . . . . , . . . S. A. L. Ry. . . Worth .. . . . . . .G. S. & F. Ry. . Wray . . . . . . . . . . . . . . . . A. B. & A. R. R. 57 83 . 390 . 95 . 121 . 500 . 17 . 140 . 286 . 55 . 18 . 315 . 348 235 . 201 . 265 . 19 . 394 ? . 528 . 116 . 247 . 319 463 . 20 . 415 . 392 ? 58 GEOLOGY OF THE COASTAL PLAIN GENERAL STATEMENT OF THE GEOLOGY OF THE COASTAL PLAIN BY OTTO VEATCH Georgia may be divided into three major geologic provinces: (1) . the Paleozoic area; (2) the Crystalline area; (3) the Coastal Plain. The Coastal Plain is the largest division of the three, covering approximately 35,000 square miles, considered purely as a geologic division. The general physiography, location, boundaries, topography, etc., of the different areas have been presented in the preceding chapter. The Paleozoic region is an area of limestone, shales, and sandstones which has been subjected to great dynamic movements and the sediments are highly folded and faulted. The strata r:mgc in age from lower Cambrian to the Coal Measures. The Crystalline area, ineluding the Piedmont Plain and the Blue Ridge, is composed of rocks of igneous ormetamorphic origin, including granites, gneisses, schists, basic eruptives, and highly metamorphosed shale, sandstone, and limestone. These constitute the oldest rocks of the State, and are urobably in the main of pre-Cambrian age. They have been subjected .o great orogenic movements, have been folded, faulted, and otherwise profoundly altered. Contrasted with the rocks of the Cryst~lline area those of the Coastal Plain are sand.s, clays, and marl, with a lesser amount of limestone and sandstone; they are to a large degree unconsolidated a:Q.d have been altered but little, comparatively, from their original condition, with an entire absence of pronounced folding and faulting. The Coastal Plain sediments constitute the youngest series of beds in the State; they range in age from Cretaceous to. Pleistocene and lie upon the upturned, planated beds of the ancient crystalline complex. They are mainly marine deposits, the component materials of which were derived from the crystalline complex to the north, their bulk representing the erosion of a vertical thickness of two thousand feet or more of beds from the Crystalline area of the State. The contact between these two major divisions, the Coastal Plain and the Crystalline area, is known as the Fall Line. Divisions of Coastal Plain Strata.-The Coastal Plain deposits underlie an immense area and aggregate a maximum thickness of 4,500 to 5,000 feet of sediments which have resulted from separate deposi- GENERAL STATEMENT OF THE GEOLOGY 59 ticns, and which correspondingly vary lithologically and faunally. Since to present a clear description en bloc of these sediments would manifestly be impossible subdivisions are necessary. While the struc- ture of the Coastal Plain sediments is simple in comparison with that oi the Piedmont, Blue Ridge, and Appalachian Valley rocks, this province, nevertheless, presents its peculiar difficulties and the classifi- cations which have been arrived at in the different States represent laborious investigations covering many years. A table of the subdi- visions made in Georgia is given on pages 60-61. The great geologic periods, Cretaceous, Tertiary, and Quaternary, are based upon the life forms preserved in the rocks and great physical or climatic changes on the earth. The broader divisions, as Lower Cretaceous, Upper Cretaceous, Eocene, Oligocene, etc., based mainly upon life forms preserved in the rocks, are time divisions, and are also of wide application. The further subdivisions are provincial and still further minor subdivisions are local and are based upon fossils, peculiar lithologic character and stratigraphic continuity, and surface configuration or physiography, or a combination of all of these. To attempt to make mappable minor divisionll of the strata entirely upon the basis of fossils or upon the basis 6f lithology alone, in either case leads to confusion. The study of fossils is carried on because of their value in correlating deposits of widely separated localities, the identity of which it is not possible to prove by stratigraphic contin- uity, or the actual tracing of a bed or formation. . Most of the formation and group names employed have been ab- stracted from literature on other States, and these names are here em- ployed, as the formations of adjoining States are continuous with those of Georgia. Certain sections in Mississippi, Alabama, and Florida have been taken as standards for comparison for the Georgia formations for the reasons that stratigraphic studies were first prose- cuted those localities. Thickness.-The general lithologic character and thickness of the divisions are given in the accompanying table, and will be considered in detail in the following chapters, together with a discussion of their structure, fossils, etc. The aggregate thickness of the deposits, as has been mentioned, is 4,500 to 5,000 feet. Of this thickness, the Ore taceous forms 2,000 to 2,500 feet, the combined thickness of the Ter- tiary is approximately that of the Cretaceous, while the Pleistocene and Recent are but little more than 100 feet. Precise measurements of thickness can not be given, the principal reasons for which are: in- constancy in the strata, both along the strike and dip, the merging of strata faunally and lithologically, and paucity of fossil remains and of natural exposures. GEOLOGY OF THE COASTAL PLAIN TABLE OF GEOLOGICAL FORMATIONS IN I I SYSTEM SERIES Recent GROUP THICK- I I I FORMATION M:EMRER NESS! FEET Quaternary Pleistocene Columbia Satilla formation Okefenokee formation J0-50 5-40 Pliocene Miocene Tertiary Appalachicola Oligocene Altamaha (Lafayette?) formation Charlton formation Duplin marl Marks Head marl Alum Bluff formati.:Jn Chattahoochee formation Vicksburg formation 150 ? (max.) Undetermined 10-15 45 150 (average) 150 300 Eocene Claiborne Upper ssiliferous limestone and calcareous and glauconitic sandy clay. Mainly red and vari-colored fossiliferous, marine sand; thin beds of silicified limestone or chert and sandstone and quartzite. Variable in its lithologic character; mainly an argillaceous and sandy, fossiliferous marl, and drab, sandy clays and fuller's earth. Dark colored, lignitic and glauconitic clay in the nature of fullers earth, and vari-colored, unconsolidated sand and clay. Ferruginous sand and local beds of white clay, together with fossiliferous limestone, marl, clay and calcareous quartzite. Gray, calcareous, micaceous sand; dark gray to black, sandy clay and shell marl with, at intervals, nodular layers of gray, calcareous sand or impure sandy limestone of marine origin; fine to coarse, crossbedded sand. with subordinate lenses of light colored clay or dark, lignitic clay of shallow water origin. Calcareous sand, sandy limestone, and more or less sandy clay of marine origin; crossbedded sands and clays of shallow marine or estuarine origin; at base of formation, arkosic, micaceous sand and dark gray to black clay containing lignite. Coarse grained, crossbedded, arkosic sand with subordinate lenses of lightcolored to pure white clays, approaching kaolin in composition; contains no marine fossils and is of shallow water, and presumably of fresh water, origin. the Tarious formations and members. 62 GEOLOGY OF THE COASTAL PLAIN StruCture.-The Coastal Plain strata have a general southward and coastward dip with the line of outcrops of the older formations running northeast-southwest. Conclusive proof of the foregoing statements is afforded by structural data obtained from natural exposures and deep wells, together with physiographic relations. The general surface slope, independent of the dip of the geological formations, from the Fall Line to sea level is about three feet per mile. The slope of the crystalline floor at the Fall Line is 50-75 feet per mile, but whether this slope is constant as far as the present coast can only be a matter of speculation, since the full thickness of the sediments in the lower part of the Coastal Plain has never been penetrated by boring. The oldest formations form the surface rock northward and disappear southward by reason of their dip, or in other words, in traversing the Coastal Plain from the Fall Line to the Atlantic Ocean and to the Gulf one descends from the oldest to the youngest or latest deposits. The dip of the Cretaceous beds is probably as much as 40 feet per mile; the lower Eocene beds have a dip of probably 20 to 30 feet; and the succeeding formations up to the Alum Bluff have a slope south- ward of not more than 8 to _15 feet per mile. The Alum Bluff formation has a very low southeastward and southward dip but the beds are, probably nearly horizontal near the Florida line. The Miocene beds as far as known are likewise almost horizontal. The Altamaha (La- fayette?) and Pleistocene deposits form a mantle over the older for- mations and conform to the general tilting of the plain. The constancy of the dip of the older formations, and the con- stancy of lithologic phases, are matters of considerable economic inter- est, and it is regretted that more accurate information can not be given at present. The attainment of this information can be _effected only by the further patient study of surface exposures and collection of accurate well data. The Coastal Plain strata present no pronounced structural disturb- ances. Some local disturbances of beds of the Cretaceous and Eocene have been noted along the Chattahoochoo River, and displacements of beds at other localities have also been observed. None of the observed local displacements are believed to be of magnitude and are probably unimportant incidents in the simple oscillations which the Coastal Plain has undergone. Broad geologic structural features which can not be proven by re- oording strike and dip of the rock outcrops, since the dips are in gen- GENERAL STATEMENT OF THE GEOLOGY 63 _ta_l_lin-.,-1 LWpiltha protuta sub-wne Upper limit ol range of typb.l U:vgrra potldt1'0114 and lower limit of range of t yp' :tl EXOf/1/T'G CD~~ta.la. I 1---i Mrt.,.iaon>uub-zone Tomhigbee mod member Ripley formati n Eutaw fonnation LEG EN D sm~":~~:: {~ S.lma chalk Cusoetn { Ripley fonnation ~ blind member c5 ~ :> R Tusc.alocma formation lLower Crelaeeoc TABLE SHOWI.J."\fG THE LJTHOLOGIO VARIATIONS OF THE EA TERN GULF CRETACEOUS DEPOSITS, Ali'D THE AGE RELATIONSHIPS OF THE CRETACEOUS DEPOSITS OF GEORGIA TO THOSE OF THE REMAINDER OF THE EASTERN GULF REGION; ALSO THE CORRELATION OF THE EA TERN GULF CRETACEOUS WITH THE CAROLINA .AND NORTH .ATLANTIC CRETACEOUS. LOWER CRETACEOUS 73 value, and Appendix D, pp. 430-447, is devoted to the bauxite deposits of the Lower Cretaceous beds. Lists of species from the known Cretaceous fossil plant localities of Georgia were recorded by E. vV. Berry' in 1910, and in the same paper a new genus and species of Euphorbiaceffi from one of the localities, McBride Ford, is described. LOWER CRETACEOUS DEFINITION Areal distribution.-The Lower Cretaceous strata present in Georgia constitute a terrane 'whose exact correlation with reference to Lower Cretaceous deposits to the northward in the Atlantic Coastal Plain is at present not definitely known, but they are believed to represent a part of the Potomac group of the Middle Atlantic States. This terrane appears in surface outcrops in Georgia in an extremely irregular belt 2 to 30 miles in width, extending entirely across the State from Chattahoochee River in the vicinity of Columbus, northeastward to Savannah River in the vicinity of Augusta. The irregularities of the belt are due partly to the unevenness of the surface of the basement rocks upon which the formation rests; partly to overlaps of younger formations; and partly to the deep erosion valleys that the streams have developed along the fall line region, causing the underlying basement rocks to appear much farther southward in the bottoms of these valleys than would otherwise be the case, and likewise causing the Lower Cretaceous beds themselves to appear . still farther down these valleys beneath the overlying younger formations. These irregu~arities are most strikingly developed in the region between Ocmulgee and Savannah rivers. (See geologic map, opposite page 58.) The area in which the beds appear includes parts of the following counties: Muscogee, Chattahoochee, Talbot, Marion, Taylor, Macon, Crawford, Bibb, Twiggs, Jones, Wilkinson, Baldwin, Washington, Hancock, Warren, Glascock, J efferson, McDuffie, Columbia, and Richmond. This Lower Cretaceous terrane continues westward from Georgia into Alabama, forming a belt four to eight miles wide lying just south of the Piedmont border, and extending to and probably somewhat beyond the Alabama River. Stmtigraphic position.-The Lower Cretaceous beds in Georgia rest upon a basement of ancient crystalline rocks, all of which are believed to be of pre-Cambrian age. The unconformity separating 1Contributions to the :\Iesozoic flora of the Atlantic Coastal Plain, VI Georgia: Bull. Torrey Botan. Club, Xo. 37, 1910, pp. 503-511. 74 GEOLOGY OF THE COASTAL PLAIN the bailement rocks from the Lower Cretaceous deposits represents an enormous time interval, including all of Paleozoic time, and the Triassic and Jurassic periods of :Mesozoic time. The surface of the crystalline rocks is very uneven in detail, but in general, slopes to tl~~ south and southeast beneath the Lower Cretaceous beds. Calcula- tions from well borings at several places have shown that the amount of this general slope in the region of the fall line nries from 25 to over 50 feet to the mile. In Jefferson County it maintains a slope of between 35 and 40 feet to the mile for a distance of nearlv 40 miles away from the Piedmont border. " Between Chattahoochee and Ocmnlgee rivers the formation is over- lain unconformably by Upper Cretaceous strata belonging to the Eutaw and Ripley formations, and to a very limited extent, when both of these formations are absent, by Eocene strata; between Ocmulgee and Savannah rivers it is merlain unconformably by Eocene strata of the Claiborne group. Locally, where the formation is crossed by the larger streams, it is overlain along the valley sides by thin Pleistocene terrace deposits. The unconformity separating the Lower Cretaceous deposits from the overlying Eutaw formation has been observed at a number of places in Muscogee and Chattahoochee counties, Ga. (see detailed sections) ; but the locality \vhere it is best exposed and least obscured by weathering, as thus far observed, is in Russell County, Ala., four miles southwest of Columbus, Ga. The contact at this point is sharp aud unmistakable. Its rharacter is well shown in the photograph, plate VI, B. The contact has also been observed on Alabama River, tive miles above Montgomery. A short distance west of Alabama River in Alabama tho formation pinches out entirely between the basement rocks and the overlying Tuscaloosa formation, allowing tho latter to rest directly upon the basement floor. Lithologic characters.-The Lo\Yer Cretaceous materials consi~t predominately of arkosic sand, with, however, a considerable percentage of clay in the form of interbedded lenses. The sands are usnal1.v coarse to very coarse in texture, and cross-bedding is general. They are composed largely of angular to subangular quartz grains, \vith, howcser, an important percentage of kaolin grains and disseminated kaolin particles. In addition, there are subordinate amounts of unrlecomposed felclspar, mica, and varjous other minerals derived from the crystalline rocks of the adjacent Piedmont region. Locally, the sand becls haw been indurated, forming friable sandstones. The cla; lenses vary \Yidely in lithologic character, shape, and extent. In thickness they range from an inch or less to a maximum of 30 or 40 LOWER CRETACEOUS 75 feet, and in horizontal extent from a few square feet to many acre~. ln general, the clays are light drab or gray in color, and are more or less sandy. Locally, howeve:r;, there are commercially important clay lenses of remarkaLlc 11hiteness awl purity approaching kaolin in com- !J08ition. Lamination is rare, the beds being as a rule massiye and breaking with a hackly or conchoidal fracture. _ For the most part the formation displays great irregularity of bed- ding. In places, however, a distinct banding of the c_lay and sand layers is apparent, indiYidual beds being traceable for considerable distances. Good examples of the latter type of bedding are presented by the bluffs of Chattahoochee River below Columbus. Locally, coarse gravel lenses and layers occur in the formation, this being especially true of the basal portions near the contact with the underlying crystalline rocks. Unconformities of little or no time significance occur locally within the formation. ~ls the result of the shifting of the channels which produced these unconformities clay beds within the formation have been torn to pieces and redeposited, as evidenced by the large number of rolled clay ball,; and Lonlders which in many places occur scattered through the sands. The better grades of commercially important clays, so far as known, occur in the region between Ocmulgee and Savannah rivers. Beds of very fine quality are abundantly developed in Twiggs County and hero mining operations have been carried on more extensively than else- where. The same formation contains similar high grade ,,.hite clay beds to the northward in Aiken County, S. C. In Wilkinson County the white clays ha1e been locally altered to bauxite with pisolitic structure. The bauxite deposits, so far as - known, occur immediately beneath the contact of the formation with overlying Eocene strata. The white clay and bauxite deposits have been described in considerable detail by Otto Veatch.' Strike, dip, and thiclcness.-Thc strike of the Lower Cretaceous beds in Georgia is in general a little south of a northeast-southwest direction. In Alabama the strike is almost clue east and west. There is a slight general dip of the beds to the southeast or south at right angles to the line of strike. On account of irregularity of bedding, and also on account of the limited extent of the exposures, the exact amount of dip can not be readily cleterminecl. It is greater, however, than the gradients of the larger streams aml probably averages 25 or 30 feet to the mile. Data are available for a fairly accurate cletnmination of the thickness of the formation in the Chattahoochee Valley below Columbus. The point on Chattahoochee RiYcr adjacent to 1GPoL Survey of Georgia, BulL ~o. 1><. 76 GEOLOGY OF THE COASTAL PLAIN Uolumb11s, \Yhere the surface of the basement rocks passes beneath zero water level, has an elevation of about 195 feet above sea level. Data furnished by well borings near the mouth of Bull Creek shmv that this surface dips southward beneath the Lower Cretaceous beds at an average rate of between 50 and 60 feet per mile. The top of the Lower Cretaceous terrane passes beneath water level at Broken Arrow Bend, an air-line distance of seven miles south of Columbus, at an elevation of about 180 feet above sea level. If the dip of the surface of the basement rocks is 50 feet to the mile, seven miles south of Columbus at Broken Arrow Bend, it would be 350 feet lower, or 155 feet below sea level. The thickness of the formation at this point + would therefore be 155 feet 180 feet, or 335 feet. If the dip of the basement rock surface is 60 feet to the mile instead of 50 feet the same method of calculation would give the thickness at 405 feet. Three hundred and seventy feet, the average of these amounts, is be1.ieved to be a close approximation to the total thickness at this point. Calculations based upon well data have shown that the probable general dip of the unconformity separating the Lo\ver Cretaceous and overlying Eutaw beds in this region is 48 or 50 feet to the mile. This slope is therefore probably a little less than the slope of the surface of the underlying basement rocks. If these two plains maintain their respective degrees of dip they must diverge slightly and the formation must thicken somewhat to the southward. It seems improbable, however, that the buried surface of the basement rocks maintains so great a degree of slope southward for any great distance away from the fall line as it is known to possess in close proximity to the fall line. A well at Reynolds, Taylor County, is said to have penetrated 600 feet of Cretaceous strata before encountering the underlying crystalline rocks. As the well starts in Lower Cretaceous strata this whole thickness, 600 feet if correctly reported, should be referred to this for- mation. Three and one-half miles southwest of Louisville, in Jefferson County, a well 1,143 feet deep is believed to have penetrated about 790 feet of Cretaceous strata between the overlying Eocene deposits and the basrment roch. X one but Lower Cretaceous strata outcrop at the surface from beneath the Eocene beds along the fall line to the northwest of Louisville, hut it is not at all certain that all of the Cretaceous beds penetrated in the Louisville well should be referred to that division. In fact it seems highly probable that buried Upper Cretaceous strata exist between the Eocene and Lower Cretaceous beds. The thickness of the Lower Cretaceous terrane at this point is therefore believed to he ronsiderahly less than 7fl0 feet. LOWER CRETACEOUS 77 From data obtained from wells, and from other considerations, it may be shown that in general along the line where the formation passes beneath the overlying Upper Cretaceous or Eocene formations, as the case may be, its thickness ranges from 350 to 600 feet, although the amount may be less or greater locally. Physiographic expression.-The belt in which this Lower Cretaceous terrane outcrops at the surface constitutes part of a dissected plain which is characterized by a broken, hilly topography, the area presenting in fact the roughest surface of any portion of the Coastal Plain of Georgia. The elevation of the upland surface ranges from 400 to 600 feet above sea level. The major streams crossing the area have elevations at the fall line at zero water level, ranging from about 100 feet to about 250 feet. The surface relief therefore reaches a maximum of at least 400 feet. This hilly topography is the result of active stream erosion caused by the relatively high elevation of the area and favored by the unconsolidated, sandy character of the materials of which the formation is predominantly composed. The surface soil throughout the greater part of the area is composed of loose gray or yellowish sands, the product of the weathering and leaching of the underlying sand beds of the formation. TheRe surface sands have been shifted more or less by winds and torrents so that in places they have been entirely removed, and elsewhere have been heaped up to abnormal thicknesses. The area forms a part of the socalled "sand hill" region of the northern part of the Georgia Coastal Plain. Paleontologic characters.-A few, faint, indeterminable leaf impressions have been observed in white, sandy clay in a cut of the Georgia Railroad at Carr's Station, Hancock County. \Yith this exception no fossil remains haYe been discovered in the beds of this formation in Georgia. A few poorly-preserved leaf remains were recently collected by the writer from this terrane at an exposure in a bluff of Tallapoosa River at Old Fort Decatur, Macon County, Alabama. These were submitted to E. W. Berry, who expresses the opinion that the beds containing them are of Lower Cretaceous age, and they are believed to represent a part of the Potomac gro1~p of the Middle Atlantic States. Further reference will be made. to these in the section on correlation, pp. 108-111. The cast of a Urzio, specifically indeter- minable, was fo.nnd in close association with thf' plant rf'mains at this locality. GEOLOGY OF THE COASTAL PLAIX DETAILED SECTIONS Chattahoochee River.-Lower Cretaceous strata are exposed in the bluffs of Chattahoochee Ri,,er from Columbus, ~Iuscogee County, to Broken Arrow Bend, Chattahoochee County. The specific localitie~ referred to on the following pages are indicated in a sketch map of the riYer, Figure 6. At Columbus the Lower Cretaceous beds rest unconformably upon a basement of ancient crystalline rocks. The latter form the body of the hills north of the city and giYe rise to the rapids in the river opposite the northern half of the city. Their surface dips rapidly to the southward under the Coastal Plain sediments, passing beneath "'ater level a short distance below the Central of Georgia RaihYa~' bridge. The following section shmYs tl1e relation of the T~mwr Crrtaceous strata to the underlying basement rocks and to the oYrrlying Pleistocene terrace deposits. Section, Chattahoochee River, bluff at Gira1d, opposite Columlms, nf II'Psf e11d of Cr11fml of Georgia Railuay bridge. Feet. In. Pleistocene (terrace deposit) 7. Red, coarsely arenaceous clay . . . . . . . . . . . . 6 G. Reddish 'and yellowish, argillaceous sand and sandy clay, coarse and pebbly, with pockets of pebbles, becoming much coarser along base. . . . . . . . 14 5. Dark, tough, plastic, sandy clay with indeterminable plant fragments . . . . . . . . . . . . . . . . . . 11 4. Coarse, irregularly bedded sand and gravel, the pebbles averaging 1/ to v~ inch in diameter and angular to partially rounded . . . . . . . . . . G (Unconformity) Lower Cretaceous 3. Light drab, massive, coarsely sandy, compact clay . 9 2. Argillaceous, very arkosic, light gray, friable sanct stone . . . . . . . . . . . . . . . . . . 3 (Unconformity) Basement rocks 1. D\'eply decayed crystalline rock (gneiss) to low water level . . . . . . . . . . 5 On the south edge of the town of Girard, west of the Central of Georgia Railway track, there is an excellent exposure of I~mYer Cretaceous strata in a sand pit. The succession of .beds as they appeared when visited, is as follows: Section at south ern outskirts of Gimrd, Ala. Feet Pleistocene? (or surface creep) . 6. Sandy and pebbly loam . . . . . . . . . . . . . . . 2 (Unconformity) Lower Cretaceous LOWER CRETACEOUS 79 N 35 Alexanders Ldg. Othosldg. Fort Gaines Scale 0 5 10 IS MILES Fig. 6.-Sketch map of Chattahoochee, River, Columbus, Ga., to Fort Gaines, Ga. 80 GEOLOGY OF THE COASTAL PLAIY 5. Reddish sandy loam, grading down into harsh, sandy clay, and this in turn into a slightly in- durated, arkosrc, micaceous sand . . . . . . . 25 4. Mottled purplish and gray, harsh clay . . . . . . . . 3 3. Hard, grayish to somewhat mottled, sandy clay . . . . 6 2. Gray, in places iron-stained, loose, cross-bedded, very arkosic and micaceous sand becoming very coarse and gravelly in lower six feet . 16 1. Light, greenish drab clay . . . . . . . . . . . . . . 12 The base of the preceding section is ao or i35 feet above zero \Yater level in the river. The first prominent exposure immediately on the river below Co- lumbus is at a point about one-half mile above the mouth of Bull Creek on the Georgia side. The section in detail is as follows: Section one-half mile above the mouth of B1tll Creek, Chattahoochee River, left bank. Pleistocene (terrace deposit) Feet 4. Yellowish sandy loam grading down into coarse simd and gravel . . . . . . . . . . . . . . . . . . . . 33 (Unconformity) Lower Cretaceous 3. Light gray to white, very coarse, cross-bedded, ar- kosic sand, containing pebbles up to 14 inch in diameter . . . . . . . . . . . . . . . . . . . . . 13 2. Harsh, greenish gray clay, mottled with brown . . . 2 6 1. Greenish gray, finely micaceous, argillaceous sand, to water's edge . . . . . . . . . . . . . . . . . . 3 The cross-bedded, arkosic layer in the preceding section undulates along the bluff but in general dips gently southward and comes to water level a few hundred feet below where the section was made. A section similar to the preceding occurs at the mouth of Bull Creek. Thirty-nine wells have been recently drilled in Muscogee County about three miles southeast of Columbus, on either side of Bull Creek and within one mile of its mouth. All passed entirely through the Lower Cretaceous beds and entered the underlying basement rocks. Logs of two of these wells are given below. Mr. N. W. Wood, Constructing Engineer of the Hudson Engineering Company, 90 ~West Street, New York City, N. Y., is authority for the lithology. GEOLOGY OF THE COASTAL PLAIN OF GEORGIA. PLATE VI. A. CLAY PIT AT PLANT OF THE GEORGIA KAOLIN COMPANY, TWO MILES SOUTHEAST OF DRY BRANCH, IN TWIGGS COUNTY, GA., SHOWING CONTACT BETWEEN WHITE KAOLIN BED OF THE LOWER CRETACEOUS AND OVERLYING SANDS AND CLAYS OF THE CLAIBORNE GROUP (EOCENE). B. EXPOSURE IN CUT OF COLUMBUS-SEALE ROAD, FOUR MILES SOUTHWES'l' OF COLUMBUS, GA., IN RUSSELL COUNTY, ALA.. SHOWING CO:::-ys. The Eocene beds rcach a thickness .of 135 feet or more on the in'tervening divides. The following data concerning occurrences of the formation in this county haYe been ahstl'acted (not qnoted) from VeatC'h's C'la.v report, pp. 159-172: On the property of J. W. Huckabee one mile west of Lewiston, near the Central of Georgia Rail~ay, a white clay bed three to twelve feet in thickness has been mined to a limited extent. The clay is overlain by ten to twenty feet of sands and fossiliferous, siliceous beds resembling quartzite of Eocene age (Claiborne group). On the Z. T. Miller place, three miles south of Gordon, a 30-foot bed of white clay appears in a natural exposure. This bed which belongs to the Lower Cretaceous is overlain by tough, plastic, impure clays and red sands referable to the Eocene (Claiborne group). There are a number of other localities in the vicinity of Gordon where similar white clays outcrop beneath sands and clays of the Claiborne group, the latter exceeding a thickness of 100 feet in places.-(See detailed sections on pp. 276-277 of this report.) White cl:hs occur at a number of localities in the vicinity of Mcintyre. Three miles east of this place there are natural exposures of white clay, four to twelve feet thicJ;. overlain by 30 to 50 feet of red sands and impure clayf. of the Claiborne group. A J:>ed of serni.h~rrl ,,hite C'hl~- reaching a maximum thickness of :lO feet outcrops on the Hatfield property one and one-half miles west of :Mcintyre, 96 GEOLOGY OF THE COASTAL PLAIN on the south side of the Central of Georgia Railway track. The exposure occurs at the base of a ridge, the overlying strata consisting of Eocene ( Claiborne) sands and clays. Three miles northwest of Mcintyre, on the property of Robert Billion, 12 feet of soft, white and cream-colored kaolin outcrops in a deep gully, oppo site the residence of William SnQw, beneath 40 feet of Eocene sands and clays (Claiborne group). On the George Bentley property, two and one-half miles north of the 159th mile post of the Central of Georgia Railway, 12 to 15 feet of white and cream-colored clay is exposed in a roadside gully. White clay beds occur in the region immediately to the north of Toomsboro, and in a cut of the Central of Georgia Railway at Beech Hill, four miles east of Toomsboro, Yeatch furnishes the following unpublished note on occurrences of Lmver Cretaceous clays in the vicinity of Irwinton: ''Irwinton is situated on a high Tertiary ridge capped with red sand. The C:'etaceous is exposed in the valleys 150 to 200 feet lower. "On the Tolar place, four miles' south of Irwinton, and on Big Sandy Creek, hard white clay, 20 feet thick, is overlain by Tertiary clay. On the basis of this white clay bed the Cretaceous is mapped along Big Sandy Creek almost to Stephensville. "There is a suggestion that there is one continuous bed of white clay underlying a large area in wilkinson and Twiggs counties. This clay bed, which is known to reach a thickness of 30 feet or more, has been observed at a number of localities to the north and west. It is characterized by its purity, freedom from any large amount of sand, absence of bedding or lamination, and absence pf anything that suggests marine conditions. With the possible exception of South Carolina, these heavy white clay beds have no counterpart in any other portion of the United States." One-half mile \vest of Irwinton the follo,ving section of a well on the property of D. H. Howell was obtained, the authority for the lithology being the owner: Section of well located at foot of high hill. Lower Cretaceous. Feet. 3. Clay . . . . . . . . . . . . . . . . . . . . about 0 18 2. Kaolin . . . . . . . . . . . . . . . . . . . about 18 53 1. Layer of rock, water from beneath rock . . . . . . 53 59 "\t nearly all of the localities described on preceding pages the Lower Cretaceous sands and clays are overlain unconformably by sands and clays of Eocene age (Claiborne group). (See detailed sections of Eocene strata in \Vilkinson Connty on pp. 276-278 of this report.) Locallv the ,vhite, Lower Cretaceous clays of Wilkinson County have bee'u altered to bauxite. The known bauxite occurrences have hcen studied bv Otto Veatch, and have been treatPrl in some detail h.v him in his cla~ report. (Appendix D, pp. 180-447.) The bauxite, ilO far as discmered, occurs at the top of the I,m\er'Cwtaceous terrane GI-JOLOGY OF' T HE COASTAL PLAIN O P GEORGIA . PLATE V lll LOWER CRETACEOUS 97 immediately beneath its contact with overlying Eocene sands and clays. The principal localities where the ore has been found are in the vicinity of Toomsboro, Irwinton, Mcintyre, Gordon, and Cooper Station. Portions of the southern and eastern parts of Baldwin County are underlain by Lower Cretaceous strata. The beds rest upon crystalline basement rocks and are overlain in a limited area in the vicinity of Stevens Pottery by overlapping Eocene beds. The bi:lst known occurrences are at Stevens Pottery, eight and one-half miles south of Milledgeville, where they are many good exposures. These show a great horizontal variation in the character of the materials. The following section describes the several strata as they appeared in the main pit east of the railroad at the time examined: Section in main pit at Stevens Pottery, Ga. Eocene. 4. Red, argillaceous sand, mottled in places. : . . . (Unconformity.) 3. Mottled pinkish and yellowish, argillaceous sand and sandy claY . . . . . . . . . . 2. Red, crossbedded, ferruginous sand containing along base a few quartz pebbles and white siliceous clay pebbles . . . . . . . . . . . . . (Unconformity.) Lower Cretaceous. . 1. White, more or less sandy, massive clay, used prin- cipally in the manufacture of fire brick, sewer pipe, etc. . . . . . . . . . . . . . . . . . . . Feet. 4 to 5 10 to 15 12 tJ 15 10 In an abandoned pit on the west side of the railroad track the following section was made: Section in abandoned pit, nest side of railroad track, Stevens Pottery, Ga. Eocene. 2. Coarse, yellowish and gray, arkosic, crossbedded sand, with boulders along base consisting of white clay penets in a darker drab clay matrix. There are also .along the base white, rounded, silicified clay pebbles and some quartz, garnet and hornblende pebbles . . . . . . . . . . . . . . . . . (Unconformity.) Lower Cretaceous. 1. Light to white, arkosic sands with lenses up to six or eight feet in thickness, of white clay, more or less sandy and micaceous. Locally, especially near base, there are irregular iron concretions . . . . Feet. 8 20 98 GEOLOGY OF THE COASTAL PLAIN About ~ne-quarter mile south of the station at Stevens Pottery, on the west s1de of the railroad track, the Lower Cretaceous arkosic sands and white clays are seen to be overlain by markedly unconformable olive-green, harsh, siliceous, and probably calcareous clay, which is certainly referable to the Eocene (Claiborne). Along the base of this green clay are numerous pebbles of quartz, silicified clay, garnet, and hornblende, and small boulders of pisolitic clay. Veatch, in his clay report, has described the clays at Stevens Pottery from the standpoint of their economic value (pp. 172-174). A well drilled at this place passed through the Lower Cretaceous beds and entered the underlying basement crystallines at a depth of about 75 feet beneath the surface. The latter, consisting of a decomposed granite rock, was penetrated to a depth of 175 feet. The authority for this data is W. C. Stevens, of Stevens Pottery, Ga. One and one-half miles a little south of east of Milledgeville, a few feet of coarse, cross-bedded, arkosic sand was observed in a roadcut on a hill slope, resting in a shallow depression in deeply decayed crystalline rocks which compose the body of the hill to its summit. The hill is about 125 feet high and the sand deposit is well down toward its base. This bed is believed to be a Lower Cretaceous remnant. Overlying the sand with .apparent unconformity is a surficial covering, three or four feet thick, of coarse sands and gravels of uncertain age. Lower Cretaceous strata have a limited areal distribution in the western and northern parts of \Vashington County. They are overlain by Eocene strata and would not appear at the surface were it not for the erosion which has produced the valleys of Oconee River, Buffalo Creek, and Ogeechee River. Veatch has noted a number of occurrences of the formation in this county. The following data has been adapted (not quoted) from his clay report, pp. 176-179, and from pp. 274-276 of the present report: Ten miles north of Oconee on the property of Mrs. S. M. Gilmore, 15 feet of white clay is overlain by 20 or 30 feet of red mottled sand. Six miles west of Sandersville, on the upper Milledgeville Road where it descends to Keg Creek, 16 feet of hard, massive, white fire-clay of Lower Cretaceous age is overlain unconformably by 125 feet of Eo.cene sands and clays. At the old Carter Mill site, five and one-half miles north of Sanders- ville, six feet of massive, white fire-clay outcrops beneath Eocene sands and clays sive, ~haintde one mile fire-clay north of this mill there is an outcrop of 12 feet of showing similar relations to the Eocene sands and mas clays above. This clay bed is underlain by typical Lower Cretaceous sands. On the road to Hebron, seven miles southwest of Sandersville. four feet of white clay outcrops at the base of a hill beneath 90 feet of Eocene sands and clays. The same relations were observed in a cut two miles southwest of Chalker. LOWER CRETACEOUS 99 One mile south of Chalker on the public road, white and yellow sands referable to the Lower Cretaceous are overlain by 80 feet of Eocene sands and clays. Lower Cretaceous sediments are present over much of the southern half of Hancock County. The total thickness of the beds is not great since the basement rocks upon which they rest appear in the valley bottoms of many of the streams. In limited areas in the southeastern part of the county overlapping Eocene strata rest upon the Lower Cretaceous beds. The best exposures of the formation in Hancock County are in the first two cuts of the Georgia Railroad, a short distance southwest of Carrs Station. At several places the contact .with the underlying basement rocks, which consist of deeply decayed granite and schist, is visible. The line o contact is very uneven, varying from below the level of the track to a maximum of 12 feet above that datum. The maximum thickness of materials exposed is 50 or 60 feet. The Lower Cretaceous materials consist of light-colored, coarse, crossbedded, arkosic sands with interstratified lenses o light to white clays, the latter reaching a maximum thickness of 10 or 12 feet, and with clay boulders and clay balls scattered somewhat irregularly through the sands. The most prominent lens of white clay is at the north end of the first cut. This bed has a maximum thickness of 10 or 12 feet, but is replaced by sand a short distance away laterally. Near the base of this lens and about eight feet above the track level, a few, taint, indeterminable lea impressions were observed in soft, mealy, laminated clay. This is the only known occurrence of leaf remains in this formation in Georgia. In the second cut there is a very conspicuous unconformity, 30 to 40 feet above the track level, probably local within the Lower Cretaceous strata. The materials above this unconformity consist of coarse, yellow, cross-bedded sands with gravelly layers near the base, the whole presenting a darker appearance than those beneath. A similar unconformity may also be seen at one place in the first cut; here above the contact, in the base of the overlying darker sands there are large boulders of white clay. In both cuts a few feet of loose, gray, surficial sands overlie the older materials. This locality has been described by Veatch in his clay report (pp. 204, 205, Pl. 13, Figs. 1 and 2). Lower Cretaceous strata underlie practically all of Glascock County. The formation is underlain by crystalline basement rocks which are exposed in stream beds at a few places in the northern part of the county, and also at one or two places near the center of the county. It is overlain over much of the area by beds of Eocene age. The following data relating to this connty have been abstracterl 100 GEOLOGY OF THE COASTAL PLAIN (not quoted) in part from Veatch's clay report (pp. 180, 181), and in part from his unpublished notes. (See also pp. 273-274 of this rport.) On the J. Newsome property, three miles east of Gibson, on the roadway leading from Deep Creek to the Newsome residence, is an outcrop of white clay or kaolin which has an overburden of some 75 feet of Eocene sand, clay, and limestone. Borings to determine the extent of the kaolin bed showed an average thickness of 23 feet in a linear distance of 200 yards. At Jumping Gully Creek on the Gibson-Mitchell road, one mile west of Gibson, ten feet of white clay underlies unconformably 23 feet of sand and clay of Eocene age. Four miles south of Gibson, at Tompkins Ford, Joes Creek, on the Grange Road, 15 feet of white, massive, semi-indurated clay occupies an unconformable position beneath about 50 feet of clay, sand, and quartzite of Eocene age. Beneath the white clay bed is a soft clay and sand con glomerate. Twelve feet of white Lower Cretaceous clay occurs on the property of J. T. Brady, two miles south of Agricola, and ten feet of similar clay on Big Creek four miles southeast of Agricola. Exposures of granite rock occur on Joes Creek, two miles south of Beall Spring Station, and also two and one-half miles north of Mitchell. There are a few small areas in the western part of J e:fferson County, ou Ogeechee River and Rocky Comfort Creek, where Lower Cretaceous strata probably appear at the surface, but detaiied information is lacking. J. W. Stapleton, of Wrens, Ga., reports that in a well owned by him, located four miles northwest of Wrens, white clay was pene- trated from 38 to 48 feet beneath the surface. Water was obtained in white gravel and quicksand immediately beneath the clay. It is probable that the clay and the water-bearing materials immediately beneath the clay belong to the Lower Cretaceous. Prof. S. W. McCallie1 has published the record of a well located three and one-half miles southwest of Louisville, having a depth of 1,143 feet. Eocene beds were penetrated to a depth of 350 feet. Basement rock, consisting of hard, diorite schist was penetrated in the lower three feet. The materials from 350 to 1,140 feet, con- sisting of sand, clay, and hard rock, are probably of Cretaceous age, but whether this whole thickness-790 feet-belongs to the Lower Cretaceous, or whether a part of the upper portion should be referred to the Upper Cretaceous can not be determined from the available data. No Upper Cretaceous strata are known at the surface nearer than Aiken County, S. C., on the one hand, and western Twiggs County; Ga., on the other, but it does not seem improbable that beds of this age exist in this intervening region, buried beneath the over- lapping Tertiary covering. Lower Cretaceous strata underlie portions of southern Warren 1Geol. Survey of Georgia, Bull. No. 15, 1908, pp. 128-131. LOWER CRETACEOUS 101 County. The beds rest unconformably upon the uneven surface of the basement crystalline rocks, which appear at the surface in all the stream valleys. The total thickness of the terrane within the county limits is not great. Light-colored sands and coarse gravels referable to the formation are well exposed in cuts of the Georgia Railroad, three or four miles southwest of Warrenton. They rest unconformably upon deeply decayed crystalline rocks. Veatch, in unpublished notes, has described a supposed occurrence of the formation on the Georgia Railroad, three miles northwest of Norwood. The materials consist of red, pebbly sand and loam, 15 feet in thickness, resting upon deeply decayed, crystalline schist. The pebbles are for the most part subangular quartz up to three or four inches in diameter, with a small percentage well rounded. Cross-bedding was observed at one place. The deposit is believed to be an isolated remnant of Lower Cretaceous strata. Veatch also notes a deposit of coarse sand and angular gravel probably belonging to this formation at Beall Spring, eight miles southwest of Warrenton. The Lower Cretaceous terrane is present over the greater part of McDuffie County south of the Georgia Railroad, and t):1ere are a few small areas extending north of the railroad. The beds rest upon crystalline basem'lnt rocks. In the southern part of the county the Lower Cretaceous strata are overlain in disconnected areas by Eocene sediments. Streams have cut through the beds at many places, revealing the underlying crystalline rocks. Materials referable to the formation are noted by Veatch in his ciay report (pp. 200-203, abstracted, not quoted), at the following places in this county: One mile east of Thomson on the Shields property a bed of white clay ten feet thick is reported. On the Brinkley plantation, three miles southwest of Dearing, 16 feet of white kaolin blotched with purplish or pink iron stain, is reported to have been penetrated in a well. Three miles west of Dearing, on the Milledgeville public road, a bed of plastic, white clay occurs at a point locally known as "Chalk Hill". About one-half mile west of this locality 30 feet of white clay is reported to have been penetrated in a well, the top of the clay bed having been encountered 30 feet below the surface. Exposures of Lower Cretaceous clay are numerous throughout the south- eastern part of the county along Boggy Gut, Headstall, and Brier Creeks. Especial note is made of such clays on the T. J. Connell and J. F. Wb.itaker properties, four and one-half miles south of Harlem. Veatch also furnishes the following unpublished notes: "At mile-post 34, near Boneville, the base of the Lower Cretaceous consists of coarse sand containing clay and sub-angular quartz gravel. Fragments of vein quartz as much as two feet long were observed. A biotite 102 GEOLOGY OF THE COASTAL PLAIN granite is exposed in a small stream one-half mile east of this locality. The Lower Cretaceous strata at Boneville is not more than 40 feet thick, according to a well record. "On the property of Thomas Jefferson, two and one-half miles southeast of Dearing, eight feet of white and stained clay underlies unconformably 20 or 30 feet of laminated clay, probably of Eocene age." Lower Cretaceous strata are present in the southern part of Columbia County in limited areas in the vicinity of Harlem, Berzelia, and Grovetown. They rest unconformably upon crystalline basement rocks and are overlain in part by overlapping Eocene strata which in places transgress northward entirely across the Lower Cretaceous beds and rest upon the crystallines. There are good exposures of arkosic sands and white and purplish clays referable to this formation in cuts one to two miles east of the station at Grovetown. Although the contact does not appear in the railroad cuts, other exposures in the vicinity of Grovetown show the Lower Cretaceous strata to be overlain unconformably by fullers earth clay of Eocene age. This relation is well exhibited in what is known as Phinizy Gully, about one mile east of Grovetown, on the old abandoned Augusta to Wrightsboro wagon road. The following sketch shows the profound character of the unconformity. W. E. ~-,{~'=~Tss~::. k----------...,_:---200'-------~ Fig. 8. Sketch showing relation of Cretaceous and Eocene strata at Phinizy Gully, near Grovetown, Ga. Explanation of sketch. Eocene. 3. Shaly fullers earth clay with fine sand partings. Contains leaf impressions and casts of pelecypods . . . . . . . . . . . . . . . . . . . . . (Unconformity.) Lower Cretaceous. 2. Coarse, gray, argillaceous sandstone . 1. Coarse, arkosic sand . . . . . . . . Feet. 12 to 15 8 12 The following references to Lower Cretaceous beds in this county are abstracted (not quoted) from Veatch's clay report, pp. 196-200 : At the works of the Georgia Vitrified Brick & Clay Company, at Cam pania, one and one-half miles east of Harlem, 12 feet of white clay is ex- posed in a pit 100 yards northeast of the plant. As shown by other pits nearby this clay is overlain by 25 feet or more of clay and sand referable to the Eocene, (Claiborne).-(See detailed section, p. 271 of this report.) , In the old fullers earth pit on the Fiske property at Grovetown, 3 or 4 feet of white clay makes up the base of the section. It is overlain by Eocene fullers earth.-(See p. 269 of this report.) LOWER CRETACEOUS 103 At ~hillips Falls, one and one-half miles southwest of Harlem, ten feet of massive gray to bluish gray, hard clay is overlain by about 40 feet of Eocene sands and clays. The clay is underlain by Lower Cretaceous sand containing large chunks of kaolin and disseminated kaolin grains.-(See detailed section on p. 271 of this report.) In unpublished notes Veatch describes Lower Cretaceous beds at the following additional localities in this county: "One-half mile west of the section foreman's house at Forest, eight to ten feet of arkose is exposed overlain by Eocene fullers earth. "Near the 17-mile post, two miles south of Grovetown, four or five feet of white clay presumably of Lower Cretaceous age is superimposed by red and yellow sands probably of Eocene age. "On the H. Merry place, four and one-half miles southwest of Berzelia, on Sandy Run Creek, ten feet or more of Lower Cretaceous clay and sand was observed beneath 90 feet of Eocene sands and clays.-(See detailed section p. 291 of this report.) At the lignite pit of the Georgia Lignite Mining Company, three miles south of Grovetown, coarse quartz sand containing white clay was encountered at the bottom of a shaft beneath the lignite. The coarse sands are referred to the Lower Cretaceous, while the overlying lignites are believed to belong to Eocene.-(See detailed section, p. 270 of this report.) Coastal Plain deposits coYer all o Richmond County except a small area in the extreme north. Lower Cretaceous strata outcrop in a belt several miles wide extending rom Augusta and south o Augusta westward to the county line, and also farther south in the county along the valley o Spirit Creek. The ormation rests unconformably upon crystalline rocks which outcrop in the northern part o the county. The Lower Cretaceous beds pass to the southward beneath overlapping Eocene strata, the latter covering nearly all o the southern part of the county. There is also a long, narrow area o Eocene strata capping the ridge between Butlers and Spirit creeks, and extending northwestward to Grovetown in Columbia County. The hills to the west anYoods back from the bluff for about. one hundred yar Chattahoochee Riter, 31 1/4 miles below Columbus, Ga.> left bank. Upper Cretaceous Ripley formation (Cusseta sand member). 4. Red and yellow, unconsolidated sand, containing small pebbles and thin limonite crusts . . . . (Typical marine beds) 3. Gray, calcareous, marine sand with some fossils Eutaw formation (Tombigbee sand member). 2. Gray, calcareous, glauconitic sand with indurated, nodular, concretionary layers several "feet apart, about . . . . . . . . . . . . . . . . . . . . . 1. Gray, calcareous, finely arenaceous, fossiliferous clay, about . . . . . . . . . . . . . . . . . . Feet. 100 50 35 10 Layers Nos. 1, 2, and 3 of the preceding section constitute part~. of Veatch's "Bluffto\vn marl." Near the top of layer X o. 3 \vere obtained Ostrea plumosa Mortm1, a young individual of Bxogyra, with costae, and Anomia sp. nov. (cf. new species from Snmv Hill, N. 0.). The fossils listed below were obtained from layers Nos. 1 and 2; but the principal fossil bed is layer No. 1. The Tombigbee sand and the overlying Ripley formation are conformable, and the materials above and below the dividing line, as indicated in the above section, are very similar physically. The division is made upon paleontologic grounds, and principally upon the evidence of a fairly typical though small specimen of Exogyra, with costae, in layer No. 3, \vhich in western Alabama and eastern central Mississippi is not known to occur so low as the Tombigbee sand. One or two species in layers Nos. 1 and 2 are relied upon as evidence that this portion of the section should be referred to the Tombigbee sand. A future more perfect understanding of the vertical range of the included forms may establish the necessity of raising or lowering this line of division. 136 GEOLOGY OF THE COASTAL PLAIN Chattahoochee River, bluff at Blufftown, Stewart County, Ga., 31% miles below Colu'mbus, Ga. Collectors, T. W. Stanton and L. W. Stephenson. Less than 45 feet above zero water level: ' Locality Nnmbers T.w.s.l L.w.s.l L.W.S. 844 5392 fA05 Vermes: Serpula sp. (nearly straight tube) X Hamulus major Gabb .. X Mollusca: ~ucula percrassa Conrad X Nucula eufalensis Gabb Leda sp. . . .. . I Cucullaea carolinensis Gabb . . . X Trigonoarca sp. (young individual ?) Perrisonota protexta Conrad Breviarca umbonata Conrad B;eviarca saffordi (Gabb) ? ~emodon sp. nov. . . X X Area sp.... X Barbatia (Polynema) lintea Conrad X Glycymeris? sp. nov. ? X X Gervilliopsis ensiformis (Conrad) X X Perna sp. nov. X X Inoceramus sp. . X X X Inoceramus sp. (large cast) X Pteria petrosa (Conrad) X Ostrea plumosa Morton .. x? x Ostrea sp. nov. (same as sp. Banks Landing, ~- C.) .. X Gryphaea sp. (small) .. X Exogyra ponderosa Roemer .. X X X Trigonia eufauensis Gabb . X x? Pecten burlingtonensis Gabb X Pecten argillensis Conrad ? .. x? Lima sp. ( cf. reticulata Forbes) X X Anomia argentaria Morton X I Anomia sp. nov. (same as sp. nov. from Hill, N. C.) Snow: X X X Liopistha sp. . X Veniella conradi (Morton) Etea carolinensis Conrad .. Venericardia ? I X X X .I X X X .I X ~o:n~a~) I Crassatellites sp. (cf. C. carolinensis Arena carolinensis Conrad X : : X X X Lucina sp. nov. ? . . . . . X X X Cardium alabamense Gabb Cardium eufaulense Conrad . Cardium spillmani Conrad . I X X I X . I X X Cardium (two undetermined species) Isocardia sp. :I X X Cyprimeria depressa Conrad I X X X Aphrodina regia Conrad ? (young indiv.) . I X X GEOLOGY OF T HE C0 .4. S 7'A. L PLA I N OF GE ORGTA.. PL.lTE }I.I/1. B. CUT Or SEABOARD AIR LINE RAILWAY, THREE ::UJT, ES EAST OF CUSSETA , SHOWY ' 0 WEA'l'HERED A ' 0 AND LA:\1INATED LAY BEDS OF 'J'HE C . E'J'A AND MEMBER OF THE RIPLEY FORMATION. EUTAw' FORMATION 137 Locality Numbers Aphrodina sp. ? . . . . . . . . . . Cyclothyris alta Conrad ? . . . . . . . Legumen planulatum (Conrad) ..... . Linearia sp. ( cf. L. carollnensis Conrad) . Linearia sp. . . . . . . . . . Leptosolen biplicata Conrad . Schizodesma appressa Gabb .. Corbula crassiplica Gabb . . Corbula carolinensis Conrad Corbula (otner species) ... Dentalium ripleyanum Gabb Cadulus obnutus Conrad . Astralium ? . . . . . . . . Capulus ? . . . . . . . . . . Lunatia obliquata M. & H. . Gyrodes, sp. . . . . . .' . . . Turritella quadrilira Johnson .. Turritella sp. . . . . . . . . . . Turritella sp. . . . . . . . . . . Pterocerella tippana (Conrad) ? Anchura decemlirata Conrad ? . Anchura sp.... Nautilus sp. nov. (large) Placenticeras ? . Scaphites ? . Arthropoda: Crabs claws . Vertebrata: Lamna texana Roemer Vertebrae of fish . . . T.w.s.i L.w.s. \ L.W.S. 844 5392 6405 :\ X X X X X X X I X X X ~ X X :I X X IX X IX I X X X X X I X IX I X I X X I X IX IX I X I . I I X :I I X \ X IX IX . I j I IX I X I X I I I X I I I I I X . I X X .About one mile below Blufftown, in materials similar to those composing layers Nos. 1 and 2 at that place, the :following species were collected: Locality No. 5393.-0ne mile below Blufftown, Ga., 32 miles below Columbu~, Ga. L. W. Stephenson, collector. Mollusca: Cucullaea carolinensis Gabb ? Ostrea sp. Pecten sp. Etea carolinensis Conrad Aphrodina regia Conraa ? (young) Legumen planulatum Conrad From Blufftown to Omaha, 37 miles below Columbus, the materials appearing in the bluffs are similar to those in layers Nos. 1 and 2 o:f the section at Blufftown. They consist o:f compact, calcareous sands and clays with indurated, calcareous layers two to 10 :feet. apart. These layers are nearly horizontal, but are seen to undulate slightly, in places to the extent o:f several :feet o:f vertical distance. There is, 138 GEOLOGY OF THE COASTAL PLAIN however, a slight general dip down stream, amounting perhaps to several feet to the mile. About one-eighth of a mile below the bridge of the Seaboard Air Line Railway at Omaha, the following fossils were colleCted in a layer five to eight feet above water level: . Loc. No. 539.4-.-0ne-eighth mile below Omaha Bridge ( S. A. L.) and about 37 miles below Columbus, Ga. L. W. Stephenson, collector. Vermes: Serpula sp. Mollusca: Nucula percrassa Conrad ? Cucullaeae ap. Nemodon ? Trigonia eufalensis Gabb ? Pecten burlingtonensis Gabb Cymella bella Conrad Veniella conra'di (Morton) Crassatellites sp. Cardium ( Trachycardium) alabamense Gabb ? Cyprimeria depressa Conrad Cyclothyris alta Conrad Cyclothyris carolinensis Conrad ? Legumen planulatum Conrad Corbula carolinensis Conrad Turritella trilira Conrad Tudicla (Pyropsis) perlata Conrad ? Gyrodes ? Vertebrata: Otodus appendiculatus Agassiz i\1 arine materials with indurated, calcareous, concretionary layers, referable to this division, were observed for two miles below Omaha, to the bend to the left below the mouth of Hatchachubbee Creek, 39 miles below Columbus. At the latter place there is a decided reverse dip to the stratification planes amounting to several degrees. The Tombigbee sand member is believed to pass finally beneath water level between this point and Florence, three miles below, for at the latter place beds referable to the Ripley formation make up the entire Cretaceous portion of the bluff. East of Chattahoochee River.-The Tombigbee~member of the formation outcrops in a belt only a few miles wide, extending from Chattahoochee River in a northeasterly direction through Chattahoochee County into :Marion County. In the latter county the member probably loses its identity as a massive, calcareous, marine formation, by horizontal mergence into coarser sands and clays of shallow-water origin. In Chattahoochee County the member has been studied at several places east of the river. The following section \Yas made along the Columbus-Lumpkin road, just north of Jamestown: Section Columbus-Lumpkin Road, northward-facing slope of Sa,nd Branch, 18 miles south of Columbus, near Jamestown postoffice. Upper Cretaceous. Ripley formation (Exogyra ponderosa.zone). 12. Reddish, massive, medium-grained, ferruginous, marine sand, partially indurated . . . . . . . Feet. 5 EUTAW FORMATION 13~ 11. Coarse, reddish and yellowish, loose sand . . . . 3 10. Fine, micaceous, unconsolidated sand, streaked with yellow and purple . . . . . . . . . . . 20 9, Dark, laminated, finely micaceous clay . . . . . 6 in. to 1 8. Fine, micaceous, greenish gray, argillaceous, mar- ine sand filled with soft pelecypod casts, with some lenses of unfossiliferous, gray sand, and a thin layer of dark, laminated clay, two feet above base . . . . . . . . . . . . . . . . . . 10 7. Greenish gray, argillaceous sand with numerous small, short, interlocking clay laminae . . . . 6 6. Dark, finely-arenaceous, thinly laminated clay . 12 Eutaw formation (Tombigbee sand member, Exogyra ponderosa zone). _ 5. Greenish gray, argillaceous, massive sand, with numerous soft casts . . . . . . . . . . . . . . 5 4. Dark, laminated, micaceous clay interstratified with lenses and layers of light greenish gray, fine, micaceous sand reaching a maximum thick- ness of three feet. Some fossil casts . . . . . 17 3. Dark greenish gray, extremely micaceous sand with occasional calcareous concretions. Con- tains an abundance of decayed fossil shells . . 11 2. Similar to layer No. 3, but light greenish gray in color. Contains soft shells . . . . . . . . . . 10 1. Poorly exposed to base of hill, but consists for the most part of greenish gray, massive, non-fossil- iferous marine sand . . . . . . . . . . . . . . 22 The dividing line between the Eutaw and Ripley formations has been placed rather arbitrarily at the point indicated in the above section, and future work may demonstrate the necessity of placing it at some other level. The fossils given in the list below were obtained from layers Nos. 2 and 3. Locality No. 6411 a-b.-Columbus-Lumpkin road, south side, about 18 or 18lj2 miles sauth of Columbus, Ga. L. W. Stephenson, col~ lector. Mollusca: Nucula sp. (cf. sp. nov. from Snow Hill, N. C.) Exogyra ponderosa Roemer Trigonia ,eufalensis Gabb Anomia sp. nov. (same as sp. nov. from Snow Hill, N. C.) Veniella sp. (cf. species from Hodges Mill, S. C.) Cyprimeria depressa Conrad Cymbophora lintea (Conrad) Schizodesma appressa Gabb ? Corbula carolinensis Conrad Turritella quarrilira Johnson Another exposure of the member is furnished by a cut of the Seaboard Air Line Railway, two and one-half miles northwest of Cusseta at the 16th milepost (south of Columbus). The materials consist of about 10 feet of dark gray, marine sand, with a layer of nodular lime concretions near the base. (See plate XII, B, opposite page 128.) The lower two or three feet, including the concretions, is fossiliferous. The determinable forms are listed below: 140 GEOLOGY OF THE COASTAL PLAIN Locality No. 5379.-Two and one-half miles northwest of Cusseta, Ga., in cut of Seaboard Air Line Railway, Milepost 16. L. W. Stephenson, collector. Mollusca: Cucullaea sp. Inoceramus sp. Inoceramus sp. Breviarca sp. Exogyra ponderosa Roemer Exogyra ponderosa var. erratis- tata Stephenson Pecten sp. nov. (cf. sp. nov. from Snow Hill, N. C.) Anomia argentaria Morton Liopist::ha alternata Weller Veniella conradi Morton Etea carolinensis Conrad Lucina glebula Conrad Cardium sp. (cast) Cardium alaobamense Gabb ? Cyprimeria depressa Conrad Aphrodina sp. Corbula carolinensis Conrad Turritella trilira Conrad One-half mile nm-thwest of Cusseta on the same railroad, the following forms were obtained in the form of casts, from a black clay at the base of a cut: Locality No. 5380.-0ne-half mile northwest of Cusseta, Ga., in cut of Seaboard Air Line Railway. L. W. Stephenson, collector. Mollusca: Cymella bella Conrad :Schizodesma appressa Gabb Undetermined pelecypod casts This horizon is near the top of the Tombigbee sand and probably occupies approximately the same stratigraphic position as the fossiliferous layers Nos. 2 and 3, in the section near Jamestown described on p. 114 of this report. The Tombigbee sand, as such, has not been traced with certainty far beyond the boundary of Chattahoochee County into Marion County. Veatch has noted an exposure of black micaceous clay near the western border of the latter county which is pelieved to represent this division. It is believed that the massive, marine beds disappear in Marion County by horizontal mergence into irregularly bedded sand and clays of shallow-water origin. CORRELATION The present attempt to establish the age and geological position of the beds here referred to the Eutaw formation, in terms of better known sections outside of Georgia, is made partly on the basis of their contained animal and plant remains, and partly on the basis of their stratigraphic position with reference to overlying beds, the paleontologic characters of which are such as to permit of more accurate correlations. The studies furnishing the paleontologic data for correlation have been of a preliminary character and it is to be expected that the exhaustive studies of the fauna of the region soon to be prosecuted will EUTAW FORMATION 141 show the necessity for many changes in nomenclature of the fossils, and will reveal some errors in the determinations of genera and species. It is also to be expected that some species now regarded as restricted in range within certain limits will be found to occur in higher or in lower horizons. But this lessening of the number of restricted forms will probably be offset by the discovery of new restricted forms, and by the recognition of specific differences in forms now regarded as having wide vertical ranges. It is believed, however, that such changes as are found necessary will be of minor importance as regards their effect upon the major conclusions reached through these preliminary studies. The lists of Eutaw species from Chattahoochee River and from Georgia, given on preceding pages, fall into two sets: first, those from horizons in the lower 100 or 150 feet of the formation; and second, those from the Tombigbee sand member which makes up the upper 120 feet of the formation. The two sets will be considered separately. Basal beds of the formation.-The following species of invertebrate fossils, 16 in number, have been identified from the beds composing the lower 100 or 150 feet of the formation: Nucula percrassa Conrad Perna sp. nov. Ostrea cretacea Morton Ostrea sp. nov. (cf. sp. nov. from House Bluff, Alabama River.) Ostrea sp. nov. ? (aff. 0. lugubris Conrad) Exogyra upatoiensis Stephenson Pecten sp. nov. (same as at Snow Hill, N. C.) Anomia sp. nov. (same as at Snow Hill, N.C.) Pholadomya sp. nov. Etea carolinensis Conrad Cyprimeria depressa Conrad Baroda sp. nov. Leptosolen biplicata Conrad Cymbophora lintea (Conrad) 'Corbula carolinensis Conrad Placenticeras sp. (aff. P. gultdalupae Roemer) Of the species listed the following five range upward throngh the Tombigbee sand and the Ripley formation, and are, therefore, of no value in close correlation: Nucula percrassa Conrad Etea carolinensis Conrad Cyprimeria depressa Conrad Leptosolen biplicata Conrad Cymbophora Iintea (Conrad) Corbula carolinensis Conrad ranges up into but not above the zone of Exogyra ponderosa of the Ripley formation. In North Carolina Corbula carolinensis is found in the invertebrate-bearing beds of the upper part of the Black Creek formation. In New Jersey a nearly related, if not identical form, Corbula bi,sulcata Conrad, occurs in the Magothy formation ("Cliffwood clay"), and in the :Merchantville clay marl and the Woodbury clay (basal formations of the Matawan). In western Alabama it occurs in the Ent~w formation at Finches 142 GEOLOGY OF THE COASTAL PLAIN Ferry, and in Mississippi :five and one-half miles east of Booneville, in glauconitic sands which fall within the zone of Exogyra ponderosa. The species is of value therefore, only as indicating an age greater than that of the extreme basal beds of the zone of Exogyra costata. In the Chattahoochee region Ostrea cretacea Morton occurs spar- ingly in the overlying Tombigbee sand. It is abundant, however, in the Tombigbee sand in central and western Alabama. In North Carolina the species occurs abundantly at Kerrs Cove, Black River, and sparingly at a number of other localities in the Black Creek for- mation. From the evidence furnished bv other forms it is believed that these Black Creek localities corresp~nd in stratigraphic position to that part of the zone of Exogyra ponderosa which lies above the Tombigbee sand in the Chattahoochee region. In New Jersey the species occurs in the Magothy formation. This form appears, there- fore, to have about the same range, and consequently the same sig- nificance, as Oorbula carolinensis. Pecten sp. nov. and Anomia sp. noY. range up through the Tom- higbee sand into the basal beds (Exogyra ponderosa zone) of the Rip- ley formation. Both occur in the marine invertebrate-bea-ring beds of the Black Creek formation in North Carolina. Ostrea sp. nov. (probably same as sp. nov. from House Bluff, Alabama River) is questionably referred to an undescribed species occurring in abun- dance at the top of the Tombigbee sand at House Bluff, Alabama River, Ala. Perna sp. nov. ranges up into the Tombigbee sand. This species is not known outside of the Chattahoochee region, although representatives of the genus occur in the Black Creek formation of North Carolina. Ostrea sp. nov.? (aff. 0. lugubris Conrad) is new to the ea1:1tern Gulf Cretaceous. Ostrea lugubris Conrad/ with which it is compared, is known only from the Eagle Ford formation of Texas. Placenticeras sp. (c. P. guadalupae Roemer) appears to be closely related to, but is not identical with PlacPnfir.rras guadalupae Roemer, a form common in the Tombig-hee sand (M ortoniceras horizon), and in the upper part of the Austin chalk of Texas. Exogyra upatoiensis Stephenson,' Philadomya sp. nm'., and Baroda sp. nov. have not been fonnd outside of the basal beds of the Eutaw formation in the Chattahoochee region. To summarize, five of the 16 species range upward into the Exogyra costata zone of the eastern Gnlf region, and 11 are restricted below that zone and its equivalents. Of the 11 reRtrictAd forms four range upward into the basal beds of the Ripley formation (Exogyra 'Since this report was written, good specimPns of an oystPr closely related to Ostrea lugubris Conrad, and good spPcimPns of Ewoqyra upntoien.i Stephenson, have been recognized In well samples ohtainPd from a deep well at Charleston, S. C., at 1lepths of between 1,974 and 2,007 feet. The horizon from which they were taken 1loubtless 'corresponds In age to the horizon which has yielded the fauna of the basal beds of the Eutaw formation in the Chattahoochee region. EUTAW FORMATION 143 ponderosa zone), two range into thE! Tombigbee sand, and five are restricted to the basal Eutaw beds. The basal Eutaw beds lack entirely the species which are regarded as characeristic of the Exogyra costata zone. They also lack certaiu species which are common in the Exogyra ponderosa zone, which includes the Tombigbee sand and a part of the overlying Ripley formation, such as Exogyra ponderosa Roemer and Gryphaea aucella Roemer. The five forms restricted to the beds of this formation, since they are all new to science, afford but little positive evidence of the age of the terrane. However, the beds in which they are found are known to occupy a position stratigraphically lower than any other marine invertebrate-bearing beds thus far discovered in the eastern Gulf region, and, for this reason if for no other, the fauna must be regarded as the oldest of its kind known in the region. The new species, Exogyra upatoiensis Stephenson, which occurs in the marine beds near the base of the formation, has a markedly different surface sculpture from the other known species of this genus in the Atlantic and Eastern Gulf Cretaceous. The presence of this species and the presence of the fluted oyster, related to Ostrea lugubris Conrad, which occurs in the Eagle Ford formation of Texas, may perhaps be considered paleo'ntologic evidence of the greater age of the fauna. Since the conditions of the preservation of one species of oyster are as favorable as they are for the preservation of any other species of the same family, this i1ew species of Exogyra and the fluted oyster would be expected to appear in the collections from the overlying Tombigbee sand if, in this region, they had lived contemporaneously with the oyster, Exogyra ponderosa Roemer, which is common in that terrane. From the range determinations as above stated, the following conclusions have been deduced: The fauna present in the basal beds of the Eutaw formation possesses elements in common with the Cretaceous faunas of. higher horizons in the same region; however, in passing from this basal horizon to the successively higher horizons the number of common species diminishes. Although showing these relationships the fauna contains elements distinct from anything known in the higher horizons. Comparing this fauna with Cretaceous faunas to the northward it is found that it bears about the same relationship to the invertebrate fauna present in the upper part of the Black Creek formation of the Carolinas that it does to the fauna of the basal beds of the Ripley formation (Exogyra ponderosa zone) in the Chattahoochee region. The basal Eutaw beds are therefore lower, stratigraphically, than the invertebrate-bearing beds of the Black Creek formation, and, in the opinion of the writer, correspond approximately to the non-invertebrate bearing beds of that formation. The actual evidence for a comparison of the basal Eutaw fauna with 144 GEOLOGY OF THE COASTAL PLAIN the Cretaceous faunas of New Jersey is slight, but combined with evidence furnished by the faunas from overlying horizons there seems t" be sufficient grounds for correlating the containing strata approximately with the Magothy formation. The invertebrate-bearing basal Eutaw beds of the Chattahoochee region are represented to the 'Yestward in Alabama and Mississippi by corresponding basal Eutaw strata in which no well-preserved invertebrates have as yet been discovered. Fossil plants have bee)l obtained at several horizons in that part of the Eutaw formation below the Tombigbee sand member. E. W. Berry, who studied them; recognized 27 species from the terrane. He furnishes the following statements, quoted from an unpublished man- uscript on the fossil plants of Georgia, giving his views of the significance of the plant remains in correlation: It is clear that the flora of the Eutaw formation of Georgia is of the same age as the Magothy flora of the northern Coastal Plain and the Black Creek flora of the Carolinas. It has much in common with the much more extensive Tuscaloosa flora of western Alabama, and these beds of Georgia are probably homotaxial with more or less of the upper Tuscaloosa of western Alabama. Whether the Tuscaloosa flora of western Alabama is essentially a unit and accidents of preservation account for its greater richness, or whether the plant beds of this fromation in northwestern Alabama are appreciably older, is a question which can not be answered positively until the flora is critically studied. The flora of the Eutaw in Georgia is strictly comparable with that of the upper Tuscaloosa of western Alabama, as for example, the flora of which a few species are preserved near Havana in Hale County, Ala., and which lies on the border line between the Tuscaloosa and Eutaw formations, as delimited in that area by Professor Smith, the State Geologist. The evidence furnished by the plants as interpreted is at least in part agreement with that afforded by the invertebrates, although in the opinion of the present writer the Magothy flora, with which Georgia flora is compared, persisted to a later time in the region of the Carolinas, and,. as will be shown later, also in Georgia, than in New .Tersey; for the fauna present in the upper part of the Black Creek formation seems to indicate clearly that this terrane includes representatives of both the Magothy and the overlying Matawan formations. The flora in the upper part of the Tuscaloosa formation in Hale County, Ala., with which Berry compares these Georgia species, oc- curs in beds the lithologic character of which would admit of their l:>eing considered as belonging to either the upper part of the Tusca- loosa formation, or to the basal portion of the overlying Eutaw for- mation. The following vertebrate species, all sharks, have been collected from the Broken Arrow Bend exposure near the base of the Eutaw formation: EUTAW FORMATION 145 Corax falcatus Agassiz Lamna texana Roemer Otodus appendiculatus Agassiz As these species are all known to have a wide stratigraphic range_ .they have no value in close correlation. Tombigbee sand member.-The beds on Chattahoochee River, here referred to the Tombigbee sand, are so correlated chiefly on the evi- dence of certain species of invertebrates, but in part upon their phy- sical characters and relations. Lithologically, the materials agree in all essential respects with those of the type region in Mississippi, al- though the content of lime is greater. The formation is immediately underlain by sands and clays containing a considerable percentage of lignite and in this respect the lower relations are in exact agreement with those of the type region. In the type region the Tombigbee sand is immediately overlain by the Selma chalk. In the Chatta- hoochee region the Selma chalk is not present as such, but is represented by marine sands and clays, the bc~ds immediately abort> t}w Torribigbee sand being of marine origin and similar to the beds of the Tombigbee member itself. The Tombigbee sand member forms the basal portion of the zone of Exogyra ponderosa of the 1Jpper Cretaceous deposits, of which the lower one-third or one-half of the Ripley formation forms the upper part. Omitting a number of questionably identified species, 57 species of invertebrates haYe been identified from the Tombigbee member in the Chattahoochee region as follows: 1. Serpula sp. (nearly straight tube) (Rc) 2. Hamulus onyx Morton (Rc, Rp) 3. Hamulus major Gabb 4. Nucula percrassa Conrad (Rc, Rp, Eb) 6. Nucula eufalensis Gabb (Rc) 6. Nucula sp. (cf. sp. nov. from Snow Hill, N. C.) 7. Leda longifrons Conrad (Rc) 8. Perrisonota protexta Conrad (Rc) 9. Cucullaea carolinensis (Gabb) (Rp) 10. Breviarca umbonata (Conrad) 11. Nemodon sp. nov. (Blufftown, etc.) 12. Barbatia lintea Conrad (Rp) 13. Gervilliopsis ensiformis (Conrad) (Rc) 14. Perna sp. nov. (Broken Arrow Bend, etc.) (Ec) 15. Ostrea plumosa Morton (Rc, Rp) 16. Ostrea cretacea Morton (Eb) 17. Ostrea sp. nov. (same as at Blue Banks Ldg., N. C.) 18. Gryphaea a'lcella Roemer 19. Exogyra ponderosa Roemer 20. Exogyra ponderosa var. erraticostata Stephenson (Rp) 21. Trigonia eufalensis Gabb (Rc) 22. Pecten quinquecostatus (Sowerby) (Rc) 23. Pecten simplicius Conrad (Rc) 24. Pecten burlingtonensis Gabb (Rp) 146 GEOLOGY OF THE COASTAL PLAIN 25. Pecten sp. nov. (same as sp. nov. from Snow Hill, N. C.) (Rp. Eb.) 26. Lima reticulata Forbes (Rc) 27. Anomia argentaria Morton (Rc, Rp) 28. Anomia sp. nov. (same as sp. nov. from Snow Hill, N. C.) (Rp, Eb) 29. Cymella bella Conrad (Rc) 30. Liopistha alternata Weller 31. Liopistha sp. (aff. F. alternata Weller) 32. Veniella ,conradi (Morton) (Rc, Rp) 33. Etea carolinensis Conrad (Rc, Eb) 34. Vetericardia crenalirata (Conrad) (Rc) 35. Crassatellites carolinensis Conrad ? (Rp) 36. Arena carolinensis Conrad 37. Lucina glebula Conrad (Rp) 38. Cardium eufaulense Conrad (Rc, Rp) 39. Cardium spillmani Conrad (Rc) 40. Cardium alabamense Gabb (Rc) 41. Cyprimeria depressa Conrad (Rc, Rp, Eb) 42. Cydothyris alta Conrad (Rp) 43. Legumen planulatum (>Conrad) (Rc, Rp) 44. Linearia metastriata Conrad (Rc) 45. Leptosolen biplicata Conrad (Rc, Rp, Eb) 46. Cymbophora lintea (Conrad) (Rc, Rp, Eb) 47. Schizodesma appressa Gabb 48. Corbula crassiplica Gabb (Rc) 49. Corbula carolinensis Conrad (Rp, Eb) 50. Dentalium ripleyanum Gabb (Rc) 51. Dentalium sp. nov. (same as sp. nov. from Owl Creek, Miss) 52. Cadulus obnutus (Conra,d) (Rc) 53. Lunatia obliquata Meek and Hayden (Rc) 54. Turritella trilira Conrad (Rc) 55. Turritella quadrilira Johnson 56. Nautilus sp. nov. (large, Blufftown, etc.) 57. Mortoniceras sp. nov. (cf. M. texanum Roemer) Of the 57 species, 30, marked (Rc) in the list, have been recog- nized in the zone of Exogyra costata of the Ripley formation in the Chattahoochee region; 20, marked (Rp), in the zone of Exogyra ponderosa of the Ripley formation; and 10, marked (Eb), in th0 underlying basal beds of the Eutaw formation. The questionably identified form, Cmssatellites carolinensis Conrad, although not cer- tainly identical with the species described by Conrad from Snow Hill, belongs to a flat type of the genus which does not appear to range above the zone of Exogyra ponderosa, and is included in the preceding list because of the value in correlation which this restriction in range gives it. The 30 species which haYe been found as high as the zone of Exo- gyra costata need not be further considered since their great vertical range rem1ers them of no value in the finer discrimination of age re- lationships. Twenty-seven of the 57 species are in this region re- stricted belO\Y the zone of E:rogyra r;ostata of the Ripley formation. The table giwn below indicates the range of these 27 species, both within and "'ithont the Chattahoochee region. EUTAW FORMATION 147 Table showing ranges of the Tombigbee species which in the Chattahoochee region are restricted below the zone of Exogyra costata. ' i " I .. """' s. " E -5 " "' '"" .s g .:< . "" "til .0p ..0.. ~ i.:,ii ~ ~ ..c..c ~.! ~< ~~ ~'.s E~ .';:"(:~l .:soso :'o:";:"..., t:'biJ...: -5"50 '0~ :0:;0:'->.g0.. ~.,oo >..C: ...8,8" -~ a";' ~ E ...."c., 0 .,:g..: " E. .... ~ """" !!:"& " .s~ o..C Ng "~.'.0c "" .e....s. " ......, ..,., >~igl" ooO _., ,., "'" ""'"' ,.,..., ~~~ "l'l..~c g:._.oc .. ..c ... ""' ~"..0c ~"~ ll1 ~ ~~-~ .s,8";;;~: s..c- ";'.]Sf~: +J : N~0.~.c."~..'. .e.,~o.;;~: ..c 0 gj .o.. .,, .~+J Q,) ..C~"'"C .... ~~s ~_g >< N ~ 0 0 N .E l! 0 ;": 0 >< ~ .".' ].". 0 -.."5.. 0 :".. ..0E.. 0"""."' .""9"' ll1 >. " ~ .."... !!: z " '0 .:.s".3. ..0.. ..c ~ ~ .>. .."""..'. !!: z " '0 "~ ' .~"s ~ Hamulus major Gabb Nucula sp. nov. (cf. sp. nov. from Snow ! I I X I I I I' X I I Hill, N. C.) X I Cucullaea carolinensis Gabb Breviarca umbonata (Conrad) X !I I x? I Nemodon sp. nov. ( Blufftown, etc.) Barbatia lintea Conrad I X x? I Perna sp. nov. (Broken Arrow Bend, etc.) X i. i Ostrea cretacea Morton Ostrea sp. nov. (same as sp. nov. from X X X: X I X I X X X Blue Banks Landing, N. C.) .. Gryphaea aucella Roemer Exogyra ponderosa Roemer Exogyra ponderosa var. erraticostatal Stephenson . . . . . . . Pecten burlingtonensis Gabb Pecten sp. nov. (same as sp. nov. froml : X ' X X X I I X I I X; i X iX X X X I X I x' I X X I xz Snow Hill, N. C.) ... X X X X Anomia sp. nov. (same as sp. nov. from I ! Snow Hill, N. C.) . . . . . . . . . . . j X Liopistha alternata Weller . . . . . . . X X X L1i~;r~h~ s~- _n~~- _c~ff-. ~- _a~te_r~a~a _':e~- ! X : ' I X x" Crassatellites carolinensis Conrad 1 : Arena caro!inensis Conrad Lucina glebula Conrad i .. ~,; Cyclothyris lata Conrad Schizodesma appressa Gabb I I I Corbula carolinensis Conrad Dentalium sp. nov. (same as X X xi x? X x? X ! ' X' i It I X I X x? I X X X X XX X I X x4 X xs from Owl Creek, Miss.) I Turritella quadrilira Johnson Nautilius sp. nov. (large, Blufftown, etc.) 1 ' II X X I X I X I X XG I Mortoniceras sp. (aff. and M. delawarensis M. texana Morton) ~~e~e.rl I I I i X I I I I x' 'Occurs m the Marshalltown clay-marl of the Matawan formatiOn. 20ccurs in the Merchantville clay-marl, the Woodbury clay, and the Wenonah Rand of the Matawan formation. occurs in the MerchantvillP clay-marl of the Matawan formation. occurs in the Wenonah sand of the Matawan formation. 'Probably same as Gnrbula bisulcata Conrad which occurs in the Magothy formation, and the Merchantville clay-marl and the Woodbury clay of the Matawan formation. occurs in the Woodbury clay of the Matawan formation. 'Occurs In the Merchantville clay-marl of the Matawan formation. 148 GEOLOGY OF THE COASTAL PLAIN Of the 27 species given in the table 10 occur in that part of the overlying Ripley formation included within the zone of Exogyra ponderosa, five occur beneath the Tombigbee sand in the basal beds of the Eutaw formation, and 15 are restricted to the Tombigbee sand member. To the westward of the Chattahoochee region in Alabama and Mississippi, seven of the 15 restricted species ar~ known to occur in the M ortonicems sub-zone of the Tombigbee sand, seven are known in that part of the zone of Exogyra ponderosa overlying the Mortoniceras sub-zone, and two in the zone of Exogyra costata (Ripley formation of northern Mississippi). The small number of forms common to the Tombigbee sand of the Chattahoochee region, and to the same member to the westward in Alabama and Mississippi, is to be explained by the fact that in the Chattahoochee region the member. is far more prolific in species than elsewhere in the eastern Gulf region; and this palentologic difference appears to be reflected in the lithology, in that the Tombigbee of the Chattahoochee region contains a much higher percentage of calcite than does the typical Tombigbee to the westward. The forms that are believed to indicate the correspondence in age of the beds under consideration with the Tombigbee sand to the westward in Alabama, and in the type region in Mississippi, are the following: Liopistha alternata Weller, Nautilus sp. nov. (large), and JJ!Iortoniceras sp. (a:ff. M. texana Roemer). These forms are not known above the M ortoniceras sub-zone in the region, and the Nautilus and M ortoniceras are distributed generally in this horizon from Montgomery, Ala., to Aberdeen, Miss. It i~ ennsidered probable that the genus Mortoniceras does not occur in the Atlantic and Gulf Coastal Plain in beds higher than this horizon. Of the 15 species restricted to the Tombigbee sand in the Chattahoochee region, seven occur in the invertebrate-bearing beds forming the upper part of the Black Creek formation of the Carolinas, and none in the Peedee sand. The three specimens given above as characteristic of the Tombigbee sand, however, have not been found in the Black Creek beds, and their absence together with the fact that the Black Creek fauna corresponds closely to that of the overlying Exogyra ponderosa zone of the Ripley formation in the Chattahoochee region, is taken as evidence that the Tombigbee sand is slightly lower stratigraphically than the invertebrate-bearing Black Creek beds, or, in other words, that it is represented by a part of the non-invertebrate, bearing beds of the Black Creek formation below the beds carrying invertebrates. Of the 15 forms restricted to the Tombigbee sand member in the RIPLEY FORMATION 149 Ghattahoochee region, two occur in the JYiagothy formation and four in the Matawan group of New Jersey. Of the four occurring in the Matawan group one, Liopistha alternata: weller, occurs only in the Merchantville clay marl, the basal formation of the group. Mortoniceras is represented in the New Jersey Cretaceous by M ortoniceras delawarensis (Morton), which is restricted to the Merchantville clay marl. The presence in this formation of Liopistha alternata Weller, and the presence of Mortoniceras which in the eastern Gulf Cretaceous is not known to range above the Tombigbee sand member, are considered evidence that the formation is approximately synchronous with the Tombigbee sand member of the Eutaw formation. It will be observed that not one of the 15 restricted forms occur in the Monmouth formation of New Jersey. Three species of vertebrate animals have been recognized from the Tombigbee sand of the Chattahoochee region. These are teeth of the sharks, Gorax falcatus Agassiz, Lamna texana Roemer, and Otodus sp.? The two former are wide-ranging forms and are of no correlative value, and the latter is not sufficiently well identified for its value in correlation to be known. The conclusions deduced from the above statements of range may be summarized as follows : The Tombigbee sand of the Chattahoochee region while containing many species in common with the overlying Ripley beds, nevertheless contains a few forms of restricted vertical range and extended geographic range, possessing great value in close correlation. On the evidence of these few forms the Tombigbee sand member of the Eutaw formation in the Chattahoochee region is correlated with the Tomhigbee sand of the type region in J\ississippi, and especially with the M ortoniceras sub-zone of that member. Referred to the Carolina Cretaceous the member is believed to be synchronous :with a portion of the Black Creek formation beneath the invertebrate-bearing beds of ' that formation. In New Jersey the Merchantville clay marl is believed approximately to represent the Tombigbee member. A diagrammatic representation of the age relationships of the Eutaw beds of the Chattahoochee region to Cretaceous deposits else. where in the eastern Gulf region and the Atlantic Coastal Plain, is given in Plate V. RIPLEY FORMATION NAME The name Ripley is derived from the town of Ripley, in Tippah County, Miss., and was originally proposed as the name of a geologic division by Dr. Eugene W. Hilgard1 in 1860. The town of Ripley lGeology and agriculture of the State of Mississippi: Jackson, Miss., 1860, pp. 62, 83-95. 150 GEOLOGY OF THE COASTAL PLAIN is situated upon Eocene strata which were erroneously referred by Rilgard to the Cretaceous. However, Cretaceous beds appear in the banks of Tippah Creek within one-half mile of town, where they are overlain by Eocene (:Midway) limestone. This error was corrected by G. D. Harris' in 1896. Layers 1, 2, and 3 of the section given b_y Hilgard,' on Tippah Creek near Hipley, belong to the Cretaceous. Concerning the distribution of the beds of this formation Hilgard says: "These strata from the Pontotoc Ridge in Mississippi, and Chunnenugga Ridge in southeast Alabama; according to the late researches by Conrad, they also exist at Eufaula, Ala." Exposures of Ripley strata in the bluffs of Owl Creek, three miles northeast of Ripley, have been rendered classic by the paleontologic researches of T. A. Conrad.' Although the equivalency of the Cretaceous beds exposed on Chattahoochee River at Eufaula, to the Cretaceous beds in Tippah County, Miss., was recognized by Conrad in 1860, the first investigator to refer this whole series of Ripley beds along the Chattahoochee River to this division was D. \V. Langdon.' He included in his Hipley group an additional 120 feet of strata at the base of the series which in this report are, on paleontologic evidence, referred to the Tombigbee member of the underlying Eutaw formation. DEFINITION. Areal disiTibution.-The Ripley formation is exposed on Chattahoochee River in the upper part of the bluff at Blufftown, thirty-one and one-quarter miles below Columbus, Ga., and in the bluffs from Florence, in Ste\Yart County, Ga., to a point not accurately determined near Othos Landing, Ala., about 15 miles below Eufanla. ft extends northeashvard from the river through Georgia in a belt 10 to 14 miles \Yide, including parts of the following counties: Clay, Quitman, Stewart, \Yebster, Chattahoochee, Marion, Schley, Taylor, Macon, Crawford, Houston, Bibb, and Twiggs. In Twiggs, Houston, southwestern Crawford, and eastern Macon counties, the formation is concealed by a relatively thin blanket of overlapping younger strata, referable in part, or perhaps in whole, to the Eocene epoch, except where the latter have been removed by stream erosion. West of Chattahoochee River in Alabama the formation appears in an area south of that occupied by the Eutaw formation, having a maximum width of 25 or 30 miles, and including parts of Russell, 'The Midway stage: Bull. Amer. Palcon., Vol. 1, No. 4, 1896, pp. 22-25 (136-139), 2Geology and agriculture of the State of Mississippi; Jackson,. Miss., 1860; p.. 87, observations on a group of Cretaceous fossil shells, found in T1poah County, Miss.. with descriptions of fifty-six new species: Jour. Acad. Nat. Sci. Phila., n. s., vol. 3. 1855-58, pp. 323-336, plates 34 and 35. 'Jour. Acad. Nat. Sci. Phila., n. s. vol. 4, 1858-1860, pp. 275-298. 'Bull Geol. Soc. America, vol. 2, 1891, pp. 587-606. RIPLEY FORMATION 151 Barbour, Macon, Bullock, Pike, Montgomery, Butler, Lowndes, Dallas, Perry, and :Marengo counties. The western boundary of the formation is determined by the horizontal mergence of the beds in that direction into the beds of the Selma chalk. .Stratigraphic position.-In western Georgia and in Alabama the formation rests with conformable relations upon the Eutaw formation. From Taylor County east\vard to the eastern limits of its occurrence in Twiggs County, the Ripley beds rest unconformably upon Lower Cretaceous strata. The formation is overlain unconformably in both Alabama and Georgia by Eocene strata. This unconformity is an important one and probably represents a long period of time. This is evidenced by the great faunal change which took place during the interval, few if any species having survived from Cretaceous to Eocene time. In :M:acon, Houston, and southeastern Cra~wford counties the formation is concealed throughout considerable : reas in which it would otherwise appear at the surface, by a relatively thin oYerlap of strata believed to be referable to the Eocene. In Twiggs County the formation passes finally beneath, and is completely overlapped and buried by Eocene deposits. In narrow areas bordering Chattahoochee, Flint, and Ocmulgee rivers the formation is overlain by thin, snrficial terrare deposits of Pleistocene age. Lithologic characters.-vVith the exception of portions of the upper parts of the high bluffs at Blufftown and at Stewart's Hill,the materials of this formation exposed in the immediate blufftJ of Chattahoochee River are all of a. strictly marine character. They consist of massive, dark gray or greenish gray to black, more or lrss calcareous, micaceous, pyritiferous, and glauconitic sands and clays, with indurated ledges of calcareous sandstone or impure sandy limestone at vertical intervals of a few feet to 10 feet or more, with, in places, interbedded layers of loose, crossbedded, yellowish, calcareous sands and shell marls of shallow marine origin. Fossils are common as shells or shell prints and at various leYels are sufficiently abundant to form shell marls. The shallow marine phases contain in places numerous fragmentary bones of dinosaurs, mosausaurs, crocodiles, and turtles, together with occasional reptile teeth, great number8 of sharks' teeth of several species, and a few other fish teeth. In the exposures in the vicinity of Woolridge Landing these vertebrate remains are closely associated with an undescribed species of gigantic oyster, and with a large number of other species of mollusks. To the northeastward away from Chattahoochee River in Georgia, the basal portion 152 GEOLOGY OF THE COASTAL PLAIN of the _formation embracing 200 or 300 feet of strata merges along the stnke of the beds into shallow-water equivalents which differ in their essential lithologic characters from the typical beds. This is the Cusseta sand member described below. The uppermost beds of the formation also merge along the strike both to the northeastward in Georgia and to the westward in Alabama into the similar shallowwater equivalents which are later described as the Providence sand member of the formation. The Cusseta sand member consists of irregularly bedded, un~on solidated sands, with subordinate cla:v lenses, probably of sound or estuarine origin, but perhaps in part of shallow marine origin. They outcrop at the surface in a belt which inclncles parts of the following counties: Stewart, Chattahoochee. ~Iarion, Schley, Taylor, :Macon, Crawford, Houston, Bibb, and Twiggs. In Stewart and Chattahoochee counties the sands vary from fine to coarse in texture, and are somewhat arkosic. Farther to the northeast in :Marion County the. materials become in general coarser, although rather fine phases are not uncommon. This same predominance of coarse materials holds true throughout the remainder of the area occupied by the member, but as in :Marion ConntY, finer sands are known to occur locally. The clay lenses present in these sands are for the most part light drab, or even white, and massive, and in general resemble the more impure clays of the Lower Cretaceous. Locally, howenr, the clays are thinly laminated. At a few places carbonaceous clays, both massive and laminated, containing considerable percentage"' of comminuted plant remains have been noted, and fossil leaves ha,-e been collected at two such localities. This non-marine phase of the formation was first discriminated by Otto Veatch' in 1909, and was designated by him the Cusseta sand. The division is here given the rank of member. The similarity of the materials of the Cusseta sand member to the shallow-water phase of the Eutaw formation in its eastern extension renders the two formations separable onl; \vith difficulty. The same :is true of this member with respect to the owtlying Providence sand member of the Ripley formation in the region betwren Flint and Ocmulgee rivers. The Providence sand member consists prrclominantlv of coarse, irTegularly bedded sands with subordinate light-rolored ~lay lenses and layers. In Georgia the member outcrops in a long, narrow belt lying along the southern border of the Cretaceous area, and including parts of Quitman, Stewart, Webster, Marion, Schley, Macon, Houston, and Twiggs counties. In Alabama it is present along the southern lSecond report on the clay deposits of Georgia: Bull. Geol. Survey of Ga. No. 18. 1909, pp. 82-90. RIPLEY FORMATION 153 borde: of the Cretaceous area in parts of Barbour, Bullock, and Pike counties. Although the sands are in general coarse there are finer phases and this is especially true of the beds towards the base of the member, or the zone of transition from the underlying typical marine beds to the overlying coarser beds of this member. Rolled clay balls are numerous at many places in the sands. In Houston County the member contains notable lenses of white clays which have been mined in a small way and which give promise of becoming of commercial importance in the future. The typical marine beds, th,e "Renfroes marl" of Veatch, which intervenes between the Cusseta and Providence members, is traceable as a narrow belt from the Chattahoochee region through Stewart, Chattahoochee, JYiarion, and Schley counties, to Macon County, where they appear to pinch out, so far as surface outcrops are concerned, between the underlying and overlying shallow-water members. Beyond this point to the eastern limit of the surface occurrence of the formation the two members, each of which has gradually increased its thickness in this direction, are in conformable contact with each other, and together appear to represent the whole thickness of the formation. However, there is evidence that buried representatives of the typical marine beds extend eastward, at least as far as Marshallville, where calcareous beds have been penetrated in a well boring. The Providmice sand was diff~rentiated and named by Otto V eatch1 in 1909. Strike, dip, and thickness.-The beds of this fqrmation have m Georgia a general northeast-southwest strike. To the west in Alabama the strike is nearly dueeast and west. That portion of Langdon's' Chattahoochee RiYer section, referred in this report to the Ripley formation, includes layers Nos. 14 to 38. the thicknesses given by him total 948 feet. The beds outcrop at zero water level along the river in an air-line distance across the strike of about 29 miles. The average dip required to produce in this distance the thickness estimated by Langdon is 32 feet to the mile. In order to determine the correct average dip it would be necessary to make a large number of dip observations. It is known, however, that the beds undulate, the dip being less in places and elsewhere amounting to as much as 40 feet to the mile. In the absence of the data necessary for an accurate calculation of the thickness, Langdon's figure may be regarded as a probable close approximation to the true amount. 1Qp. cit., pp. 82-90. Geological Survey of Alabama, Geology of the Coastal Plain of Alabama, 1894, pp. 439-445. 154 GEOLOGY OF' THE COASTAL PLAIN A well at Buena Vista, 11arion County, penetrateJ strata believed to be referable to this information, to a depth of 583 feet. No other wells properly located, or of sufficient depth, to give an idea of the thickness of the terrane, have been drilled along the belt of its occurrence, but it is probable that it maintains approximately this thickness to the eastern limits of its areal extent. However, to the south of the belt of outcrop at Albany, in Dougherty County, Ga., Tertiary and Cretaceous strata were penetrated in a well to a derth of 1,320 feet. The upper 500 feet of the section is referred to the Tertiary. The remainder of the strata, 820 feet, should probably be referred in their entirety to the Ripley formation. Besides the Albany well a well at Blakely, Early County, drilled to a depth of 812 feet, passed entirely through the overlying Tertiary strata and entered the Ripley formation at less than 500 feet below the surface, the exact depth at which the Ripley was first encountered, however, being unknown. Physiographic expression-The general upland surface throughout the areal extent of this formation is a dissected plain, ranging from 400 to 600 feet above sea level. Topographically the region may be said to have advanced to the stage approaching that of maturity, the surface, therefore, being broken and hilly. The formation througout the greater part of its areal extent in Georgia is composed predominantly of beds of a sandy character. A thin, surficial blanket of loose, gray sand, resulting from the weathering and leaching of these sand beds, is almost universally present. In Macon, Crawford, and Houston counties the formation is concealed over considerable areas by a thin overlap of red, ferruginous sand of probably Eocene age. Where the latter is present, and especially in the region surrounding Fort Valley, the surface is remarkably level, and is in strong contrast to the remainder of the belt. In narrow area::; bordering Chattahoochee, Flint, and Ocmulgee rivers the valley sides have bern modified by terracing processes. Paleontologic characters.-As previously explained,,the typical rna rine beds of this formation contain in many layers an abundance of fossil invertebrate remains, and scattered fragmentary remains of vertebrates. The formation in the Chattahoochee region is divisible on the basis of the ranges of the contained species of Exogyra into two parts. The lower, embracing approximately the lower one-third to one-half of the terrane, is characterized by the presence of Exogyra ponderosa Roemer; the upper, embracing the remainder of the formation is characterized by the presence of Exogyra cosfa.ta Say. The former is given the name E::rogyra ponderosa zone, and to the latter Exogyra costata zone. RIPLEY FORMATION 155 Since the species E:rogym Tombigbee sand member of ponderosa the Euta1v occurs also formation in the thEea;lomgyllrearlpvoir1w~ derosa zone includes this member also. The formation contains a large number of invertebrate species which range from the base, or even below the base of 'the terrane, to its top; but there are in addition numerous species IYith restricted ranges, some confined abme and some below the horizon separating the two zones. DETAILED SECTIONS. (PART 01!' FOR:\IATI0:-.1 INCLUDED WITHIX TilE :;r,O);E OF EXOGYRA PO>..'DEROK.t.) Chattahoochee Biver (typical marine beds) .-The Hipley formation is exposed on Chattahoochee River in the upper part of the section at Blufftown, 31% miles below Columbus, Ga., in Stewart County, Ga., and in bluffs from Florence, 42 miles below Columbus, to a point near Othos Landing, Ala., not exactly determined, about 15 miles below Eufaula, a total distance by the river of about 44 miles. (For the location of the. exposures described, see sketch map of the river, figure 6, p. 7D.) The details of the exposure at Blufftown have been deocribed in a section on page 134 of this report. The upper 100 feet of the section is believed to represent the Cusseta sand member of the formation. The next 50 feet, consisting of gray, calcareous, marine sand, with some fossils, is the upper part of the "Blufftown marl" of Veatch, and constitutes the basal portion of the Ripley formation of this report. The following fossils were obtained near the top of this 50-foot divi:;:ion: Ostrea plumosa Morton, Exogyra sp. (young indi' vidual with cost:), Anomia sp. nov. (same as sp. nov. from Snow Hill, N.C.) This gray sand is similar physically to the materials lo1ver do:wn in the section, but the latter contain some fossils which in the light of our present knowledge of their range do not occur at horizons higher than the Tombigbee sand or the extreme base of the Selma chalk. Below Blufftown to a point two miles below Omaha the river bluffs reveal the beds of the Tombigbee sand member only. From here to Florence there are no exposures, but at the latter place the following section appears : Section at Florence, Chattahoochee River, left bank, 42 miles below Columbus. Pleistocene (terrace deposit) 3. Yellowish sandy clay and sand with gravel band at base . . . . . . . . . . . . . . . . . . . . (Unconformity.) Feet. 12 to 15 Upper Cretaceous Ripley formation (Exogyra ponderosa zone). 156 GEOLOGY OF THE COASTAL PLAIN 2. Gray to greenish gray, marine sands and clays, more or less glauconitic, micaceous, and calca- reous in the different layers. Several rows of calcareous concretions occur near the base. Fossiliferous in lower five or six feet. Shells very soft . . . . . . . . . . . . . . . . . . . 20 to 25 1. Laminated sands and clays with lenses of gray, yellow, and brown sands and seams of lignite . lO The bluff at this place is about one-half mile long, and in this distance the bedding plains are seen to dip gently southward. Of the fossils collected here the following "'ere identified. Ohatta}wochee River> bluff at Florence, Ste~cart County> Ga. L. W. Stephenson, collector. Locality Number. 5395 6404 Vermes: ........... . Hamulus onyx Morton . . Mollus,ca: . . . . . . . . . . . X X Nucula percrassa Conrad . X Le,da longifrons Conrad ? . X Trigonoarca sp. X Area ? . . . . . . . Barbatia (Polynema) lintea Conrad X x' Barbatia sp. . . . . . . . . . . . . X Ostrea sp. . . . . . . . . . . . . . . . . X Ostrea sp. nov. (same as large species at Woolridge Landing) . . . . . . . . . . . . . . . . . . . X lilxogyra ponderosa var. erraticostata Stephenson . X X Trigonia sp. nov. (same as at Snow Hill, N. C.) . . X Anomia argentaria Morton . . . . . . : . . . . . X Crassatellites sp. nov. (cf. C. pteropsls Conrad) X Cardium eufaulense Conrad X Cyprimeria depressa Conrad X X Aphrodina regia Conrad . . X Cyclothyris alta Oonrad . . X Cymbophora lintea Conrad . X Corbula carolinensis Conrad X Undetermined pelecypods X Vertebrata: Crocodilian teeth X Lamna sp. X Two miles below Fl0rence, 44 miles below Columbus, right bank, there is exposed at the foot of a bluff, 25 or 30 feet of dark gray, micaceous marine clay. A layer of lime concretions occurs about 12 or 15 feet above the base. Fossils, mostly fragile and in a fragmentary condition, occur near zero water level. The horizon is probably about the same as that at Florence. RIPLEY FORMATION 157 About 46 miles below Columbus there appears at the base of a bluff 10 or 12 feet of dark gray, compact, marine clay with t:~everal layers of slightly indurated light gray sand, each about six inches in thickness. Fragmentary shells occur near water level. In the vicinity of Woolridge Landing, 46lj2 miles below Columbus, 131h miles above Eufaula, Ala., there are several interesting ex- posures. A short distance above the landing on the opposite side of the river, left bank, the bluff presents the following section: Section opposite Woolridge Landing, Chattahoochee River. Pleistocene (first Pleistocene terrace.) 5. Not well exposed, but mostly yellow sand . (Unconformity) Upper !Cretaceous Ripley formation (Exogyra ponderosa zone). 4. Greenlo~h gray, very glauconitic sand, with some indurated layers . . . . . . . . . . . . . . . . 3. Yellow, laminated, loose sand, and dark drab clay. A layer of decayed shells, among them some large oysters, occurs along the top . . . . . . 2. Dark gray shell marl with gray sand matrix. The most conspicuous fossil, a large undescribed species of oyster. Other fossils are: Trigonia, Oyprimeria densata (Conrad) sharks teeth (numerous), crocodilian teeth, bones, etc. . . 1. Dark gray, argillaceous, micaceous, marine sand, with dark clay streaks . . . . . . . . . . . . Feet. 15 10 15 3 3 Just below Woolridge Landing, right bank, the bluff reveals strata as described in the following section: Section below Woolridge Landing) right bank) Chattahoochee River. Pleistocene (second terrace). 5. Pebbly sand, not well exposed . . . . . . about . Concealed by talus, but probably Cretaceous . Upper Cretaceous. Ripley formation. (Exogyra ponderosa zone.) 4. Dark gray, compact, argillaceous, finely micaceous, calcareous, glauconitic sand. One small specimen of Exogyra sp. with costae obtained near base .......... 3. Yellow, rather loose, sandy shell marl with some dark drab clay laminae. Contains soft shells, including Exogyra, Anomia, Cardium, Trigonia, a large undescribed oyster, etc. Also sharks teeth, crocodilian teeth and bones . . . . . . 2. Shell marl with gray sand matrix. Shells very soft. About three feet above base a discontinuous layer of large massive oysters, some specimens of which have a measured length of 17.5 inches . . . . . . . . . . . . . . . . . . . . . 1. Dark gray, micaceous, argillaceous, marine sand . Feet. 25 15 20 6 5 From the marl, layer No. 2, in the preceding section the following forms were identified: 158 GEOLOGY OF THE COASTAL PLAIN Chattahoochee River, Woolridge Landing, 461!2 miles below Columbus, 13lj2 miles above Eufaula, in Barbour County, Ala. L. W. Stephenson, collector. Locality Numbers ~~ Vermes: Serpula sp. X X Hamulus ? X Mollusca: Nucula percrassa Conrad X X Cucullaea carolinensis (Gabb) . X Trigonoarca sp. nov. ( cf. with sp. nov. from Kerrs Cove, Black River, N. C.) . X Breviarca safl'ordi (Gabb) ? X X Nemodon brevifrons Conrad X Area sp. ( cf. A. uniopsis Conrad) . X Glycymeris sp. ( cf. G. congesta (Conrad) ) X Glycymeris sp. X Inoceramus sp. . . . . . . . X Ostrea tecticosta Gabb . . . . X Ostrea plumosa Morton . . . X Ostrea sp. nov. (very large) X X Exogyra ponderosa var. erraticostata Stephenson . X Exogyra sp. (medium sized individual with costae) X Trigonia sp. nov. (same as sp. nov. from Snow Hill, N.C.) ......... . X Pecten burlingtonensis Gabb ? g Pecten sp. ? . . . . . . . X Plicatula sp. . . . . . . . X Anomia lintea Conrad . . X Venlella conrad! (Morton) X Crassatellites sp. nov. . . X X Crassatellites sp. ( cf. C. carolinensis Conrad) X Lucina glebula Conrad . . . . . . X Cardium eufaulense Conrad ... X Isocardia clifl'woodensis Weller ? X Cyprimeria depressa Conrad . . X X Aphrodina regia Conrad . . . . X Cyclothyris alta Conrad . . . . X Legumen planulatum (Conrad) X Baroda carolinensis Conrad . X Cymbophora lintea (Conrad) X Corbula carolinensis Conrad . . . .. . . . X X Gyrodes crenata Conrad . . . . . . . . . . . . . . . . X Pugnellus densatus Conrad . X Undetermined gastropods . . . X Vertebrata: Lamna texana Roemer . . . Corax falcatus Agassiz ..... . Otodus sp. . . . . . . . . . . . x? X x? X x? X Ischyrhiza mira Leidy (identified by J. W. Gidley) . X Thecachampsa rugosa Emmons (identified by C. W G1.more) . . . . . . . . . . . . . . . . . . . . X Polydectes biturgidus Cope (identified by C. W. Gil more X \ \ \ RIPLEY FORMATION 159 _ .At "Roanoke_ Island," a sho:t distance below \Yoolridge Landing, Uapt. J. W. Smgleton, Supermtendent, U. S. Engineers, obtained from dredged materials the Yertebrate remains listed below. The island referred to no longer exists, having been destroyed by riYet" currents. Chattahoochee River, bellceen Upper and Lower Roods Bend, and just above mouth of Soapstone Creek. Capt. J. W. Singleton, collr;ctor. Identified by C. W. Gilmore. Various fragments of the turtle, Taphrosphys ( ?) Fragment of dinosaur limb bone Vertebra of mosasauroid reptile Tooth of large crocodilian, probably Polydectes Coprolites One mile below \Vcolridge Landing at Lower Roods Bend, the following section is well exposed : Section at Lower Roods Bend, 47 1/2 miles below Columbus, .12 1/2 miles above Eufaula, left bank. Pleistocene (terrace deposit). 3. Unconsolidated, yellowish sand, loamy in upper part and with a band of pebbles and cobbles along the base . . . . . . . . . . . . . . . . . (Unconformity) Upper Cretaceous. Ripley formation. (Exogyra ponderosa zone.) 2. Dark gray, massive, marine sand. One specimen full of soft shells. Same as marl, layer No. 3 of Gryphaea vestcularis Lamarck obtained . . 1. Dark gray, micaceous, argillaceous, sandy marl fult of soft shells. Same as marl, layer No. 2 at Woolridge Landing section . . . . . . . . Feet. 25 20 10 From the marl at the base of the preceding section, layer No. 1, the following species were recognized : Locality No. 6401.-Chattahoochee River, left bank, Roods Lower Bend, just below the mouth of Soapstone Creek, 121j2 miles above Eufaula, Stewart County, Ga. L. W. Stephenson, collector. Molluca: Nucula percrassa Conrad Leda sp. Trigonoarca sp. nov. (large) Glycymeris sp. Ostrea plumosa Morton Ostrea sp. nov. (large) Trigonia sp. nov. (same as sp. nov. from Snow Hill, N. C.) Pecten sp. nov. (same as species from Snow Hill N. C.) Anomia argentaria Morton Crassatellites pteropsis Conrad? Cardium eufaulense Conrad 160 GEOLOGY OF THE COASTAL PLAIN Aphrodina regia Conrad Cyclothyris alta Conrad Lepto:solen biplicata Conrad Corbula carolinensis Conrad Vertebrata: Lamna tex~na Roemer Corax falcatus Agassiz Otodus ? About three-quarters of a mile below Lower Roods Bend, the top )f the marl bed just described is seen to pass finally beneath water level. . Along the outside of the broad bend on the Georgia side of the river between 48 and 49 miles below Columbus, a bluff presents a nearly vertical wall, 40 or 50 feet in height, of dark green, compact, argil- laceous, marine sand. Although no fossils were obtained from them, these beds are tentatively regarded as forming the upper part of the Exogyra ponderosa zone of the Ripley formation. The top of this zone is believed to pass beneath water level between this bend and the mouth of Cowikee Creek, the materials exposed on this creek, a short distance above the mouth, being regarded as forming the base of the overlying Exogyra costata zone. Northeast of Chattahoochee River (typical marine beds).-The upper part of the section near Jamestown postoffice in Chattahoochee County, 18 miles south of Columbus, Ga. (see section on p. 138 of this report), including layers Nos. 6 to 12 inclusive, is probably referable to the lower part of the Ripley formation. In stratigraphic position these beds are believed to correspond approximately to lay!3r No. 3 of the section at Blufftown on Chattahoochee River (see p. 134 of this report.) This is the farthest point to the northeastward that basal marine beds of the formation have been traced in Georgia. Beyond this point the basal beds appear to merge rapidly into materials of the Cusseta sand type. :fifarine beds overlying the Cusseta sand member, and probably occupying positions near the top of the zone of Exogyra ponderosa, have been examined at several places northeast of the river as follows: In a cut of the Seaboard Air Line Railway at Manta (Hichitee P. 0.) in Chattahoochee County, weathered, marine materials make up the upper seven feet of the beds exposed and similar materials are poorly exposed on the hill-slope south of the cut, the whole totaling a thickness of about 27 feet. Although no fossils were found in these materials they are thought to belong to the upper part of the zone in question (see section, p. 162.) Four miles northeast of Buena Vista on the road leading to Taze- well, where it ascends the southward-facing slope of Richland Creek GEOLOGY OF THE COASTAL PLAIN OF GEORGIA. I:'Ld'l'E XIV. EXPOS RE IN GULLY IN BUENA VISTA-TAZEWELL ROAD, SIX MILES NORTHEAST OF BUE A VISTA, MARION COUN'.rY, GA.. SHOWING LEAF-BEARING CLAY LENS IN CUSSETA SAND MEMBER Otr THE RIPLEY FORMATJQ::-;. B. . "SAND STREAM," ONE MILE NORTH OF TAZEWELL. MARION COUNTY, GA., THE AND HA BEEN TRANSPORTED BY TORRENTS FR0:\<1 GULLIES I::-< THE CUSSETA SAND i\1E)1BER RIPLEY FORMATION 161 Yalley, there is in the road ditch near t~1e base of the hi~l an exposure of 1~ or 15 feet of dark g:ay, fine, arglll~ceous, marine sand bearing fossil casts. On the basis of the contamed fossils this horizon is correlated approximately with the marl beds exposed at the bases of the bluffs on Roods Bend, Chattahoochee River (see pp. 135, 136 of. this report.) The following forms \vere recognized:. Locality No. 5381.-Buena VistacTazewell road, about four miles northeast of Buena Vista, Ga., on southward-facin,q slope of Richland Creek Valley. (All casts.) L. W. Stephenson, collector. Vermes: Serpula sp. Mollusca: Exogyra sp. (cast of young with costae) Ostrea sp. (large cast probably same as sp. nov. from Woolridge Landing.) Pecten quinquenarius Conrad Veniella lineata (Shumard) ? Crassatellites sp. (same as sp. nov. from Woolridge Landing, Chattahoochee River.) Cyprimeria densata Conrad Cyprimeria depressa Conrad Cyclothyris ? Aphrodina sp. A section on the Buena Vista-Tazewell road six miles northeast of Buena Vista has already been given on page 139 of this report. The upper 70 feet of the section, consisting of weathered, brownish, marine sand, is believed to fall Writhin the upper part of the zone of Exogyra ponderosa. This sand rests upon the coarse, unconsolidated sands of the Cusseta sand member of the Ripley formation. The contact separating the two kinds of materials is somewhat obscured by weathering process and by surface creep, but the relation appears to be that of conformity. Region between Chattahoochee and Ocmulgee rivers (Cusseta sand member).-From Chattahoochee River northeastward in Georgia, the basal portion of the Ripley formation loses its deeper marine character, being replaced by unconsolidated, coarser, more irregularly bedded sands and clays of shalbw marine or estuarine origin. These near-shore deposits have been designated by Veatch' the Cusseta sand, from Cusseta, Chattahoochee County, in the vicinity of. which they are typically developed. The materials referred to this member first make their appearance in the high bluff at Blufftown on Chattahoochee River, a section of w:hich is given on page 134 of this report. The upper 100 feet of this section (layer No. 4) is thus referred. 'ClaY, Report: Geol. Survey of Ga., Bull . .!'l L. C. Johnson> T. W. Stanton, L. W. Stephenson. Locality Numbers L.c.J.I w.P.c.l T.w.s.l L.w.s.l L.w.s \ 186 389 854 5416 64UO Coelenterata: Undetermined coral Echinodermata: Hemiaster lacunosus Slocum (lden- ti:fied by W. B. Clark) Cassidulus micrococcus Gabb Ident. by W. B. Clark) Vermes: Serpula barbata Morton Hamulus onyx Morton Mollusca: Nucula percrassa Conrad Nucula distorta Gabb ? Nucula sp. Leda pinnaforma Gabb Cucullaea vulgaris Morton (var.) Breviarca cuneata (Gabb) . Nemodon eufaulensis Conrad Glycymeris subaustralis (d'Orbig- ny) Gervilliopsis ensiformis Conrad Inoceramus sp. Pteria ? Ostrea larva Lamarck X Ostrea tecticosta Gabb. X Ostrea subspatulata Forbes X Ostrea plumosa Morton Ostrea peculiaris conrad .: I Gryphaea vesicularis Lamarck . X Exogyra costata Say X X Trigonia eufalensis Gabb X Trigonia sp.. Pecten simplicius Conrad Pecten argillensis Conrad Pecten tenuitestus Gabb Pecten sp. Lima reticulata 1.<1orbes Anomia argentaria Morton X Anomia sp. Paranomia scabra (Morton) X Grenella serica Conrad I Dreissensia tippana Conrad Pholadomya occidentalis Morton . X Anatimya anteradiata (Conrad) . Veniella conrad! (Morton) Vetericardia crenalirata (Conrad). Crassatellites eufalensis Gabb Crassatellites pteropsis Conrad I Tenea pinguis Conrad ? Sphaerella concentrica Conrad. Cardium eufaulense Conrad X I I ! X X X .x X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X x X X X X X I X X X X X X X X X I X i X I X I X ! I X I I GEOLOGY OF THE COASTAL PLAIN OF GEORGIA. PJ,ATE XV. ON MERCERS MILL CREEK, ' EAR GEORGETOWN IN QUITMA r GA., BOWING FOSSILIFEROUS. MARINE A D OF THE RIPLEY FORMA'riON. B. BLUFF ON CHATTAHOOCHEE RIVER. AT EU~'AULA, ALA., 'BOWING 0 FEE'.r OF GRAY, CAL ARE US, :llARINE ANDS AND CLAY OF THE RIPLEY FORMATION. RIPLEY FORMATION 177 Locality Numbers L.C.J.I w.P.c.l T.w.s.l L.w.s.l L.w.s.l 186 389 B54 5416 6400 Cardium spillmani Conrad X Cyprimeria depressa Conrad X Cyprimeria alta Conrad X Aphrodina tippana (Conrad) Legumen planulatum (Conrad) X :X: X X Aenona eufalensis Conrad X . . . . . . . Linearia sp. ( cf. L. carolinensis Con. Linearia sp. X X Leptosolen biplicata Conrad X X :X: Cymbophora lintea (Conrad) X Corbula crassiplica Gabb X Corbula Teredo sp(.ot.he.r .s.pe.ec.ie.s). . X X X Dentalium ripleyanum Gabb X Lunat~a obliquata M. & H. X Turritella vertebroides Morton X Turritella trilira Conrad X X . Pterocerella sp. Anchura sp. . . X X Pugnellus densatus Conrad X Ringicula pulchella Shumard X Nautilus dekayi Morton X Baculites sp. X Turrilites ? X Arthropoda: Bairdro sp. (Ostracoda indentified by R. S. Bassler) X Crab remains X X I I I Prof. Eugene A. Smith' has published the log of a well located at Eufaula which throws light on the character of the materials beneath water level at this place. It is quoted as follows: Record of Eufaula 01z and Gin Company's 1tell, Rufaula. Feet. Top soil and sand . . . 0 to 30 Marl . . . . . . . . . . . 30 " 380 Soft sandstone . . : . . . :>80 " 381 Cavity with a little water . 381 " 389 Marl, water below in very fine sand . . 389 " 950 More than half the thickness of strata described in this log doubt- less belongs to the Ripley formation, but it is probable that several hundred feet of the underlying Eutaw strata ~were penetrated. Below Eufaula, typical beds of the formation are exposed in JJ\1- merous bluffs. The fossils listed below were collected by Dr. T. W. Stanton at a point two miles below the landing at Enf~ula. 1Geoi. Surv. of Alabama. The Underground Water Resources of Alabama, Mont gomery, 1907, p. 240-241. 178 GEOLOGY OP THE COASTAL PLAIN Localif.u So. iY!/. Clwtfaltoochee R1:cer, bettceen Eufaula and Barbour C'1C!'k. T. 1\'. Stanton> collector. 1\Iollusca: Nucula eufalensis Gabb Nucula perc:rassa Conrad ::'>!ucula cuneifrons Conrad Leda pinnaforma Gabb Ledo longifrons Conrad Cucullaea sp. Breviarca cuneata (Gabb) Nemodon eufalensis Conrad Glycymeris subaustralis (d'Or- bigny) Glycymeris subaustralis (d'Orbigny) (var. ?) Glycymeris sp. ? Gervilliopsis ensiformis (Con- rad) Perna sp. Exogyra costata Say Gryphaea vesicularis Lamarck (small) Trigonia eufalensis Gabo Pecten argillensis Conrad Pecten simplicius Conrad Pecten quinquenarius Conrad Lima ac:utilineata (Conrad) Lima reticulata Forbes Lima pelagica (Morton) Anemia argentaria Nlorton Anomia sp. Pul\inites argentea Conrad Crenella serica Conrad Arthropoda: Crab remains Dreissensia tippana Conrad Cuspidaria ventricosa Meek & Hay- den Liopistha protexta Conrad Veniella conradi (Morton) Vetericardia crenalirata Conrad Crassatellites eufalensis Gabb Crassatellites pteropsis Conrad Crassatellites sp. Cardium l'iimmeli Weller Cardium eufaulense Conrad Cyprimeria alta Conrad (var. ?) Linearia metastriata Conrad Linearia (other species) Corbula crassiplica Gabb Corbula (several other species) Undetermined pelecypods Gastrochaena americana Gabb Dentalium ri11leyanum Gabb Dentalium sp. Cadulus obnutus (Conrad) Lunatia obliquata M. & H. Turritella trilira Conrad Turritella vertebroides Morton Turritella (other species) Fusns sp. Volutomorpha dumanensis Dall ::Vlorea cancellaria Conrad ~Undetermined gastro11ods Turrilites alternatus Tuomey One mile below the month of J3arbour Creek on the Georgia side of the riYer, eight or ten feet of gray, 1narine sand with indurated ledges is exposed. The materials above mw of the~e ledges, six or seven feet above low water, have been washed away over a considerable area by the high waters, forming a shPlf. I~arge numbers of specimens of BJ;ogyra costafa Say and Grypha'a Lamarck, washed from the Cretaceon~ materials, haYe accnmn1ated in the shallo\\' basins on this shelf. Eight miles below Eufaula, near Alexanders Landing, on the Alabama side, materials outcrop as described in the following section: Section> Chattahoochee River, rilexanders Landing, eight miles beloll' Eufaula, Ala, right bank. Pleistocene (terrace deposit) 3. Slope covered with vegetation except a gravel band along base . . . . . . (Unconformity.) Feet. 20 or 30 Upper Cretaceous. Ripley formation. (Exogyra costata zone). RIPLEY FORMATION 179 2. Coarsely arenaceous limestone with numerous specimens of Echinodermata. One specimen of Ostrea subspatulata Forbes (variety) also ob- tained . . . . . . . . . . . . . . . . . . . . . 15 1. Dark gray, more or less argillaceous, very micace- ous marine sand . . . . . . . . . . . . . . . . 15 Prof. \Ym. B. Clark, to whom the specimens were submitted, identified the following species of Echinodermata from layer X o. 2 of the preceding section: Cassidulus porrectus Clark Cassidulus subconicus Clark Cassidulus subquadratus Conrad \\'hen this locality was visited by Dr. t-ltanton there was ex]JO>Oed, wmcwlwre near Alexander's Landing, above layer No. 2 .of the preecding seetion, a bed, eonsisting 'of unconsolidated marine material from \Yhich Dr. Stanton collected the following species: Locality "-Vo. 8B6.-Chattahoocl1ee River, Alexanders Landing, eight miles be~oll' Eufaula, Ala. Collector, T. \\'. Stanton. Mollusca: ~ucula percrassa Conrad Nucula distorta Gabb ? Nucula sp. Leda pinnaforma Gab Leda sp. cf. L. marlboroensis Weller Cueullaea antrosa Morton Breviarca cuneata (Gabb) Nemodon eufalensis Conrad Glycymeris subaustralis (d'Or- bigny) Pecten argillensis Conrad Pecten simplicius Conrad Anomia linifera Conrad Anomia sp. nov. (same as "Nar- rows" of Pataula Creek) Dreissensia tippana Conrad Pholadomya occiden talis Morton Pholadompa sp. nov. (same as at "Narrows" of Pataula Creek) Liouistha protexta Conrad Crassatellites pteropsis Conrad Cyprimeria depressa Conrad Linearia ? Aenona eufalensis Conrad Cymbophora lintea Conrad ? Corbula ( several species) Lunatia obliquata Meek & Heyden Gyrodes sp. Undetermined pelecypods and gastro- pods Hamites sp. nov. (same as at Prairie Bluff, Ark., etc.) Arthropoda: Crab claw Vertebrata: Undetermined tooth of fish. Two miles below the preceding, about 10 miles below Eufaula, 25 or 30 feet of similar echinoid bearing rock with interbedded soft sand pockets and layers, appears in a bluff on the Georgia side of the river. The same species of Echinodermata were obtained here, also Ostrea subspatulata Forbes (variety) and Caadium kummeli Weller. At the mouth of Pataula Creek, 12% miles below Eufaula, Doctor Stanton collected the following fossils from typical marine materials: 180 GEOLOGY OF THE COASTAL PLAIN Locality No. 855.-Chattahoochee River at mouth of Pataula Creek, Ga. T. W. Stanton, collector. Mollusca: Nucula percrassa Conrad Nucula distorta Gabb ? Nucula eufalensis Gabb Leda pinnaforma Gabb Leda longifrons Conrad Le'da sp. (cf. L. marlboroensis Weller) Perrisonota protexta Conrad Cucullaea littlei (Gabb) Breviarca cuneata (Gabb) Nemodon eufalensis Conrad Glycymeris subaustralis (d'Or- bigny) Glycymeris ? Gervilliopsis ensilformis (Con- rad) Gervilliopsis sp. Gryphaea vesicularis Lamarck Trig'lnia eufalensis Gabb Pecten argillensis Conrad Pecten argillensis Conrad Pecten simplicius Conrad Pecten tenuitestus Gabb Lima acutilineata (Conrad) Lima reticulata Forbes Anomia argentaria .Morton Anomia sp. nov. (same as at "Narrows" of Pataula Creek) Pulvinites argentea Conrad Crenella serica Conrad Dreissensia tippana Conrad Pholadomya sp. nov. (same as at "Narrows" of Pataula Creek) Liopistha protexta Conrad Veniella conradi (Morton) Etea carolinensis Conrad Vetericardia crenalirata (Conrad) Crassatellites pteropsis Conrad Crassatellites eufalensis Gabb Crassatelhtes sp. Tenea pinguis (Conrad) ? Sphaerella concentrica Conraa Cardium eufaulense Conrad Cardium spillmani Conrad Cyprimeria alta Conrad (var. ?) Cyprimeria depressa Conrad Legumen planutatum (Conrad) Aphrodina tippana Conrad Aenona eufalensis Conrad Linearia metastriata Conrad Linearia sp. Leptosolen biplicata Conrad Cymbophora lintea (Conrad) Corbula crassiplica Gabb Corbula (several other species) Dentalium ripleyanum Gabb Pleurotomaria ? Lunatia obliquata Meek & Hayden Turritella sp. nov. (with two spiral ribs) Turritella sp. Sphenodiscus pleuriseptus (Conrad) Undetermined pelecypods and gas- tropods Vertebrata: Dermal scute of gavial-like crocodile (Identified by C. W. Gilmore.) One mile below the mouth of Patan1a Creek Dr. Stanton collectrd the following fossils: Locality No. 859.-Chattahoochee River, one mile below the mouth of Pataula Creelc. T. W. Stanton, collector. Mollusca: "Narrows" of Pataula Creek.) Cucullaea littlei (Gabb) Crassatellites sp. Glycymeris subaustralis ( d'Or- Cardium spillmani Conrad bigny) Cardium eufalensis Conrad Exogyra costata Say 'Cardium tippanum Conrad Trigonia angulicostata Gabb Aphrodina tippana Conrad ? Pholadomya sp. nov. (same as at Thirteen and one-haH miles below Eufaula, and one and one-half miles above Othos Landing, on the Alabama side, the foUowing section occurs : RIPLEY FORMATION 181 Section 13 1/2 miles below Eufaula, and one and one-half miles above Othos Landing, right bank. Tree-covered slope probably in part Eocene . . . . . Upper Cretaceous. Ripley formation. (Exogyra costata zone) 2. Gray, coarsely arenaceous clay, with poor fossils, Anomia argentaria Morton recognized.. Brown- ish band a few inches thick along base . . . . 1. Gray marine sand alternating with numerous ledges of coarsely arenaceous limestone. Contains Oassidulus subquadratus Conrad, Exogyra costata Say, Cardium kiimmeli Weller, and undetermined gastropods, about . . . . . . . . . Feet. 50 3 25 Between the preceding locality and Morris Landing, 15 miles below Eufaula, indurated ledges were seen at intervals .projecting from bluffs partially overgrown with vegetation, but no detailed observations were made until Morris Landing was reached. Somewhere in this distance the Cretaceous beds have passed finally beneath water level, for at J\forris Landing only Eocene rock is exposed. The basal three feet here consists of partially indurated, calcareous, argillaceous sandstone containing numerous casts of Turritella mortoni Conrad and some other Eocene fossils. This is overlain by coarse, sandy limestone, which grades upward into white limestone, containing but little sand, the whole thickness amounting to about 20 feet. Region between Chattahoochee and Ocmulgee 1ivers (typical marine beds).-Typical marine beds of the Ripley formation, referable to the zone of Exogyra costata, appear at the surface in a belt which extends from Chattahoochee River to the northeastward, including parts of Clay, Quitman, Stewart, Chattahoochee, Marion, Schley, and ~Iacon counties. From Quitman County, so1).theast of Georgetown, to the northeastern extremity of their occurrence in Macon County, the beds are overlain by the Providence sand member of the formation. Fossiliferous exposures have been studied at several localities in Quitman County. At the bridge of the Central of Georgia Railway over Mercers Mill Creek, one-half mile south of the station at Georgetown, there is exposed eight or ten feet of dark gray to black, finely arenaceous, micaceous sand containing bits of lignite and many fossils. (See plate XV, A, opposite p. 176.) Many of the species oc curring here are small forms. They are for the most part pelecypods and gastropods. The following forms have been identified: 182 GEOLOGY OP THE COASTAL PLAIN Locality No. i5417.-1viercers Mill Creek, CcHtml of Georyia Railway bridge, near Georgetown, Ga. L. lr. ~'J'tephenson, collector. Protozoa: Nodosaria sp. Coelenterata: Stephanophyllia (near bowerbankii M. E. & H.) (Identified by T. W. Vaughan) Vermes: Serpula sp. (long, nearly straight tube) Hamulus onyx Morton Hamulus squamosus Gabb Mollusca: Crassatellites eufalensis Gabb Nuc1:1la distorta Gabb ? Scambula perlana Conrad Nucula sp. 'Lucina sp. Breviarca cuneata (Gabh) ? Tenea pinguis Oonmd (young) Cardium kiimmeli Weller Leda pinnaformIARR O\Y S OF PATArLA RENK. NINE MILES GAINES. BOWI:'IIG TEN FEET OF ALCAREOUS MARINE SAND WITH J:'IIDU RATED LAYEH. Ob. TUP. RIPI~EY FOR)!ATIO::'\ . WAT E RFALL AT UPPER END OF THE " ~ARROWS " OF PATA ULA PRODUCED BY I~DURA'l' ED CALCAREOUS LAYER AT TOP RIPLEY FORMATION 185 Locality Number. 0. v. 5376b Echinodermata: Cassidulus porrectus Clark (rdentrfied by W. B. Clark ) I 1 X Vermes: I Serpula sp. cf. (s. cretacea (Conrad) Mollusca: I Nucula percrassa Conrad . . . . . . Nucula sp. a (cf. N. slackiana Gabb) Nucula sp. b . . . . . . . . Perrisonota protexta Conrad Leda pinnaforma Gabb (var. ?) Cucullaea sp. . . . . . . . . . . Breviarca cuneata Gabb . . . . Nemodon eufalensis Conrad (var. ?) Glycymeris subaustralis (d'Orbigny) . . . 1 Exogyra costata Say . . . . . . . . X Ostrea sp. . ....................... . Trigonia angulicostata Gabb . . . . Anomia argentaria Morton Anomia sp. nov. . . . . . . Pholadomya sp. nov. X Crassatellites pteropsis Conrad Crassatellites sp. . . . . . . . . . . .... Lucina swedesboroensis Weller ? Lucina sp. nov. . . . . . . Tenea pinguis Conrad Cardium eufaulense Conrad X Cardium eufaulense Conrad (var. ? ) Cardium spillmani Conrad . . . . . X Cyprimeria depressa Conrad . . . . . . .. Legumen planulatum (Conrad) Aenona eufalensis Conrad . . . Linearia carolinensis Conrad ? Linearia sp. nov. . . . . . . . Leptosolen biplicata Conrad . . . . . . . . .. Cymbophora lintea (Conrad) ? Corbula sp. . . . . . . . . . . . . . . . . . . . Undetermined pelecypods . . . . . . . . .... . Dentalium sp. Eulima sp. . . . . . . . . . . . . . . . . . Solarium ? . . . . . . . . . . . . . . . . . Lunatia obliquata Meek & Hayden . . . Lunatia sp. . . . . . . . . . . . . . . Turritella trilira Conrad Turritella sp. nov. (two spiral ridges) . Pterocerella tippana Conrad . . . . . . .............jI X X : : : : :! Anchura sp. 0 0 Ancilla sp. . . . . . . . 0 Actaeonina sp. . . . . . Cylichna recta Gabb . . ...... I Undetermined gastropods . . . . . . . . . . 0 Vertebrata: Corax falcatus Agassiz . . . . . . . . . . . Undetermined shark's tooth Monotygma sp. . . , . . . . . . . . . . . . :I IL. W.S. 6412 I I j X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 186 GEOLOGY OF THE COASTAL PLAIN At Credilles :Mill, Pataula Creek, about one mile abon~ the "S ar- rows," Vcatch collected the following fossils from a horizon probably slightly higher than the marl bed described in the preeeding section: Locality No. 5376a.-Credilles 1llill, Pataula C'1eek, about one mile above the ''Narrous," Clay Gowdy, Ua. Offo l"eafch, collectm. Echinodermata: Cassidulus conoideus Clark (Identified by W. B. Clark) Vermes: Serpula cretacea (Conrad . Mollusca: Cucullaea littlei (Gabb) Cyprimeria depressa Conrad Breviarca cuneata (Gabb) Volutomorpha sp. Glycymeris subaustralis (d'Or- Undetermined gastropod bigny) The beds exposed on Pataula Creek and on the river near the mouth of the creek are in stratigraphic position near the extreme uppermost part of the Ripley formation. Typical marine beds of the formation are exposed at numerous localities in Ste>vart Conntv. About one and one-half" miles east of Coffinton, in a deep gully just north of the road leading east to the Eufaula-Lumpkin road, the following fossils were collected from dark gray marine sands, with indurated layers, about 100 feet: belmv the level of the road: Locality No. 5382.-0ne and one-half miles east of Coffinton,. Ga. Mollusca: Collector, L. W. Stephenson. Ostrea subspatulata Forbes Anomia argentaria Morton Exogyra costata Say Baculites sp. \bove the fossil layer at the preceding locality the marine ma- terials appear to grade up into fine, unconsolidated sand, which may represent the basal part of the overlying Providenee sand member. The fossil horizon probably corresponds approximately to the horizon exposed at J\Iercers Mill in Quitman County, Ga. (seep. 182 of this report), anl at Eufaula, Ala. (see p. 175 of this report.) The basal -0 feet of the section exposed in the deep gully near Providence postoffice (now abandoned), described on page 194 of this report, is made up of typical marine beds of the Ripley formation. Among the casts observed near the top of layer ?\o. 1 in that section the following forms were recognized: Serpula sp., Leda sp., Cucnl- lCEa sp. (large), Cardium sp. (with spines), Cardium eufaulense Conrad ( ?) , Oyprimeria depressa Conrad, Leptosolen biplicata Conrad, and T unitella trilira Conrad. Tn the shell layer at the base E,rogyra costata Say and Cyprimeria. depressa Conrad, were recog- nized. RIPLEY FORMATION 187 Four mile~ north of Lumpkin the following interesting section is exposed where the road passes down a steep northward-facing slope known as J olmsons Hill. ~ection, .fohnsons Hill, Lumpkin-Luumlc road, j'our miles north of Lumpkin. Upper Cretaceous. Ripley formation (Exogyra costata zone). (Providence sand member). 5. Reddish brown, rather fine, ferruginous, somewhat argillaceous, weathered sand. Grades downward into next layer . . . . . . . . . . 4. Weathered, pinkish, somewhat argillaceous, ferruginous sand . . . . . . . . . . . . . . . . (Typical marine beds) 3. Fine, greenish, micaceous sand, weathered in the upper part to pinkish anP. yellowish tints . . . 2. Fine, greenish gray, calcareous, more or less argillaceous, marine sand with indurated ledges about 6 inches thick, 2 to 5 feet apart. Fossiliferous. One specimen of Pholadomya sp. nov. 12 ft. below top . . . . . . . . . . . . . . . 1. Dark gray, massive, argillaceous, calcareous sand, with indurated ledges similar to those in layer No. 2. Fossiliferous . . . . . . . . . . . . . . Feet. 15 8 20 40 22 The fossils listed below were obtained in lavers Nos. 1 and 2 of the preceding section. The fossiliferous part ;f this section is prob- ably approximately at the same stratigraphic level as the Cretaceous section of Enfanla, Ala., although the presence of the large Phola- dornya may indicate a slightly higher horizon. J ohnsons Hill, Stewart County, Ga., fovr miles north of Lumpkin on Lurnpkin-l~onmle road. Collecfo1's, Otto Veatch and L. W. Stephenson. Locality Number 0. v. IL- w. s. 5375 6418-a-j Mollusca: I I Ostrea tecticosta Gabb . . . . . . . . . . . . . .I Ostrea plumosa Morton . . . . . . . . . . . . ...... . Ostrea larva Lamarck var. falcata Morton ... . I Gryphaea vesicularis Lamarck (varieties) ... . I ~ I X Exogyra costata Say . . . . . . . . . . . I X I X Exogyra costata var. cancellata Stephenson .. I X I X Trigonia thoracica Morton ? . . . . . Pecten quinquecostatus (Sowerby) .. I . . . . .I I X X Lima reticulata Forbes . . . . . . . . . . . . . . .... -~ X Anomia argentaria Morton ................. . X X ~~;~~am~~- s~~br~ ( M-o~t~~). . . ..... .. . : : : : . . . . : I X X X Pholadomya sp. nov. (same as sp. nov. from Pataulal Creek) . . . . . . . . . . . I X Turritella trilira Conrad . . . . . . . . . . . . . . . . . . -I X 188 GEOLOGY OF THE COASTAL PLAIN In the extreme northeastern corner of Stewart County the typical marine beds are well exhibited in a se1ies of cuts of the Seaboard Air Line Railway from Renfroes Station northward for a distance of one and one-quarter miles. At the north end of the first cut near the water tank the the following s~ction was made: Section in cut of Seaboard Air Line Railway, one-quarter mile north of Renfroes Station. Upper Cretaceous. Ripley formation (Exogyra costata zone). (Providence sand member). 5. Gray residual sand . . . . . . . . . . . . . . . 4. Red, ferruginous, slightly indurated, rather coarse sand . . . . . . . . . . . . . . . . . . . . . . 3. Light gray, coarse, massive sand, partially mottled with yellow . . . . . . . . . . . . . . . . . . 2. Gray, pebbly, argillaceous sand with numerous small angular quartz pebbles up to one inch in diameter, poorly exposed . . . . . . . . . . . (Typical marine beds) 1. Dark greenish gray, compact, massive, calcareous clay, resembling an impure phase of the Selma chalk of Alabama . . . . . . . . . . . . . . . Feet. 3 4 to 7 5 5 4 From the cut just described northward for one mile there are a number of cuts exhibiting marine sands and clays. The track passes down a steep grade to the north. The thickness of strata exposed could not be determitned with exactness, but the beds are nearly horizontal, and it is probable that the amount does not exceed 60 or 70 feet. These are the type occurrences of the "Renfroes marl" of Veatch. The best section is f,urnishcd by the cut farthest north. Section in cut of Seaboard Air Line Railway, one-quarter mile north of Renfroes Station. Upper Cretaceous. Ripley formation (Exogyra costata zone). 3. Weathered, yellow, fine, calcareous, sand with an indurated, calcareous, nodular layer 5 feet above base. Fossiliferous. One specimen of Pholadomya sp. nov. 10 feet above base . . . . 2. Gray, massive, calcareous, sandy clay, with an indurated, nodular, calcareous layer 3 feet above base. Resembles certain impure phases of the Selma chalk in Alabama. Fossiliferous . . . . 1. Massive, argillaceous, micaceous sand, apparently non-fossiliferous . . . . . . . 1 Feet. 20 25 7 The following list is compiled from collections obtained from the exposures in the several cuts from one-quarter to one and one-quarter miles north of Renfroes station. Most of the specimens were found RIPLEY FORMATION 189 loose on the talus slopes, having weathered from the beds. On account of the mixing of the specimens on the talus slopes, and because all the species identified (with the exception of the new species of Phola:domya whose position in the section is indicated) are wideranging within the zone of Exogyra costata, no attempt is made to designate in which of the above described layers they ~were originally in place. The stratigraphic position of the beds exposed in these cuts probably corresponds approximately to the Cretaceous portion of the section at Eufaula, although the presence of Pholadomya sp. nov. may indicate a slightly higher position in the section for layer No.3. Cuts of Seaboard Air Line Railway, one-quarter to one and onequarter miles north of Renfroes Station, Stewart County, Ga. L. IV. Stephenson, collector. Loc. Nos. 6413-6417. Mollusca: Cucullaea sp. Pecten quinquecostatus (Sowerby) Ostrea tecticosta Gabb Pecten sp. nov. ? Ostrea' larva Lamarck Dianchora sp. Ostrea plumosa Morton Lima reticulata Forbes Grymphaea vesicularis Lamarck Anomia argentaria Morton (varieties) Paranomia scabra (Morton) Gryphaea sp. (small) Paranomia sp. nov. Exogyra costata Say Pholadomya sp. nov (same as sp. Exogyra costata var. cancellata nov. from Pataula CreekJ Stephenson Vertebrata: Ischyrhiza mira Leidy (Iden. by J. W. Gidley) The typical marine beds of the formation have been penetrated in two wells in Stewart County. Information concerning the strata penetrated in these wells has been obtained from the owners, as follows: G. L. \Valton, of Charles, Ga., owns two wells; one, 65 feet deep, located near the station at the hivel of the track (Seaboard Air Line Railway), and another 85 feet deep, seven-eighths of a mile east of the station, 80 feet above the level of the track. :Mr. \V alton states that "the land is underlaid with hard marl and no one in the neighborhood has ever been able to carry a well through it." Log of well owned by E. H. Acker, two miles southwest of Charles, Georgia. Upper Cretaceous. Ripley formation. (Exogyra costata zone). 3. Sand . . . . . . . . . . . . . . . . . . . . . . . 2. Hard, dark brown, and gray, streaked clay, with one small layer of sand, water-bearing . 1. Black marl at bottom of well . Feet. 0 to 10 10 to 26 ? Total . . . . . . . . . . . . . . . . 26 190 GEOLOGY OF THE COASTAL PLAIN 11r. Acker states that the black marl has been encountered in other wells in this neighborhood. Mr. C. Y. Stephens, of Renfroes, states that blue marl is encountered 10 to 15 feet below the surface in wells one and one-half miles west of Renfroes, and that wells 90 feet deep have failed to penetrate through this kind of material. In }lariou County weathered phases of the typical marine beds of the formation appear at intervals in the Buena \Tista-Tazewell road, from t\Y() to four miles northeast of Buena Vista. Prof. S. \Y. }IcCallie' has published the log of a deep well drilled at Buena Vista, \Yhich throws light on the character of the strata underlying the central part of the county. It is as follows: Log of well at Beuna V isla, Ga. Feet. Blue clays . . . . . . . . . . . . . . . . . . . . . . . . . . 0- 35 Sand and clays ......................................... 35-105 Sort limestone . . . . . . . . . . . . . . . . . . . . . . . . . . 105-155 Marl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155-158 Rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158-159 Marl . . . . . . . . . . . . . . . . . . . . . . . . . . 159-252 Flint . . . . . ................................... .... 252-254 Indurated marl .. '. . . . . . . . . . . . . . . . . . . . . . . . 254-263 Hard rock .......................................... 263-270 Marl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270-297 Limestone (water-bearing) . . . . . . . . . . . . . . . 297-331 Coarse gray sand . . . . . . . . . . . . . . . . . . . . . . . . . 331-343 Marl (water-bearing) . . . . . . ........................ 343-364 Marl . . . . . . . . . . . . . . . . . . . . . . . . . . 364-551 Hard, compact rock . . . . . . .......................... 551-583 The npper 105 feet of strata described in the above log is referable to the Providence saud member of the Ripley formation, and the remainder of the section are typical marine beds of the same formation. Profe,.;,;or }lcCallie has collected fossils in Marion County from marine materials in the E.Togyra costata zone, as enumerated in the following lists: Locality 'Xo ..W:)2.-Bivens Plantation on Dry Creel.:, ih1ee miles //'est of hueville. .Marion County, Ga. S. W. llfcCallie, collPcfor. Mollusca: Ostrea tecticosta Gabb Gryphaea vesicularis Lamarck Exogyra costata Say Exogyra costata var. cancellata Stephenson ' Anomia argentaria Morton Paranomia scabra (M.orton) Cardium sp. 'Gcol. Snrv. of Ga., Bull. No. 15, l!l08, p. 146. RIPLEY FORMATION 191 Locality Ko. 30:)3.-Lanneyhassey Creel.:, four miles sovfh of Buena: Vista, Jfarion County, Ga. S. 1Y. McCallie, collector. :Mollusca: Cucullaea sp. Inoceramus sp. Exogyra costata Say Pecten argillensis Conrad Cardium eufaulense Conrad ? Panopea decisa Conrad Locality Xo. :w:14.-Cul ill public: road nea.r Crntral of Ge01gia Railway bl'idge across 1Yinchafoonrr crrcl., fire miles north II'PS! of Burna l'ista, J!arion County, Ga. 8. 11". J!cCallir. Collrtfor. Mollusca: Veniella sp. (cf. sp. from Hodges old mill, S. C.) Cardium (Trachycardium) alabamense Gabb Aphrodina sp. Turritella trilira Conrad Fossils hme been collected from typica1 mari nc he\ls of the formation at one place in Schley County. This locality is at the water mill of J. L. B. Usry, seven miles north of Ellaville and one-half mile east of Murray Crossroads. The fossils were obtained just below the ivest end of the milldam from a poor exposure of light green to greenish yellmv, massi,e, marine sand, indurated in layers at the \Yater's edge, anc1 one foot above the water's rc1ge. The remains consist of vcr~- soft she11s and shell prints. The forms listed hrlO\i' \Yere recognized : Locality No. (J-'!-82.-List of fossils from J. L. B. Usry's milt, seuen miles north of Ellarillc, Ga., and onr-half mile cast of Jiurmy Cross1oads. L. W. Stephenson, collector. Mollusca: Nemodon sp. Ostrea plumosa Morton Gryphaea vesicularis Lamarck (small) Exogyra costata Say (small, but apparently typical) Pecten argillensis Conrad ? Pecten simplicius Conrad Lima sp. Pecten quinquenarius Conrad Anomia argentaria Morton P!aranomia scabra (Morton) Pholadomy,a sp. Lucina sp. Tenea ? Oardium spillmani Conrad Cardium sp. Legumen planulatum (Conrad) Turritella trilira Conrad Undetermined pelecypods Corbula crassip!ica Gabb The farthest locality to the eastward at which the typieal marine Ripley beds have been observed is in a cut of the Atlanta, Birmingham & Atlantic Railroad, one and one-eighth miles north of Ideal, Macon County. The section exposed here is described below: (See also plate XII, B.) 192 GEOLOGY OF THE COASTAL PLAIN Section in cut of Atlanta, Birmingham & Atlantic Railroad, one and one-eighth miles north of Ideal, Ga. Upper Cretaceous. Feet. In. Ripley formation. (Exogyra costata zone.) 7. Loose, yellow, pebbly sand, probably creep . 4 6. Yellow massive fine, micaceous, argillaceous sand, a weathered marine sand 7 5. Gray, laminated, micaceous, sandy, marine clay, with fine sand partings . . . . . . . 4 4. Weathered, fine, yellow, argillaceous, marine sand 8 3. Iron crust . lh 2. Dark, gray, finely arenaceous and micaceous, corn pact clay, weathering somewhat shaley. Con- tains poor prints and casts of fossils . . . . . 20 1. Dark gray to yellow, '!Ilassive, marine sand with numerous fossil prints at south end of cut . 4 The fossils listed below >vcre obtained from layers K os. 1 and 2 in the above section. Locality No. 6483.-List from cut of Atlanta, Birmingham & Atlantic Railroad, one and one-eighth miles north of Ideal, Ga. At base of layer No. 2. L. W. Stephenson, collector. Mollusca: Cucullaea vulgaris ::vrorton ? Crassatellites sp. Crassatellites pteropsis Conrad Cardium spillmani Conrad Cardium sp. Vertebrata: Larnna texana Roemer Corax falcatus Agassiz Otodus appendiculatus Agassiz? Gyprimeria depressa Conrad Cyprimeria densata (Conrad) Aphrodina sp. Cymbophora lintea (Conrad) ? Turritella trilira Conrad Fragments of bones Tooth of mosasauroid reptile (ldent. .by C. W. Gilmore) At Marshallville in the eastern part of Macon County, beds >Yhich probably represent the eastward buried extension of the typical marine beds have been penetrated m a well boring. (See section, p. 197 of this report.) Region between Chattahoochee and Ocmulgee nvers (Providence sand member).-\Yestward from Chattahoochee River in Alabama, and northeastward from the river in Georgia, the uppermost of the typical marine beds of the Ripley formation merge into shallow water equivalents. These strata constitute the Providence sand of Veatch. In this report they are treated as a member of the Ripley formation. The points farthest south in Georgia where the Providence sand has been observed are in two cuts of the Central of Georgia Railway, five and three-quarters and six miles, respectively, southeast of Eufaula, Ala., in Quitman County, Ga. The first cut reveals 20 or 25 fret of coarse, irregularly bedded, rrcl Log' of well at Perry, Ga. 6. Red massive clay . . . . .. . . . . . . . 5. White clay . . . . . . . . . . . . . . . . . . . . 4. Yellowish sand, with 4 inches of impervious iron at its base . ,. . . . . . . . . . . . . . . . . . 3. Sand with thin partings of clay . . . . . . . . 2. Dark carbonaceous materials-possibly hgnite . 1. Coarse gravel at . . . . . . . . . . . Feet. 0-10 10-10% 103-50 50-132 132-136 136 1Geol. Survey of Georgia Bull. No. 15, 1908, p. 121. 200 GEOLOGY OF THE COASTAL PLAIN An undetermined upper portion of the section just described is referable to the Eocene, but the greater part of the section belong~ to the Prov\dence sand member of the Ripley f?rmation. DETAILED SECTIONS. (WELLS SOUTH OF THE BELT OF OUTCROP.) At a number of places in Georgia well borings have been made that have passed through overlying Tertiary beds, entering and penetrating to various depths the beds of the Ripley formation beneath. Few reliable records have been kept, however, and the available information if meager. A well at Albany, Dougherty County furnishes the most instructive section of any yet recorded from the region. The log of this well was furnished by :Mr. C. W. Tift, of Albany. The fossils, also furnished by ::\Ir. Tift, were determined by Dr. T. Wayland Yanghan. This log was published in Bulletin No. 15 of the Geological SurYey of Georgia, 1908, pp. 98, 99. It is here repeated, and in addition an attempt is made to correlate the Cretaceous portion of the section with the Cretaceous formations eutcropping at the surface to the northward in the State. The writer has examined a part of the Cretaceous fossils obtained from the well and has made one or two slight changes in the determinations. Lqg of Oity Artesian Well No. 2, Albany, Ga. Tertiary: 35. Red clay . . . . . . . . . . . . . . . . . . 34. Light colored clay . . . . . . . . . . . . . . . 33. Coarse sand (Vicksburg) . . . . . . . . . . . . 32. Light colored clay and coarse quartz sand . . . . . 31. Limestone, Orbitoides sp. at 150 feet, and from 190 to 200 feet . . . . . . . . . . . . . 30. Gray limestone, Orbitoides sp., Echinoid, Bryozoa, Terebratulina lachryma (Morton), some shale from 230 to 240 feet . . . . . . . . . . 29. Gray sand with comminuted shells ( Ostrea) . . 28. Some shale, coarse sand, shell, and sharks' teeth, at . . . . . . . . . . . .. 27. Hard layer, Ostrea divaricata Lea 26. Ostrea divaricata Lea at . . . . . 25. Ostrea alabamiensis Lea at . . . 24. Shale or marl, water vein at . . . 23. Ostrea divaricata Lea and Ostrea alabamiensis Lea at ..... 22. Bed of lignite at . . . . . . . . . . . . . . . . 21. Bed of lignite at . . . . . . . . . . . . . . . . 20. Sand . . . . . . . . . . . . . . . . . . . . . . . 19. Stiff blue clay Echinoid spines, Lamna sp. (teeth) 18. Stiff blue clay . . . 17. Hard gray sandstone . . . . . . . . . . . . . . .Upper Cretaceous Ripley formation. 16. Ostrea sp. and Exogyra costata Say ? 15. Pyrite and small oysters at . . . . . . Feet. 0- 20 20- 23 23 25 25 35 35-200 200-280 280-285 311 318-320 330 340 350 363 367 400 400-475 470-475 475-480 485-488 500-510 520 RIPLEY FORMATION 201 14. Greensands and greenish micaceous shales 530-540 13. Gray sand with black particles at . 600 12. Water-bearing horizon, limestone, with pieces of nard gray sandstone between 785 and 790 feet . 690-790 11. Hard rock 790-800 10. Clay shales, white limestone between 835 and 840 800-850 9. Limestone, shales, etc. At 880 feet limestone or calcareous sand, also light gray micaceous sand 850-890 8. Grayish sand, calcareous, fragments, hard black pieces of pebbles, Ostrea sp.; Anomia argentaria Morton. [Gryphaea vesicularis Lamarck (young)] at 890 feet; water-bearing micaceous stone between 920 and 930 feet . 890-940 7. Blue, micaceous clay at 950 feet, thick shelled oyster, Gryphaea sp., the same also at 1,080 feet; at 1,100 feet gray sand with Ostrea sub- spatulata Forbes, Exogyra costata Say . . . . 940-1100 6. Stiff blue clay, micaceous sandstone, Ostrea cre- tacea Morton ( !) 1100-1200 5. Very stiff blue clay, at 1255 feet, streaks of sand and shells, a small flow of water; from 1240 to 1260 soft shiny blue clay 1200-1260 4. Marl, gray sand, sandstone lumps . 1260-1270 3. Gray and black sand, sandstone lumps 1270-1310 2. Black, irregular, water-worn pebbles with hard crystalline fracture; coarse and fine quartz sand, shells, decayed wood, third water-bearing stratum; 50 gallons per minute 1310-1315 1. Well ends in quartz sand at . . 1320 A well at Blakely, in Early County, entered the upper beds of the formation at some depth between 160 and 500 feet, but probably nearer the latter depth. The log was furnished by l\r. S. S. Chandler and the fossils were determined by Dr. T. wayland Vaughan. This log was published in Bulletin No. 15 of the Geological Survey of Georgia, 1908, pp. 105, 106. It is here repeated. Log of town well, Blakely, Early County, Ga. 14. Red, sandy clay . . . . . . . . . . . 13. Coarse, grayish sand . . . . . . . . 12. Coarse, light-yellowish sand . . . . . 11. Yellowish cherty limestone (Vicksburg) 10. Yellowish, or grayish, sandstone . . . . 9. Light-colored, almost white, calcareous sand- stone, probably base of Vicksburg . . . 8. Gray sands, darker at bottom . . . . . . 7. Greenish sands, with Ostrea divaricata Lea 6. Fine gray sand, hard ledge at bottom 5. Fine sand, with some clay . . . . 4. Bluish clay . . . . . . . . . . . . . . . . 3. Quartz sand, with glauconite . . . . . . . 2. Hard sandstone with glauconite. Two oysters, apparently Gryphaea sp. and Exogyra costata Say . . . . . . . . . 1. Grayish or bluish sands . . . . . . . . . . . . Feet. 1- 10 10- 20 20- 30 30- 40 40- 50 50- 70 70-140 140-160 160-285 285-290 290-490 490-500 500-510 510-580 / '-. 202 GEOLOGY OF THE COASTAL PLAIN Mr. George R. Irwin, o Fort Gaines, Ga., has furnished the following log o a well drilled by S. S. Chandler, in August, 1909, in Henry County, Alabama, two and one-hal miles northwest o Fort Gaines, Ga. The writer is authority or the attempted correlation: Log of well owned by George R. Irwin, located two and one-half miles northwest of Fort Gaines, Ga., in Henry County, Ala., on Chattahoochee River bottom, 700 yards west of the river at an elevation of 15 feet above high water mark. Pleistocene (terrace deposit). 17. Clay and sand . Eocene. 16. Soft lime rock . 15. Hard lime rock 14. Marl . . . . . . . . 13. Hard lime rock .. 12. Marl . . . . . . . 11. Coarse sand . . Upper Cretaceous. Ripley formation. 10. Hard sand rock (or indurated sand) . . . . . . 9. Coarse sand . . . . . . . . . . . . . . . . . . . 8. Hard sand rock (first flow of 10 to 11 gallons per minute at this depth measured from top of pump 7 feet above the surface) 7. Coarse sand . . . 6. Hard sand rock . 5. Coarse sand . . . 4. Sand rock . . . . 3. Coarse sand . . . 2. Marl . . . . . . . . . . . . . . . . . . . . . . 1. Hard sand rock with some soft spots. At 230-235 feet the second flow of 25 to 30 gallons per minute was found, flowed this amount from top of 6-inch pipe. Well stopped in the rock . . . . Feet. 1- 3.0 30- 75 75-125 125-135 135-140 140-170 170-180 180-186 186-190. 190-196 196-202 202-207 207-210 210-212 212-215 215-217 217-240 A number o flowing artesian wells have been drilled at Montezuma. The log o the deepest o these has been published in Bulletin No. 15 o the Geological Survey o Georgia, 1908, p. 142. The log was furnished by Mr. E. J. Wilson, the contractor. It is as follows: 18. Sand to . . . . . 17. White clay to . . 16. Limestone to . . . 15. Sand and clay to 14. Bluish tough clay to 13. Sand with mica to . 12. Blue clay to . . . . . 11. Sand and blue clay to . 10. Fine, micaceous sand to 9. Sand and clay to . . . . . . . . 8. Sand with thin layers of flint to . 7. Clay and fossil wood to . . . . . 6. Limestone containing shells to . . Feet. 6 18 20 50 60 75 95 155 160 190 310 350 352 RIPLEY FORMATION 203: 5. Micaceous sand to . , . . . . . . . . . . 356 4. Clay interstratified with sand to . . . . 416 3. Fossiliferous limestone with layers of sand to 480 2. Clay to ... 496 1. Sand to . . . . . . 500 No fossils were observed from the above described well and an attempt to distinguish the formations penetrated can be nothing more than a rough guess based upon the descriptions of the materials as furnished by the driller. Layer No. 18 is probably Pleistocene terrace sand; layers 10 to 17 inclusive probably belong to the Eocene; layers 1 to 9 probably include representatives of the Providence sand and the typical marine beds o the Ripley formation. If these correlations are correct the two water-bearing strata referred to by Pro. Jl.fcCallie at 60 and 150 feet, respectively, are Eocene horizons, and those at 350 and 500 feet, respectively, are Ripley Cretaceous horizons. An oil-prospecting well, located three and one-hal miles southwest o Louisville, in Jefferson County, penetrated Cretaceous strata i~ part. The log is given on page 107 o this report. Fossils characteristic o the Claiborne group of the Eocene were obtained at a depth o 250 feet. A fragment o a turtle plate, supposed to be referable to the Upper Cretaceous, was obtained at a depth of 380 feet. On the basis o these fossils the contact between the Cretaceous and Eocene is believed to be somewhere between the depths indicated, and it is here tentatively placed at 350 feet. Crystalline basement rocks were encountered at 1,140 feet. The probable total thickness of Cretaceous strata penetrated, therefore, is 790 feet. The data obtained from the Louisville well w'as insufficient to permit distinguishing between Upper and Lower Cretaceous strata, but it is believed that beds of both ages are represented. Doubtless the lower 500 or 600 feet of the Cretaceous portion of the section should be referred to the Lower Cretaceous and the remainder to the Upper Cretaceous, perhaps to the Ripley formation. Wells at Arlington and Leary in Calhoun County, at Dawson in Terrell County, at Cuthbert in Randolph County, at Fort Gaines in Clay County, at Richland in Stewart County, at Americus in Sumter 204 GEOLOGY OF THE COASTAL PLAIN County at Oglethorpe in :Macon County, at Perry m Houston County, at Byromville in Dooly County, at Cordele in Crisp County, and at Dublin in I,aurens County, and perhaps at other places, are of sufficient depth to pass through the Eocene deposits and enter the underlying Cretaceous beds. How!3ver, either n'o logs have been kept, or, in cases where logs have been recorded, the information given is too indefinite to permit discrjminating between Eocene and Cretaceous beds. Such detailed information as is knovm concerning these wells has been published by Prof. S. W. :McCallie in Bull. No. 15 of the Geological Survey of Georgia. CORRELATION The typical marine beds of the Ripley formation in Georgia are very prolific in fossil invertebrates. On the basis of the ranges of t\YO species of Exogyra the formation has been divided into two . parts. The first part embraces the lower one-third or one-half of the formation and forms the upper part of the zone of Exogyra ponderosa, of which the lower portion is the Tombigbee sand member of the Enta\Y formation. The second part, embracing the remainder of the formation, is characterized by the presence of Exogyra costata and is designated the Exogyra costata zone. These two parts will be considered separately. Part of Ripley formation included within the zone of Exogyra ponderosa. Omitting numerous forms identified generically out not specifically, and an occasional form whose specific identification . is questioned, 34 species of invertebrates have been recognized in these beds, as follows: 1. Hamulus onyx Morton (Rc. Tp.) 2. Nucula percrassa Conrad (Rc. Tp. Eb.) 3. Cucullaea carolinensis ( Gabb) ( Tp.) 4. Trigonoarca sp. nov. (Roods Bend) 5. Nemodon brevifrons Conrad 6. Barbatia lintea Conrad (Tp.) 7. Ostrea plumosa Morton (Rc. Tp.) 8. Ostrea tecticosta Gabb (Rc.) 9. Ostrea sp. nov. (large, Roods Bend, etc.) 10. Gryphaea vesicularis Lamarck (Rc.) RIPLEY FORMATION 2Q5 l 1. Exogyra ponderosa var. erraticostata Stephenson ( Tp.) 12. Trigonia sp. nov. (same as sp. nov. from Snow Hill, N. C.) 13. Pecten burlingtonensis Gabb (Tp.) 14. Pecten quinquenarius Conrad (Rc.) 15. Pecten sp. nov. (same as sp. nov. from Snow Hill, N. C.) (Tp. Eb.} 16. Anomia argentaria Morton (Rc. Tp.) 17. Anomia lintea Conrad 18. Anomia sp. nov. (same as sp. nov. from Snow Hill, N. C.) (Tp. Eb.) 19. Veniella conradi (Morton) (Rc. Tp.) 20. Crassatellites carolinensis Conrad ? (Tp.) :n. Crassatllites sp. nov. (Roods Bend, etc.) 22. Lucina glebula Conrad (Tp.) 23. Cardium eufaulense Conrad (Rc. Tp.} 24. Isocardia cliffwoodensis Weller ? 25. Cyprimeria depressa Conrad (Rc. Tp. Eb.) 26. Cyprimeria densata (Conrad) (Rc.) 27. Aphrodina regia Conrad 28. Cyclothyris alta Conrad (Tp.) 29. Legumen planulatum (Conrad) (Rc. Tp.) 36. Baroda carolinensis Conrad 31. Leptosolen biplicata Conrad (Rc. Tp. Eb.) 32. Cymbophora lintea (Conrad) CRc. Tp. Eb.) 33. Corbula carolinensis Conrad (Tp. Eb.) 34. Gyrodes crenata Conrad In the Chattahoochee region, 14 of the 34 specws in the list~ marked (Rc), range up into the overlying Exogyra costata zone; 20, marked (Tp), occur in the underlying Tombigbee member of the Eutaw formation; 7, marked (Eb), occur in the basal beds of the Eutaw formation, and 10 are restricted to the beds in question. . The 14 species in the list which range up into the zone of Exogyra costata are eliminated from further consideration on account of their wide vertical range. The table given below shows the ranges of the remaining 20 both within and without the Chattahoochee region: Table showing ranges of species which in the Chattahoochee reg1:on occur in that part of the Ripley formation included within the Exogyra ponderosa zone exclusive of those which range upward into theExogyra costata zone. 206 GEOLOGY OF THE COASTAL PLAIN . 1. Cucullaea carolinensis (Gabb) -~ ."... Q) ".<:: " 0 0 .<:: ~"' .<:: Q !3 0:: 3 ."as' ~ ~"' r.:l 'S ."-"";c";' Q"":''l d -~ .Q..). Q) ".<:: 8 " .<:: !..S. .<:: Q .!3 .:::: "a...'. .8 ~ ~ r.:l 'S .... ~ " a i""""0"::'' a ~ "" ~ Q) 0:: ""a'' .<":': .."6' Q " "' ..o... ....: ttl,..; .f~.:.".~e' ~ :;;: i-~~.~ .::::!; .!3 ""' "'"' ~"' .,.~ o::>i o~ to:::>.,i I _b-.; ::S " '".<:: 58 "-.<:l "~ ' " ~ :Sg .."'"' ""~ ...,.!~ S .s "'"'.... ~,...cu:: ~s. 00. """" "...". ' ~..c:: r.l'c; '0~ ~;; ~ ~ ~..c:: ~~ p... ~:i ~ .; ~"' Q"' -"5 'S 0:: -~ "a...'. ...8.. Q) .Q..). Q.... ~ " ...; 0:: 0 ."s' .!! ~ "."""0>.<.'' r.l II .!""3'' 8 Q"' -"5 'S "~" " " Q) ""Q) p... X xa X :>. ..z"".;, ~ z " 'S 0:: 3 :>. ..""z.;, .z.~... 0 E"' p, .8 .... bO 0:: -5 0 :~:a "~ ' ."..' ::a 2. Trigonoarca sp. nov. (Roods Bend, etc.) X 3. Nemodon brevifrons Conrad 4. Barbatia lintea Conrad 5. Ostrea sp. nov. (large, Roods Bend, etc.) X X X X X x? X X xl 6. Exogyra ponderosa var. erratioostata Stephenson 7. Trigonia sp. nov. (Same as sp. nov. from Snow Hill, N. C.) X XX X X X 8. Pecten burlingtonensis Gabb X X x2 9. Pecten sp. nov. (same as sp. nov. from Snow Hill, N. C.) XX X 10. Anomia lintea Conrad 11. Anomia sp. nov. (same as sp. nov. from ' Snow Hill N. C.) 12. Crassatellites earolinensis Conrad. 13. Crassatellites sp. nov. (Roods Bend, XX XX x'? X x'? etc.) 14. Lucina glebula Conrad 15. Isocardia cliffwoodensis Weller. 16. Aphrodina regia Conrad 17. Cyclothyris alta Conrad 18. Baroda carolinensis Conrad 19. Corbula carolinensis Conrad 20. Gyrodes crenata Conrad X X x'? x'? X X X XX X XX XX X X X X X X X X X X X X X X X x X x4 X x" xs Note.-See footnotes on page 207. RIPLEY FORMATION 20~ 0 the 20 species restricted below the zone o Exogyra ponderosa in the Chattahoochee region, 10 (one questionably, see oot-note 7 in the table) range down into the underlying Tombigbee sand member o:f the Eutaw ormation. Eight o the species (two questionably, see oot-note 7 in the table) occur in the M ortoniceras sub-zone o the Tombigbee sand in the region to the west o the Chattahoochee region in Alabama and Mississippi. Thirteen (our questionably, see footnote 7 in the table) occur in that part o the zone o Exogyra ponderosa above the M ortoniceras sub-zone in the same region; and two occur in the Exogyra costata zone in northern Mississippi. In the Carolina region all but one o the 20 species occur in the Black Creek ormation, and one (qr questionably two) ranges up into the overlying Peedee sand. In New Jersey three o the 20 species occur in the Magothy ormation and five (two questionably, see oot-notes 3 and 5 in the. t;;tble) occur in the Matawan groups. The Merchantville clay marl which orms the basal portion o the Matawan group is believed to correspond approximately to the Tombigbee sand member o the Eutaw ormation (see pp. 145-149 o this report), which underlies that portion o the Chattahoochee section now being considered. By referring to the oot-notes in the table it will be seen that all o the five species occurring in the Matawan groups are present in beds above the Merchantville clay-marl, but that three o .the five also range down into the Merchantville beds. 0 the 20 restricted species given in the table only three are known to range above the zone o Exogyra ponderosa into the zone o Exogyra costata: anywhere in the Atlantic coast and eastern Gul regions. The conclusions reached regarding the ag(l and stratigraphic relations o the beds under consideration. may be summed up as follows: In the Chattahoochee region these beds fill in the gap between the underlying M ortoniceras sub-zone o the Tombigbee sand and the base o the overlying Exogyra costata zone. These two delimiting horizons are traceable throughout the greater extent o the eastern Gul Upper Cretaceous, and by this means the equivalents o the 10ccurs in Wenonah sand of Matawan group. 20ccurs in Merchantville clay-marl, Woodbury clay, and Wenonah sand of Matawan group. 'Probably same as Luoina oretaoea Whitfield from the woodbury clay of the Matawan group. Occurs in the Woodbury clay and Wenonah sand of the Matawan group. 'Probably same as Oorbula bisuloata Conrad which occurs in the Magothy formation and in the Merchantv!lle cla;s:-marl and the Woodbury clay of the Matawan group. occurs In the Merchantville clay marl, Woodbury clay, and Wenonah sand of the Matawan group. 7The questionably Identified species Crassatellites carolinensis Conrad and Lucina glebula Conrad, although not confidently referred to these species belong to types of the genus not known to occur above the zone of Exogyra ponderosa. 208 GEOLOGY OF THE COASTAL PLAIN beds are fixed for practically the whole of the region. The contained fauna as developed in the Chattahoochee region is traceable westward between these limits into Alabama as far as the central part of Bullock County, being well developed in the vicinity of Union Springs. In Bullock County the beds merge horizontally into the strata forming the lower half of the Selma chalk. The conditions under which the chalk beds were laid down appear to have been unfavorable for the existence or for the preservation of many of the species characterizing the fauna in the Chattahoochee region, for in the chalk the fauna is poorly represented; however, many of the forms reappear again in non-chalky representatives of the same beds in northern Mississippi. The evidence for correlating the beds in question with the invertebrate-beari:r~g beds of the Black Creek formation of the Carolinas is very strong; for of the 20 species restricted below the zone of Exogyra costata in the Chattahoochee region 19 occur in the Black Creek formation, and only one (or questionably two) of the 19 is known in the overlying Peedee beds. Six of the 20 species (two questionably) occur in the :Matawan group of New Jersey and none of the six are known in the overlying Monmouth formation. The evidence is satisfactory therefore for regarding the Chattahoochee beds under consideration as corresponding to the l\Iatawan group exclusive, however, of the :Merchantville clay-marl which forms the base of the Matawan. For reasons given in a preceding chapter (p. 149) the Merchantville beds are considered the equivalents of the underlying Tombigbee sand member of the Eutaw formation. The remains of a.few vertebrate animals, consisting of teeth and fragments of bones, have been found in the formation. The forms thus far identified are given in the list below: Pisces: Corax falcatus Agassiz Lamna texana Roemer Otodus sp. Ischyrhiza mira Leidy (Identified by J. W. Gidley) Reptilia: (Identified by C. W. Gilmore.) Fragments of the turtle Taphrosphys Fragment of large dinosaur limb bone Vertebra of mososauroid reptile Thecachampsa rugosa Emmons (vertebra) Polydectes biturgidus Cope (teeth) The sharks, Corax falcatus Agassiz and Lamna texana Roemer, are \vide ranging forms, both geographically and stratigraphically, and have no value in correlation. Of the sphyrreoid, Ischyrhiza mira Leidy, ::\Ir. Gidley says: "This species is abundant in the- GEOJ,OGY OF THE COAS1'AL PLAiN OF GEORGIA. PJ,.l1' N XI ' JJJ . A. GULLY lO 'h 1\UJ"ES NORTHEAST OF GEORGETOWN. ROWING COAR E. UNCON OLTDA'l'ED SAND OF 'l'HE PROVIDENCE AND MEMBER OF THF. RIPLEY FOR11ATIOX B. CU'l' 01~ C. O l? GA. HY.. NE ~llLE o "THEAST OF BUENA , ; IS'l'A. SHOWJN G UNCO~FORMABLE 0 :\'TA '1' BE'l'WEE ' PROVIDENCE SAND ME~IBER OF n -IE RIPLEY A~D OYERLYING EOCENE. RIPLEY FORMATION 209 green sand formations of the eastern and southeastern United States coast, and ranges in time through the Tertiary period." The two crocodilian species, Thecachampsa rugosa Emmons, and Polydectes biturgidis Cope, have also been identified by Mr. Gil- more from Phoebus Landing, Cape Fear River, N. C., an upper Black Creek horizon. This evidence is therefore corroborative of that afforded by the fossil invertebrates. Too little is known of the range of the remainder of the forms listed to render them of value in correlation. Fossil plants have been found in the Cusseta member of the Ripley formation at two localities; one, six miles northeast of Buena Vista, in Marion County, and the other near Byron, in Houston County. E. W. Berry, to whom the plants were sub- mitted, recognized from the first named locality six species. Con- cerning these he says: (Quoted from an unpublished manuscript.) "Three of the foregoing occur in the underlying Eutaw beds and all but the Ficus, which is new, are found in the Black Creek beds of North and South Carolina. The Andromeda, Araucaria, and Doryanthophyllum, occur in the Tuscaloosa formation, but are confined, so far as known, to the socalled upper Tuscaloosa beds near Havana in Hale County, Ala., although it is probable that the former will be identified from earlier horizons in Tuscaloosa. They are all, moreover, especially characte_ristic species of the Black Creek beds, and the Andromeda is one of the type fossils of the Magothy formation of the northern Coastal Plain, although it makes its earliest ap- pearance in the Raritan formation, as does also the Eucalyptus. * * * Concerning those from Byron, he says: "These plants number but three species: Dryopteris sp. nov. Berry, aunninghamites elegans (Corda) End!., and Araucaria jef{reyi Berry, the former being new to science. Since the genus Dryopteris ranges from the Lower Cretaceous to the. Recent and the Georgia species are not closely allied to any described form, it has no value in correlation. Of the other two forms, Ounninghamites elegans has a rather wide goegraphical range occurring both in this country and abroad. Its geological range is also considerable. In Europe it ranges from the Cenomanien to the Senonian inclusive, and in this country it has a parallel range from the Magothy flora of the east to the Montana flora of the west. It has been recorded from Lower Cretaceous horizons in Europe but the latter determinations are believed to be erroneous. The nearest geographical occurrence to th:J.t in Georgia is that of the upper Black Creek beds of North Carolina, hence the conclusion that the exposures near Byron are not older than those of the Magothy or the Black Creek beds appears to be firmly established. "The remaining species, Araucaria jeffreyi, is not a widespread form, but its intimate association, in the Eutaw formation at Chimney Bluff, Ga., and in the Black Creek formation of North Carolina, with Araucaria bladenensis, renders it extremely probably that the former represents the cone scales of a species of which the latter represents the foliage. Taken alone, Araucaria jef{reyi points to the same conclusions regarding the age of the deposits at Byron, as does the distribution of Araucaria bladenensis, but since the latter furnishes more definite data it will be briefly considered. "Araucaria bladenensis is one of the most abundant and typical forms of the Black Creek beds in North and South Carolina, ranging from their base to their summit. It has also been found in the Cusseta member near 210 GEOLOGY OF THE COASTAL PLAIX Buena Vista, at the top of the Eutaw formation at Chimney Bluff, and at the top of the Tuscaloosa, or in the base of the Eutaw of Smith in western Alabama, while a closely allied form occurs in the MaE:othy of New Jersey." The eri~,: ..=a ~~ 'bi !: ..""<''; " 8 ...""-g"".', ,2< ".5 ..<; ~ '"" "'" ;o:;;,, -a ... J"l"~ .a,<- a.5 " '00:: .,&"!0 '..~. Jt.ol.!.=l .. ... .eoC~..oo=" "o.o- NbO ~~: oi;..$.; "5'i_Sg ~~ ~o~o ~'S 'tj~ t"~' "..<; 0 ..... 0 ~ "0 ' ~"-...: ~: <..l';) _ E>.:~:l ~=- ... E-< !l.. .; "0:: ~ 0"' .-."5... 0 .0s:: ."es" .... "~ ' .0... ii""S' I' "0:: 0 N s ~ 8 .~ ,.. ."0.,..' >. .!L ""0:'': ..".""...,''' :;. ~... z" 0"' '0 " 0:: -5 '0 "e' ~"""""""""'' . >-5 ~ ::";:' >. .."~., :;. z " p. ~ 0:: s":;.' ::";:' ~ 0:: 0 N ~ ~ 0 :",.:'. ."0.,..' .!L >- ..".""..,.''' :;. .z."..'. 0 .0s:: ."e...s". -5 6 e 0:: ::0;: >. .."~., :;. z"' '0 0:: ._ .."e..s.' 8""'' 0:: 0"::' 1. Gassidulus porrectus Clark*. ' ;:;, Cassidulus subconicus Clark*. 3. Cassidulus conideus Clark* . 4. Cassidulus micrococcus Slocum* . 5. Cassidulus subquadratus Conrad 6. Hemiaster ungula (Morton)* X X X X 7. Hemiaster lacunosus Slocum* X 8. ? Coptostoma mortoni (de Lorio!)*. 9. Serpula cretacea (Conrad) 10. Serpula barbata Morton* X X X X 11. Hamulus squamosus Gabb 12. Nucula cuneifrons Conrad* X X 13. Leda pinnaforma Gabb X 14. Cucullaea vulgaris Morton* 15. Cucullaea littlei Gabb* Hi. Cucu.llaea antrosa Morton 17. Breviarea cuneata Gabb . . . . . -~ 18. Nemodon eufalensis Conrad . . . . I X X X X X I 1- X X X X X X HI. Glycymeris subaustralis ( d'Orbigny) X X X 20. Ostrea subspatulata Forbes* . . . . X X 21. Ostrea larva Lamarck X X X 22. Ostrea peculiaris Conrad* X 23. Exogyra costata Say* 24. Exogyra costata var. cancellata X X Stephenson* X X 25. Trigonia angulicostata Gabb* X 26. Pecten argillensis Conrad X 27. Pecten tenuitestus Gabb* X X 28. Lima acutilineata (Conrad)* X X 29. Lima pelagica Morton x? X X 30. Anomia linifera Conrad X 31. Anomia sp. nov. (Pataula Creek, etc.)* X x? 3') Paranomia scabra (Morton) X X X 33. Pulvinites argentea Conrad* X 34. Crenella serica Conrad X X X X X X X X x? X X X X xl? X X X X X X I X X X X X - RIPLEY FORMATION 213 .... ~ "".0., '""" ""0 j, ~ ~ ~ ' . ...,., '-"' ~ 'Hc.,..: ,Q ~-...: "'"' ""' .E ~.; ~ .~;n . ""' " ..,_"' ~ - ::0: ~:~ o::;: So ;::;;'"" ~ '"' """""' .C~!wJ ...,., !l "'"' """"."a ""' ~~ ~., E~ ;: Q) ~""S' 8 0"0 ~; .. " "" ;::;; ~s "' "< +> ..,"C 0 0~ ~.s ~ ""ss"'""".<""s-"'' '""s. :l"".blC<'')!."."gCl: ..c: ~b "o..C": ".,_,.'.8"c: ~o~., ~5 '0~ +> ~~ +> "~ ' "".0., ~"' ....: ~: !,l';j ~~ ~""~' E-o P; ~ ".0., i ~ .E .E 0 <.> .E :: .E <.> ,; .s"' ..0""...'. 0 ~ 0 '5" ~ ~ " J."L. ~",_ :3" 0"' @ '5" ,~.,. " ~ ,0.,. .."$ ~ ~ ..''P""""<"""""l>;' >. " ~ .."... ~ z " ~ ~ " 'H >. ..'5 0 b. .."","._.'. ~ z " ~.,. g " ..b. .."""....'.. ~ z " ~ ".~. 0 'H '5g s ::;: >. " ~ .."... ~ z " 'H 0 :0 "' 0 'H ~""""""0'' 35. Dreissensia tippana Conrad* X 36. Pholadomya occidentalis Morton X X X 37. Pholadomya sp. nov. .(Pataula Creek, etc.)* X 38. Anatimya anteradiata Conrad X X 39. Liopistha protexta Conrad X X xl? X 40. Cuspidaria ventricosa Meek & Hayden X X X 41. Crassatellites pteropsis Conrad X X 42. Crassatellites eufalensis Gabb* X 43. Scambula perplana Conrad X X X X 44. Tenea pinguis (Conrad) X X X 45. Sphaerella concentrica Conrad* X ....46. Cardium kiimmeli Weller* Cardium tippanum Conrad* X X X 48. Cyprimeria alta Conrad X X 49. Aphrodina tippana (Conrad) X X X 50. Aenona eufalensis Conrad X X 51. Panopea decisa Conrad X X X X X 52. Gastrochaena americana Gabb X X X X 53. Scala sillimani (Morton) X X X 54. Turritella vertebroides Morton* X X X 55. Turritella sp. nov. (two spiral ridges*) 56. Pt'erocerella tippana Conrad 57. Pugnellus densatus Conrad X x' X X x? X 58. Strepsidura interrupta Conrad* X 59. Rapana stantoni Weller X GO. Volutomorpha dumasensis Dall* 61. iv'Iorea cancellaria Conrad* 62. Pleurotoma ? melanopsis (Conrad) 63. P!eurotoma ? laqueata (Conrad) * 64. Ringicula pulchella Shumard* 65. Cylichna recta Gabb 66. Nautilus dekayi Morton* ' 67. Sphenodiscus pleuriseptus (Conrad)* 68. Hamites sp. nov. (same as from Prairie Bluff, etc.)* 69. Turrilites alternatus Tuomey * X X X X X X X X X I X X x' X X 10ccur only in the Wenonah sand which forms the uppermost formation of the Matawan group. The form from the Wenonah sand referred to Ostrea subspatu!ata Forbes is probably Incorrectly identified. 214 GEOLOGY OF THE COASTAL PLAIN In the eastern Gulf region to the west of the Chattahoochee region, three of the 69 restricted species occnr in the Tombigbee sand member (Mortoniceras sub-zone) of the Eutaw formation; 12 (one questionably) occur in that part of the Exogyra pondei'Osa zone which lies above the Mortoniceras sub-zone; and 38 ocem in the zone of Exogyra costata. The Peedee sand (Exogyra cos tata zone) of the Carolinas has furnished a small fauna as compared with that of the zone of Exogyra costata in the eastern Gulf region-the total milnber of species known being 28. Of the U9 species giveH in the above list 18 occur in the Peedee sand, and nine occur in the underlying Black Creek formation. Of the 18 species common to the Exogyra costata zone of the two regions at least nine are characteristic species of that zone. In New .Jersey two of the 69 species occur in the ::\Iagothy formation; 22 (four questionably) in the J\fatawan group; 21 in the Monmouth formation, and two in the Rancocas formation. Of the 21 species common to the Monmouth formation at least seven are regarded as characteristic of the zone of Exogyra costata. The comparison with 'New Jersey is made on the basis of the distribution of species as given by Dr. Stuart \Yeller.1 The percentage of the 69 species common to the Matawan group which is below the zone of Exogyra costata is rather larger than would be expected. However, four of the species are reported only from the Wenonah sand, which forms the uppermost formation of the Matawan group, and it is probable that several of the species are incorrectly identified since obviously many of the specimens upon which the identifications are based are poorly presen-ed. Of the 69 species restricted to the zone of Exogyra costata in the Chattahoochee region, 38, marked in the table with asterisks, are not known to occur in beds lower than that zone anywhere in the eastern Gulf or Atlantic Coastal Plain. Of the 38 restricted species, 30 occur in the zone of Exogyra costata to the west of the Chattahoochee region in Alabama or MiE'sissippi ; nine (one questionably) in the Peedee sand of the Carolinas, and seven in the Monmouth formation of New .Tersey. From the distribution of species as given on preceding pages the following conclusions have been deduced: The Exogyra costata zone of the Chattahoochee region is the Chattahoochee representative of a paleontologic zone which in western Alabama and east-central Mississippi is represented by approximately the upper one-half of the Selma chalk, and in northern ::\fississippi is represented by the Ripley formation and by a part 1Geol. Survey of Xew Jersey. Vol. 4, Paleontologic series, text and plates, 1907. RIPLEY FORM4.-TION 215 of the underlying Selma chalk. In the Carolinas this zone is represented by the Peedee sand, and in New Jersey by the Monmouth formation. A diagrammatic representation of these equivalencies is given in Plate V. The vertebrate remains thus far found in the zone of Eaogyra costata in the Chattahoochee region include the following: Pisces: Reptuia: Corax falcatus Agassiz Lamna texana Roemer Otodus sp. ? Ischyrhiza mira Leidy Tooth of mososauroid reptile Dermal scutes, probably of the preceding form. Corax falcatus Agassiz, Lamna texana Roemer, and Ischyrhiza rn.ira Leidy are species of wide geographic and stratigraphic range and are valueless in correlation. The ranges of the remaining forms are not known and consequently they throw no light on the age relationships of the deposits. With the exception of occasional pieces of lignite: fossil plants have been found at bnt one place in the beds under consideration. ,\ few imperfect )eaf remains \vere collected near the base of the zone of Exogyra costata on Cowikee Creek, a few hundred yards above its junction ,,ith Chattahooehee RiYcr i11 11arbonr County, Ala. E. \Y. Berry, who collected and studied these specimens, in a letter to the writer says: "The fossil plants from Cowikee Creek are few in number and poorly preserved. The following forms are represented: Bauhinia sp. nov. Platanus sp. nov. Laurus sp. Salix sp. Sapindus sp. Fern, not determinable "The remains of the Bauhinia and Platinus are complete enough to dem onstrate that they are new, the balance are too poor for accurate determina- tion, although they all appear to be distinct from any forms of the earlier Eastern Cretaceous floras." The slight e\idence afforded by these plant remains seems to indicate that a change in the Cretaceous flora of the region took place approximately coincident with the inauguration of the fanna characterizing the zone of Exogyra costata. 21G GEOLOGY OP THE COASTAL PLAIN TERTIARY AND QUATERNARY BY OTTO VEATCH A~D LLOYD WILLIAM STEPHE~SON EOCENE MIDWAY FORMATION NAME The Midway formation comprises the basal Eocene of the Georgia Coastal Plain. The term Midway was first used by Dr. E. A. Smith' and L. C. Johnson to apply to a formation on the Alabama River in Wilcox County, Alabama. From this locality, it has been traced eastward to the Chattahoochee River, and the strata described by D. W. Langdon' under the name Midway series (Clayton division). The Midway group of Alabama comprises the Clayton limestone, the Sucarnochee clay, and N aheola formation ("Matthews Landing") ; the two latter were not originally included in the Midway group. The upper part of the Midway group of Alabama is apparently missing on Chattahoochee River as the Wilcox formation there rests on the eroded upper surface of Midway strata. The term Midway has received general recognition as a permanent stratigraphic name in the literature on the Coastal Plain geology of Alabama, Mississippi, and Louisiana. Dr. J. W. Spencer" published some notes on the formation in Georgia and described sections along Flint River. Brief descriptions of a general nature have also been written by McCallie and Veatch.' DEFINITION Straligraphic relations.-The Midway formation rests unconformably upon the Upper Cretaceous.. Irregular contacts that appear to represent erosion unconformities between the two divisions were noted, especially in the gullies north and west of Lumpkin, Stewart County. The strata of the basal Midway and the Upper Cretaceous seem to be lithologically similar and on account of inadequate exposures considerable difficulty is experienced in determining the exact location and nature of the contact. A probable contact between the Cretaceous and the Eocene is exposed in the first railroad cut east of the depot at Lumpkin, where 1Bull. U. S. Geol. Surv. :'olo. 43, 1887, p. 62. 'Ala. Geol. Surv. Rept. on the Geology of the Coastal Plain, 1894, pages 418 to 743. Geol. Surv. of Georgia. First Report of Progress, 1890-91, pp. 43-49. Geol. Survey of Georgia. Bull. No. 15, Underground Waters of Georgia, 1908, pp. 34-35. 'Ge<:>loglcal Survey of Georgia, Bull. No. 18, Clay Deposits of .Georgia, 1909, pp. 79-82. MIDWAY FORMATION 217 the base of the Eocene eonsists of four to six feet of iron stained clay containing ferruginous sandy layers bearing poorly preserved fossils, resting upon light colored sandy clay of probable Cretaceous age. There is only slight evidence of an unconformity, however. A probable uncomformity was also noted about one and a half miles south of Lumpkin on the Cuthbert public road. Here a ferruginous sand is separated from a kaolinic sand by a line of pebbles and what seems to be certainly Eocene strata appears a short distance to the southward. In Marion, Schley, and Macon counties the Midway formation lies in contact with the Upper Cretaceous which it closely resembles in lithologic character, but in mapping it is not possible to draw a sharp line between the two. It consists mainly of unconsolidated red, purplish and white sands in which thin, siliceous limonitic layers and crusts and highly ferruginous sandstone are common. Thin beds of impure clays also occur, but neither the clays nor the ferruginous sandstone contain well preserved fossils. A probable contact between the Upper Cretaceous and the J\'l:idway formation occurs in a cut of the Central of Georgia Railway, one mile east of Buena Vista. The two divisions are separated by thin limonitic layers imbedded in a stained clay. The lower part of the section is white or light colored sand and sandy clay, the upper part, probably representing the Eocene, is a bright red ferruginous sand. At Underwood Ferry, on Flint River, six miles southwest of Marshallville, Macon County, the base of the bluff consists of gray or yellow rather compact argillaceous sand which contains poorly preserved fossils. From this locality a specimen of Venericardia planicosta was obtained and on the basis of this fossil the strata are classed as Eocene. This is evidently near the northern margin of the Eocene, but the relations to the Cretaceous in this vicinity are obscure. It is also not positively known whether the Eocene represents the Midway or Wilcox. A gray and black, laminated, sandy clay bearing V enericardia planicosta was also discovered at Barrow's Mill in Houston County, five miles east of Marshallville. There is here a poorly exposed unconformity which may represent a Cretaceous-Eocene contact. Venericardia planicosta and Turritella humerosa were obtained in a similar tiandy clay on Robert Slappy's land, four miles east of Marshallville, The fossils are inadequate for determining whether the exposure is Midway or Wilcox. No good physical evidence of an unconformity representing a con~iderable time interval between the Cretaceous and Midway has yet 218 GEOLOGY OF THE COASTAL PLAIN been discovered in Georgia, but there is paleontologic evidence that this intenal is as great here as in adjoining states. The J\fidway is separated at Fort Gaines from the overlying Wilcox by a remarkable unconformity, which will be subsequently describe<1. Superficial gray and brownish sand is spread over the formation in places and Pleistocene terrace deposits overlie it almig Chattahoochee [;nd Flint rivers. Lithologic characters.-The 1\lidway is mainly a marine formation and consists of sands, clays, marls, and limestones. Much of the sand, however, has a fresh water aspect. The lower part of the formation consists principally of sands and clays and the upper part consists of marls, clays, and limestones, but there is such variety in the character of the sediments that sharp lines of divisions based upon lithology can not be drawn. Thin layers of flint interbedded with sands and clays were noted in the lower part. The sands are vari-colored, generally friable, and in several places contain lenticular, massive layers of white clay. In the lower part of the formation lim,1nite is rather widely distributed in the sands in the form of thin crusts and as hollow concretions having black, polished, and botryoidal interiors. The limestones are fossiliferous, usually very hard and generally highly arenaceous, but in a few places sufficiently pure for use in the manufacture of lime. Friable marl, made up of glauconite, quartz sand, clay, and shells, occurs, and also laminated, black clay, and fullers earth. The limestones are conspicuous at several localities and are more abundantly fossiliferons than other parts of the formation. Individual beds of limestone in natural exposures are thin, from two or three to 25 feet in thickness, and are interbedded with clays, marls, and sands. Sands and clays make up by far the greater part of the vo miles southeast o:f Preston. The rock is a hard grayish limestone or indu .. rated, argillaceous marl, merlain by ferruginous sand. About 15 feet is exposed in the hiilside which forms the swamp bluff. The rock is fossiliferous, but ~rood fossil specimens are rather difficult to obtain. Dr. Vaughan has identified the following fossils from this locality: Fossils from Lime Spring. Turritella humerosa Conrad Mesalia alabamiensis (Whitfield) Ostrea pulaskensis Harris? Ostrea crenulimarginata Gabb Protocardia sp. Crassatellites sp.. At a point one mile south of Preston on the \Veston road then 1~ a thin bed of flint from which Dr. Vaughan has identified: Tm- 224 GEOLOGY OF THE COASTAL PLAIN titella> Ostrea apparently thirsae (Gabb), and Venericardia. It is very probable that tnis bed lies beneath the marl on Kinchafoone~ Creek and is hence Midway.' A marl, that occurs in the bed of the creek at the old Harrell distillery, about one mile farther south, is similar to that at Lime Spring and contains Ostrea crenulimarginata (?). At Bell's Mill, four and a half miles northeast of Preston, Dr. Vaughan has identified, Ostrea thirsae, Leda pharcida, Dentaliurn, Cardium> Lucina. The fossils were collected from thin flint beds. The geographic position of the beds, (four or five miles north of the Midway at Lime Spring on Kinchafonce Creek) their low topographic position, (lower than the higher ridges and hills of this vicinity, with no suggestion of an overlap), are considered evidence that the strata here may belong to the Midway. Ellaville.-Near the site of old Quebec, eight miles southwest of Ellaville, there is an exposure of 20 feet of highly siliceous limestone and clay with siliceous nodules, overlain by red, highly ferruginous sand and sandstone. The rock here might be properly termed a calcareous grit. Large angular, crystalline quartz grains are imbedded in a white, opaque and enamel-like calcareous matrix. The rock is very hard and compact and the quartz g-rains fracture rather than fall out when the rock is broken; the compactness is due in part to a cement of amorphous or opaline silica. Oyster shells, Ostrea crenulima"'r;inata, were observed. The rock contains a small amount of phosphate in the form of brown gTains or pellets. At Walls Crossing, four and one-half miles northwest of Ellaville, Midway fossils were collected from a thin marl bed. The marl and limestone bed which is about four feet thick is exposed at the head of a small branch about 200 yards northwest of the cotton gin of Mr. C. H. Wall. Dr. Vaughan has identified the following fossils from this locality: Fossils from Walls Crossing. Turritella humerosa Conrad Turritella alabamiensis Whitfield Ostrea crenulimarginata Gabb. Venericardia smithii Aldrich Cytherea ripleyana (Gab:b) Montezuma.-Good exposures of the Midway formation appear in the bluffs of Flint River above and below Montezuma. The following section appears in the bluff at the wagon bridge one mile northwest of the town : 1See note by T. W. Vaughan, p. 222. MIDWAY FORMATION 225 Section one mile northwest of Monte~uma. Pleistocene (terrace deposit). 6. Red sand with a covering of brown, incoherent Age ? superficial sand . . . 5. Laminated, drab clay . . . . . . . . . . . . . . . Eocene. Midway formation. 4. Compact limestone, variable thickness; contains large oysters . . . . . . . . . . . . . . . . . . 3. Clay, marl and limestone . . . . . . . . . . . . 2. Massive limestone layer, contains 0. crenulimargi- nata, Cardium, Orassatellites . . . . . . . . . 1. Bluish, massive bedded clay and coarse gritty ar- gillaceous sand . . . . . . . . . . . . . . . . Feet. 15 to 20 2 8 5 15 Northward from the bridge, No. 1 reaches a thickness of 25 feet; the lower end of the blufi is not well exposed and fragments of beds Nos. 2 and 3 have fallen to the base. The dip of the strata is southward, and bed No. 5 doubtless dips beneath the river between the upper wagon bridge and the Central of Georgia railroad bridge. At a locality two and a hal miles north, and on the east side of the river, on the De Yaughn plantation, the following section occurs: Section on De Vaughn plantation. Feet. 5. Red, argillaceous sand capping bluff . . . . . . 4. Clay with nodules of limestone, oyster shells abundant; the materials are weathered and not well exposed . . 8 3. Compact, gray, sandy limestone, fossils . 3 2. Friable, calcareous, gray, clayey sand . . . . . . . . . . 10 1. Sandy, glauconitic limestone . . . . . . . . . . . . . . . 20 Another section ,exposing limestone occurs at Dripping Blufi, nine miles south of Oglethorpe. Tpe limestone is compact, bluish-gray, glauconitic and fossiliferous, containing the characteristic Midway oyster, 0. crenulimarginata and other fossils. Dripping Blufi is on the west side of Flint River and about half way between the mouths of Sweetwater and Camper creeks. Section at Dripping Bluff. Pleistocene (terrace deposit) Feet. 12. Reddish sand poorly exposed . . . . . . . 12 to 15 Eocene. Midway formation. Feet. In. 11. Poorly exposed and partly concealed, but probably calcareous clay, containing limestone nodules . 10 10. Interbedded, very thin layers of hard, nodular limestone and clay 5 9. Clay . . . . . . . 1 8. Limestone . . . . 8 7. Black clay marl . . 1 226 GEOLOGY OF THE COASTAL PLAIN Feet. In. 6. Nodular limestone and black argillaceous sand . 1 5. Clay marl . . . . . . . . . . . . . . . . . . . . 2 4. Limestone . . . . . . . . . . . . . . . . . . . . 6 3. Black, compact, argillaceous sand . . . . . . . 22 2. Hard, pitted, sandy and glauconitic limestone; contains fossils, principally large 0. crenuli- marginata . . . . . . . . . . . . . . . . . . . [l 1. Black, argillaceous sand and sandy marl, not ex- posed except at low water . . . . . . . . . . . 3 Bed No. 2 is apparently dipping soutlmard at the rate of about 30 feet per mile. The following is a section of a bluff one-fourth to one-half mile above Dripping Bluff. Section one-half mile above Dripping Bluff. ,4. Red and crossbedded, rather coarse sand with small quartz pebbles at the base. This material underlies a terrace 'Plain 45 to 50 feet above the river, and is doubtless Pleistocene . . . . Midway formation 3. White and red fine sand, containing clay laminae 2. Black, massive, pyritiferous argillaceous sand, yellowish at the top, with thin limonitic crusts . . 1. Massive bluish-white, jointed clay . . . . . . . . Feet. 12 7 10 14+ Bed No. 2 contains a few poor fossil prints. X o marl or limestone appears; this indicates the variable nature of the J\!Iidway deposition. Furthermore, no limestone or even calcareous strata have been observed between this point and the bluff at :Montezuma. A clay bed very similar to No. 1 of the preceding section occurs at Copperas Bluff, about three miles farther dmvn-stream. Section at Copperas Bluff. Pleistocene (terrace deposit). 3. Yellow and orange sand, variable thickness, maxi mum .. Eocene. Midway formation ? 2. Black, pyritiferous, massive argillaceous sand, contains a few prints of fossils . . . . . . . . . . 1. Massive, jointed, bluish-white clay, maximum thickness . . . . . . . . . . . . . . . . . . . Feet. 20 15 15 Beds 1 and 2 are almost identical lithologically with Nos. 1 and 2 of the 'above section. WILCOX FORMATION NAME The Wilcox formation derives its name from wilcox County, Alabama, where the formation is typically exposed. Strata of this for- WILCOX FORMATION 227 mation were formerly embraced in the "Lignitic Group." Dr. E. W. Hilgard1 used the term "Lignitic" in Mississippi or all o the strata lying between the Claiborne and the Cretaceous, and included in it come beds belonging to the Claiborne group. Also in early literature' the term was applied to all o the formations lying between the ''Burhstone" and the Cretaceous o Alabama. Subsequently; however, the calcareous beds at the base o the Tertiary in Alabama were differentiated and given the name Clayton (a division o the Midway). The term "Chickasaw" was later substituted or "Lignitic", excluding the Flatwoods belt o Mississippi, by Dr. Hilgard and Dr. Dall, and by a still later decision o the committee on nomenclature o the U. S. Geological Survey,' the name Wilcox was substituted or that portion o Hilgard's "Lignitic", which lies below the Claiborne group and above the Midway. D. W. Langdon studied strata o the Wilcox on the Chattahoochee River and made the following divisions: Hatchetigbee Lignitic Bashi (Woods Bluff) { Tuscahoma Nanafalia (Bell's Landing) These divisions can not be discriminated eastward rom the ChattahDochee. In view o the small thickness o the Wilcox at Fort Gaines, and the probable occurrence o strata o the Claiborne group on Chattahoochee River near water-level our miles south o Fort Gaines (see following pages), it is not unlikely that a portion o the strata classed as "Lignitic" by Langdon, belongs to the Claiborne. DEFINITION Stratigraphic relations.-In Georgia, the Wilcox ormation includes the strata lying between the Midway ormation and the Claiborne group. At Fort Gaines on Chattahoochee River, the Wilcox and the Midway are separated by a remarkable erosion unconformity, represented by holes in the white limestone o the Midway ormation filled by black sandy clay o the overlying ormation. These holes must originally have had a depth o 20 eet or more. Paleontologic and lithologic differences and the erosion unconformity furnish a sufficient basis or the separation o the Midway and Wilcox formations 1Hilgard. E. W., Geology and Agri~ulture of Mississippi, 1860, p. 108. 'Smith, E. A., and Johnson, L. C., U. S. Geol. Survey, Bull. 43, p. 38. 'Geol. Surv. of Ala., Report on the Geology of the Coastal Plain, 18\!4, p. 147. 'Crider, A. F., Geology and Mineral Resources of Mississippi, U. S. Ceol. Survey, Bull. 283, p. 25. 228 GEOLOGY OF THE COASTAL PLAIN at Fort Gaines. East of this locality, however, the paucity of the :fossils, the fact that no unconformity could be discovered, and the unsatisfactory character of the evidence' furnished by the lithologic composition of the strata, has rendered the discrimination of the two formations very difficult; therefore, the boundary line as mapped is necessarily tentative. The contact with the overlying Claiborne group, where this has been observed, is marked by an undulating line of small pebbles or a stratum of coarse sand, but there is no physical evidence of any considerable time interval having elapsed between the deposition of the two. An unconformity marking the contact between the Claiborne group and the Wilcox formation has been noted at the following localities: in the bluff at Fort Gaines, 50 to 55 feet above Chattahoochee River; in a cut of the Central of Georgia Railway two and one-half miles west of Cuthbert; at Hall's Bridge on Kinchafoonee Creek seven miles southwest of Plains ; doubtfully in the public road at Blacks Mills five miles north of Plains; and one and one-half miles southeast of Andersonville, on the south side of Sweetwater Creek, about one mile below Hodge's Mill. Unfortunately, the strata are not fossiliferous, except at Fort Gaines, and the evidence that the unconformities are of stratigraphic importance is not entirely conclusive. Lithologic characters.-On Chattahoochee River, the formation is made up of sandy, glauconitic, shell marl, dark colored, laminated, often lignitic, sandy clay, in places consolidated into mudstone, and usually dark or gray glauconitic and lignitic sand. The laminated clay exposed in the bluff at Fort Gaines can be traced northeastward, having in Randolph County north and west of Cuthbert, the nature of fullers earth, which in places is glauconitic. At Greer 'Cave, there seems to be a considerable thickness of vari-colored and kaolinic sand between the Wilcox clay and the limestone of the :Midway formation. Black and drab laminated, glauconitic clay and sand were observed on Bear Creek northeast of Weston, Webster County. Gray and black argillaceous and glauconitic sand appears at Magnolia Spring, two and one-half miles north of Plains; in the bed of a branch on the old Morgan plantation, six miles northeast of Plains; and at Hall's Bridge on Kinchafoonee Cr:eek, seven miles southwest of Plains. Farther eastward in Schley and Macon counties and in the vicinity of Andersonville, the strata which might be referred to this formation on the basis of geographic position, are mainly red and varicolored sands with massive beds of white clay, very pure and in the nature of sedimentary kaolin, bearing little resemblance to the strata on Chattahoochee River. WILCOX FORMATION 229 Thickness.-It seems very probable that Langdon's1 estimate of 402 feet is excessive, in view of the small thickness of Wilcox at Fort Gaines, and from the fact that Dr. Vaughan has determined Exogyra costata from the Blakely well at a depth of 500 to 510 feet. (See page 312). The thickness of strata between the McBean and the Midway formations at Fort Gaines does not exceed 75 feet. The maximum thickness at any place over the area of outcrop probably does not exceed 150 or 200 feet. It is difficult to form an accurate estimate of the thickness of the Wilcox formation as is true also of the underlying Midway formation, for east of Chattahoochee River, neither the base nor the top of the formation has been accurately established. There is a natural exposure of the formation revealing an estimated thickness of 100 feet of strata at Peterson Hill, four and a hal miles northwest of Cuthbert. The following is the record of a well at Shellman, Randolph County: Record of well at Shellman. 5. Red clay . . . . . . 4. Quicksand . . . . . 3. Blue marl . . . . . 2. Very hard limestone . . 1. Water bearing formation Feet. 0 to 1& 1& to 14& 148 to 300 300 to 400 400 to 410 Assuming the limestone layer No. 2 to be the same as the Midway limestone which is exposed at Greer Cave about 16 miles northwest, the overlying 152 feet of "blue marl" may belong to the Wilcox formation. There is no positive proof of strata of Wilcox age on Flint River. It may be entirely overlapped by the Claiborne, but assuming that the strata lying between the Midway formation at Dripping Bluft (see page 225) and the McBean or Vicksburg formations is Wilcox, the thickness is perhaps 100 feet. Paleontologic chariwters.-The formation is on the whole poorly fossiliferous. The following Georgia forms have been identified by Dr. Vaughan from collections made by the writer east of the Chattahoochee. River: List of fossils from the Wilcox formation in Georgia. .A!ctaeon Turritella mortoni Conrad Turritella !Praecincta Conrad Ostrea thirs,ae (Gabb) Venericardia planicosta Caroium 1Langdon, D. W., Report on the Geology of the Coastal Plain, Ala. Geol. Survey, 1894. p. 369. McCallie, s. W., Underground Waters of Georgia, Bull. 15, 1908, p. 156. 230 GEOLOGY OF THE COASTAL PLAIN C.alyprtrea ,aperta ('Solander) Denrtalium Leda pharcida Dall Glycymeris Proto-cardia Cytherea Cassidulus ( ?) sp. At a locality five and one-hal miles south o Lumpkin the following fossils were obtained: Fossils from five and one-half miles south of Lumpkin. Endopachys maclurii (Lea)1 Pyrula juvenis Whitfield ? Turritella sp. Leda (ap;parently rpharcida Dall) Cytherea nurtalliopsis Heilprin ? Nucula sp. Paracyathus ? sp. Cucullaea macrodonta Whitfield Lucina sp. Cytherea sp. The species 0. thirsae, 0. compressirostra, Chlamys greggii, and Cucullaea macrodonta have been identified rom beds near Fort Gaines. Dr. Vaughan has also identified a small oyster as 0. thirsae, a species considered characteristic o the Wilcox ormation, rom beds our and one-hal miles northeast o Preston, and a specimen apparently 0. thirsae rom a flint bed one mile south p Preston. There, is however, a possibility o these beds belonging to the Midway. As the collections are small and the material in general poorly preserved, oten stratigraphic deductions rom fossils can not be made with the same surety or Georgia as or states to the west where fossils are more abundant and better preserved. Further mention o the material near Preston and a note by Dr. Vaughan will be ound on pages 222-223. Areal distribution.-The Wilcox ormation extends in a northeastward direction rom the vicinity o Fort Gaines on Chattahoochee River probably to Flint R~ver in the northeastern part o Sumter County. The width o the belt o outcrop is on the average perhaps not more than five or six miles. It is, to some. extent, overlapped and obscured by the McBean and Vicksburg formations. The ormation has not been recognized east o Flint and Ocmulgee rivers. Pro. G. D. Harris referred strata at Roberts, nine miles east o Macon, to the horizon o the "Woods Bluff" (Bashi), ormation o the Wilcox group, but it seems now more probable that they are Claiborne. (See page 279.) Physiographic expression.-The area underlain by the ormation is small and it has produced no notable physiographic features. The topography o the area is rather broken and hilly similar to that o the Midway area to the north. , 1Note by Dr. Vaughan: "Endopachys maclurii suggests Claiborne; while Oucullaea macrodonta is usually not later than Wilcox." WILGOA'; FORMATION 231 Structure.-The strata dip southward or southeastward. No dat:.t are at hand for accurately estimating the rate of this dip. It is probably less than 30 feet per mile. No evidence of local deformation was. noted, although, doubtless, such may have taken place-in the area adjacent to Chattahoochee River, as noted in the case of the Midway formation. Economic geology.-Friable, glauconitic shell marl occurs at the base of the Wilcox formation at Fort Gaines, and should be of local value as a fertilizer. This marl, in addition to calcium carbonate, carries small percentages of phosphoric acid and potash. Massive beds of white, fire-clay, which probably belong in this formation, occur in the northern part of Randolph County and in Schley and Sumter counties and will probably be of some commercial value in the future. LOCAL DETAILS Fort Gaines.-The Chattahoochee River bluff at Fort Gaines, Clay County, affords exposures of great stratigraphic importance. Sections of the bluff have'been published by Loughridge/ Spencer," Langdon' and Veatch.' Sections made by different observers differ in details, from the fact that the layers are of somewhat variable lithologic composition. The following is a section made by Dr. Stephenson: Section of bluff on Chattahoochee River at Fort Gaines, Ga. Pleistocene (terrace deposit). 12. Coarse, red, ferruginous sand, pebbly in lower half 11. Pebble and cobble layer, the pebbles and cobbles well rounded; also numerous fragments of greenish, gray, calcareous sandstone . . . . . Eocene. McBean formation. 10. Greenish gray, laminated clay with, fine sand partings, and occasional thin layers of glauconitic sand ..................... . 9. Very glauconitic sand with irregular iron concretions ..................... . 8. Indurated layer of large oysters with sand matrix. Contains also large prints of Venericardia planicosta, and in loose glauconitic sand pockets along base small fragile pectens. (Fossils col- lected . . . . . . . . . . . . . . . . . . . . . 7. Light gray, calcareous sand with small scattered fragile shells . . . . . . . . . . . . . . . . Feet. 18 2 8 10 'Tenth Census, Vol. VI, Cotton Prt~duction, Georgia, p. 14. 2Spencer J W., First Report of Progress, Geol. Surv. of Ga., 1890-91, p. 46. Landon,' D: W., Report on the Geology of the Coastal Plain, Ala. Geol. Surv, 18!!4, p. 4V0e6a.tch, Otto, Clay Deposits of Georgia, Geol. Surv. of Ga. Bull. 18, 1909,. p. 8"" 232 GEOLOGY OF THE COASTAL PLAFX 6. Indurated layer of argillaceous, calcareous sand- stone with a few prints of fossils . . . . . . . Wilcox formation. 5. Dark gray, calcareous rather coarse argillaceous sand, with scattered lime- concretions . . . . . 4. Dark gray, more or less sandy clay with pockets of sand . . . . . . . . . . . . . . . . . . . . 3. Dark gray shell marl with rather coarse sand matrix. Lime concretions irregularly distributed through the marl, especially near the mid' dle of the bed. <;ontains numerous large pieces of lignite also near the middle of the bed. Shells most numerdus 8 to 10 feet above base of section. (The horizon is the same as that from which a collection was made on the west side of river above the bridge at Fort Gaines) . . . . 2. Light gray, mealy, very micaceous sand, streaked with iron stain. (This stratum and the preceding separated from the following bY a marked unconformity) . . . . . . . . . . . . . . Midway J'ormation. 1. Rather soft, yellowish limestone (stage of water about eight feet above normal) . . . . . . . . 2 12 13 17 to 20 0 to 4 3 to 10 From Layer No. 8, Dr. Vaughan identified 0. sellceformis, Pecten deshayesii, and 0. georgiana ?, and determined the horizon to be Claiborne. A ~ection and description which includes some details not given in the preceding sections was made by Veatch. The location is about one-fourth mile below the wagon bridge. Section of Bluff at Fort Gaines. Pleistocene (terrace deposit) 13. Coarse red sand with quartz pebbles in the lower half; caps the bluff . . . . . (Unconformity). Eocene McBean formation. 12. Drab, fine-grained, laminated clay with sand part- ings . . . . . . . . . 11. Yellow and grayish glauconitic sand . 10. Clay and sand, in part calcareous 9. Indurated clay layer or drab claystone; contains fossils and is similar lithologically to the Claiborne claystone east of the town of Fort Gaines .. 8. Grayish, argillaceous sand 7. Yellowish and gray quartz sand; contains calcarll- ous sand nodules; small pebbles noted at the base; fossils Xenophora, Venericardia planicosta wilcox formation. 6. Gray and black laminated, sandy carbonaceous clay; part of the thickness is indurated and jointed . . . Feet. 15 8 10 to 12 20 2 to 2lh 6 2 to 2lh 18 WILCOX FORMATION 5. Calcareous, compact, argillaceous sand, contains fragile shells and is in the nature of a marl; Balanophyllia . . . . . . . . . . . . . . . . . 4. Nodular calcareous layer . . . . . . . . . . . . . 3. Ash-colored, lignitic sand, unconsolidated bed of small oyster shells, 0. thirsae, at the base . . . 2. Gray, mealy, lignitic sand, variable thickness, in erosion pockets in limestone . . . . . . . . . (Unconformity.) Midway formation. 1. White to yellowish soft massive bedded limestone poorly fossiliferous, contains 0. pulaskensis, maximum thickness exposed . . . . . . . . . 233 8 2 7 4 20 At very low water stages, circular pockets of black, or gray lignitic, argillaceous sand can be seen in the limestone in the bed of the river beneath the wagon bridge. No. 13 of the section underlies the terrace plain upon which Fort Gaines is situated, and is a Pleistocene terrace deposit. In the west bank of the river at the wagon bridg, the white sandy limestone of the Midway formation is overlain by three to six or eight feet of friable, sandy, glauconitic marl, in which the shells of the small oyster, Ostrea thirsae, are very abundant. Above the marl there is a sandy clay which contains white calcareous nodules. At the mill and cotton-gin on Commochechebbe Creek, one mile north of town, the Midway-Wilcox unconformity is again well exposed. A lignitic, argillaceous sand fills holes and cracks in the limestone, and the limestone is overlain unconformably by a glauconitic sandy marl which contains in abundance small oyster shells, 0. thirsae, small fish teeth and fragments of bones. At the mouth of Flat Creek, four and one-half miles south of Fort Gaines, a glauconitic, sandy argillaceous, shell marl was found in the bed of the creek a few yards above its junction with the river. The creek has cut a narrow trench in the first terrace bordering the river, formi}\g bluffs about 30 feet high. Only two or three feet of marl is exposed above the water, and the upper part of the bluff is a dark, lignitiferous, argillaceous sand, and Pleistocene alluvium. From fossils collected here, Dr. Vaughan has identified: Cucullaea macrodonta Whitfield Ostr,ea comvressirostra Say. Chlamys greggii Harris Pecten sp. Ostrea sellaeformis Conrad The 0. sellmforrnis suggests Claiborne strata at this point, while the other fossils are Wilcox in age. However, no other evidence of two Eocene horizons was observed in the field examination. The evivest of Cuthbert. Vertical section in strata at Peterson Hill. Claiborne group ? 8. Incoherent red sand, very fine . . . . . . . . . . Wilcox formation. 7. Orange-colored, fine-grained, clayey sand, residual 6. Gray, silty, laminated clay . . . . . . . . . . . ] 5. Gray, slate-colored and drab laminated clay, con- tains thin glauconitic layers . . . . . . . . . 4. Clay in the nature of fullers earth, slightly glau- conitic . . . . . . . . . . . . . . . . . . .. 3. G-lauconitic layer, a few fossils noted . . . . . . 2. Coarse red and yellow quartz sand, contains a lens of white and yellow massive clay 8 feet thick . 1. Rather coarse, current-bedded sand, probably glau- conitic near the top . . . . . . . . . . . . . Feet. 15 15 55 4% 25 15 What is probably an unconformity between the glauconitic clay and the red sand of the overlying Claiborne group appears in a cut of trre Central of Georgia Railway near the 121 mile-post about three miles west of Cuthbert. The Wilcox strata here consist mainly of gray or drab laminated and jointed clay. The beds lying above the marl and limestone on the upper Lumpkin road to eight miles north of Cuthbert, as exposed in the cuts and gullies along this road, are mainly drab or gray, sandy, laminated clay in the nature of fullers earth. At a few places red; incoherent sand was noted and a bed of white, very pure clay occurs between the five and six-mile posts. The thickness of the strata is inferred from natural exposures to be 125 to 150 feet. Red sand, either Claiborne or Vicksburg, appears on the highest hills. Weston.-The following section appears in the Weston-Preston public road, one and one-half miles northeast of Weston, Webster County: 'Aldrich, T. H., Report on the Geology of the Coastal Plain, Ala. Geol. Survey. 1894, p. 236. CLAIBORNE GROUP 235 Section one and one-ha!f miles northeast of Weston. Age ? Feet. 4. Red sand containing flint fragments; the flint fragments contain characteristic Oligocene fos- sils . . . . . . . . . . . . . . . . . . . 40 to 50 3. Coarse, red sand . . . . . . . . . . . . . . 10 to 15 Wilcox formation? 2. Drab, laminated clay, slightly glauconitic; some poorly preserved fossils . . . . . . . . . 20 1. Black, sandy, glauconitic clay . . . . . . . 8 Beds 1 and 2 appear to be similar to the clays near Fort Gaines and Cuthbert and probably represent the Wilcox formation. Plains.-Gray, glauconitic sand appears at Magnolia Spring, two and one-half miles north of Plains, Sumter County, which is also probably a part of the Wilcox, although no fossils were observed. Ellaville.-Fossils of the Wilcox formation were found south and southeast of Ellaville, Schley County. On the Lumpkin farm, on Goldendale Creek, six miles southeast of Ellaville, fossils were found in fragments of flint in a clay soil. The natural exposures are poor at this locality, and the field observations afford no evidence supplementing that of the fossils. Dr. Vaughan identified the following fossils from this locality: Fossils from Lumpkin farm) Goldendale Creek. Cassidulus ( ?) sp. Actaeon Turritella mortoni Conrad Calyptrea aperta (Bolander) Dentalium Leda pharcida Dall Glycymeris Ostrea thirsae (Gale) Cardium Cardium Andersonville.-The weathered exposures at Andersonville, Sumter county, reveal deep red sands and the fresher exposures in gullies reveal white and red cross-bedded incoherent sands. A thick bed of white clay is reported in a well 90 feet deep, near the station. In a cut of the Central of Georgia Railway, two miles north of Andersonville, 35 feet of white and red, incoherent quartz sand which presents a most wonderful display of eross-bedding, is exposed. Thin beds of limonite or ferruginous sandstone in the loose sands were noted in this vicinity. A sandy clay containing scattered glauconite grains resembling the glauconitic clays of the Wilcox formation was found near Hodge's Mill on Sweetwater Creek, one mile E>Outh of Ander- sonville. I CLAIBORNE GROUP The Claiborne group, or Claiborne formation, where the strata representing the group are not subdivided into constituent formations, derives its name from the old town of Claiborne, on Alabama River, 236' GEOLOGY OF THE COASTAL PLAIN once a prosperous village but now represented by only a warehouse and boat-landing. The boat-landing is at the foot of the Claiborne Bluff, one of the classic localities of American geology. It was from a study of fossils collected here that Conrad1 first recognized the pres- ence of strata of Eocene age in the United States. The Claiborne group is continuous from Alabama into Georgia, where it occupies the same stratigraphic position, above the Wilcox and beneath the Jack- son, and is characterized by the same species of fossils as in the former State. The Eocene age of the marl and limestone at Shell Bluff in Georgia, along with the strata of Claiborne Bluff of Alabama, was first recog- nized by Conrad.' In 1900, Dr. T. Wayland Vaughan' visited the Shell Bluff locality and established the Claiborne age of the exposure below the Ostrea georgiana bed. In 1908, Prof. S. W. McCallie gave a brief description of the Claiborne and published an extensive list of Claiborne fossils, chiefly identified by Dr. Vaughan, obtained mainly from the region east of Ocmulgee River. D. W. Langdon' first recognized the presence of Claiborne strata on Chattahoochee River, while beds of Claiborne age were first discrim- inated on the Flint by J. W. Spencer." The Claiborne group in Alabama is subdivided into three forma- '1 twns, v1z. : Gosport greensand Lisbon formation Tallahatta buhrstone Although in a general way the correlatives of these formations may be recognized in Georgia, the extension of the use of these terms to this State is inappropriate, since the Claiborne group is not naturally -divisible into the same units as in Alabama; therefore, in Georgia the group is divided into two formations, with the recognition of a member in one of the formations, viz. : Barnwell sand McBean formation, with. the Congaree clay member. 1Proc. Acad .Nat. Sci., Philadelphia, 1834, Vol. 7, pp. 116-157. 2Amer. Jour. Sci., 2d ser., Vol. 41, 1866, p, 96. Science, n. s., Vol. 13, Feb. 15, 1901, p. 270. Bull. Geol. Survey of Georgia, No. 15, 1908, pp, 33, 34, 336-348. Bull. GNL Soc. America, Vol. 2, 1891, pp. 597, 598. Rept. of Progress, Geol. Survey of Georgia, 1890-1891, p, 51. Smith, E. A., Underground water resources of Alabama: Geol. Survey of Alabama, ~907, pp. 17, 18. :tchEAN FORMATION 237 Sloan1 has proposed a number of phase nam~s for the various aspects of the Claiborne group as it is exhibited in South Carolina and in two instances the usage of names for subdivisions of the Claiborne group is extended from there into Georgia. McBEAN FORMATION NAME The name McBean is derived from the town of McBean in Richmond County, Ga., and from McBean Creek which forms the boundary between Richmond and Burke counties. The formation to which the name is here applied is well exposed near the town of McBean and southward along McBean Creek to its confluence with Savannah River. According to Dr. Vaughan the formation is equal to the Tallahatta buhrstone plus the Lisbon formation of Alabama, and the top of it may include the base of the Gosport greensand of the Alabama section. DEFINITION Stratigraphic relations.-The McBean formation rests unconformably u_T;>on strata of Lower Cretaceous age east of Ocmulgee River. This unconformity represents a long interval of time, for the two lower Eocene formations, the Wilcox and Midway, and all of the Upper Cretaceous deposits, aggregating a thickness of 3,000 feet or more, are absent in this region. Tongues of McBean strata also lap over the Cretaceous and even extend to the crystalline rocks of the Piedmont Plain. The most notable of these overlaps are at Roberts, Harlem, and Grovetown. Between Flint and Chattahoochee rivers the McBean formation rests upon the Wilcox formation. Along Chattahoochee River, in the vicinity of Fort Gaines, there is evidence of an erosion unconformity, probably of minor importance, separating the two formations. The formation in eastern Georgia is overlain by the Barnwell sand which in this region constitutes the upper formation of the Claiborne group. The relations between the two divisions are somewhat obscure. Along the northern margin of the areal occurrence of the Barnwell sand there is evidence of an unconformity of slight time importance separating it from the McBean formation, but farther southward the former seems to rest upon the latter with conformable relations. It seems probable that near the close of the time of deposition of the McBean formation there was an uplift which brought the northern margin of the area of Claiborne deposition above sea-level, permitting erosion to take place in the emerged area, while deposition continued in tile area which remained under water. The uplift was of 1Catalogue of mineral localities of ~outh Carolina: Geol. Survey of South Carolina, 1908. 238 GEOLOGY OF THE COASTAL PLAIN short duration, however, the emerged tract being soon submerged again allo~wing deposition to continue as before over the whole belt. The Barmvell sand may be, in fact probably is, present west of Flint River, but as there is some doubt as to its identification in this area there is lack of definiteness regarding the stratigraphic relations between the McBean and the overlying formations. Lithologic characters.-The formation consists mainly of clays in the nature of fullers earth, shell marls, sandy limestones, and calcareous, glauconitic sands. The marls are for the most part massivebedded and friable, but hard, compact, and even partially silicified beds were noted on Savannah River. They may also be represented by alternate layers of marl or calcareous sand and laminated clay. The greatest thickness of the marl beds is in the Savannah River bluffs where, at Shell Bluff, there is an exposed thickness of over 100 feet. The' marls of the :McBean formation reach their greatest development on Savannah River; they extend southward from Shell Bluff about 11 miles in a direct line to a point one and one-half miles below Griffins Landing, where they appear in the bluff 50 feet above the water level. westward from Savannah River, marls are exposed near McBean, Louisville, Tennille, Sandersville, and at other localities. The Flint River exposures are friable, calcareous sands, sandy limestones, marls, and sa:o.dstones. On Chattahoochee River, Langdon recognized a lower "Buhrstone" member and an upper calcareous member. The formation here presents a variety of lithological phases as elsewher~gray, glauconitic limestones and marls resembling those on Savannah River; calcareous clays and claystones, and red and vari-colored unconsolidated sands. Exposures of the formation are of small areal extent, and the marls and other materials have had but little effect upon the soils of the region underlain by them. The marls are usually replete with fossils, the casts and shells of mollusca being the most common. Vertebrate remains, fish teeth, fragments of bones, etc., Bryozoa, and corals have been collected. A portion of the McBean formation consists principally of fullers earth, and drab or greenish sandy clays. This is a depositional phase of the terrane. It is best exposed along the northern margin of the formation, extending approximately from Grovetown, Columbia County, to near Macon. This phase will be described on following pages as the Congaree clay member of the McBean formation. The McBean formation as a whole presents a marine aspect, and was doubtless deposited near shore and in shallow water. McBEAN FORMATION 239 Thickness.-The thickness of the McBean formation east of Ocmulgee River is estimated at 300 to 400 feet. The maximum expo;ed thickness occurs at Shell Bluff, Savannah River, where 115 feet of strata were measured. The thickness of the Claiborne group near Louisville, Jefferson County, estimated from the record of an oil-prospecting well, is 350 feet the greater part of which is referable to this formation, although the upper 68 feet may belong to the Barnwell , sand. The lithologic character of well drillings from Waynesboro indicate that the maximum thickness of the Claiborne group is not over 500 feet, perhaps less, at this place; all except about 100 feet of this is referabte to the }\fcBean formation. In parts of the area over which the McBean is the surface formation, the thickness will vary from not over 50 to 150 feet., The thickness along Ocmulgee and Oconee rivers is certainly much less than that along the Savannah, suggesting that there was probably a basin in the Savannah area during the Claiborne epoch. Between Ocmulgee and Chattahoochee rivers where the Barnwell sand has not been certainly identified the thickn~ss of the Claiborne group seems to be in general less than in Burke County. On Chattahoochee River, the estimated thickness of the Claiborne group is 250 to 300 feet. On the Flint, judging from the width of the outcrop, the thickness does not exceed that on the Chattahoochee and is probably less. The thickness between these two rivers, as shown by natural exposures, is not greater than 150 or 200 feet. Southward, under cover of the younger formations, the Claiborne group may diminish in thickness since the combined thickness of the Eocene is not more than 700 or 800 feet as shown by the record of an artesian well at Albany. (See page 317.) Paleontologic characters.-The most extensive collection from any single locality in the area underlain by this formation was made by Mr. Earle Sloan, at Sloan's Scarp on McBean Creek, between Me Bean Station and Savannah River. J\1:r. Sloan submitted his fossils to Dr. Vaughan who contributes the following list and notes. List of fossils from Sloan's Scarp, McBean Creek. Collected by Earle Sloan. Endopachys maclurii (Lea) Ringicula biplicata (Lea) Conus sauridens Conrad Pleurotoma kelloggi Gabb Pleurotoma texacona Harris Pleurotoma terebriformis Meyer Pleurotoma childreni Lea Pleurotoma lesueuri Lea Pleurotoma nodocarinata Gabb Turritella arenicola Conrad Turritella carinata Lea Mesalia claibornensis (Conrad) Tuba antiquata Conrad Amalthea pygmaea (Lea) Calyptrea aperta (Sol.) Crepidula lirata Conrad Lunatia eminula (Conrad) Natica aemilunata Lea 240 GEOLOGY OF THE COASTAL PLAIN Pleurotoma afl'. rugosa Lea Sigaretus declivis Conrad ' Amblyacrum Amblyacrum stantoni Vaughan . huppertzi var. penrose11 Solarium elaboratum Conrad (young) Solariorbis depressa (Lea) var. Harris ? Dentalium annulatum Meyer Mangelia infans Meyer Nucula ovula Lea Marginella columba Lea Nucula magnifica Conrad Marginella semen Lea Leda media Lea Caricella demissa var. texana Gabb Yoldia psammotaea Dall Caricella aff. pyruloides (Conrad) Area rhomboidella Lea Clavelithes humerosus Conrad Ostrea sellaeformis Conrad Fusus bellus Conrad Pecten wahtubbeanus Dall Fusus morton! Lea Crassatellites protextus (Conrad) Lirofusus thoracicus (Conrad) Venericardla sp. (also at Lisbon, Ala.) Typhis gracilis Conrad Venericardia alticostata (Conrad) Pyrula (Fusoficula) texana Harris Venericardia planicosta Lamarck Lelornynus prorutus Conrad Phacoides papyraceus (Lea) Laevibuccinum prorsum Conrad Bornia prima (Ald.) Mitrella mississippiensis Meyer & Cytherea discoldalis Conrad Aldrich Metis raveneli (Conrad) Phos sagenum (Conrad) Tellina mooreana Gabb Buccinanops altile (Conrad) Pteropsis lapidosa Conrad Pseudoliva vetusta (Conrad) Corbula alabamiensis Lea Lacinia alveata Conrad Corbula densata Conrad Turritella nasuta Gabb Corbula fossata var. extenuata Dall Turritella nasuta var. houstonia Harris "Mr. Sloan also obtained a number of species that I was not able specific ally to identify; some of these are new, while others have probably been de scribed, but the groups to which they belong have not been thoroughly studied, This is a most interesting collection as it furnishes an excellent basis for correlation with other South Atlantic and Gulf Coastal Plain States. Deposits of the same age occur at Keitt's Ravine and Lang Syne in South Carolina, where Sloan calls them Warley Hill marl; at Pooser's Hill and Caw-caw Swamp, where they are called Cawcaw shale and marl by Sloan; at Decariduc place, near Aiken, and at Hixon bridge, Tinkers Creek, Aiken County. At the last named locality Sloan calls the horizon Barnwell phase, The horizon in Alabama and Mississippi is represented by the Lisbon formation; in Louisiana by the Upper portion of the St. Maurice formation; and in Texas by the Cook Mountain formation. "In Georgia the McBean formation includes two paleontologic horizons. The lower one has been discussed in the preceding remarks. It is especially characterized by ;?leurotoma nodocarinata Gabb, Turritella nasuta Gabb, Turritella nasuta var. houstonia Harris, Ostrea sellaetormis Conrad, Pteropsis lapidosa Conrad, and Corbula tossata Meyer and Aldrich, "A higher horizon is represented especially well along Savannah River, between Shell Bluff, upstream, and Griffin's Landing, downstream. Along this stretch of the river a prominent ledge, largely composed of Ostrea georgiana Conrad, forms the top of the McBean formation. Although this formation could be subdivided along Savannah River it was found impractica;ble to extend the subdivision westward, for which reason the Ostna georgiana bed is considered as constituting its upper portion. "Mr. E. W. Berry has studied the fossil plants of the Congaree clay mem ber and his results are ready for publication as a Professional Paper of the U. S, Geological Survey." Areal distribution.-Outcrops of the McBean formation occur in an extremely irregular belt, varying from a few miles to 25 miles or more in width, and extending entirely across the State. In the re GEOLOGY OF THE COASTAL PLAIN OF GEORGIA. PLATE XIX. B. LAYER OF PISOLITIC CLAY BOWLDERS NEAR THE BASE OF THE CLAIBORNE GROUP IN A PIT OF THE AMERICAN CLAY COMPANY, ELEVEN MILE POST. TWIGGS COUNTY. McBEAN FORMATION gion between Savannah and Ocmulgee rivers this belt lies to the south of the belt in which the Lower Cretaceous strata come to the surface, and between Ocmulgee and Chattahoochee rivers it lies to the south of the area in which the Midway and Wilcox formations outcrop. On account of the difficulty in distinguishing between the weathered phases of this formation and the overlying Barnwell sand, the Claiborne group has ben given one color bn the geological map, no attempt being made .to map the two formations separately. East of Flint River, exposures have been studied in the following counties: Columbia, Richmond, Burke, McDuffie, Jefferson,_ Glascock, \Vashington, Baldwin, Wilkinson, Jones, Twiggs, Bibb, and Houston. Exposures also occur on Flint and Chattahoochee rivers. It is evident that east of Ocmulgee River the formation originally entirely concealed the Lower Cretaceous and lapped over to the crystalline rocks of the Piedmont Plain, but it has been extensively modified by erosion and the northern limit of outcrop, as marked on the map, is a jagged line, since streams haYe cut through it and exposed the underlying Cretaceous. Physiogrq,phic expression.-Over practically the wh;le of the area ot its occurrence east of Ocmulgee River the formation is overlain by the Barnwell sand, the beds appearing at the surface only in the stream bluffs and on the lower slopes and in the bottoms of the val~eys. On account of the compactness of the materials composing it, the formation has been effective in places in preventing the rapid reduction of the valley sides from steep to gentle slopes, but otherwise it has had only a subordinate part in determining the topographic aspect of the region that it underlies. Structure.-The McBean formation shows a low dip southward. The dip of individual beds is so slight that they appear horizontal in natural exposures. The slope southward for the formation as a whole is perhaps not more than 10 or 1.5 feet per mile. No pronounced folding or faulting of beds has been observed. Langdon1 noted low flexures along Chattahoochee River; only purely local disturbances such as might be due to land slips or weathering and solution of calcareous strata, were noted in the Ocmulgee-Savannah area. The thick clay and fullers earth beds show minute jointing. Clay laminae show slight crumpling at a few localities but this is of doubtful regional significance. An exposure of the McBean occurs four and one-half miles south of Perry, Houston County, at an elevation higher than Jackson outcrops lying to the north. The structural relations are unexplained. It is probable there has been folding or faulting. 1J..angdon, D. W., Report on the Coastal Plain; Geol. Survey of Alnbama. 18-Hl. p. 38!l. 242 GEOLOGY OP 'l'HE COAS'l'AL PLAIN LOCAL DETAILS l\ICllEAX CREEK AREA, RICHM:OXD AND BURKE COUNTIES 111cBean and vicinity.-McBean, Richmond County, is situated on the Central of Georgia Railway, 22 miles south of Augusta. The exposures of the :McBean formation are principally on the south or Burke County side of McBean Creek. The following notes are by Dr. T. Wayland Vaughan: Section in gully on ~Jouth side of McBean Creek, one-quar.ter of a mile south of :McBean Station. BarnwEll sand. Feet. In. 5. Silicified coquina rock imbedded in sand . . . . 4. Yellow and white sands, portions very fine, others coarse . . 32 6 McBean formation. 3. Drab clay forming an indurated stratum, some lignitic matter . . . . . . . . . . . . . . . 1 6 2. Greenish-yellow, rather fine-grained, argillaceous sands, with black specks and lignitic pockets. These sands becoming variably yellow and red 6 1. Light greenish-yellow, non-laminated clay, with a little calcium carbonate . . . . . . . . . . . 2 6 Gully 300 or 400 feet east of the preceding, Southern end of gully. Barnwell sand. 5. Red, sandy clay . . . . . . . . . . . . . . . . 2 :lvicBean formation. 4. Thin seam M lignite . . . . . . . . . . . . . . . llh 3. Greenish clays, containing lignite . 5 6 2. Marl with calcareous concretions . 6 Feet In. 1. Greenish-yellow, calcareous clay . . . 1 Western side of gully. Barnwell sand. 5. Red sands . 3 9 McBean formation. 4. Greenish clay similar to No. 2 . . . . . 0 7 3. Thin seam of lignite following irregular contour l } of upper surface of No. 1 (corresponds to No. 4' of preceding section) and 2. Greenish clay . . . . . . . . . . . . . 2 1. Greenish-yellow calcareous marl . . . . 2 Eastern side of gully. Barnwell sand. 3. Reddish sands . . . . . McBean formation. 2. Greenish-yellow lignitic clay . . 1. Calcareous marl with 0. sellaeformis Westerly exposure at McBean Creek. three-tenths of a mile west of Bates Miller's store. Barnwell sand. 2. Yellow, gray, and red sands . . . . . . . . . . 32 6 McBean formation. 1. Soft, chalky limestone, indurated in places, con- taining 'l'urritella carinata, Nucula ovula, Corbula gibbosa, Pteropsis lapidosa . . . . . 12 1WcBEAN FORi\IIATIOX 243 Along the road to Thos. B. Cox's house deep red, compact sands, and de- composed glauconite with pebbles near 'base, are seen overlying the material composing the preceding sections. Large masses of silicified coquina and chalcedony (buhr-rock) with numerous poorly preserved fossils, Mortonia, Turritella obruta, Oorbuld alabamiensis, etc., Claiborne fossils, occur from eight f.eet of the base to the hill summit. The observed thickness along this road was 52 feet. Sechor~ on Thos. B. Cox's land, six rniles southeast of McBean station, from his residence to creek, one-half mile to the northeast. Barnwell sand. 4. Red sand with "buhr-rock" . . . . . . . . . . . McBean formation. 3. Blue-green gray shale, nonfossiliferous . . . . . 2. Glauconitic, friable, or indurated limestone (chalky) with Claiborne fossils . ' 1. Blue clay with rot1oen calcareous fossils ( Clai- borne) Oorbula alabamiensis . . . . . . . . . Feet. 105 20 4 1 SAYAXXAII RlYEH, DURKE COUNTY Shell Bluff.-Sht~ll Bluff is a classic locality and stratigraphically one of the most important exposures in the Georgia Coastal Plain. The bluff is located in Burke County, on Savannah River, 40 miles by river below Augusta, and 15lh miles by the public wagon road, northeast of Waynesboro. The bluff has been referred to in geologic literature more often than any other Georgia locality. Probably the first reference was made by William Bartram,' the English traveller, in 1791. Prof. John Einch' probably had this locality in mind in a paper published in 1824, though it is not mentioned specifically. V anuxem3 furnished the first geologic description of any consequence, for a paper read by S. G. }\lorton in.1828, and regarded the strata as upper Tertiary. The fauna of the bluff was studied by Conrad/ 1834, who was tho first to ciassify the beds as Eocene. He gave the name Ostrea georgiana to the common oyster, ;:tlthough this fossil was apparently known to Vanuxem' before this date ancl was named by him Ostrea gigantea. This locality was visited by Sir Charles Lyell in 1842, and is described in "Travels in North America," published in 1845. Lyell" collected 40 specimens and determined the rock to be Eocene. The stratigraphic.position of the beds was a subject of discussion in 1866, when Conrad' proposed the name "Shell Bluff Group" for strata characterized by Ostrea georgiana:, and which he placed below the "Orbitolite limestone of the Jackson group." Hilgard,' ho\vever, 1Travele through North Carolina. Sonth Carolina. Georgia and WeRt Florida, etc.. Philadelphia. 17Pl. 2Amer. Jour. Sci., Vol. 7. 1824, pp. 31-43. 3Jonr. Acad. Nat. Sci., Philadelphia, Vol. 6, pp. 59-71. 'Idem. Vol. 7, 1834, pp. 156-157. 5Ibid, Vol. 6. 1830. Travels in North America, Vol. 1, p. 158. John Murray. 1815. 7Amer. .Jour. Sci. 2d ser., Vol. 41. 1866, p. 96. 8Ibid. Vol. 42, 1866. pp. 68-70. 244 G~OLOGY OF THE COASTAL PLAIN placed the "Shell Bluff group" above the Jackson, and disputed the occurrence of Orbitoides below the Vicksburg. Dr. W. H. Dall,' in 1895, placed the "Shell Bluff group" under the lower Oligocene or Vicksburgian, but stated that its position was not definitely settled. Dr. Vaughan' made paleontologic studies later and concluded that the marl below the Ostrea georgiana bed belonged in the lo-wer portion of the Claiborne group o:f the Eocene. Recent studies of the strata by the writers in the vicinity of Shell Bluff post-office, Burke County, and Hancock Landing, Savannah River, have establi::.hed the fact that the OstJea georgiana bed, 75 to 110 feet above Savannah River, and the overlying red sands should also be referred to the Claiborne group. Sections and O:escriptions of the bluff have been published by Ruffin,' Loughridge,' W. B. Clark, and Earle Sloan." Sections made by different observers vary greatly in detail,-the variations are perhaps due in the main to the imperfection of the exposures and to the fact that the sections were made at different points along the bluff; also, to differences in the usage of descriptive terms, completeness or incompleteness of the sections, and to the object in view, whether stratigraphic or economic. The length of the bluff against which the river impinges is about 1,000 feet and it attains a maximum height of 150 feet. According to the reports of the 11. S. Army Engineers the river level here is 87.1 feet above sea-level. Dr. Vaughan has made careful stratigraphic studies here and has supplied the following section and notes: Section of Shell Bl11f{, mouth of Boggy Gut Creek, on Savannah River. Feet. 15. Soil and humus . . . McBean formation. 14. Indurated fossiliferous limestone . . . . . . . 1 13. Softer limestone with some sand, (in the upper- most part of this a specimen of Pteropsis lapidosa was collected) . . . . . . . . . . . . 6.5 12. Ledge of hard limestone . . . 3.4 11. Softer sandy stratum . . . . . . . . . . . . . 3.7 10. Harder stratum . . . . . . . . . . . . . . . . 1 9. Softer stratum . . . . . . . . . . . . . . . . . 1.1 8. Whitish limestone, blotched yellow or brown, with Claiborne fossils . . . . . . . . . . . . 4.25 1U. S. Geol. Surv., 18th Ann. Rept., pt. II, p. 342. 2Sci., D. s., Vol. 13, p. 270, 1901. 'Report of Commencement and Progress of the Agricultural Survey of South Carolina. 'Tenth Census, Vol. 6, pt. 2, p. 280 (bottom pagination). 5Bull. U. S. Geol. Survey No. 83. p. 55. catalogue of minPrnl localities: Geol. SnrvPy of South Carolina, p. 271. McBEAN FORMATION 245 Feet. 7. Yellow sand, more calcareous at top, containing Ostrea sellaeformis 13 6. Softer ledge . 7 5. Harder limestone ledge . 4.5 4. Softer ledge .5 3. Harder ledge 2.3 2. Soft limestone, whitish or yellowish, loosely granular . 5.5 1. Talus above water's edge . 7 "The whole section at Shell Bluff Landing is not well exposed because of talus coverings of portions of it. The base of the Ostrea georgiana bed is about 80 feet above zero water level in the river, or between 70 and 75 feet above the river bank at the landing. There is 8 to 12 feet of the section unexposed. The total thickness of the Ostrea georgiana bed is approximately 24 feet, above which are yellowish sands and soil. Detailed section of a portion of the Ostrea georgiana bed is as follows: McBean formation. 9. The upper 9lh feet of thickness of this bed is largely talus-covered, but fragments of oysters were found on the surface, and it was inferred that the thickness is approximately as repres.ented . . . . . . . . . . . . . . . . . . . . 3. Calcareous conglomerate containing small quartz pebbles and poor fossils, one of them a coral, apparently Oladocora . . 2. Talus of yellowish sands . 1. Oyster ledge . . . . . . . Feet. 9.5 3.5 6 5 Top of stratum No. 13, Shell Bluff, Ga.,, near mouth of Boggy Gut Oreek: Pteropsis lapidosa Conrad stratum 11, near mouth of Boggy Gut Oreek: Ostrea sellaeformis Conrad Stratum No. 8 or 9 near mouth of Boggy G-ut Oreek: Carophyllia subdichotoma Lons. Dendrophyllia sp. Endopachy maclurii (Lea) Plejona petrosa (Conrad) Fusus trabeatus Conrad Fusus limulus Conrad ? Fusus irrasus Conrad ? Calyptraea aperta (So}ander) Crepidula lirata Conrad Dentalium thalloides Conrad Nucula magnifica Conrad Leda pharcida Dall ? Glycymeris trigonella (Conrad) Glycymeris sp. indet. ( ?) staminea (Conrad) Crassatellites protextus (Conrad) var. Venericardia planicosta Lamarck Venericardia alticostata (Conrad) Cytherea texacola Harris Cytherea perovata Conrad ? Cytherea discoidalis Conrad Cytherea poulsoni Conrad ? Corbula alabamiensis Lea Cobula oniscus Conrad Corbula fossata Meyer and Aldrich 246 GEOLOGY OP THE COASTAL PLAIN Stratum No. 8, near mouth of Boggy Gut Greek: Endopachys maclurii (Lea) Ostrea sellaeformis Conrad Turritella (Mesalia) vetusta Conrad Cytherea sp. Turritella humerosa Conrad ? Pteropsis lapidosa Conrad small variety Lunulites bouei Lea Nucula magnifica Conrad ? Oxyrhina desori Agassiz Stratum No. 3, near mouth of Boggy Gttt Creek: Marginella constrictoides Meyer Nucula magnifica Conrad and Aldrich Pecten sp. Turritena (Mesalia) vetusia Conrad ? Corbula fossata ;\feyer and Aldrich Shell Bluff Landing, from horizon below the Ostrea georgiana bed anfl the same as stratttm No. 8 of the Boggy Gut Greek section. Coral----Astrangia? Mesalia claibornensis (Conrad) Turritella humerosa Conrad small v-ariety Calyptraea aperta (Sol.). Leda sp. indet. Ostrea alabamiensis Lea. Venericardia planicosta Lam. Nucula (internal cast, probably mag- nifica Con.). Besides these: Lima? fragment, and a large gastropod, apparently a Naticoid. "The strata in the bluff at Shell Bluff from the base upward including bed No. 13 correspond in stratigraphic position to the Lisbon formation and probably a portion of the Tallahatta buhr-stone of Alabama." The following section was made by the anthors at a point abom 200 yards above the boat landing: Section at Shell Bluff. Barnwell sand. 10. Slope, true character oJ: the rock largely concealed; upper part red sand with thin covering of gray sand . . . . . . . . . . . . . . . . . McBean formation. 9. Poorly exposed; fragments of Ostrea georgiana: strata probably calcareous sand and argillaceous limestone . . . . . . . . . . . . . . . 8. Hard, white limestone, full of shells . . . . . . . 7. White calcareous clay and sand with thin layers of pure limestone . . . . . . . . . . 6. Light, yellow or brown, fine sand, only slightly calcareous, partly consolidated . . . . . . . . 5. Soft, calcareous sandstone . . . . . . . . . . . . 4. Hard, calcareous sandstone full of comminuted shells . . . . . 3. Soft, friable, sandy marl . . . . . . . . . . 2. Hard, sandy limestone . 1. Yellowish, friable, sandy marl, glauconitic . Feet. 70 20 1 15 8 8 3 4 1 12 Total ........ . 142 The following section occurs just below the boat landing and "' partly exposed in the wagon road leading to the top of the bluff: McBEAN FORMATIOY 247 Section below the landing at Shell Bluff. Eocene Barnwell sand. 4. Yellow and gray incoherent sand . . . . . . . . 3. Partly concealed, but largely coarse, red sand . . McBean formation. 2. Sandy and argillaceous marl, varying in hard- ness; contains some quartz pebbles as much as one inch in diameter. Large oyster shells were found at 110 feet above the river, and a conspicuous bed of Ostrea georgiana occurs 75 feet above the river. The shells are also found in soil at lower elevations but these may have rolled down from the higher beds . . Recent and Pleistocene. 1. Talus and alluvium to river level . . . . . . Feet. 5 20 90 20 The calcareons rock at Shel1 Bluff, takPn as a whole, is a :-anvn and red sand, poorly exposed. Ostrea georgiana was noted here at a point 80 feet above the river, and it also appears at lower levels. The specimens show the ch.aracteristic ribbed markings. The beds in the lower part of the bluff, contain in addition to ::t lmge number of mollusca, fragments of bones, fish teeth and dental plates. The Hancock Landing bluff recedes from the river for a short distance and is again washed by the river at Utley Point, one-half :mile below. Here, there is about 20 feet of ash-colored marl at tlh~ hase of the bluff, similar to that at Hancock Landing. The Btrata at ihe upper end of the bluff are partly concealed by humus and talus. On account of the occurrence of Ostrea georgiana a de.scription of this exposure 1s g1ven. Section at Hancock Landing. Barnwell sand. Feet. 8. Red, argillaceous sand, poorly exposed; contains no hard rock, and seems to be devoid of fossils . . . . . . . . . . . . . . . . . . . . 40 McBEAN FORMATION 249 Feet. McBean formation. 7. Sandy, aluminous marl; contains large shells of Ostrea georgiana; other fossils are Endopachys maclurii, Oalyptrea aperta, Turritella carinata, Venericardia, Modiolus. This stratum is 80 feet above the river. Thickness exposed . . 5 6. Concealed by humus and talus; soil contains large oyster shells . . . . . . . . . . . . . . 35 5. Sandy limestone, containing Ostrea georgiana. This may have rolled down from a higher level, but the rock is unlike bed No. 7 . . . . . . . 4 4. Strata concealed . . . . . . . . . . . . . . . . 15 3. Laminated clay . . . . . . . . . . . . . . . . 4 2. Poorly exposed, but probably in the main, bluish, sandy marl, and rather hard, bedded clay . . 15 1. Concealed to the river level . . . . . . . . . . 7 Blue Bluff.-This bluff is two miles below Hancock Landing. The lower part is a gray or ash-colored glauconitic marl which assumes a bluish color due to moisture. The secti::m about on,-third mile above the bluff proper is: Section about one-third mile above Blue Bluff. Barnwell sand. Feet. 5. Brownish, incoherent sand, forms a thin veneer) over the plateau . . . . . . . . . . . . . . 4. Strata almost entirely concealed, small ex- 60 posure of red argillaceous sand . . . . . . . 3. Red sand, exposed on roots of blown-over trees . 2. Laminated, drab and greenish, sandy clay, partly concealed . . . . . . . . . . . . . . . . . . 10 McBean formation. ' 1. Bluish and ash-colored, glauconitic marl; variable in percentage of clay and sand. At the base contains lines of white and blue limestone nodules. The marl is fossiliferous and con- tains the characteristic McBean species Ostrea sellaetormis and Pteropsis lapiaosa . . 40 According to Dr. Vaughan, the basal bed of this section representE a horizon below the Gosport greensand of Alabama, probably within the Lisbon. The part of Blue Bluff washed by the river shows the following~ Section of part of bluff washed by the river. McBean formation. 2. At top, grayish and brown argillaceous marl :..nd thin bedded layer of jointed, aluminous sandstone. The upper part of the bluff lighter in color and more argillaceous than the lower part . . . . . . . . . . . . . . . . . . . . . Feet. 25 250 GEOLOGY OP THE COASTAL PLAIN Feet. 1. Bluish, glauconitic marl, massive bedded, con- tains white fragile shells and casts; fossils, Tttrritella nasuta, Letla pharcida, Lucina subvexa, Pteropsis lapidosa . . . . . . . . . 12 "Stratum 1 represents a horizon in the lower portion of the Claiborne." T. W. V. The lower end of Blue Blu:ff shows a bluish marl which is similar to that in the sections described, and which contains limestone nodules. The marl is overlain by 50 feet of red, yellow and gray unconsolidated sands. These sands contain clay laminae, rarely small pebbles, and near the base imperfectly preserv-ed fossils. Griffin Landing.-This locality is three miles below Blue Blu:ff, and 147 miles above Savannah. The large fossil oyster, Ostrea georgiana, is conspicuous in certain layers. Section at Griffin Landing. f Barnwell sand. 6. Gray, structureless sand covering the upland, probably residual . . . . . . . . . . . . .. 3. Red, rather coarse, quartz sand, free from pebbles; glauconitic? . . . . . . . . . . . . 4. Brown or yellow argillaceous sand, glauconitic . J McBean formation. 3. Large specimens of Ostrea georgianct embedded in greenish-gray argillaceous sand and drab- clay . . . . . . . . . . . , . . . . . . . . . 2. Drab, laminated clay in the nature of a fullers earth; not a persistent bed . . . . . . . . . . 1. Bed of large Ostrea georgiana in a matrix of pale greenish-clay; one specimenfound which meas- ured 20 inches in length; in addition to Ostrea georgiana, contains Calyptrea aperta, Motliolus, Balanus . . . . . . . . . . . . . . . . . . . Feet. 100 10 5 10 Lirne-lciln Bluff.-Exposures of stratigraphic interest occur in the blu:ff one and one-half miles below Griffin's Landing. Next to Shell Blu:ff, this is the highest blu:ff along the river; the level of the upland to the west was estimated to be 140 feet above t4e river. This is the site of an old lime-kiln, and since no local name for the blu:ff is known, the name "Lime-kiln" bln:ff is an appropriate designation. Section at Lime-kiln Bluff. l Barnwell sand. 5. Surface covered with gray sand . . . . . . l 4. Largely concealed, but probrbly yellow or red 3. Br~~nd a~d ~ed ~a~d . : : : : : : : : : : : : J Feet. 80 McBEAN FORMATIOY 251 McBean formation. 2. Thinly laminated clay, with micaceous sand partings, grades downward into layers No. 1 . 1. Sandy and clayey marl, both friable and consolidated; glauconitic; contains oyster shells, casts of other fossils, fish teeth and small fragments of bones . . . . . . . . . . . . Another part of the bl.uff shows: Barnwell sand. 7. Slope, largely concealed, but probably sand and clay ........ , ....... (about) . McBean formation. 6. Laminated clay with sand partings and thin layers of aluminous sandstone . . . . . . . . 5. Marl, containing Flabellum cuneiforme, Dendrophyllia, Oalyptrea aperta, Ostrea . . . . . . . 4. Sandy, laminated clay . . . . . . . . . . . . . 3. Bed composed of large oyster shells, Ostrea geargeorgiana in a matrix of sandy marl . . . . 2. White, massive bed of sandy marl; a few oyster shells in the upper part . . 1. Concealed to river 1evel . . . . . . . . . . . . Feet. 10 50 50 20 2 to 3 3 20 20 5 or 6 The marl formation from Shell Bluff southward is regarded as representing a single formation of the Claiborne group, for no basis for a division was discovered. The red sands in the upper part of the bluffs are also regarded as part of the Claiborne group; there seems to be a transition from the marl to the red sands. RICHMOND COUNTY H ephzibah.-Marl of the :McBean formation occurs on the farm of W. G. Tarver on McBean Creek, six miles south of Hephzibah, where Pteropsis lapidosa was collected. The exposure is on the edge of the swamp at McBean Creek where one foot of the marl bed appears. The overlying red sand of the Barnwell division has a thickness of 50 or 60 feet. The marl bed lies at a lower level than the base of the Claiborne group at Hephzibah and probably is underlain at a slight depth by Cretaceous strata. Across this territory there is a marl bed (McBean formation) bearing a lower Claiborne fauna overlain by red sand which seems to correspond to similar lithologic material (the Barnwell sand) in the vicinity of McBean, where it contains an upper Claiborne fauna. .JEFFERSO:"f COUXTY Louisville.-The character of the strata of the Claiborne group in this region may be ascutained from, the record of an old oil prospe0ting well, three and one-half miles southwest of Louisville. From an examination of the borings it is belieYed "lime biscuit." The marl is overlain by red sand containing white sandstone beds. Sandstone containing Ostrea georgiana and thin layers of quartzite occur at "The Spring" 0n the east side of the road, a short distance east of the limesink. Prof. S. W. :McCallie has furnished the following description of a section at Rocky Branch bridge two miles northwest of Sandersville, (unpublished notes:) Section a:t Rocky Branch Bridge. Barnwell sand. 4. Reddish clays . . . . . . . . . 3. Sandstone . . . . . . . . . . McBean formation. 2. Greenish sandy, glauconitic clay weathering yellow. This clay in places becomes silicified into flint-like layers, the total thickness being about . . . . .......... ...... . 1. Greenish glauconitic sand with shark's teeth and fragments of bone. About 100 yards further down the creek and apparently underlying the greenish glauconitic sands is a greenish, finely laminated clay with fragments of shells and plants .................... . Feet. 10 8 8 The exposure in the vicinity of the spring, one mile south of Sandersville Court House, consists of sandstone mostly as loose boulders in the soil. The only fossils noticed here were oysters which are always more or less fragmentary. A section at Limestone Creek, two miles south of Sandersville, made out from several exposures along the stream seems to be as folows: Section at Limestone Creek. McBean formation. 3. Sandstone with oyster shells (near top) . . 2. Sands and possibly some clay (only partially exposed) . . . . . . . . . . . . . . . . . . 1. Rotten fossiliferous limestone . . . . . . . . . . Feet. 10 10 20 'fhe exposure along the creek is not continuous and the section here given is only approximately correct. 254 GEOLOGY OP THE COASTAL PLAIX Tennille.-A soft, argillaceous marl occurs in a gully along the Central of Georgia Railway near the 139 milepost. Section at 139-Mile Post. Barnwell sand. 5. Bright, red sand, fresh exposures not seen . 4. Fragmentary, siliceous layer; contains fragments of an oyster and Scutella . . . . 3. Coarse,brown and yellow sand . . . 2. Interval concealed, probably sand . McBean formation. 1. Soft, calcareous rock, glauconitic and probably contains a higher percentage of clay than lime; casts of fossils abundant . . . . . . . . . . . Feet. 10 12 10 4 12 Prof. McCallie has compiled the following section from expowres betiYeen the 138 and 139 mile-posts (unpublished notes) : , Section between ~Mile-posts 138 and 139. Barnwell sand. Feet. 9. Surface sands . . . . . . . . . . . . . . . . . . 0-3 8. Massive, orange-colored, sandy clays unconform- able with beds below . . . . . . . . . . . . . 10 7. Stratified sands and clays with fragments of oyster shells . . . . . . . . . . . . . 12 6. Sandstone often fossiliferous along the parting planes . . . . . . . . . . . . . . . . 4 McBean formation. 5. Greenish-gray clayey sand with fragments of oyster shells . . .. . . . . . . . . . . . . . . 3 4. Whitish, putty-like clay with layers of flint con- taining fossils . . . . . . . . . . . . . . . . 3. Sandy, glauconitic clay . . . . . . . . . . . . 3 2. Fossiliferous, soft limestone with hard ledges . 10 1. Bluish, tough clay with sand partings . The following fossils were obtained by Prof. McCallie at this localit:v: Fossils from near Tennille. Glycymeris trigonella (Conrad) Corbula alabamiens!s Lea . Glycymeris idonea (Conrad) Crassatellites altus (Conrad) Mortonia sp., the common Eocene Crassatellites protextus var. lepidus species of eastern Georgia Dall Endopachys maclurii (Lea) Ostrea alabamiensis Lea According to Dr. Yanghan the geologic horizon is Claibornian and seems to be in the uppermost portion, i. e., above the Ostrea sellae- formis-Pteropsis lap1:dosa zone, or the fossils come from the Barnwell sand. Snnhill.-A bed of compact, crystalline limestone outcrops one- quarter of a mile south of the depot, and was at one time used in the mannfactnre of lime. J![cBEAN FOKWATI0-:\7 255 Section at old lime-lciln, 8unhi1l. Barnwell sand. 3. Dark, red, fine-grained, sand, surface aspect due to weathering, contains vitreous fiint, prob- ably due to replacement of a calcareous rock . . . . . . . . . . . . . . . . . . 2. Argillaceous sand . . . . . . . . . . . . . . . McBean formation ? . 1. White, compact limestone, containing shells and Bryozoa; Flabellum cuneiforme Lonsdale, Venericardia alticostata, etc. . . . . . . . . Feet. 15 1.5 6+ Davisboro.-Large boulders of flint, which are residual and eYidently a replacement of limestone, occur two miles southeast of Davisboro, on the property of S. J. Taylor, on a small tributary of Williamson's Swamp Creek. The rock contains poorly preserved fossils and has the appearance of the flint of the Claiborne group. The following section occurs at Tarver's :M:ill, eight miles southeast of Davisboro: Pliocene ? Section at Tarvers' Mill. Altamaha (Lafayette?) formation 6. Mottled argillaceous sand covered with gray sand . . . . . . . . . . . . . . . Eocene. Barnwell sand ( ?) o. Red sand . . . . . . . . . . . 4. Red and yellow sand . . . . . . 3. Clay layer . . . . . . . . . . . 2. Yellow and white quartz sand. McBean formation. 1. White, sandy claystone; contains fragments of shells and sharks teeth, exposed to water's edge . . . . . . . . . . . . . . . . . . . . . Feet. In. 10+ 20 12 0 6 15 5 There are no data to establish the stratigraphic position of the beds here definitely; the succession, red and yellow sands over clay, suggests identity with sections of the Claiborne group elsewhere. TWIGGS COUXTY The northern part of Twiggs County presents much the same succession of beds as Wilkinson County, (see page 293. )-namely, red and vari-colored sands over drab, massive and laminated clays and fullers earth, both of which rest uncomformably upon white clay beds and kaolinitic sands of the Cretaceous. There are also beds of sandstone, quartzite, and limestone in the Claiborne group. Dry Branch.-Fine exposures appear at the ''arions clay mmes near Dry Branch. 256 GEOLOGY OF THE COASTAL PLAIN Section at the rnines of the Georgia Kaolin Company, two southeast of Dry Bra1nch. Barnwell sand. Feet. 5. Fine, red sand observed along the slope to the top of the ridge-dark, red color, probably a surface phenomenon due to weathering . . 100 McBean formation? 4. Greenish and drab, faintly laminated clay of low specific gravity, contains casts of fossils; contains local lenses of soft, friable limestone, a foot or two in thickness . . . . . . . . . . 15 3. Fine, yellow, quartz sand . . . . . . . . . . . . 12 2. Soft, white limestone, and limestone and kaolin breccia; contains characteristic Claibornian fossils, corals, a large oyster, Nucula ovula Lea, Leda sp., Grassatellites altus (Conrad), Venericardia planicosta Lamarck, Cytherea perovata Conrad, etc. . . . . . . 4 (Unconformity) Lower Cretaceous. 1. Massive beds of white clay . . . . . 20 miles Stratum No. 2 presents a curious breccia, consisting of soft fossiliferous limestone and chunks of white clay. The white clay was evidently derived from the underlying bed but the limestone is in its place of origin. Another local development of limestone appears in a ravine a short distance southeast of the mines. This lies 10 to 15 feet above the Cretaceous, but from. the fossils it is known to belong to the Jackson formation, (see page 304.) Gallemore.-A fossiliferous marl or limestone occurs in the bed of the creek at the mill near Gallemore or Willis Station. The rock it> a bluish-gray, siliceous marl which in places is indurated. It consists of fine quartz sand, imbedded in a matrix of clay and calcium carbonate,_ and has much more the lithological aspect of the McBean formation than of the Jackson or the Vicksburg, which appear a short distance farther south.. Fossils are abundant, and an oyster wlls noted, the species of which has not been determined. Prof. McCallie collected the following fossils at Gallemore Station, Twiggs County: Fossils frorn Gallemore Station.. Plejona pretosa (Conrad) Calyptrea aperta (Solander) Turritella carinata Lea Mesalia vetusta (Conrad) Leda sp. Glycymeris sp. Diplodonta ungulina (Conrad) ? Phacoides alveatus (Conrad) Corbula sp. McBEAN FORMATION 257 The following succession of beds was noted at Rocky Hill, onp mile southwest of Gallemore: Section at Roclcy Hill. Barnwell sand. Feet. 3. Red sand similar to the Barnwell sand at other localities . . . . . . . . . . . . . . . 40 2. Siliceous limestone or flint . . . . . . . . 8 McBean formation. 1. Drab, clay, laminated, porous, and like fullers earth . . . . . . . . . . . . . . . . . ( ?) South of this locality the Altamaha (Lafayette ? ) and Vicksburg formations appear at the surface. In the western part of the county there are numerous exposures, showing the McBean formation in contact with the Cretaceous. At a point one mile south of Bond's store, or Delzel postoffice, the Congaree clay member reaches a thickness of 80 feet and is overlain by red sand. The red sand of this formation, which is frequently coarse and contains limonite crusts and hollow nodules, is in pl1lccs in contact with the Cretaceous, the heavy fullers earth-day beds being absent. Local beds of limestone are reported. AREA WEST OF OCMULGEE RIVER The strata between Flint and Chattahoochee rivers present a close general lithologic similiarity to those of the eastern area. Along the northern margin of the formation, red, rather coarse sands at the surface overlie laminated or thin bedded clay, while southward or seaward the beds are calcareous, and sandy marls, very similar to those along Savannah River, interbedded with clay, are overlain by red sand similar to the Barnwell sand. Flint appears to be absent, but there are occasional thin sandstone or quartzite layers in thA sand. Clay or fullers earth is less extensively developed, but H1is phase is represented by drab, laminated, fossiliferous clays, such as occur at the base of the formation at Fort Gaines. Within the area lying between Ocmulgee and Chattahoocher rivers exposures of strata belonging to the Claiborne group have bren examined four and one-hal miles south of Perry, Houston County; along Flint River at several localities, notably at the old Danville Ferry and at Penny Bluff; and along Chattahoochee River for a considerable distance below Fort Gaines. Other localities in the Chattahoochee drainage area are described on subsequent pages of this paper. Fair collections of fossils have been obtained from a number of exposures rendering it safe to state that the ]\fcBean formation extends uninterrupted]~- from Savannah to Chattahoochee rivers. However, 258 GEOLOGY OF THE COASTAL PLAIN the formation is often masked by later deposits ranging in age from Jackson and Vicksburg to perhaps Pleistocene. The red, rather coarse sands that underlie the Vicksburg and overlie the recognizable McBean may be the westward continuation of the Barnwell sand, but as no fossils have been obtained from the sands between Ocmulgee and Chattahoochee rivers, a positive correlation with the Barnwell sand of the Savannah drainage can not be made. Perry, Houston County-Strata four and one-half miles south of Perry on the Perry-Elko public road, have been referred to the Claiborne group by Dr. Vaughan, who has furnished the following section and list of fossils. "On the top of Mossy Hill, four and one"half miles south of Perry, Pecten perplanus and Cytherea sobrina were found in the chert. These fossils indicate that the northern slopes of Mossy Hill", from the summit of the hill to 45 feet below the summit, are covered by the Vicksburg formation. Section down Mossy Hill along an old road leading to the northwest. Oligocene. Vicksburg formation. 7. Brownish or reddish soil with chert. Vicksburg fossils ..... . 20 Eocene Jackson formation ? 6. Brownish soil, underlying material concealed . 5 5. Gray clay . . . . . . . 4. Mostly concealed . . . . . . . . . . . . . . 10 3. Gray clay . . . . . . . . . . . . . . . . . . 5 McBean formation. 2. Limestone ledges with Claiborne fossils, list follows . . 5 1. Gray or buff clay 5 Total . . . 50 Fossils from Mossy Hill. Flabellum cuneiforme Lonsdale Turbinolia pharetra Lea Endopachys maclurii (Lea) Turritella carinata Lea x Mesalia vetusta (Conrad) X Calyptrea aperta ( Solander) Dentallium thalloides Conrad Nucula ovula Lea Leda sp. Leda sp. Glycymeris idoneus (Conrad) Phacoides alveatus (Conrad) x Venericardia, 2 or 3 sp. Cytherea sp. Crassatellites sp. , Corbula oniscus Con. or wallesiana Harris Corbula densata Conrad ? Geologic horizon.---Claiborne. "x" not known from the Jackson." A list of the species in a collection by Prof. McCallie from this locality, as furnished by Dr. Vaughan, is as follows: McBEAN FORMATION 259 Fossils from Perry-Elko public road, four and one-half miles south of Perry, Houston County. Turbinolia pharetra Lea Flabellum cuneiforme Lonsdale Plejona petrosa (Conrad) Levifusus trabeatus Conrad Turritella carinata Lea x Mesalia vetusta (Conrad) x Dentalim thalloides Conrad Nucula ovula Lea Leda sp. Glycymeris trigonella (Conrad) x Pteria sp. Phacoides alveatus (Conrad) x Phacoides aff. claibornensis (Con- rad) x Venericardia planicosta Lamarck Venericardia alticostata (Conrad) x Cytherea sp. Crassatellites protextus (Conrad) x Corbula oniscus Conrad x Pteropsis lapidosa (Conrad) x "x" not known from above the Claiborne. Pteropsis lapidosa is characteristic of the lower Claiborne. According to V~atch the beds at this exposure consist mainly o drab, calcareous clay and thin layers o limestone, similar lithologically to the upper part o the Ross Hill section. Fossils were collected at an old quarry about 100 yards west o the public road, and our and one-hal miles south o Perry. The strata forming the upper and lower part o the hill are concealed or poorly exposed. The following is a section by Veatch: Section at qua:rry, four and one-half miles south of Perry. Feet. In. 10. Red, residual sand capping the top of the hill . 9. Probably calcareous clay, about . 40 . Quarry exposure: 8. Calcareous clay . 4 7. Limestone. 0 10 6. Drab, calcareous clay, contains calcite nodules. 4 5. Limestone. 1 6 4. Clay. 2 3. Limestone. 1 2. Clay. 2 6 1. Poorly exposed, probably limestone and clay, about. 20 Both the clay and the limestone contain fossils. The fossils collected rom this locality were rom beds 5 to 8. Dr. Vaughan submits the following note on Veatch's collections: Besides material similar to that obtained by Prof. McCallie and myself, Mr. Veatch obtained specimens as follows: F'ossils from quarry, tour and one-half miles south of Perry. Mortonia sp. Clypeaster sp. Pecten perplanus Morton Panopaea sp. 260 GEULOGY OF THE COASTAL PLAIN Lunulites distans (Lonsdale) Idmonea n. sp. (Identified by Doctor Bassler, who states that it occurs at various Jackson localities, among them Rich Hill, Crawford County;) "The paleontologic evidence indicates the presence at this locality of two horizons, viz.: a lower one of Claiborne age, from which Prof. McCallie and I collected, and from which Mr. Veatch also obtained material; and an upper ho~izon of Jackson age, from which Mr. Veatch obtained Pecten per- planus Morton and the species of Idmonea reported upon by Doctor Bassler. According to Mr. Veatch, as he could observe no lithologic differences in the section, he was unable to differentiate the exposure into two formations. The Barnwell seems to be absent." . This exposure of the Claiborne group described in the preceding paragraph, lies south of and at a higher elevation than the exposure of the Jackson formation at Ross Hill, three miles south of Perry (see page 301), indicating that at this locality, as Dr. Vaughan sug- gests, there has been either a fold or a fault in the strata or that the Claiborne here represents an erosion knob. The natural exposures in the neighboring areas aTe very poor, the contact between the higher formations and the Claiborne being concealed, so that it is impossible t) make dip observations. Flint River.-A small area of rock, exposed in the bluffs of Fli~t River in the southern part of Dooly and the' eastern part of Sumter counties, belongs to the McBean formation. The following is a section of a bluff near the old Danville ferry, located 16~,Z miles east of Americus, and one mile above the present ferry on the Americus-Drayton road. The bluff is on the right side of the river and is 50 feet high. Section at old Danville Ferry, Flint River. Pleistocene terrace deposit. 6. Yellow, sandy loam, grading down into light mot- tled, sandy residual clay . . . . . 7 Oligocene. Vicksburg formation. 5. Sand, coarse to fine, variegated in color, with scattered fragments of flint; contains residual clay. . . . . . . . . . . . . . . . . . . 23 Eocene. McBean formation. 4. Soft, calcareous sand and sandy limestone . 8 3. Layer of indurated limestone containing Pecten, Mortonia and an oyster . . . . . . . . . . . 2 2. Soft, glauconitic shell-marl . . . . . . . . . . . 2 1. Compact, sandy limestone with rows of limestone concretions in places becoming an argillaceous marl with varying amounts of glauconites . 8 Dr. Vaughan furnishes the following note: McBEAN FORMATION 261 "Dr. L. W. Stephenson made a collection at this locality and obtained the following fossils: Fossils from old Danville" Ferry. Endopachys maclurii (Lea) Mortonia lyelli (Conrad) Turritella carinata Lea Calyptrea aperta (Sol.) Nucula ovula Lea Ostrea sellaeformis Conrad Pecten lyelli Lea Phacoides alveatus ( Conrac:t) Phacoides cariniferus (Conrad) Miltha claibornensis (Conrad) Tagelus ? sp. Corbula oniscus Conrad Lunulites distans Lonsdale "It seems possible that two horizons may be represented in this collection, as Ostrea sellaetormis is not known to range upward to the upper Claiborne, and Lunulites liistans is not known to range downward below the upper Claiborne. Miltha claibornensis is so far as at present known confined below the Gosport horizon of Alabama. A part of this section is positively the equivalent of the Lisbon horizon of Alabama, and that portion of Shell Bluff below the Ostrea georgiana bed." Claiborne strata appear at Penny Bluff, 12 miles west of Vienna, and about one and one-half miles above old Danvill3 Ferry. Section at Penny Bluff. Pleistocene (terrace sand) Feet. 4. Gray incoherent sand 2 or 3 Eocene. McBean formation. 3. Fossiliferous, thin-bedded sandstone; disinte- grates into thin slabs which cover the face of the bluff and partly obscure the bed in the lower part . . . . . . . . . . . . . . . . . . 6 2. Greenish and drab sandy clay, contains calca- reous nodules in places . . . . . . . . . . . 8 1. White, semi-indurated calcareous sand. Has a pitted appearance and shows root-like or fucoid-llke protuberances. Large Ostrea geor- giana occur in this sand, as well as masses of comminuted shells . . . . . . . . . . . 3 Fossils frorn Penny Bluff. "Turritella sp. OalY'Ptrea aperta (Sol.) Leda sp. Area rhomboidella Lea Ostrea georgiana Conl.'ad Venericardia pianicosta Lamarck Venericardia alticostata (Conrad) Cytherea Mactra Corbula, etc. Spencer' gives the following .description of the Flint River Claiborne: "Along the Flint River the Claiborne beds are well marked; commencing in the bluff just above the old Danville ferry. This bluff is over half a mile long and is composed of alternate layers of hard and soft sandy limestones, with beds as much as four feet thick, the softer beds having a more marly and clayey appearance. The rock is of a greenish or yellowish-white 'Report of progress: Geological Survey of Georgia, 1890-1891, pp. 51, 52. 262 GEOLOGY OF THE COASTAL PLAIN color, its surface weathers into somewhat rough, but hardly jagged forms. which are so characteristic of certain beds of an overlying cherty formation. These Claiborne beds are well characterized by Ostrea sellaetormis, which are most abundant at the base of and in the harder ledges. In these bluffs the limestones rise to somewhat over 20 feet above the water and they are capped by an equal thickness of superficial sands and loams. "Above and below the mouth of Ebenezer Creek, upon the left bank, excellent exposures occur in steep bluffs rising to 15 or 20 feet above high water. Here, the beds appear for considerable distances as quite horizontal. but again suddenly bend down at steep angles, which are rollowed by a return dip, thus producing undulations. The hard ledges stand out in bold relief, and the softer have a clay-like appearance. In some or the beds these harder layers form the larger proportions of the mass; in others but a small proportion.' Chattahoochee River.-According to Langdon1 the Claiborne extends from the mouth of Yantayabba Creek, Ala., to a point near Gordon, Ala., a distance approximately 25 mileh air-Jine. Langdon's description from the base upward follows: (Base) Feet. 57. Plain buhrstone, rather sandy. . . . . . . . . 40 58. Light, yellowish green sand containing numbers of small Ostrea sellaetormis . . . . . . . . 45 59. Buhrstone, supposed summit of the series . . . 55 60. Greenish-yellow, calcareous clay with a few de- composed fossils and an occasional large Ostrea se!laetormis . . . . . . . . . . . . . 12 61. White, sandy limestone, with Ostrea sellaetormis in abundance, and pockets of large-sized shells. Makes capping ledge to island at mouth of Omussee Creek, where the bluff is about twenty feet high. This stratum is made up of alternate beds of hard and soft strata, all con- taining more or less Ostrea sellaetormis. The harder strata weather out into root-like shapes and are sometimes rather argillaceous. Many return dips occur in this stratum stringing it along the banks for many miles further than it would be normally. The dips are all steep both ways and many gaps in the succession are caused by the washing out of the soft strata. Owing to these gaps and return dips it is rather hard to estimate the thickness of the stratum with much accuracy. It dips below the surface of the river two miles below Gordon, Ala., and is last seen on the Georgia bank. At Gordon there is a very pronounced return dip, estimated at and not exceeding . 60 62. The "Scutella bed" weathers so as to make it not possible to count up its thickness. It is liter- ally full of fossils, mainly Scutel!a lyelli and Pecten nuperus with a few smaller and thicker Scute!la. A bluff about 20 feet high occurs opposite the mouth of Sowhatchee Creek, Ga. . . . . . . . . . . . . .' . . . 25 to 30 1Qeology of the Coastal Plain of Alabama : Geol, Survey of Alabama, 1894, pp, 744, 745. McBEAN FORMATION 263 Nos. 57 to 61 belong to the Claiborne group and represent the Mc- Bean formation. No. 62 is suggestive of the Jackson and the prob- ability of its being Jackson rather than Claiborne is mentioned by Langdon.' ' The following section made by Dr. Stephenson from expos- ures along a road running east from the town of Fort Gaines reveals the character of the strata forming the upland above the second ter- race plain; the base of the section i8 about 105 or 110 :feet above the level of the river : Section, Fort Gaines, above the Upper Terrace Plain. Age ? Feet. 8. Coarse, red, ferruginous pebbly sand. (Similar ma- terials extend down over the hill for some distance -probably creep) about . . . . . . . . . . . 15 McBean formation. 7. Greenish sandy clays, and argillaceous sands, more or less weathered and mottled, about . . . . 40 6. Compact, fine, greenish-gray sandstone, with fossil prints. (Fossils collected) about. . . . . . 3 5. Pale green, fine loose sand, about . . . . . . . . 3 4. Compact, fine, greenish-gray sandstone , with fossil prints. (Fossils conected) about. . . . . . . 3 3. Light green, compact, finely arenaceous clay about . . 7 2. Fine, green sandstone, about . . . . . . . . . . . . 3 1. Greenish clays and sands, more or less weathered and mottled, about . 65 Total, about . . . . . . . . . . . . . . . . . . . . 140 Fossils collected from 55 to 65 feet below the top of the hill W('n identified by Dr. Vaugh an as follows: Plejona sp. Turritella sp. Leda pharcida Dall ? Venericardia planicosta Lam. Miltha claibornensis (Conrad) Cytherea sp. Solen lisbonensis Aldrich ? On the basis of these fossils the strata Nos. 1 to 7 ~re referred to the McBean formation. The age of bed No. 8 in the section is in but no well pre- served forms were found . . . . . . . . . . . . . . 3 'Clark, W. B., Bull. U. S. Geol. Survey Xo. S3, p. fl4. 272 GEOLOGY OF THE COASTAL PLAIN 2. Massive bed of gray to bluish gray indurated clay; not laminated . . . . . . . . . . . . . . . . 10 1. Coarse, quartz sand, containing large chunks of white clay . . . . . . . . . . . . . . . . . . . . . . . . 10 A small exposure o lignite and dark lignitic clay also occurs along: a small stream on the south side o the railroad, on the old Lucky place, about three-quarters of a mile from the station at Harlem. This is overlain by 12 feet or more of fullers earth and red and yellow limonitic sand. JEFFERSON COUNTY Wrens.-A peculiar claystone, together with a shaly, aluminous sandstone, was found at R. R. Hatcher's mill on Reedy Creek, five miles north of Wrens. The shaly sandstone contains fragments of lignitized wood and stem and lea impressions. The hard clay is bluish-white in color, compact, breaks with a conchoidal or angular fracture, and is almost entirely free from sand. A chemical analysis shows the proportion o silica ( 65.21 per cent.) to alumina (21.62 per cent.) to be much greater than that of the hard white clays o the Cretaceous. The clays here are overlain by red,. pebbly sand representing the Barnwell sand. At Patterson's Bridge on Briar Creek, six miles north of Matthews, there is 10 feet of sandy, laminated fullers earth, with which is, associated some silicified clay similar to that at Hatcher's :1\Ell. A short distance south of the bridge there is an outcrop of quartzite containing fossils. The exact relations of this quartzite to the fullers earth could not be determined, but it is inferred that it lies above the fullers earth. At Wrens old mill, two miles south of Wrens, about 25 feet of sandstone and quartzite appears. This rock contains oyster shells that could not be specifically identiied. On the road between Wrens and Matthews outcrops of vitreous quartzite and laminated clays were noted. These outcrops probably belong to the Congaree clay member. GLASCOCK COUXTY Gibson.-There are a number of good exposures of the Claiborne group in the vicinity of Gibson. The group lies unconformably upon the Lower Cretaceous and is divisible into two formations, as. indicated in the following section: GEOLOGY OF 1'HE COASTAL PLAIN OF GEORGIA. PLATE XX. A. FL'LLERS EARTH IN CONGAREE CLAY MEMBER OF McBEAN FORMATION, PIT OF GENERAL REDUCTION CmlPANY, TWELVE :\1ILES 0 THEAST OF MACON, IN TWIGGS COU 'TY. B. CUT OF MACON. DUBLIN & SAVANNAH RAILROAD. PIKES PEAK STATION. TWIGGS COUNTY, SHOWING CO 'GAREE CLAY MEMBER OF )lCBEAN FORl\IATIO . McBEAN FORMATION 273 Section at the J. Newsome property) three miles east of Gibson. Eocene. Barnwell sand. 6. Red, crossbedded sand capping the hill . 30 McBean formation ( Congaree clay member). 5. Massive; drab, and greenish clay . . . . 20 4. Soft, fossiliferous limestone . . . . . . . 5 3. Calcareous sandy clay . . . . . . . . . 5 2. Sand, containing large pellets of white clay . 15 (Unconformity) Lower Cretaceous. 1. White clay or kaolin . . . . . . . . An instructive exposure appears along the Gibson-Mitchell road at Jumping Gully Creek, one mile west of Gibson. Section at Jumping Gully Creek. Eocene. Barnwell sand. Feet. 5. At the top of the hill, fine, red, argillaceous sand . 10+ McBean formation (Congaree clay member). 4. Gray laminated clay, somewhat in the nature of fullers earth . . . . . . . . . . . . . . . . . . . . . . . 10 3. Laminated, sandy, clay , containing thin limonitic, crusts; very fossiliferous. Fills narrow "V" shaped erosion gullies in the underlying white clay . 3 Lower Cretaceous. 2. White clay . . . . . . . . . . . . . . . . . . . . . . 10 1. Talus to level of creek . . . . . . . . . . . . . . . . From bed No. 3 the Claiborne fossils, Flabellum cuneiforme) Turritella ca?"inata) and M esalia vetusta have been collected. Prof. :McCallie collected fossils at the English plantation, one and one-half miles north of Gibson. These have been identified by Dr. Vaughan, who furnishes the following list and annotation: Fossils from the English plantation. Flabellum cuneiforme Lonsdale Endopachys maclurii (Lea) Mazzalina inaurata Conrad Turritella carinata Pecten wilcoxii Dall ? Pteria sp. (the internal mould of a rather large species) Venericardia planicosta Laimarck Venericardia alticostata (Conrad) Lucina sp. Panopaea aff. oblonga Conrad Cytherea sp. "The matrix is a light gray, in some instances blotched yellow, indu rated sandstone, some pieces considerably silicified. "The fauna is Claibornian but whether upper or lower could not be Jetermined from the fossils submitted." Good exposures appear in road cuttings and gullies south and sonth,Yest of Gih~on. 274 GEOLOGY OF THE COASTAL PLAIN Section at Tompkins Ford on Grange road, four miles south of Gibson. Eocene. Barnwell sand. Feet. 6. At top of hill, red sand . . . . . . . . . 10 5. Sandstone or quartzite containing fossils . 4 4. Red sand, fine-grained, and argillaceous . . 15 McBean formation (Congaree clay member). 3. Massive, stiff, tenacious, greenish or drab clay; massive surface aspect may be due to weathering . . . . . . 30 Lower Cretaceous. 2. White, massive, semi-indurated clay, distinguished from that above 'by its much greater purity . 15 1. Soft clay and sand conglomerate . . . . . . . . . . . WASHINGTON COUNTY Sandersville.-Limestone occurs near Sandersville, which will be discussed later. A considerable thickness of clay and sand is exposed north and west of Sandersville, while at Sandersville and southward limestone and calcareous strata occur. The following section was observed along the upper Milledgeville road on the descent to Keg Creek, six miles west of Sandersville. Section St-x miles west of Sandersville. Eocene. Feet. Barnwell sand. 4. At top of the hill, bright, red sand, hardened at the sur- face by iron oxide cement. Fresh exposures show yellow and red, coarse, unconsolidated sand . . . . 60 3. Red sand, containing gray, waxy, clay laminae. The clay is in layers often not more than one-half or one inch thick . . . . . . . . . . . . . . . . . . . . . 20 McBean formation (Congaree clay member.) 2. Gray, greenish or drab clay, tough and waxy where weathered; fresh exposure laminated in the nature of fullers earth; apparent gradation between.. this and the overlying sand . . . 45 Lower Cretaceous. 1. Hard, massive, white fireclay . . . . . . 16 Sand and clay, which can be correlated with that in the foregoing section, appears in a deep gully to the north of the J\iilledgeville road, four and one-half miles west of Sandersville. Section four and one-half miles west of Sandersville. Eocene. Feet. Barnwell sand. 5. Red sand at top of gully . . . . . . . . . . . . . . . 15 4. Lighter colored sand . . . . . . . . . . . . . . . . . 10 McBean formation ( Congaree clay member). 3. Laminated, fullers earth-l_ike clay, becomes gandy at top, and there is an apparent gradation between 3 and 4. . . . . . . . . . . . . . . . . . . . . . . 20 McBEAN FORMATION 275 2. Marl layer, a fossiliferous, bluish mud, and in places a bed of comminuted shells (Claiborne fossils) . . . . 3 1. Bluish mudstone . . . . . . . . . . . . . . . . . 15 At the Carter Mill site, our and one-hal miles north o Sandersville, the following succession o beds was observed: Section five and one-half miles north of Sandersville. Eocene. Barnwell sand. 4. Red sand, contains a siliceous, fossiliferous rock . . . 3. Coarse quartz pebble conglomerate, a few feet m thick ness . . . . . . . . . . . . . . . . . . .. McBean formation (Congaree clay member). 2. Laminated clay and argillaceous sand, the latter prob ably reworked Cretaceous . Lower Cretaceous. 1. Massive, white, fire clay . . . . . . . . . . One mile north o this locality the following successiOn was observed in the hill on the public road : Section six and one-half miles north of Sandersville. Eocene. Feet. J 5. Red sand, in places large, well rounded quartz pebbles 1 4. Red sand, thin beds of greenish laminated clay . . 40 to 50 3, Coarse red sand . . . . . . Cretaceous. 2. White massive fire clay . . . . . . . . . . . . . } 1. Typical Cretaceous sand . . . . . . . . . . . . 10+ In a well at Thena, eight miles west o Warthen, 50 eet o laminated, shaly clay, in the nature o fullers earth and containing casts o fossils, was encountered in a well. The underlying Cretaceous is exposed in the valley o Keg Creek a short distance east, and the upland is covered with the red Barnwell sand and gray surficial sand. A section o a hill on the road to Hebron, seven miles southwest 0f Sandersville shows : Section seven miles southwest of Sandersville. Feet. Eocene. Barnwell sand. 3. At the top, fine red sand apparently conformable on No. 2. . . . . . . . . . . . . . . . . . . . . . . 10 McBean formation (Congaree clay member). 2. Greenish and drab, massive and laminated clay . 80 Lower Cretaceous. 1. White clay . . . . . . . . . . . . . . . . . . . 4 There appears to be a gradation between 2 and 3 where the sand is superimposed; both clay and sand are in contact with the Cretaceous in exposures west o this locality. 276 GEOLOGY OF THE COASTAL PLAIN Chalker.-Exposures along the public road, one-half mile south of Chalker, show at the top of the hill, 30 feet of fine, red sand, becoming more argillaceous at the base, and 50 feet of laminated, sandy clay (Congaree clay member) overlying white and yellow sands of the Cretaceous. In the railroad cut, one mile south of Chalker, a thin-bedded, aluminous sandstone two or three feet thick, at the base of the Tertiary, overlies a white clay bed of the Cretaceous. From a cut two miles southwest of Chalker, Prof. McCallie collected fossils from a sandstone that directly overlies white clay of the Cretaceous. These fossils have been identified by Dr. Vaughan, who furnishes the following list: 7!'ossils from two miles southeast of Chalker. Flabellum cuneiforme Lonsdale Cucullaearca cuculloides (Conrad) Cerithium ,2 sp. both apparently new , Turritella carinata Lea MesaUa vetusta (Conrad) Venericardia Ostrea georgiana Conrad-? Cytherea Corbula alabamiensil;! Lea WILKINSON COUNTY Gordon..- A number of good exposures of Tertiary _and Cretaceous beds occur in this vicinity. A section made along the public road on the Ezell or W. S. Smith place, one and one-half miles south of Gordon shows: Section one and one-half miles south of Gordon. Eocene. Feet. Barnwell sand. 5. At the top of the hill, dark, red sand with small quartz pebbles. . . . . . . . . . . . . . . . . . . . . . . 40 4. Red, orange, and brown sand, contains thin, greenish clay layers about .an inch in thickness . . . . . . . 15 McBean formation (Congaree clay member). 3. Greenish or drab clay, containing casts of fossils; in places white, siliceous concretions. The clay is mas- sive, where weathered, but in fresh exposures is bedded and resembles fullers earth . . . . . . . . 50 2. Bluish sandy clay with red splotches, due to weathering 10 Lower Cretaceous. 1. White, massive-bedded clay . . . . . . . . . . . . . . 12 The same general succession prevails southward in numerous gullies and road cuts. At a few localities the red sands at the surface seem to overlie the greenish and drab clays uncontormably, but most of these are not true erosion unconformities but are due to "creep" of the red sands down hill slopes. At Ball's Church, about eight miles south of Gordon, a deeply eroded gully on a hillside shows: McBEAN FORMATION 277 Section in gully at Ball's Church. Eocene. BlairnweU sand. Feet. 3. Top of hill, dark, red sand. Becomes more argillaceous at the base . . . . . . . . . . . . . . . . . . . . 70 McBean formation (Congaree clay member). 2. Drab, laminated clay layers, with sand partings. Clay porous, low specific gravity, and in the nature of fullers earth . . . . 50 Lower Cretaceous. 1. Massive white clay . . . . . . 5+ Pro. McCallie has furnished a description o a section two miles west o Gordon, on the Gordon-Macon public road, as follows: Section two miles west of Gordon on public road. Eocene. Barnwell sand. 9. Stratified, red, sandy clays, upper part massive . 7. Yellowish, stratified sands . . . . . . . . . . . 6. Thin-bedded, tough, drab colored clays . . . . . 5. Thin-bedded, reddish sands with clay partings . McBean formation (Congaree clay member) 4. Fullers earth ( ?) with fossils . . . . 3. Fine, orange-colored sand . . . . . . (Unconformity) Lower Cretaceous. 2. White clay (kaolin) massive. . . . . . . . . . . . . 1. Massive, micaceous, sandy clay, base of section . . . . Feet. 10 6 10 3 15 4 4 Fossils from stratum No. 4 were identified by Dr. Vaughan. Fossils from Stratum No . .!,.! Platytrochus stokesi (Lea) Plejona petrosa (Conrad) Nucula ovulia Lea Leda bella Leda sp. ? Leda sp. Tagelus sp. Diplodonta (Sphraerella) aff. inflata Lea Miltha aff. claibornensis (Con.) Cytherea sp. Lewiston.-Ladd giVes the following section m a clay pit a.t Lewiston: Section in clay pit at Lewiston. Eocene. McBean formation (Congaree clay member) Feet. 5. Red and yellow, clayey sand, with seams of laminated clay; also thin seams of brown iron ore, containing many coarse pebbles . . . . . . . . . . . . . . 6 1These fossils do not furnish horizon within the Claiborne.-T. Wsu.ffvic.iently definite information to determine the 2Bull. Geol. Survey of Georgia No. 6-A, p. 113. 278 GEOLOGY OF THE COASTAL PLAIN Feet. 4. Irregular siliceous beds, resembling quartzite, and con- taining drusy quartz cavities and many fragments of shells . . . . . . . . . . . . . . . . . . . . . . 4 3. White sand, free from iron stain, cross-bedded in places, containing mica and kaolin, and also nodules or fragments of white clay, in the upper surfaces of which are sharply outlined pear-shaped cavities, each filled with a yellowish clay. These cavities vary in diameter from one-quarter to one inch . 7 Lower Cretaceous. 2. White, gritless clay, or kaolin . . . . . . . . . . . . . 2 1. White sand . . . . . . . . . . . . . . . . . . . . . . 2 The white clay is probably Cretaceous; characteristic C1aii)orne fossils occur in the quarzite at this locality. Prof. McCallie has collected fossils on the farm of J. W. Huckabee, one and one-half miles west of Lewiston, which have been identified by Dr. Vaughan as follows: Fossils from farm of J. W. Huckabee. "Endopachys maclurii (Lea) Turbinella sp. Turritella carinata Lea Mesalia vetusta (Conrad) Nucula ovula Lea Venericardia planicosta L!Lmarck Crassatellites protextus (Conrad) Corbula oniscus Conrad Corbula alabamiensis Lea "Although this is clearly a Claiborne fauna the precise horizon within the Claiborne is indefinite." TWIGGS COUNTY Pikes Peak station.-Three-quarters of a mile west of Pike Peaks Station, in the Dry Branch region, the formation is more argillaceous than in the foregoing sections, being represented by a heavy .bed of fullers earth. Fossils identified from this locality are Nucula aff. ovula, Ostrea georgiana, Orassatelliles protextus. Section at General Reduction Company's fullers earth m~ne. Barnwell sand. 3. Red and white sand . . . . . . . . . . . . . . . 2. Greenish and drab, waxy and tough clay, only laminated, locally known as "gum" McBean formation (Congaree clay member). 1. .l:Ieavy-bedded fullers earth . . . Feet. 10 6 to 10 15 No unconformities occur in this pit. In an abandoned pit a si m- ilar succession appears : Barnwell sand. 3. Red and white sand, contains thin layers of fossiliferous sandstone . . . . . . . . . . . . . . 2. Greenish, waxy, faintly laminated clay, "gum" from 2 or 3 to 10 or 12 feet in thickness . (Apparent unconformity) Feet. 15 McBean formation (Congaree clay member). 1. Heavy-bedded fullers earth . . . . . . 10 to25 McBEAN FORMATION 279 The fullers earth is a drab or olive color when moist, becoming almost w;hite when dry. The beds or layers are from a few inches to two or three feet in thickness, and are separated by fine, micaceous sandy partings. The fullers earth itself is sandy and contains circular or lenticular pockets of gray sand reaching two or three inches in their greatest dimensions. The earth is o'Oft, unctuous, very porous, and of low specific gravity; it is minutely jointed and the joint .cracks are filled with limonitic coatings or show thin black scales of manganese dioxide. The following section appears in the railroad cut at the overhead wagon bridge a short distance southeast of the fullers earth mill: Section in railroad cut near Pikes Peak Station. Barnwell sand. Feet. In. 8. Red sand . . . . . . 4 7. Red and white sand 6 6. Greenish clay 5 5. Drab fullers earth clay, thin layered sand partings 8 4. Yellow sand . . . . . . . . . . . . 0 2 McBean formation (Congaree clay member.) 3. Heavy bedded, jointed earth 6 2. Gray, fossiliferous sand 4 1. Talus ............ . 4 In the first cut beyond the overhead bridge and near Pikes Peak station, a striking unconformity appears between red sand and fullers earth-like clay. The cut shows 10 feet of fine, red sand mantling 25 feet of bedded and jointed fullers earth and clay. The full significance of this unconformity is not known; however, it is believed that the red sand belongs to the Claiborne group. JONES COUNTY Roberts Station.-Bluish, fossiliferous mud and thinbedded ~lay in the nature of fullers earth occur in a cut on the Georgia Railroad one mile east of Roberts. This locality was studied by Prof. G. D. Harris,' who referred the strata to the "Woods Bluff" (Bashi) beds of the "Lignitic" (Wilcox). Dr. Vaughan has identified a large number of species from this locality, a greater number than i& 1American P~leontology, Bull. No. 16, 1902, p. 4. 280 GEOLOGY OF THE COASTAL PLAIN given by Professor Harris, which shows the Claiborne (not Wilcox) age of the beds. There is also lithologic similarity to the Claiborne sections at other nearby localities. This clay represents the Congaree clay member of the McBean formation, and the sand probably the Barnwell sand of the Claiborne group. Section in cut one mile east of Roberts. Eocene Barnwell sand ( ?) 6. Beginning at top, loose red sand, contains a few scattered quartz pebbles, no fossils observed . McBean formation (Congaree clay member.) 5. Greenish and drab laminated sandy clay, porous and of low specific gravity . . . . . . . 4. Laminated, sandy clay containing white calcareous nodules and casts of fossils . 3. Bluish, fosiliferous mud Crystalline basement rock. 2. Concealed a few feet . . 1. Crystaline, igneous rock . Feet. 8 to 10 12 8 8 ? The igneous rock does not appear in the deep cut, but outc1ops in the next cut east. There is no evidence of an unconformity between the red sand and the clay. The red sand, No. 6, was traced north from the cut as far as Slocumb on the Central of Georgia Railway. It contains fragmentary beds of quartzite in which are comminuted shells, and since these have no appearance of having been transported there is little doubt about its Eocene age. In the cut about one-quarter of a mile east of the "shale" cut, the red sand, (at the base interbedded sand and clay) is in contact with a decomposed granite and a diabase dike, the latter having a width of about 100 feet. There is no evidence that the dike was intruded in the Tertiary strata. In the first cut west of Roberts, red sand, containing small fossiliferous, quartzite fragments, appears. In the second cut west, what is probably red Claiborne sand uncomformably overlies gray, micaceous, kaolinic sand of the Cretaceous. Dr. Vaughan has tabulated the fossils collected in the cut one mile east of Roberts. Collections have been made by G. D. Harris, S. W. McCallie, Earle Sloan, and T. W. Vaughan. The initials above the eolumns indicate the collectors. McBEAN FORMATION 281 'l'able of fossils from cut on Georgia railroad, one mile east of Roberts, Jones County. NAME OF SPECIES Endopachys maclurii (Lea) Cylichna sp. Plejona petrosa (Conrad) Clavelithes sp. Mazzalina sp. Fusus (Levifusus) trabeatus Conrad Chrysodomus striatus ? Pseudoliva vetusta (Conrad) Turritella apita de Greg Turritella nasuta Gabb Turritella clevelandia Harris Turritella carinata Lea . Turritella arenicola Conrad . Natica semilunata Lea Calyptrea aperta (Sol.) Adeorbis sp. Nucula ovula Lea Yoldia aldrichiana Yoldia aff. psammotaea Dall . Leda aff. albirupiana Harris Leda plicata Lea . T,rigonarca sp. Trigonarca sp.. Glycymeris staminea (Conrad) Glycymeris trigonella (Conrad) CUcullaea macrodonta Whitfield Ostrea alabamiensis Lea . Pteria limula (Conrad) Pecten wilcoxii Dall Amusium sp. Modiolus alabamensis Aldrich Periploma sp. Venericardia planicosta Lamarck Protocardia lenis Lucina papyracea Lea Lucina cf. pandata Conrad . Lucina claibornensis Conrad Cytherea var. nuttalliopsis Heilprin . Cytherea texacola Harris . Cytherea subimpressa Conrad . Psammobia ozarkana Harris . Psammobia blainvillei Lea ? . Psammobia papyria Conrad ? . Spisula parilis (Conrad) . Corbula oniscus Conrad .. Corbula alabamiensis Lea H.l M.l G. D. S. W. E. S. I T.W.V. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 282 GEOLOGY OF THE COASTAL PLAIN Dr. Vaughan states: "Of the specimens collected by Professor 1lcCallie, Mr. Sloan and myself, only CucullaJa macrodonta and Cytherea subimpressa suggest Wilcox age; however, the horizon is low in the Claiborne, probably the very base, as indicated by Turritella nasuta, Pecten wilcoxii, etc., and their overlapping with two species usually not ranging above the Wilcox." Griswoldville.-The red sand which appears at Roberts (see sec- tion, page 280) can be traced, covering the ridge, three miles south to the cuts on the Central of Georgia Railway, one and a quarter mnes west of Griswoldville. Here the red, argillaceous sands fill erosion gullies in Cretaceous beds. About three-quarters of a mile south of these cuts there is a notable exposure of quartzite full of casts and silicified shells. This rock has the appearance of having been origi- nally a calcareous sand. It lies near the base of the Claiborne and is 100 feet or more below the tops of the high ridges which are made up of red, argillaceous sand. The quartzite is probably only a local de- posit. The hard rock here is provisionally considered a part of the Congaree clay member.. Prof. G. D. Harris' has made the following notes: "About a year ago, while on our way to take charge of geological work ip. Louisiana, we collected at some fine fossiliferous localities of this horizon in the vicinity of Griswold, and heard of several others in the same general region, but had no time to inspect them. This outcrop is in a Vshaped valley about two miles south of Griswold, or about 10 miles east of Macon. The lower Claiborne rock consists of a hard bed of the typical "buhrstone'' of former geological works, about 10 feet in thickness, replete with fossil remains. In less indurated, or in sandy seams, and just below the main bed many fine specimens of silicified shells were collected. Sandy beds were noted below the above mentioned hard layer for a distance of 40 feet. Above and between this outcrop and the station, red sandy hills rise to the height of 140 feet above the fossiliferous bed or above the station, the latter two points being upon about the same level. Near the station were noted red sands mottled with white clay. One mile west of Griswold extensive white clay deposits were found along the line of the railway leading to Macon." Prof. McCallie has collected fossils on the property of J. R. Van Buren and Company, one and one-half miles west of Griswoldville, which Dr. Vaughan has identified as follows: Fossils from J. R. Van Buren Company's property. "Platytrochus stokesi (Lea) Flabellum ouneiforme Lonsdale Turbinolia pharetra Lea Endopachys maclurii (Lea) Turbinella sp. Plejona sp. Levifusus trabeatus Conrad Mesalia vetusta (Conrad) ? Calyptrea aperta (Selander) Dentalium aff. blandum de Greg. Nucula ovula Lea Nucula magnifica Lea Crassatellites protextus (Conrad) Phacoides cariniferus (Oonrad) Protocardia sp. Corbula alahamiensis Lea Panopea sp. 'American Paleontology, Bull. No. 16, 1902. J.1cBEAN FORMATION 283 "The species obtained at this locality are not sufficiently restricted in their stratigraphic range to decide where in the Claiborne group the exposure belongs." BlliB COUNTY Macon.-Both the Congaree clay member and Barnwell sand appear in gullies 10 miles southeast of Macon, near the eastern boundary of Bibb County. Prof. McCallie furnishes the following section: Section in Macon-Marion public road, ten miles southeast of Macon. Feet. McBean formation, (Congaree clay member). 7. Red clays. . . . . . . . . . 5 6. Porous, cream-colored clay with fossil leaves and bivalves . . . . . . . . . . . . . . . . . . . . 10 5. Clay filled with bivalves . . . . . . . . . 1.5 4. Same as No. 6, with no fossils, but containing sand partings . . . . . . . . . . . . 8 3. Same as No. 6 . . . . . . . . . . . . . . . . . . . . 10 2. Fossiliferous sandstone and chert . . . . . . . . . . . 10 1. Crossbedded sands and white clays . . . . . . . . . . 30 Fossils from this locality are Nucula ovula, Diplodonta, Orassatellites protextus, and several species of fossil leaves. Exposures of fullers earth and sand appear in large gullies on the John Tharpe estate near the public road. The following section was made at or near the same locality as the preceding section: Section in gu!lies on Tharpe estate. Feet. Barnwell sand. 11. Fine, red sand . . . . . . . . . _. . . . . . . 50 McBean formation, (Congaree clay member). 10. Thick-bedded, fullers earth, partly concealed by the "creep" of the overlying red sand . . . . 15 9. Alternating thin layers of clay and fine sand 10 8. Heavy-bedded fullers earth . . . . . 5 7. Fullers earth, sand partings . . . . . 15 6. Thick layered, jointed fullers earth . 5 5. Interval concealed . . . . . . . . 4. Thin layers of clay, sand partings . 3. Thick layers, sandy . . . . . . . } 20 2. Concealed interval of a few feet . ? Lower Cretaceous. 1. White clay and sand . . . . The fullers earth contains casts of fossils, leaf impressions, and bits of lignitic wood. ECONOMIC GEOLOGY OF MCBEAN FORMATIOl'l The Oongaree member contains beds of fullers earth at several lJ calities between Grovetown and Ocmulgee River, which should 284 GEOLOGY OP THE COASTAL PLAIN prove to be of considerable economic value. A bed of fullers earth is at present being mined near Pike's Peak station, Twiggs County,. by the General Reduction Company, and some development work was done several years ago on the Fiske property at Grovetown. 'lhe better quality of the fullers earth of this formation possesses excellent clarifying properties, fully equal to or superior to those of the English earth. In the tests which have been made it has not proved equal to the English earth for clarifying culinary oils, but it should prove suitable for other uses to which fullers earth is put. The McBean fullers earth occurs in enormous quantities, the beds in places reaching a thickness of as much as 50 feet. McBean marls occur in abundance in the bluffs of Savannah and Chattahoochee rivers, and at localities in Burke, J e:fferson and Washington counties. The marls, in addition to lime, contain small amounts of phosphoric acid and potash, and on certain soils and under certain conditions should be of local value as a land fertilizer. Lime has in the past been manufactured from a shell bed near Griffin's Landing, Savannah River, Burke County; near Sunhill, Washington County, and near Bond's Store, Bibb County. However, under present industrial conditions, lime manufacture as a permanent industry would not be profitable in this region, on account of the high price of fuel, unfavorable quarrying condition, the general softness of the rock, and the presence of a high precentage of sand and clay impurities. However, it is suggested that where lime is desired for local agricultural purposes, the limestone and marl might be advantageously used at several localities. In this case expensive kilns and equipment would be unnecessary. The Congaree clay members of the formation contains clay Df some commercial value. Plastic clay from this member is being utilized, mixed with other clays, in the manufacture of sewerpipe and fire clay products, near Harlem, Columbia County, and at Stevens Pottery, Baldwin County. A deposit of lignite and lignitic clay occurs three miles south of Grovetown (see page 270), and has been developed in a small way. The lignite is in thin beds, interbedded with dark colored or lignitic day; the cqmbined thickness exposed in a prospect pit is 12 feet. Although a large number of nearby exposures of.strata have been examined, no evidence of any considerable amount of lignite has been found. It is believed that the area underlain by the lignite is very small, and that it is not in sufficient quantity to be an important source of fuel, although this particular deposit may possibly have a small local value. A small amount of the lignite and lignitic clay has been mined and sold as a filler for commercial fertilizers. BARNWELL SAND 285 BARNWELL SAND NAME Mr. Earle Sloan1 has used the name Barnwell "buhr sands" or Barnwell "phase" for red, ferruginous sands that immediately overlie the McBean formation, as defined in this report. The type area of the Barnwell sand is in Barnwell County, S. C., where its stratigraphic position is as stated. Sloan, who has also studied the area in Georgia adjacent to Savannah River, states that the Barnwell "phase" is represented by the same thickness south of Perry, not including the sands underlying the fossiliferous strata. Paleontologic characters.-The limestones of the formation are highly fossiliferous, but the clays and sands only sparingly so. As in Mississippi and Louisiana, the formation in Georgia seems to mark the upper limit of V enericardia planicosta. In places, Bryozoa make up the greater part of the rock, this being especially true of the ,'Pages 111, 128, 381, 383. 298 GEOLOGY OF THE OOA.STAL PLAIN occurrences at Rich Hill, Crawford County, at Ross Hill, three and a quarter miles south of Perry, and at other localities. Of the 24 species which have been determined from the Jackson formation in Georgia, but six are common to the overlying Vicksburg formation. The whale-like mammal, Zeuglodon (Basilosaurus), is a characteristic fossil of the Jackson, and some fragments of its remains have been found in Georgia. As in the Vicksburg formation, Pecten and Orbitoides, are abundant; the species Pecten perplanus, Pecten nuperus, and Orbitoides mantelli, appear in both formations. All of the fossils which have been identified from the Jackson formation are given on succeeding pages. Areal distribution.-The area underlain by the formation, so far a~ known, is small. The largest area is in Houston, Twiggs, and Pulaski counties. There is an isolated area at Rich Hill, Crawford County, and on Chattahoochee River near Alaga, Ala., there is a probable small occurrence which is mentioned by Langdon.' On Oconee River the strata exposed at Wring Jaw Landing, Johnson County, are referred to the Jackson by Dr. Vaughan. Further detailed work may reveal occurrences east of the Oconee. Evidence of the Jackson between Flint and Chattahoochee rivers has been found at only one locality, namely, on Ichawaynochaway Creek, one and one-half miles below Cordray Mill, Calhoun County. If it is present to any considerable extent as a surface formation it has not been distinguished from the strata of the Vicksburg formation and the Claiborne group. Physiographic expression.-The limestone member of the formation has produced a prominent scarp on the south side of Indian and Mill Creeks in Houston County. Rich Hill, in Crawforw County, is a conspicuous topographic feature due to the greater resistance to erosion of the limestone and clays of the formation than that exerted by the Cretaceous sands and clays. A few limesinks occur north of Bonaire. Structure.-The formation has a low dip southward. Visual evidence of folding was not noted in field work. However, in order to explain the conditions (see page 260) four and one-half miles south of Perry, either a fold or fault in the strata or an erosion unconformity between the Jackson formation and the Claiborne group is necessary. Economic geology.-The limestones of the Jackson formation, south of Perry and south of Tivola, Houston County, could be used 'Report on the Coastal Plain of Alabama : Geol. Survey of Alabama. 1S94, p. 383. JACKSON FORMATION 29~ in the manufacture of lime or for road metal. The chief objection to the stone as a road metal is its softness; however, if used in conjunction with the flint rock, which also occurs in this part of the State, it should make a fair road-surfacing material. The bryozoan, friable limestones or marls, together with some glauconitic layers, mentioned in succeeding pages, should be of some local value as fertilizers, but up to the present they have not been so utilized. LOCAL DETAII,S CALHOUN COUNTY Cordray Mill.-The Jackson formation doubtless underlies the Vicksburg formation between Flint ,and Chattahoochee rivers, but an exposure has been found at only one locality. Probable Jackson occurs in the left bank of Ichawaynochway Creek, at Bateman "Hammock," one and one-half miles below Cordray Mill, 12 miles east of Edison. Section at Bateman "Hammock" Jackson formation. Feet. 3. Red sand . . . . . . . . . . . . . . . . . . . 10 2. Hard, white sandy limestone; contains a Pecten, probably P. perplanus Bryozoa, and a large oyster . 3 McBean formation. 1. Aluminous sand and sandstone, slightly calcareous; Ostrea divaricata . . . . . . . . 1 CRAWFORD COUNTY Rich H ill.-One of the most interesting localities of the .Tackson formation is at Rich Hill, five miles southeast of Roberta. The hill rises about 150 feet above the small valley on the south side, and is a: conspicuous topographic feature. This is an isolated exposure and indicates that the northward extension of the formation was formerly much greater than at present. The hill is capped by brilliant red sand, probably referable to the Jackson formation, overlying the calca- reous beds undoubtedly belongingto the Jackson formation; the latter rests upon white clays and 'sands of the Lower Cretaceous. The hill is deeply trenched by erosion gullies in which the strata are laid bare. The following section was made from the exposures in the gullies on the south side: Section at Rich Hill. Eocene Jackson formation ? Feet. In. 13. Brilliant red sand capping the hill and forming "creep" on the upper slopes . . . . . . . . . 30 300 GEOLOGY OF THE COASTAL PLAIN 1Jackson formation. Feet. In. 12. Purplish and yellow sand, containing thin clay laminae. . . . . . . . . . . . . . . . ., . . 12 11. Greenish, laminated clay, thin lignitic partings . 4, 10. Plastic, calcareous clay with fossils . . . . . . . 0 6 9. Drab, jointed laminated clay, with sand partings 6 8. Fossiliferous nodular calcareous layer . . . . . 0 12 7. Drab, soft, laminated clay with fossils; contains nodular, calcareous layers . . . . . . 12 6. Limestone, generally soft and friable but in places hard and compact; in places it is a bryozoan marl so soft that it may be scraped up with the hands. Fossils chiefly Bryozoa, Pecten perplanus, and Mortonia sp.; fish teeth are also abundant in places . . . . . . . . . 20 5. Brown and yellow unconsolidated sand which in places is replaced by limestone . 12 Lower Cretaceous. 4. White, micaceous clay; maximum. 10 3. White, crossbedded clayey sand . . 10 2. White micaceclus clay . . .. . . . . 3 1. Coarse, white sand . . . . . . . . 10 List of fossils from ,Rich Hill. (Identified by T. W. Vaughan.) Mortonia sp. Lucina sp., found also five and one- Plejona sp. half miles south of Perry. Calyptrea aperta ( Solander) Panopaea sp. Ostrea georgiana Conrad (The Mortonia referred to above is Pecten perplanus Morton .also found at Castle Hayne and Pecten (probably P. nuperus Conrad) Wilmington, N. C., .and nine miles east young and poor specimen. of W:aynes1:>oro, Burke Oo., Ga.) Venericardia sp. HOUSTON COUNTY Bonaire.-A small exposure of limestone appears m the railroad cut one-quarter of a mile north of the station. The rock is very similar to that at the quarry south of Tivola described on a subsequent page. From this locality the following fossils' have been identified: List of fossils from one mile north of Bonaire. Mortonia sp. Caricella sp. Turritella sp. Pecten perplanus Morton Cytherea Basilosaurus sp., probably B. macrospondylus (Harlan) Residual boulders of both limestone and flint cap a hill one and one-half miles north of Bonaire, near the railroad. This is probably the northern limit of the Jackson formation, for to the northward 1Bull. Geol. Survey of Georgia No. 15, p. 351. J.AOKSON FORMATION 301 of this place there is a decided change in the character of the materials, and at Wellston there is an exposure having the characteristic appearance of the Cretaceous. Perry.-Very good sections of the Jackson formation occur in the escarpment on the south side of Flat Creek and Mill Creek, at Ross Hill three miles south of Perry, and on the Perry Henderson road, five miles southwest of Perry. The section "of the northern slope of Ross Hill, along the publi~ road, is as follows: Section at Ross Hill Feet. Qlig_ocene. Vicksburg formation. 11. Flint fragments in red, clayey soil . . . . . . . . . . 10 Eocene. Jackson formation. 10. Soft, fossiliferous limestone or marl . . . . . . . . . 4 9. Largely concealed, but probably an argillaceous marl or calcareous clay . . . . . . . . . 1. 12 8. Limestone and marl . . . . . . . . . . . . . . . . . 4 7. Laminated, fine-grained, drab clay; contains small friable, calcite nodules . . . . . . . . . . . . . . . 15 6. Ash-colored, friable marl, made up of fragments of Bryozoa, pectens, echinoderms, et.c. . . . 5 5. Soft, fossiliferous limestone, more compact than the above layer . . . . . . . . . . . . . . . . . . . . 4 4. Yellow and ash-colored, fossiliferous marl . . . . . . . 6 3. Hard, compact limestone . . . . . . . . . . . . . . . . 6 2. Massive soft, fossiliferous limestone; contains charac- teristic Jackson fossils . . . . . . . . . . . . . . . 15 1. Greenish, fine-grained, laminated clay . . . . . . . . . 10 A collection of fossils was made at this locality by Prof. McCallie and identified by Dr. Vaughan as follows: List of Fossils from the J aclcson Formation south of Perry Locality.-Perry-Elko public road, three and one-quarter miles southeast of Perry. Plejona petrosa (Conrad) Fusoficula cf. Iilia (Meyer) Turritella sp. Calyptrea aperta (Solander) Dentalium thalloides Conrad Nucula ovula Lea Leda multilineata Conrad Leda sp. Glycymeris sp. Pecten perplanus Morton Pecten cf. nuperus Conrad Venericardia cf. rotunda Lea Cytherea, 2 sp. Spisula cf. funerata Conrad At the same locality Veatch collected the following- fnssils f,,,:n the limestone in the lower part of the hill : Orbitoides Mortonia sp. Protocardia nicoletti Conrad GEOLOGY OF THE COASTAL PLAIN Along the road between this hill and Perry only vari-colored, un~onsolidated sands appear. These sands evidently underlie the calcareous strata of the Jackson formation but their age has not been definitely ascertained. They probably belong either to the Jackson formation or to the Claiborne group. Section five miles southwest of Perry along Perry-Henderson public road. Oligocene. Feet In. Vicksburg formation. 13. Top of hill, red, argillaceous sand; character istic appearance of the residual sand of the Vicksburg . . . . . . . . . . . . . . . . . . 12. Re,sidual flint and "rotten" limestone; contains fossils . . . . . . . . . . . . . . . . . . . 6 Eocene. Jackson formation. 11. Red, sandy clay, containing quartzite nodules . 15 10. Gray, laminated, shaly clay, in the nature of fullers earth . . . 6 9. Glauconite layer . . . . . . . . . . . . . . . . 2 8. Black clay . . . . . . . . . . . . . . . . . . . 0 3 7. Glauconite layer . . . . . . . . . . . . . . . . 0 12 6. Gray and drab, calcareous clay; contains soft nodules of white calcite . . . . . . . . . . . 10 5. Limestone layer, very hard . . . . . . . . . . 0 6 4. White, soft, argillaceous limestone and ash- colored friable marl . . . . . . . . . . . . . 3 3. Strata concealed, probably limestone or calcareous clay . . . . . . . . . . . . . . . . . . . . . 10 2. Red and greenish, stiff, plastic, sandy clay; con- tains fossiliferous flint fragments . . . . . . 10 Age? 1. Red, unconsolidated sand to level of Mill Creek; contains fragments of silicified wood, but no other fossils . . . . . . . . . . . . . . . . 25 Characteristic Jackson fossils have been identified from this locality. In proceeding north from Mill Creek to Myrtle, only vari-colored sands are exposed. Stratigraphically these sands lie beneath the Jackson formation. They may belong in part to the Jackson formation, but are more probably referable to the Claiborne group and Midwav formation. From the preceding section Dr. Vaughan has identified the following fossils: Fossils' from Perry-Henderson road, five and a quarter miles south of Perry Flabellum cuneiforme Lonsdale Endopachys sp. Turritella Leda multilineata Conrad 'Collection made by S. W. McCallie, Bull. 15, Geol. Surv. Ga., p. 351. JACKSON FORMATION 303 Leda, very large species, cf. pharcida Dall, but apparently new. Lucina sp., also found in the clay bed at Rich Hill Protocardia nicoletti Conrad Corbula, apparently wailesiana Harris Tivola.-A good section of the formation is exposed at the old quarry on the east side of the Georgia Southern & Florida Railroad, vne and one-hal miles south of Tivola. Section at Georgia Southern & Florida quarry Oligocene. Feet. In. Vicksburg formation. 16. Flint layers and fragments in red, argillaceous sand; strata partly concealed and actual con- tact with lower beds not seen; flint fossili- ferous . . . . . . . ......... . Eocene. Jackson formation. 15. Greenish, laminated clay; contains calcareous concretions and thin sandstone layers . 5 14. Argillaceous limestone . . . . 0 5 13. Drab clay . . . . . . . . . . . 2 6 12. Indurated, calcareous clay . . . . 0 6 11. Plastic, drab, laminated clay . . . 4 10. Hard, calcareous layer . . . . . . 0 3 9. Greenish or dra:b, laminated clay . 4 8. Sandstone . . . . . . . . . . . . 0 3 7. Yellow, laminated, calcareous 'clay 4 6. Hard limestone . . . . . . . . . 0 f5 5. Soft limestone, contains fossils . . 0 12 4. Hard limestone, no fossils . . . . . 0 12 3. Laminated clay . . . . . . . . . . . . . . . . 4 2. Massive bedded, white and cream colored, highly fossilliferous limestone; contains Bryozoa pec- tens, Orbitoides, echinoids, a rather large oyster, and sharks' teeth; fragments of large bones are reported to have been found . 25 1. Stratum partly concealed, but probably a calcareous clay . . . . . . . . . . . . . . . ~ . . ? Stratum No. 16 has every appearance of the residual Vicksbnrg formation from which fossils have been identified a short distance south of this locality. The limestone is, on the whole, soft, but there is some hard rock which seems to be due to crystallization of the calcium carbonate. It is very fossiliferous, being made up entirely of organic remains; parts of the beds resemble the friable marl at Rich Hill; the section is, on the >Yhole, similar to that at Ross Hill, three and one-half miles south of Perry. The rock here has been quarried for road metal. Northward from the quarry only sand is exposed. This is a red, fine-grained quartz sand with occasional thin, impure, clay layers; no fossils could be found but this sand does not appear to be of Pleistocene age or a surficial formation, and probably belongs to the Jackson formation. 304 GEOLOGY OF THE COASTAL PLAIN The limestone again appears in a railroad cut two miles south of Tivola. A calcareous clay, probably a part of this formation, was noted a short distance east of Kathleen. TWIGGS COUNTY Near Dry Branch.-Acco~ding to Dr. Vaughan the evidence of the fossils shows that .Tackson strata occur near the mines of the Georgia Kaolin Company, two miles southeast of Dry Branch. There is an exposure of 15 feet of soft, white, argillaceous marl in a small ravine one-half mile southeast of the clay-working plant, which contains Bryozoa and other fossils, and is similar lithologicallY to the marl at Rich Hill. It lies 10 to 15 feet above the white clay beds of the Cretaceous, and is overlain by 125 feet of bluish or drab, laminated, sandy clay and red sand, the clay containing thin slabs of quartzite or sandstone. In this vicinity Claiborne fossiliferous strata occur at both higher and lower levels than this marl, and the presence of Jackson beds in this position implies either a deep erosion unconformity between the two formations, or a flexure. Exposures in this vicinity, so far as they have been examined, afforded no evidence either of an unconformity, or of any faulting or folding of the beds. Further detailed field work is necessary to solve this problem of stratigraphy. List of fossils from ravine one-half mile southeast of the mines of the Georgia Kaolin Company, identified by T. Wayland Vaughan. Platytrochus stokesi (Lea) Mortonia Leda multilineata Conrad Pecten perplanus Morton Protocardia Tellina Corbula densata Conrad Bryozoa (very numerous) Westlake.-On the old McRae plantation at a point about three and one-half miles northeast of Westlake, is an exposure of limestone that has the lithologic appearance of the Jackson formation. The soil at this particular locality is a tough clay with a much ranker vegetation than the higher sandy land. The rock is exposed at a few places, is highly fossiliferous, and has much the appearance of the limestone south of Tivola and Perry. However, Amusium ocalanum has been found here and this fossil suggests a higher horizon. About four and one-half miles northeast of West] ake, on the J effer sonville road, ab~mt 20 or 25 feet of calcareous, laminated clay similar to that above the limestone at Rich Hill and Tivola is exposed in a gully on the land of Mr. S. G. Kitchens. Scutella ( ?) was noted in calcareous layers in the clay. The higher land above this clay is JACKSON FORMATION 305 eovered by a bright red, ferruginous, argillaceous sand in which there are scattered fossiliferous flint fragments having the aspect o the Vicksburg formation. On the Macon-Cochran public road, on Shell Creek, near Westlake; Prof. McCallie collected Peden perplanus Morton; on the ,;arne road one mile east of \Vestlake, he obtained Platytrochus stokesi (Lea), and Endopachys maclurii. (Lea). These exposures probably represent the Jackson formation. On the McRae farm, three miles east of Westlake, he collected Mortonia} Pecten perplanus Morton, :;nd Amusium ocalanu1n Dall, which suggest the presence of the Vicksburg formation, since Amusium ocalanum has hitherto not been found lower than the Vicksburg. PBLASKI COUNTY. Hawkinsville.-The Jackson formation appears on Ocmulgee River in the lower part of Taylor's Bluff, three miles above Hawkinsville. Section of Taylor}s Bluff three miles above Hawkinsville. Feet. 6. Concealed by vegetation . . . . . . . . . . . . . . . . 32 5. Massive wall of soft, argillaceous limestone, no bed- ding; few fossils . . . . . . . . . . . . . . . . . . 25 4. Fossiliferous limestone, with alternate hard and soft layers; somewhat argillaceous . . . . . . . . . 17 3. Very hard, compact, greenish-gray clay. . . . . . . . 2 2. Greenish-gray, calcareous sandstone . . . . . . . . . . 1 1. Bluish drab, compact, sandy clay to water's edge . . . 3 The fossils collected from the lower 20 feet of the section, Flabellum cuneiforme, SphenotrochWi sp.J Endopachys maclurii (Lea), Leda nultilineata} Conrad, Venericardia planicosta} Lam, and Lunulites sp., are regarded by Dr. Vaughan as of Jackson age. Amusium ocalanum} collected 22 feet from the base of the bluff, indicates that the upper part is of Vicksburg age. No unconformity was observed betw,een the two formations. JOHNSON COUNTY. Kittrells.-Prof. :McCallie has furnished the following section descriptive of the strata exposed in the bluff at Wring Jaw Landing on Oconee River, two miles west of Kittrells. Section at Wring Jaw La.nding Jackson formation. 8. Massive, red, sandy clay . . . . . . . . . . 7. Stratified, red, sandy clay 6. Bluish, lignitic clay . . . . 5. White and yell?w sands Feet 8 8 8 4 306 GEOLOGY OF THE COASTAL PLAIN 4. Bluish clay with fossil leaves . . . . . . 3. Hard, glauconitic limestone, fossiliferous . 2. Bluish clay with fossil shells . . . . . . 1. Soft glauconitic limestone or marl . . . Feet 4 8 .. 2 Dr. Vaughan has identified the folluwing fossils from this locality; List of fossils from Wring Jaw Landing Orbitoides sp. Flabellum cuneiforme Lonsdale Platytrochus stokesi (Lea) Endopachys mac!urii (Lea) :\!Iortonia sp. ;.Jucula ovula Lea Leda Pecten perplanus Morton Ostrea trigonalis Conrad Protocardia nicolleti Conrad Lunulites distans Lonsdale Lithologically, the strata are similar to the Claiborne material near Sandersville and west of Tennille. The red sand which over- lies the marl extends about smen miles east of the river, beyond which it becomes obscured by strata of Oligocene age and by 1he Altamaha (Lafayette ?) formation. SAVANNAH RIVER Johnson's Landing.-Dr. Vaughan examined an exposure of fossiliferous, silicified limestone on the South Carolina side of the river, on the north side of the upper road to the lanJing, in a field just above the margin of the river swamp. Pecten perplanus Morton and numerous Bryozoa were obsen-ed. This exposure probably be longs to the Jackson formation but the evidence is not entirely conclusive. OLIGOCENE VICKSBURG FORMATION NAME This division of the Tertiary receives its name from Vicksburg, ;Miss., where it \Vas first studied and named by Conrad.' It is in part the equivalent of the St. Stephens limestone of Alabama, and includes in Florida2 the Ocala, "Peninsular," and 11arianna limestone. Vaughan' has recently stated that it is probable that the Florida elivisions should be grouped as one formation. The St. Stephens limestone of Alabama has been traced from Mississippi to Chattahoochee River; it, however, includes the Jackson, ~whereas in Georgia the Jackson has been differentiated from the Vicksburg. 'rhe possibility of subdividing the Vicksburg in Georgia into t\vo formations has been considered but the present work has not been sufficiently de- 'Prof. Acad. Nat. Sci.. Philadelphia; Vol. 3, 1846. pp. 280, 281. 2Matson, G. C., and Clapp, F. G., Preliminary report on the geology of Florida; Florida Geol. Survey, HlOfl. . 'Contributions to the Geologic history of the Floridian Plateau, Publication No. 133, Carnegie Institution of Washington, 1910, p. 150. VICKSBURG FORMATION 307 tailed to furnish either a lithologic or paleontologic basis for the consistent extension of such subdivisions across the area. That subdivisions may later be made is probable. In the previous literature on Georgia geology this formation has been briefly described under the name "White Limestone series" by Spencer/ and under the names "Vicksburg-.Jackson" and "Vicksburg" by :McCallie,' Veatch' and others. Parts of the underlying Jackson fDrmation and of the overlying Chattahoochee formation have been included under these divisions by the authors mention~C-1. The Vicksburg formation or group was in the earlier literature referred to the Eocene division of the Tertiary, but in most of the more recent publications on Atlantic and Gulf Coastal Plain geology it has been placed under the Oligocene. The adoption of this EuroyJean division (Oligocene) of the Tertiary in the classification of the strata of the Atlantic and Gulf Coastal Plain of the United States is due largely to the studies of Dr. W. II. Dall' of the U. S. National Museum. DEFINITION Stratigraphic relations.-The Vicksburg formation, which is classified as Oligocene, occupies a stratigraphic position between the Jackson and the Chattahoochee formations. Contacts with the Jackson formation were seen in Houston and Pulaski counties where there seems to be no physical break between the two divisions. \Vest of Flint River, the Vicksburg extends northwar~d to the Midway and Wilcox belts of outcrop, and has overlapped and largely obscured the Claiborne group and Jackson formation. Unconformable contacts with the Claiborne group, the Jackson apparently missing, were noted near Fort Gaines, Cuthbert, Shellman, Americus, and Andersonville. Unconformable relations or erosion contacts have been observed tdween the Vicksburg formation and the overlying Chattahoochee formation, in the vicinity of Bainbridge, Decatur County, by Pumpelly and Vaughan (see under Chattahoochee formation). Northward from Decatur County, in the escarpment on tho east side of Flint River, the Chattahoochee formation is doubtfully present in natural exposures, and the Vicksburg seems to be directly overlain by 'Spencer, J. W., First Report of Progress; Geol. Survey of Georgia, 1890-1891. 2McCallie, S. W., Underground waters of Georgia; Geol. Survey of Georgia, Bull. :'-!o. 15, p. 33. 3Veatch, Otto, Clay aeposits of Georgia; Geol. Survey of Georgia, Bull. No. 18, pp. 75-76. 'For a discussion of the Oligocene see papers by Dall: Proc. U. S. Nat. Mus., Vol. 19, No. 1110, 1896, pp. 303-305. Table of North American Tertiary horizons, U. S. Geol. Survey, Eighteenth Ann. Rept., 1896-1897, part 2. Trans. Wag. Inst. Sci., Philadelphia, Vol. 3, pt. 4, 1903, pp. 1546-1549. 308 GEOLOGY OF THE COASTAL PLAIN the Alum Bluff, but it is probable that the Chattahoochee formatio~ exists in this region and is merely concealed by weathering and by the Alum Bluff formation. Eastward in Dooly, Pulaski, Laurens, Burke, and Screven counties, and other counties along the northern margin of the formation, as the Vicksburg formation is overlapped and partially obscured by the Altamaha (Lafayette {) formation, Alum Bluff formation, and by Pleistocene deposits, its relation to the Chattahoochee formation is not known, other than that it is sr:ratigraphically lower than that formation. Lithologic characters.-The formation is made up largely of white limestones, but also contains beds of sand and clay. The limestones have been extensively silicified and in many places do not appear at all at the surface, but are concealed by vari-colored, very coarse grained, sandy clays, which are probably residual, in which residual flint fragments are imbedded. The limestones are generally white or cream colored, soft and earthy and very abundantly fossiliferous. Flat, disc-like Orbitoides, Bryozoa, and pectens, and their fragments form nearly the whole of the rock in places. Along Flint River the rock has a characteristic vesicular or pitted appearance due to solution. There are cave-like recesses in the bluffs producing a rough jagged appearance. Bedding planes and joint planes are almost entirely absent. At a few localities, however, the limestones are hard, white, and crystalline, and sufficiently pure for use in the manufacture of lime. The softer rocks contain varying percentages of silica and clay. The silica is generally not in the form of quartz grains, but has been introduced in solution in circulating waters replacing the limestone. The limestones have been extensively silicified and the formation is often represented by flint fragments and large siliceous boulders; at no place does the flint appear in continuous, solid or undisturbed beds. The flint is either porous and tripoli-like, or brittle, compact and translucent, having been converted into jasper and chalcedony. The white porous flint is prominent wherever the Vicksburg is the underlying geological formation. The white or cream color is due tt the porous condition of the rock, the silica of which when examined under the microscope is seen to be in translucent grains probably in the form of chalcedony. These flint rocks are in many places as fossiliferous as the limestones, and are evidently replacements of the soft, porous limesto:r;es o:f the Vicksburg formation. The alteration in most cases has been complete, the rock rarely showing effervescence with acids. Some o:f the flint is dense, compact, vitreous or brittle and either translucent or red, yellow or brown. VICKSBURG FORMATION 309 This variety shows fewer traces of fossils than the porous flint, but it is probably a replacement o! the limestones; as an exception, jasper in the form of nodules in the limestones, apparently produced by the segregation of silica and not by replacement has been observed at Albany. Large boulders of int appear along Flint River from Albany to Bainbridge and form some of the most picturesque spots along the river. The boulders are characteristically vesicular and contain spherical cavities an inch or more in diameter. These cavities appear to have been originally occupied by echinoids and often a spongy skeleton-like kernel of silica remains in place of the fossil. The Vicksburg formation is deeply weathered, the weathered product appearing at the surface as deep red, argillaceous sands, containing scattered flint fr~oments and black and brown iron oxide accretions about the size of buckshot. "\Vhere the sands have been exposed to the atmosphere for long periods of time as in old railway and road cuts, they have become case-hardened or slightly cemented by iron oxide, and crack into polygonal figures. At a number of places the residual clays and sands present a mottled appearance not unlike that of the Altamaha (Lafayette ?) formation. The freshly exposed residue of decomposition and solution is a highly siliceous, bluish or gray, tenaceous clay. Sand beds which probably belong to the Vicksburg formation have been reported in a number of wells. In a cut of the Central of Georgia Railway, one-hal mile east of Dawson, there are two beds of varicolored sand associated with residual flint and clay, but which themselves do not appear to be residual. 'l'hiclcness.-The thickness of the formation can not be determined from natural exposures. Estimating from well records, the thickness in the western part of the State can hardly be more than 300 feet and at many localities is much less than this amount. Along the northern margin of the formation in Clay, Randolph, Webster, and Sumter counties, the thickness is less than 100 feet. Sepncer1 estimated the -thickness at Bainbridge to be 500 feet. It is probable, however, that a part of the strata included by him in the Vicksburg formation should have been referred to the underlying Eocene. The formation also appears in Burke and Screven counties, but no data for estimating its thickness in that region are available; however, it probably does not exceed that in the western part of the State. Paleontologic characters.-The formation is highly fossiliferous. The most abundant forms are foraminifera and bryozoans. So :abundant is one genus, Orbitoides, a flat, disc-like foraminifera, va- 1Report of Progress, Geological Survey of Georgia, 1890-1891, p. 55. 310 GEOLOGY OF THE COASTAL PLAIN rying from one-quarter inch to two inches in diameter, that the formation has been named in older literature the "Orbitoidal lime- stone." The fauna of the Vicksburg formation possesses certain distinctive characteristics, although some of the common Vicksburg forms such as Orbitoides and Pecten perplanus are also found in the underlying Jackson formation. One of the characteristic fossils of the formation is Amusium ocalanum. Venericardia planicosta which ranges up into the underlying Jackson form_ation has not been found in the Vicksburg formation. Common Vicksburg fossils are Orbi toides mantelli, Orbitoides papyracea, Nummulites wilcoxi, Glycymeris arctatus, Pecten poulsoni, Pect'en perplanus, Amusium ocalanum, and Cytherea sobrina. Areal distribution.-The Vicksburg formation underlies a large area in the western part of the Coastal Plain, including parts of or all of the counties of Sumter, Lee, Terrell, \Vebster, Randolph, Clay, Early, Calhoun, Dougherty, Baker, Mitchell, Miller, and Decatur. Areas also occur in Crisp, Dooly, Houston, Pulaski, Twiggs and Laurens counties. Eastward from Oconee River the formation has been largely concealed by later formations and only small areas are known in Screven and Burke counties. With the exception of the Altamaha (Lafayette?) and Pleistocene surficial deposits, the area over which the Vicksburg is the surface formation is greater than that of any other Coastal Plain formation. Physiographic expression.-The formation has exerted a notable effect upon the topography. The general surface areas underlain by it are more nearly level than is usual in the case of the' other older Coastal Plain formations. Underground solution has been extensive and the plains are dotted by limesinks and ponds. These ponds vary from shallow, circular depressions not more than 50 feet across, to sinks occupying several hundred acres. The region is also characterized by a scarcity of surface streams tributary to the larger streams since much of the drainage is underground by way of the sinks. Structure.__:__The beds are almost horizontal, but dip slightly to the southward, at an angle less than that of the underlying older strata. Est{mating from the supposed base of the formation at Americus and Cuthbert, and the supposed base at Albany as determined from the record of an artersian well, the dip southward probably does not exceed eight feet per mile. No flexures or faulting were observed at any place, although detailed geologic work may reveal disturbances of this character; it is certain that the Coastal Plain has undergone oscillations subsequent to the deposition of the Vicksburg formation. VICKSBURG FORMA~TION 311 Economic geology.-The Vicksburg formation contains at a few places beds of hard, comparatively pure limestone, suitable for limeburning. The most suitable rocks of this character noted during field work are near Armena, Lee County, and on the Jones plantation three miles west of Arlington; similar rocks, however, doubtless exist at other localities. The harder phases of the limestone are also suitable for road metal when surfaced with flint; such material has been used for this purpose with some success at Albany. The flint rock of the formation may be used locally for road metal and in concrete work J\1ost of the more important hard rock exposures of the formation are mentioned on succeeding pages. LOCAL DETAILS CHATTAHOOCHEE RIVER On Chattahoochee River, the Vicksburg formation appears at Miriam Landing, Decatur County, and is described by Langdon1 as a white orbitoidallimestone, having a thickness of 200 feet. At Saffold, Georgia, and Alaga, Ala., beds of flint containing Vicksburg fossils appear in the escarpment of the seeond Pleistocene terrace at an elevation of 50 to 75 feet above river level. Limestone occurring near the river level at the Atlantic Coast Line railroad bridge, is probably referable to the underlying Eocene, and has been previously discussed. BETWEEN FLINT AND CHATTAHOOCHEE RIVER :Much of the region between these rivers is a nearly flat plain in which limestone exposures are rare. The surface materials consist of red, argillaceous sands, for the most part residual, in which are embedded fragments of flint that contain the same fossils as the l]mEJstone of the formation as exposed on Flint River. Cuthbert, Randolph County.-Residual boulders of flint are numerous over the surface >vest and southwest of Cuthbert; the rock is in part hard and vitreous and in part soft and porous. In a cut of the Central of Georgia Railway, one and one-half miles west of the station, fossiliferous Vicksburg flint in clay rests unconformably upon red sand which is supposed to be Claiborne (see page 266.) At one place there is a pocket of laminated, lignitic clay in the Vicksburg formation. The flint at this locality contains Orbitoides; Pecten perplanus, Cytherea sob.rina, and other Vicksburg forms. Blakely, Early County.-Dr. Vaughan has furnished the following notes on the geological conditions at Blakely: '~eport on the Co~stal Plain of Alabama: Geol. Survey of Alabama, 1894, p, Hfi, 312 GEOLOGY OF THE COASTAL PLAIN "The surface is composed of red sands, underlain by Vicksburg limestone changed to chert. Orbitoides mantelli (Morton) is very abundant and an apparently undescribed species of Pecten was obtained." Prof. S. W. McCallie1 has published the record of a deep well at Blakely. Blakely Deep lVell, Blakely, Ga. Feet Red, sandy clay . . . . . . . . . . . . . . from 1 to 10 Coarse, grayish sand . . . . . . . . . . . 10 " 20 Coarse, light-yellow sand . . . . . . . . . 20 " 30 Yellowish, cherty limestone (Vicksburg) 30 " 40 Yellowish, or grayish, s~ndstone . . . . . . 40 " 50 Light-colored, almost white calcareous sandstone prob- ably base of Vicksburg-Jackson .. 50 " 70 Gray sands, darker at bottom . . . . . 70 " 140 Greenish sands, with Ostrea divaricata . 140 " 160 Fine, gray sand, hard ledge at bottom . 160 " 285 Fine sand, with some clay . . . . . 285 " 290 Bluish clay . . . . . . . . . . . . . . 290 " 490 Quartz sand, with glauconite . . . . . . . . . . . 490 " 500 Hard sandstone with glauconite; two oysters ap- . parently Gryphaea and Exogyra costata . . . 500 " 510 Grayish or bluish sands . . . . . . . . . . . . . 510 " 580 From 580 feet to the bottom of the well, limestone interstratified with clays and sands is reported. The third water-bearing stratum, which is probably upper Cretaceous, is said to consist of a coarse sand. The flint from the Vicksburg formation in this vicinity has been used for macadamizing the streets of Blakely. Hilton, Early County.-In a railroad cut one mile west of Hilton Station, 20 feet of white, siliceous clay of the Vicksburg is exposed, overlain unconformably by coarse, pebbly sand, probably a Pleistocene terrace deposit. The residual, siliceous clay probably originated from the decomposition of a partially silicified argillaceous limestone. It lies near the base of the formation. Dawson, Terrell Oounty.-Interesting occurrences of the Vicksburg formation are revealed in a cut of the Central of Georgia Railway one-half mile east of the station. Soft, porous, or "rotten" flint Occurs in mottled, residual, siliceous clay, but there are layers of coarse, purplish, red, and yellow sand, and pockets of clay, which .apparently are original and not residual. Bronwood, Terrell County.-Flint fragments of the Vicksburg formation are especially abundant in the fields, three to four miles northeast of Bronwood. These are evidently near the base of the formation. 1Bull. Geol. Survey of Georgia No. 15, pp. 105-107. GEOLOGY OF THE COASTAL PLAI OF GL>OIWJA. PLATE XXIJ. A. ::IIA SES OF FLINT FRO:\! THE VICKSBURG FOR111ATI0)1. EIGHT OR NINE :\ULES ABOVE BAINBRIDGE. DECATUR COU TY. B. EXPOS RE OF FLI T AND LIMESTONE OF THE VICKSBURG FORllfATIO ' JU 1.' AI:IOVE DE \\' IT'l' FERRY, FLINT RIVER, MITCHELL COUN1.'Y. VICKSBURG FORMATION 313 Arlington, Calhoun County.-There i::. a notable outcrop of limestone near Arlington. The rock appears in a bluff on the edge of the swamp of Spring Creek, on the T. F. Jones plantation, three and one-half miles west of Arlington. The natural exposure shows a maximum of 20 feet, of very compact, white, crystalline limestone. The purity of the rock is exceptional and it is exceedingly hard and C)mpact, whereas the formation elsewhere is generally soft. Crystallization of the calcium carbonate has probably largely destroyed fossils, but Orbitoides, Pecten, and Bryozoa were detected, though no species were determined. The fossils and the geographic position of the outcrop seem to be sufficient evidence of its Vicksburg age. There is a conspicuous occurrence of Vicksburg flint in a cut of the Central of Georgia Railway two miles west of Arlington. The flint is embedded in a bluish red and mottled, siliceous clay. Colquitt, Miller County.--,-Flint in the form of large projecting boulders is exposed on Spring Creek, one-half mile West of Colquitt, and on Long Branch, two and one-half miles north of Colquitt. At each place the rock is porous and tripoli-like, a condition probably due to a partial replacement of limestone, the remainder being carried away in solution. Casts and moulds of Pecten, Orbitoides, small gastropods, and a large oyster are numerous. Andersonville, Sumter County.-Exposures of stratigraphic interest occur on the Battle plantation, five miles southeast of Ander- , sonville, and near the ninth milepost on the lower Americus-Oglethorpe road. The following succession occurs: Section on Battle plantation. Oligocene. 1 Vicksburg formation. Feet. 8. Knoll of hard, vitreous flint with Vicksburg fossils 7. Red, argillaceous sand . . . . . . . . . . . . . . 6. Thin flint layer with the fossils, Orbitoides, Pee- ( . 30 ten, etc . . . . . . . . . . . . . . . ...... J 5. Red sand . . . . . . . . . . . . . . . . . . . . . 4. Yellow, sandy, glauconitic clay . . . . . . . . . . . . 12 3. Thin layer of quartzite . . . . . . . 2 2. Purplish sand . . . . . . . . . . 4 (Unconformity) -Eocene. Claiborne group ? 1. Fine, incoherent, quartz sand . . . . . . . . . . . . . . 10+ The base of the Vicksburg here contains a small amount of lignitic matter. The Vicksburg-Claiborne unconformity is also revealed near the seventh milepost on the Americus-Oglethorpe road. 314 GEOLOGY OF THE COASTAL PLAIN Americus, Sumter County.-ln this vicinity flint fragments are abundant in the soil and are prominently exposed in a cut of the Seaboard Air Line Railway three miles west of Americus. Vickoburg flint also occurs smith and east of Americus. In the city of Americus, the Vicksburg formation consists of deep red argillaceous sand capping the higher land and resting unconformably on non-fossiliferous sand believed to belong to the Claiborne group. This unconformity is revealed in a cut one-quarter of a mile east of the Seaboard Air Line Railway station. Armena, Lee County.-A fine exposure of Vicksburg limestone occurs on the plantation of J\Ir.T. F. Cocke, at Annena, 11 miles northwest of Albany. About three-quarters of a mile northeast of the station 10 feet of the rock appears in a bluff of Fowltown Creek, and about one-quarter of a mile east of this latter locality, at a cave known as the "Indian Den," there is 18 feet of limestone. The limestone is overlain by a small thickness of red, residual sand, containing scattered flint fragments. The rock at both localities is a hard, white, crystalline limestone in massive beds; it is of sufficient purity to make it a valuable stone for the manufacturing of lime. The fossils, Orbitoides, Operculina, Pecten perplanus, and Amusium ocalanum, were collected here. The rock is correlated with the Vicksburg limestone at Alba1_1y and at other points on Flint River. Palmyra, Lee County.-A fine exposure of Vicksuurg limestone also occurs on Fowltown Creek, at DaYis's Mill near Palmyra, six miles north of Albany. The limestone is soft, contains Orbitoides, Pecten, Bryozoa, etc., and resembles that at the power plant north of Albany. A maximum of 30 feet of rock is exposed and it is overlain by dark red sand. EXPOSURES ON AND NEAR FLINT RIVER The most typical exposnres of the Vicksburg formation occur along Flint River. For an airline distance of about 80 miles the channel of the river is entirely cut in the Vicksburg formation. Near Oakfield, ~Worth and Lee Counties.-Limestone is exposed at the Albany & Northern Railroad bridge over Flint River, and in the bluff on the southern side of the Great Bend of the river, one and onehalf miles above the bridge,in Lee county. The rock contains characteristic Vicksburg fossils, such as Orbitoides, Pecten, etc. A minute, curled foraminifera, Operculina, is especially abundant. One and one-half miles above the bridge a precipitous bluff 25 to 50 feet high exposes at its base 10 or 15 feet of ~white, compact, noncrystalline limestone. The rock presents a jagged and pitted appear- VICKSBURG FORMATION 315 ance and the river has cut cave-like recesses into it. The strata over- lying the limestone consists of red, argillaceous sand containing flint fragments, doubtless residual, above which is a variable thickness of Pleistocene terrace sand. This locality was described by Spencer as the southern limit of the Claiborne group, but paleontologic evi- dence establishes its Vicksburg age. The limestone probably extends up the r~ver above Oakfield to a point a short distance above the Seaboard Air Line Railway bridge. The rock exposed in the river bank at this latter place, and at Clegg's siding a short distance to the eastward, resembles the Vicksburg lime- stone. The fossils noted were Orbitoides, Pecten perplanus Morton, and Bryozoa. The possibility, however, of its being the equivalent of the Jackson limestone south of Perry should be considered. Dr. Vaughan furnishes the following geologic notes on eastern Lee County and western Worth County: "At Philema, Ga., there is a well 163 feet deep with a flow of good water. I could not get a reliable record of the well, but apparently the water comes from the Vicksburg limestone. "There are numerous sinkholes four miles west of Philema. The subsurface rock is a soft, porous; often reddinsh-stained limestone, sometimes silicifiPri. Orbitoides is abundant. This rock apparently belongs to the Vicksburg formation. "Specimens of limestone were obtained from a well four and one-half miles west of Philema at a depth of about 30 feet. "Topographically, the country from Flint River about two miles above Philema, to four miles west of Philema, is 'fiat-woods,' very level, and probably does not rise more than 50 feet above the river for several miles back. About four miles west of the river there are numerous limesinks in which are deep ponds or pools. The surface formation consists of reddish sands or reddish sandy clays in which chert is abundant. It is probable that wuch of the clay is residual. The elevation of this area is higher above the river than that of the 'flatwoods,' According to the best information obtainable, the surface sands and clays are from 30 to 50 feet thick. These are underlain by limestone, the thickness of which could not be positively ascertained. According to some informants the thickness of the limestone is about 50 feet, below which there is a sand bed. However, limestone certainly occurs to a depth of about 160 feet on James Martin's place, four or five miles southwest of Philema. When I visited this place a well was being bored and the boring had reached about 160 feet, and was at that time in limestone containing Orbitoides. This place is estimated to be 75-100 feet above Philema. A bed of sand had been penetrated, but the driller did not wish to give a detailed record. "In going down Flint River from Philema to Albany, a distance by river of 30 to 50 miles, outcrops of limestone were seen from place to place from a few miles below Philema entirely to Albany. The rock is yellowish or whitish, often indurated on exposed surfaces, and belongs to the Vicksburg formation. About a mile below the mouth of Mill Creek is an exposure of blue sandy. clay, aparently alluvial, but very different from the usual alluvium. "The structure is extremely simple, the beds frequently showing no perceptible dip, but occasionally showing a dip slightly greater than the fall of the river. No marked flexures were observed, but at one place there were slight undulations of the strata over a distance not exceeding 100 or 200 feet." "Fossils were collected in Lee County as follows: il16 GEOLOGY OF THE COASTAL PLAIN List of fossils from Lee County. Four miles west of Philema, Lee county, Ga. Orbitoides mantelli (Morton) Echinoid Scaphander sp. Pecten perplanus Morton Four and one-half miles south of east of Philema, out of a well 40 feet below surface. Pl)cten (Chlamy cf. indecisus Dall) Amusium ocalanum Dall Thirty feet below surface: Operculina complanata (Defrance) Operculina complanata var. granulosa Lymeriea Albany and vicinity.-Limestone and flint of the Vicksburg formation appear at a number of localities along Flint River in the vicinity of Albany. The country to the west of Albany is covered by a red, argillaceous sand, and limestone is rarely seen, though there is abundant evidence that it is the underlying formation. The best locality for studying the limestone is at the power plant on Kinchafoonee Creek two miles north of Albany. A large amount of rock has been excavated in constructing the dam at this place, and the bluffs of the creek also present a good section. Section on Kinchafoonee Creek two miles north of Albany. 4. Pleistocene sand, flint fragments at the base . Vicksburg formation. 3. Limestone . . . . . . . . . 2. Nodular and discontinuous flint layer; may thickness of . . . . . . . 1. Massive limestone . . . . . Feet . 10 . 5 reach a . 2 . 8 The limestone here i.s, on the whole, white or cream colored, soft, some parts friable, and massive bedded. It contains flint which seems to be both a replacement of limestone and also a jasper, which may be due to the segregation of silica and not to re.placement. The 'abundance of remains of marine life is notable, the rock in places being composed almost entirely of a friable mass of Bryozoa and shells. The following notes on the Vicksburg formation in the vicinity of Albany are furnished by Dr. Vaughan: "At the crossing of the Albany Northern Railroad over Muckafoonee Creek there is an exposure of whitish, soft, chalky limestone stained yellow in places, containing an abundance of poorly preserved fossils. "On the east side of Flint River opposite Albany, there is an outcrop of white limestone which is in places silicified. Orbitoides and Pecten poulsoni VIOKSBURG FORMATION 317 are abundant. This material seems to l::relong to the Ocala limestone division of the Vicksburg. Tlie limestone is overlain by red sands and clays which form the surface. ' "At the springs about 3 miles south of Albany an enormous volume of water comes to the surface through channels in the Vicksburg limestone. Specimens of Amusium ocalanum Dall, echinoid spines, and Bryozoa were collected at this locality. I did 'not see any Orbitoides. "At Rock Hill about one and onehalf miles west of Albany on the road to Dawson (not the main road) a spring issues from the limestone. The limestone is in places cherty with numerous Orbitoides and Pecten, apparently poulsoni. "About three miles west of Albany there is a rise of some 30 feet and a change in surface soil from grayish sands to red, sandy clay. "Thirteen miles west of Albany at Providence plantation yellow limestone and chert occur in brownish and reddish sands. Orbitoides and Pecten were collected. , "About a mile south of Providence plantation a specimen of a large Pecten was obtained. "The following are lists of fossils collected in the vicinity of Albany: Fossils from Albany and vicinity. Three miles west of Albany, Ga. Monoporella-a species common in the VicKsburgian Oligocene, and until now found in collections from no other horizon. Determined by R. S. Bassler. Just above bridge of Albany Northern Railway over Muckafoonee Creek, Operculina Cidaris Macropneutes? Amusiurri ocalanum Dall. Western end of railroad bridge at Albany, Ga. Orbitoides mantelli (Morton) Lyria costata (Sowerby) Orthaulax? sp. Pecten perplanus morton Crassatellites mississippiensis (Conrad) Venus sp. Albany, Ga., western end of wagon bridge. Orbitoides mantelli (Morton) Orbitoides papyracea Boubee Nummulties wilcoxi Heilprin. Muckafoonee Creek, Albany, Ga. Operculina complanata (Defrance). Prof. S. W. Mc0allie1 has published the record of a deep well at Albany which is here repeated: Log of City Artesia~n Well, No. 2. (Albany, Ga.) Bored by Mr. E. F. Joyce. Log by Mr. 0. W. Tift. Feet. Red clay . . . . . . . . . . from 0 to 20 Light-colored clay 20 " 23 Coarse sand (Vicksburg) . 23 " 25 Light-colored clay and coarse quartz sand . 25 " 35 Limestone, Orbitoides, at 150 feet, and from 190 to 200 feet . . . . . . . . . 35 " 200 1Geol. Surv. Ga., Bull. 15, 1908, pp. 98, 99. 318 GEOLOGY OF THE COASTAL PLAIN Gray limestone, Orbitoides, echinoids, Bryozoa, Tere- bratula; some shale from 230 to 240 ft. . . . . Gray sand with comminuted shells (Ostrea) . _ . Some shale, coarse sand, shells and sharks' teeth at Hard layer, Ostrea divaricata . . . . . Ostrea divaricata at . . . . . . . . . . Ostrea alabamiensis at . . . . . . . . Shale or marl, water vein at . . . . . Ostrea divaricata and alabamiensis at . Bed of lignite at . . . . . . . . . . . Bed of lignite at . . . . . . . . . . . Sand . . . . . . . . . . . . . . . . . Echinoid spines, lamna teeth, stiff blue clay . Stiff blue clay . . . . . . . . . . . . . . Hard gray sandstone . . . . . . . . . . . . Oligocene and Eocene from the surface to . . Pyrite and small oysters at . . . . . . . . . Green sands and greenish micaceous shales . Gray sand with black particles at . . . . . . Water-bearing horizon, limestone, with pieces of hard, gray sandstone between 785 and 790 . . Hard rock. . . . . ............ . Clay shales, with limestone between 835 and 840 . Limestone and shales . . . . . . . . . . . . . . . Chiefly sand, at top a little gravel. At 880 feet limestone or calcareous sand, also light gray micaceous sand; at. 890 feet, grayish sand, cal- careous fragments, hard, black pieces of pebbles and Ostrea, water-bearing micaceous sandstone between 920 and 930 feet . . . . . . . . . . . Blue micaceous clay at 950 feet, thick shelled oysters, Gryphaea, the same also at 1,080 feet; at 1,100 feet gray sand with Ostrea and Exogyra costata . . . . . . . . . . . . . . . . . . . . Stiff, blue clay, micaceous sandstone, oysters . . . Very stiff blue clay, at 1,255 feet, streaks of sand and shells, a small flow of water; from 1,240 to 1,260 soft, shiny, blue clay . . . . . . . . . . Marl, gray sand, sandstone lumps, shells . . . . . Gray and black sand, sandstone lumps . . . . . . Black irregular, waterworn pebble, with hard crys- talline fracture; coarse and fine quartz sand, shells, decayed wood, third water-bearing stratum; 50 gallons per minute. Well ends in quartz sand at . . . . . . . . . Feet 200 to 280 280 " 285 311 318 " 320 320 340 350 363 367 400 400 " 475 470 " 475 475 " 480 485 " 488 500 520 530 " 540 600 690 " 790 790 " 800 800 " 850 850 " 890 890 " 940 940 " 1,100 1,100 " 1,200 1,200 " 1,260 1,260 " 1,270 1,270 " 1,310 1,310 " 1,315 1,320 The base of the Vicksburg formation according to this section IS probably between 200 and 280 feet, and the base of the Eocene is probably above 940 feet, since according to fossils the strata between 940 and 1,100 feet are Cretaceous. Dr. Stephenson has made a recent examination of the fossils obtained from the borings of this '. VIOKSBURG FORMATION 319 well and reports the Cretaceous fossils Anomia argentaria) at 890 feet, and Exogyra costata (?) at 500 feet.* Nigger Head Bend) Mitchell County.-This locality is about onf' and one-hal miles south o Hardaway and on the east side o Flint River. The bluff at this place has a maximum height o 30 feet at low water. White limestone o the Vicksburg ormation appears at the base o the bluff. Section at Nigger Head Bend Feet. Pleistocene. 4. Stiff, bluish clay, which weathers yellowish or brown, variable in thickness . . . . . . . . . . . . . . . . 4 3. Yellow, gray, and brown stratified sand; has a layer of pebbles at the base . . . . . . . . . . . . . . . . . 8 (Unconformity) Oligocene. Chattahoochee formation. 2. Drab, bluish, and purplish stiff clay, having embedded in it fossiliferous flint fragments; the whole appears to be residual . . . . . . . . . . . . . . . . . . . . . 15 Vicksburg formation. 1. White or gray pitted limestone; appears both lithologic ally and paleotologically similar to limestone at Albany. . . . . . . . . . . . . . . . . . . . . . . . 2 From paleontologic evidence Dr. Vaughan has classed stratum No. 2 as Chattahoochee. Dewitt) Mitchell County.-Sot, gray or white marl appears near the boat landing about three-quarters o a mile northwest o Dewitt. This rock rises about three feet above low water. It contains Orbitoides and the characteristic Ocala limestone fossil, A musium ocalanum. Small fragments o bones were also noted. Flint boulders, probably resulting rom the silicification o the limestone, were ob- served. Newton) Balcer County.-Both limestone and flint appear in the bluffs o Flint River in the vicinity o Newton. The lithologic and paleontologic appearance o the rock is similar to that at Bainbridge. A thickness o three or our feet o limestone appears in the bed o *NOTE.-Dr. Stephenson has, in his study of the log of this well, placed the top of the Cretaceous at 500 feet. (See page 200.) This leaves a possible thickness of only about 220 feet for the combined Eocene. Based on observations over the belts of outcrop, the thickness of the Claiborne formations has been estimated at 250300 feet on Chattahoochee River and at or near the same thickness on Flint River; that of the Wilcox formation at 150 feet; that of the Midway formation froi)J. 218 feet on the Chattahoochee to 400 feet on the Flint. The thickness of the Jackson is small, but will probably increase considerably the total for the Eocene. If the top of the Cretaceous is at 500 feet in the Albany well section, then there is a surprising decrease in the thickness of the Eocene southward from the belts of outcrop.-0. V. 320 GEOLOGY OF THE COASTAL PLAIN Cooleewahee Creek; it is a brownish, soft, somewhat granular, and oolitic rock containing Vicksburg fossils which Dr. Vaughan identi:fies as: Fossils from Cooleewahee Creek. Operculina complanata Orbitoides mantelli Nummulites wilcoxi Amusium ocalanum Excellent exposures of flint were found at Bagg's Ferry, :five miles below Newton. The flint is fossiliferous and is evidently a silici:fication and replacement of limestone. All degrees of silici:fication were noted, from soft, white, siliceous limestone to vitreous, dense, translucent flint. The greater part of the rock is a soft, white porous flint. Huge blackened fragments appear in the channel of the river and form a picturesque scene. At Red Bluff, seven miles above Bainbridge, a limestone similar to the rocks exposed at Bainbridge appears in the bluff 25 feet above Low water. The fossils furnish evidence that the residual flint overlying the limestone at this place belongs to the Chattahoochee formation. (See pages 325, 329.) The limestone presents an uneven upper surface due to solution and- decay, and presents protrusions in the residual sandy clay. The following fossils were collected from the limestone and identi:fied by Dr. Vaughan:' Fossils from Red Bluff. Orbitoides papyracea (Boubee) Cassidulus sp. Orbitoides n. 'sp. (stellately marked Clypeaster sp. form) Pecten suwanneensis Dall Nummulites wilcoxi Heilprin Pecten indecisus Dall Echinolampas sp. Amusium ocalanum Dall" Further references to the Vicksburg formation along Flint River will be found in the chapter on the Chattahoochee formation. Bainbridge.-Limestone of. the Vicksburg formation is exposed in the bluff on the west side of the river at Bainbridge, between the wagon bridge and the Atlantic Coast Line Railroad bridge. The river bluff here is about 20 feet high. The section is as follows: 1The foraminifera in this list were Identified by Dr. IL M. Bagg. VICKSBURG FORMATION 321 Section at Bainbridge. Pleistocene ? 3. Brown sand and clay . . . . . . . (Unconformity) Oligocene. Vicksburg formation. 2. Gray or bluish residual clay . . . . 1. Soft limestone, maximum thickness Feet .. 8 . 2 . 10 The limestone rises 10 feet above low water. It is white or gray in color, massive, and shows no bedding. Near the water's edge it has a pitted, vesicular appearance. The rock is very soft, has a granular appearance, and is in places merely a loosely compacted mass of fora.minifera and pectens. Brown, limonitic clay occurs at the top of ~e limestone. This latter material also appears at Blue Springs and Red Bluff. Soft limestone is also exposed on the left bank of the river between the wagon bridge and the Georgia, Florida, & Alabama Railread bridge, and may be seen in the low bluffs of the river at a number of points below Bainbridge. At Blue Spring, four miles below, it is overlain by the coralline flint of the Chattahoochee formation. The following notes on the strata at Bainbridge were supplied by Dr. Vaughan: Section of bluff on ea.st side of Flint River, back of old factory, about two miles above Bainbridge. Pleistocene. Feet. In. 3. Reddish sands and reddish sandy clay mixed with some blue clay . . . . . . . . . 15 Oligocene. Chattahoochee formation. 2. This stratum presents diverse characters: a. Lower end of bluff along Vicksburg contact,the material consists of whitish clay, sometimes slightly sandy, and blotched with ver- million. In the clay are pockets of limonitic iron ore. The clay occurs in the iron ore, on its sides, and beneath it. In the iron carbonaceous particles were found. At the lower end of the bluff is 10 feet or more of this clay and limonite. b. Face of bluff proper,-impure lignite, and blackish lignitic clay, 5 feet. This is a pocket not extending to the lower end of the bluff and is replaced by purplish and bluish clays. Bluish clays, more sandy at top, overlie the lignite and lignitic clay . . . . . . . . . . . . . . . . . 17 6 322 GEOLOGY OF THE COASTAL PLAIN Vicksburg formation. 1. The lowest stratum seems to be that seen at the lower end of the bluff. It is a yellowish, argillaceous limestone, sometimes hard and sometimes soft and granular, composed of the remains of various calcareous organisms which show signs of trituration. Fossils are abundant but the species are few. Amusium ocalanum Dall and a very large Orbitoides, 0. papyracea Boubee, are the commonest. This stratum has evidently suffered great loss by solution, also the upper surface is extremely irregular. The thickness at one place, at the bottom of which is limestone, is fully 15 feet. In places the limestone appears as dike-like masses, the next stratum or its derivations being plastered against the sides. "The total height of this bluff is 37 or 38 feet. The lignitic stratum is. also seen upstream from the bluff in the river bank. In this stratum were found large pieces of lignitized wood. "The upper surface of the Vicksburg frequently rises much above the level of the base of the next higher formation, but where contacts could be found the Vicksburg passes below it. It seems that the Vicksburg has been sub-aerially eroded. Another possible explanation is that the irregular surface is due to the underground solution of the limestone. The latter hypothesis is discarded and the former accepted because of the sudden change in the lithologic character of the next higher stratum. "Westward from Bainbridge the limestone does not appear at the surface and the formation is represented by fragments of flint, which bear the characteristic fossils of the Vicksburg formation. Limestone, however, is encountered in wells at varying depths." Brinson, Decatur Courdy.-Large residual masses of flint occur in the pine woods on the west side of Spring Creek. The rock contains Orbitoides papyracea, Amusium ocalanurn, etc. BETWEEN FLINT AND OCMULGEE RIVERS Elko, Houston County.-There is a well-known occurrence of flint in the railroad cuts one mile south of Elko. The flmt appears as massive fragments of compact jasper, breaking with a sharp, splintery, conchoidal fracture, and also as friable, very fossiliferous masses in r-ed clay. The locality is of stratigraphic interest, and the flint and clay may be of economic value for road metal. At Taylors Ford, four miles south of Elko, on the Unadilla road, fossiliferous flint fragments embedded in red and yellow clay are ' prominently exposed. A collection of Vicksburg fossils was made near this locality by S. W. :McCallie.1 OCJIIULGEE RIVER Hawkinsville, Pulaski County.-The Vicksburg formation near Hawkinsville consists of soft, white, fossiliferous limestone, contain- 1Underground waters of Georgia: Geol. Survey of Georgia, Bull. No. 15, 1908, p. 352. VICKSBURG FORMATION 323 ing abundant fossils, together with :fragments of :fossiliferous flint embedded in residual clay. Exposures occur in the river banks near the city, at Harrells Landing, McDonnells Landing, Ways Landing, and Taylors Bluff, three miles above Hawkinsville. The formation has a similar lithologic and paleontologic aspect to that farther west. The section at Taylors Bluff is of much stratigraphic interest, since the relation of the Vicksburg :formation to the Jackson :formation are shown. (For section see page 305.) Fossils collected :from the lower 20 :feet are regarded by Dr. Vaughan at Jacksonian in age; at 22 feet :from the base of the bluff the characteristic Vicksburg :fossil, Amusium ocalanum, was collected. No unconformity or break in sedimentation was observed between the :formations. OCONEE RIVER. Dublin, Laurens County.-Gray, brown and white, both porous and vitreous, compact flint rock, appears as residual remnants at a number of localities along Oconee River. The :following :fossils were obtained :from the rocks thrown :from an excavation for a reservoir at the pumping station of the city water works: Fossils from Dublin. Cassidulus sp. Scutella sp. Glycymeris arctatus (Conrad) Pecten pouisoni Morton Pecten perplanus Morton There are no natural exposures of the limestone of the Vicksburg formation at Dublin, although it is encountered in wells. EXPOSURES ON AND NEAR SAVANNAH RIVER Girard and Flint Branch, Burke County.-Flint, bearing Vicksburg :fossils, "outcrops at Buxton's Mill, two and one-quarter miles south of Girard, and on the Millhaven public road at the ford at Mill Branch, two and one-half miles a little east of south of Girard. This shows that the Claiborne has dipped beneath the cover of the younger :formations at this point. There is residual red sand over the Vicksburg :formation resembling that of the Barnwell sand, rendering the precise location of boundaries difficult or even impossible. At Ellisons Bridge, three miles southwest of Girard, vitreous flint :forming a bluff 10 :feet high is exposed a short distance above the bridge on the west side of Briar Creek. No determinable fossils were :found and it is not possible to determine whether the rock belongs to the Claiborne group or to the Vicksburg :formation. 324 GEOLOGY OF THE COASTAL PLAIN Fragments of flint appear along Flint Branch, one and one-half miles north of Stony Bluff, Savannah River, which contain a few imperfect prints and casts of fossils. Doctor Vaughan identified Orbitoides from this locality. J ohnsons La.nding.-At J ohnsons Landing, Savannah River, S. C., flint rock appears near the level of the river, a short distance below the landing, and also as residual fragments in the escarpment of the second terrace. The rock is white, and porous, and is similar in appearance to much of the flint in the Vicksburg formation along Flint River. Pecten, Orbitoides, and corals were noted. This rock is included in Sloan's1 "King's Creek Phase" of the Oligocene. Hershman Lake, Screven County.-Large fragmental blocks of flint, as much as three feet in thickness, were discovered at the western end of Hershman Lake. The rock appears similar to that at J ohnsons Landing and is doubtless of Vicksburg age. No outcrops of the formation of Vicksburg were found in the river bluffs below this point. Millhaven, Screven County.-An exposure of flint rock, which may be the equivalent of the flint of Vicksburg age on Savannah River occurs on Briar Creek a short distance above the bridge at Millhaven, o1 Garnett. It is very poorly fossiliferous, however, and it is difficult to determine its stratigraphic position beyond question. A small echinoid, Orbitoides (?), and a few poorly preserved siliceous bivalve casts were the only fossils found. APALACHICOLA GROUP CHATTAHOOCHEE FORMATION NAME The name Chattahoochee is applied to a limestone formation intervening between tlie Vicksburg and Alum Bluff formations. ThP name was first applied by D. W. Langdon' to a group of beds lying between the Vicksburg or "Orbitoidal" limestone, on Chattahoochee River, and the upper beds at Alum Bluff, Apalachicola River, 25 miles belmv River ,Junction, Fla. The age of the beds was given as "newest Eocene" or "oldest l\Iiocene," since the Oligocene equivalence of the fauna was not at that time recognized. The Chattahoochee group as described by Langdon probably included beds which are now referred to the Alum Bluff formation, as the Pecten he mentions can scarcely be other than Pecten madisonius var. sayanus Dall, an Alum Bluff fossil. 1Catalogue of Mineral Localities of South Carolina: Geol. Survey of South Carolina, p. 464. 2Amer. Jour. Sci., 3d ser., vol. 38, 1889, p. 324. CHATTAHOOCHEE FORMATION 325 Notes on the formation in Georgia have been published by Pumpelly,' Foerste,' Spencer; Vaughan; Harper; and McCallie." It is evident that in much of the previous literature, beds which are described in this report under Alum Bluff formation, have been induded under the name Chattahoochee "beds," "series," or "group" .as used by various writers. The name Chattahoochee, as now used, is restricted to the lower portion of the Chattahoochee group of Langdon. DEFINITION Stratigraphic Relations.-Pumpelly' and Vaughan' have recognized an erosion unconformity between the Chattahoochee and the underlying limestone of the Vicksburg formation in Decatur County. At Blue Springs on Flint River, four miles south of Bainbridge, both formations are present, but the co,ntact between the two is much obscured by the weathering of both the Vicksburg and the Chattahoochee. At Red Bluff, seven miles north of Bainbridge, an exposure similar to that at Blue Springs occurs. The Chattahoochee formation appears as fragments of flint in residual, sandy clay, and the weathered limestone of the Vicksburg formation appears at the base of the bluff. There is evidence at this locality, and also at the bluff back of the Old Factory ab<;mt two miles above Bainbridge (see p. 321), of an erosion unconformity. However, at Forest Falls, eight miles northwest of Whigham, no unconformities were observed in a section the base of which, according to paleontologic evidence, is referable to the Vicksburg formation, and successively higher portions of which, on the same kind of ,evidence, belong to the Chattahoochee and Alum Bluff formations. There was probably continuous deposition from the beginning of Chattahoochee deposition to the end of Alum Bluff deposition. No evidenc~ of" any time interval between the deposition of the two has been observed in the field. Prof. J\fcCallie,' howiever, has noted an unconformity at the old Toy phosphate pit, three and one-half miles west of Boston, but whether this is an erosion unconformity or one due to the solution. and irregular weathering of the limestone 'Amer. Jour. Sci., 3d ser., vol. 46, pp. 445-447. 2Amer. Jour. Sci., 3d ser., vol. 48, 1894, pp. 41-54. 8!Wport of Progress : Geol. Survey of Georgia, 1890-1891, op. 57-59. Science, n. s., vol. 12, 1900. pp. 873-875. 'Annals New York Acad. Sci., vol. 11. pt. 1, 1906, p. 17. Underground waters of Georgia: L.eol. Survey of Georgia Bull. No. 15, 1908, p. 32. 70p. clt., pp. 445-447. 'Op cit., pp. 873-875. "'Geol. Survey of Georgia Bull. No. 5-A, 1896, p. 62. 326 GEOLOGY OF THE COASTAL PLAIN has not been determined. When this locality was visited the relations of the clay to the limestone were obscure because the pits had become largely filled by debris. Lithologic Cha'!'acters.-The Chattahoochee formation is in general calcareous and varies from compact, pure, crystalline limestones to earthy and argillaceous limestones, and calcareous sands ai:td sandstones. Comp~ct gray, drab, or white, fossiliferous limestones make up the bulk of the formation. A brecciated or conglomerate structure is characteristic of some of the beds. This phenomenon was observed at nearly all localities where there were good exposures. These conglomerate beds do not seem to be confined to a particular horizon, and their origin and significance are not well understood. Both the matrix and the angular or rounded fragments are limestone. Some beds appear to be pseudo-conglomerates, and consist of fossil echinoids in a limestone matrix, the structure of the echinoids having been partially obliterated, giving the appearance of waterworn fragments. The rock is phosphatic in a number of places, containing brown or black rounded pebbles of phosphate or fragments of bones and teeth. The limestone at the base of the formation has in a number of localities been replaced by silica; while in other instances the base of the formation is represented by fragmental beds of flint, containing corals and other fossils, in a matrix of residual clay. The flint closely resembles that of the underlying Vicksburg formation and can not always be easily distinguished from it. Thickness.-In the gorge northwest of Faceville, Decatur County, the Chattahoochee formation has a probable total thickness of 100 feet. At Forest Falls, or Limesink, in the northern part of Grady County, it has an exposed thickness of 60 or 65 feet. No very reliable data are at hand for estimating its total thickness to the eastward and northeastward, under the cover of later formations. It is not great, however, and the maximum probably does not exceed 200 or 250 feet. Examination of borings from wells at Valdosta, Waycross, and Savannah indicate such a thickness, but the probability of a part of the limestone penetrated in these wells belonging to the underlying formation must be considered. Paleontologic Characters.-Although there is no abrupt faunal break betwem the Chattahoochee and the Vicksburg formations, and there are a number of forms common to both, their faunal differences are marked. The base of the Chattahoochee contains a rich coral fauna which, in the vicinity of Bainbridge, has been studied by OHA.TTAHOOOHEE FORMATION 327 Doctor Vaughan.' In a coral reef our miles south o Bainbridge he estimated that there were between 25 and 30 species o corals, and correlated the beds with the Oligocene o Antigua. The characteristic Vicksburg species Amusium ocalanum does not appear in the formation; the genus Orbitoides is common to both the Vicksburg and Chattahoochee formations, but the Chattahoochee species are usually different from those of the Vicksburg. Orbitolites compla'Rata, a foraminifera, occurs in the Chattahoochee formation, but has not been found in the Vicksburg. Orthaulax pugnax, a gastropod common in the Tampa formation of Florida> has been found in two localities. Areal Distribution.-The area over which the Chattahoochee formation appears at the surface is small, as the terrane is largely concealed by the Alum Bluff and later formations. Good exposures occur along Flint River in Decatur County; and strata belonging to the formation were noted by Langdon on Chattahoochee River, nine miles above River Junction, Fla. The formation appears at Forest Falls and other lime-sinks in the northern part o Grady County; in the vicinity of Metcalf and Thomasville, Thomas County, and in the beds and bluffs of Withlacoochee and Allapaha rivers near the Georgia-Florida line. It may be represented on Ocmulgee River near Abbeville and Hawkinsville by fragmentary beds and residual flint containing corals. Limestone, outcropping near Jacksonboro, Screven County, correlated by Dr. Vaughan with the Chattahoochee formation, has a small distribution along Briar Creek in Screven County. Limestone outcropping in a small area northwest o Millen, Jenkins County, is provisionally considered as a part ITY. CHATTAHOOCHEE FORMATION 337 The lower 10 feet of the limestone is hard, brittle, brecciated, and vesicular, presenting a rough, jagged surface. The breccia consists of angular fragments of hard, dense, homogeneous limestone ir a matrix of dull gray, porous limestone. There is a distinct difference between the color and texture of the angular fragments and the matrix, but both are comparatively pure calcium-carbonate. The breccia fragments are cream-colored or white, exceedingly fine-grained, homo-genous, and break with a sharp, angular, conchoidal fracture; they have much the same texture as lithographic limestone. The probable explanation of the breccia is that as the rock consisted of alternate bands of dense, fine-grained limestone and more porous, earthy limestone, the sinking of the rock consequent from underground solution caused fracturing and resulted in the brecciated condition. There is no evidence that the fragments have been transported. Incipient silication of the fine-grained limestone has taken place and specimens representing moss agate in the process of formation were obtained . . The upper 15 feet of the exposure is dull-white, chalky limestone, less indurated than the lower rock. Foraminifera and other fossils are abundant. The slope of the hill above the limestone is strewn with fragments of phosphatic sandstone, probably weathered from the sandy clays of the Alum Bluff formation. The highest hills in this vicinity are 80 to 90 feet above the level of the pond. The fossils observed were: numerous small Orbitoides) small gastropods, Area,) Glycymeris) Pecten) a small oyster, and corals. A large silicified coral, Siderastrea, not in place, was found. Dr. Vaughan identified from this locality: Orbicella cavernosa (Linn), and Orthaulax pugnax Heilprin. Limestone similar to that at Original Pond occurs on the Mcintyre plantation, five miles west of Metcalf, and lllj2 miles south of Thomasville on the Thomasville-Tallahassee road. An exposure of 15 feet may be seen. This is hard, fine-grained, and brittle at the base, becoming soft and chalky at the top of the exposure. The soil above the limestone is red, sandy clay, strewn with fragments of siliceous concretions and fragments of phosphatic sandstones. Lying above the limestone there are about 4-0 feet of strata that belong to Alum Bluff formation. Greenish clay and brown sand, probably representing the base of the Alum Bluff formation were observed directly above the limestone in a gully along the public road. Specimens of Ostrea mauricensis occur in this clay. Another exposure of'the limestone of the Chattahoochee formation occurs at the old Copeland plantation, nine miles west of Metcalf, near the State line. Two or three feet of the rock is exposed at the 338 GEOLOGY OF THE COASTAL PLAIN site of an old limekiln. It appears in every way similar to the limestone at Mcintyre plantation and at Original Pond. The limestone occurs at the base of a hill, while on the slope above it there are fragments of flint and phosphatic sandstone. Boston.-Limestone was observed at the abandoned phosphate pits three miles west of Boston, and at the Mitchell plantation six miles west of Boston. The character of the fossils, the lithologic appearance, geographic location, and stratigraphic relations, indicate that it probably belongs to the Chattahoochee formation. At the old Toy phosphate pit three miles west of Boston, there are, at the base of the hill, poor exposures of limestone overlain by 30 or 40 feet of clay and sands, and some thin, interbedded, sandstone layers. The base of the hill is strewn with fragments of white flint, of hard, white to cream-colored, limestone, and phosphatic nodules. The limestone has been largely silicified. A small Orbitoides (Chattahoochee species), a Pecten, and other fossils suggesting the Chattahoochee formation were observed. An oyster, which is probably Ostrea maruricensis, occurs in the overlying greenish, sandy clays. The overlying material is regarded as the equivalent of the Alum Bluff formation. The limestone at this locality was studied in 1890 by Spencer' and was referred to "Middle Miocene.' The locality was subsequently visited by McCallie and upon the basis of "numerous orbitolites" the rock was considered as probably the equivalent of the "White Limestone" of the upper Eocene (Vicksburg). Limestone is exposed in a sink one-half mile north of the ,public . road on the Mitchell plantation, six miles west of Boston. Onl] five or six feet of the limestone is exposed; it is a grayish or brownish compact limestone and in places has a conglomeratic appearance. ]twas formerly used in the manufacture of lime. Some of the partially burned limestone, when rubbed or struck with the hammer, gives off a pungent odor similar to that of hydrogen sulphide. On the whol'e the rock is similar to that exposed on the Mcintyre plantation south of Thomasville. The fossils observed were Orbitoides, a Pecten, and poor specimens of gastropods and pelecypods. The overlying strata are not exposed. There is a second sink about onP-quarter of a mile south of thP .road but no natural exposures of limestone occur. There are a few large boulders of quartzitic, slightly phosphatic clay breccia or conglomerate. These probably belong to the Alum Bluff formatior which directly ovPrlies the limestone. --'First Report of Progress: Geol. Survey of Georgia. 1890-1891, p. 82. 2Bull. GeoL Survey of Georgia No. 5-A, 1896, p. 60. CHATTAHOOCHEE FORMATION 339 OTHER LOCALITIES. Withlacoochee River.-What is probably the northern-most exposure of the Chattahoochee formation on this river appears a~ Stony Lake, five and one-half miles southeast of Quitman. Limestone is exposed for about one-half mile along the west bank of the river and rises four or five feet above low water. Section of the Bluff at Stony Lake. Pleistocene. 3. Gray and brown incoherent sand . . . . . . Oligocene. Alum Bluff formation. 2. Drab and white, semi-indurated fullers earth Chatt::thoochee formation. 1. Limestone and marl . . . . . . . . . . . . Feet . 20 . 14 . 4 The limestone is white or gray,-in places yellowish, argillaceous, very hard, non-cry5talline, and in places bears numerous fossils. The bed of the river is strewn with fossiliferous chalcedony fragments that represent a silicification of the limestone. At one point along the bluff soft, marly clay and sand, one or two feet thick, containing Pecten, an echinoid, Orbitoides, and pieces of bones were observed. This soft layer seems to mark a transition from the limer,tone to the fullers earth. No evidence of an unconformity between the Alum Bluff and Chattahooohee formations was observed. Impure, very sandy, and argillaceous limestones are found along Withlacoochee River above Stony Lake, but are regarded as phases of the Alum Bluff rather than of the Chattahoochee formation. Near Olympia, a short distance north of the Georgia-Florida State line, limestones typical of the Chattahoochee formation, appear in th: bluffs and channels of the river. Sections on Withlacoochee River at New Bridge three miles below the Valdosta-Southern Railway bridge. Feet Pleistocene. 4. Yellow, sandy clay . . . . . . . . . . . . . . . . . . . 5 Oligocene. Chattahoochee formation. 3. Layer of silicified coral, some specimens as much as a foot in diameter . . . . . . . . . . . . . . . . . . . . . . . 1 2. Soft, white, or cream colored limestone . . . . . . . . . 7 1. White, compact, pure limestone containing Orbitoides and other fossils . . . . . . . . . . . . . . . . . . . . . . 8 The limestone is prominent on both sides of the river and may be: seen at considerable depths beneath water-level. From this locality 340 GEOLOGY OF THE COASTAL PLAIN Urbitoides complanata, Cyphastrea, Orbicella cavernosa, and Siderastrea, have been identified by Dr. Vaughan. Near Olympia, a foot or two of white, compact limestone, apparently residual, may be seen at low water, overlain by a bluish sandy clay containing chalcedonic corals. Allapaha River.-Limestone of the Chattahoochee formation was not observed above Statenville. A short distance below Statenville the limestone rises to 10 or 12 feet above the river. The Chattahou chee formation below Statenville consists of sandy and argillaceous compact limestone and some phosphatic conglomerate or phosphat':\ pebbles in a calcareous matrix. It is overlain by unconsolidated, phosphatic sand and greenish, sandy clay. The formation is poorly fossiliferous, an echinoid being the only identifiable fossil except fragments of bones and sharks teeth. Rock House, Crisp Oounty.-This locality is five miles southeast of Cordele, and probably is an isolated occurrence of limestone of the Chattahoochee formation. The locality was called to our !l.ttention through a reference to it by Dr. R. M. Harper.' The appearance of the limestone here is due to a sink as it is elsewhere concealed by the Alum Bluff and Altamaha formations. The section follows: Section five miles southeast of Cordele. Feet Pliocene? Altamaha (Lafayette ?) formation. 5. A thickness of 30 or 40 feet, not well exposed; red sandy, and mottled clay containing a few quartz pebbles, ap- pears in places . . . . . . . . . . . . . . . . . . . . . . . 40 Oligocene. Alum Bluff formation ? 4. Massive, weathered, greenish and drab clay . . 11 3. White, sandy clay,partly silicified and indurated 6 2. Grayish, very sandy clay . . . . . . . . . . . 10 Chattahoochee formation. 1. Massive, argillaceous limestone; contains Orbitoides com planata, the common Chattahoochee .species, Pecten, and small gastropods. The clay and the limestone are not sharply separated . . . . . . . . . . . . . . . . . . . 12 Ocmulgee River.-It is not improbable that the Chattahoochee formation is represented near Hawkinsville and Abbeville. In 8 bluff, one-half mile below Hawkinsville, Dr. Vaughan has iden tified Alveopora and Amauropsis, and suggests that the Chattahoochee formation is present. A coral was found in flint at Poor Robin Spring near Abbeville. 'Phytogeographical sketch of the Altamaha grit region of Georgia: Annals New York Acad. Sci., Nov. 1906, p. 17. CHATTAHOOCHEE FORMATION 341 1vlillen, Jenkins County.-There is a small area underlain by limestone north of :Millen. X atural exposures of the rock are rare, but its pre,-,ence near the surface is indicated by the flat topography and occasional limesinks. At :Magnoli~ Spring, six miles north of Millen, a soft, yellow, marly limestone is exposed. An exposure, three feet thick, also oc curs at a mill one mile south of the spring. The only fossils are bryozoans and a small, ribbed Pecten which has not been specificially identified. On the Alexander Murphy place, nine miles northwest of :Millen, limestone has been thrown from a well. The rock is white, finegrained, sandy and rather hard. It contains a small Pecten and other poorly preserved fossils. 'The age of the rocks exposed at the three preceding localities is in doubt. There are only a few exposures and the materials are poorly fossiliferous. Lithologically, the materials are unlike those of either the Claiborne group or Vicksburg formation, although from their geographic positions they might be referred to either of these. They are overlain by clays resembling those of the Altamaha and Alum Bluff formations. The rocks bear some lithologic resemblance to the limestones of the Chattahoochee formation, to which they are tentatively referred. Jacksonboro, Screven Oounty.-An exposure of limestone occurs on Briar Creek near the site of old Jacksonboro, about eight miles I!ortheast of Sylvania, Screven County. This is one of th~ classic geologic localities of Georgia, yet only one natnral exposure of the limestone bas been found, and its distribution as a surface :fonnation is insignificant. Sir Charles Lyell, who visited the locality in 1842, re~arded the ,-,trata as of Eocene age. Dr. W. B. Clark1 studied the fauna and expi'essed the opinion that it was probably N eocene in age. Dr. W. H. Dan: also discussed the age of the formation and expressed an opinion in favor of an early :Miocene age. Dr. T. Wayland Vaughan in 1902 made a careful study of Lyell's locality, collected a number of fossils, and prepared a list of them which clearly showed their Oligocene age. Dr. Dall incorporated Dr. Vaughan's results in his "Tertiary fauna o:f Florida,'' stating: "The locality was again visited by Doctor Vaughan in 1902 and more material obtained, leaving no reasonable doubt that the Jacksonboro horizon is practically that of the Tampa limestone or Orbitolites bed of Florida." The following are the fossils identified by Dr. Vaughan from the Jacksonboro locality: tBull. Bull. U. U. sS.. Geol. Geol. Survey Survey No. No. 83, 84, p. p. 55. 88. Trans. Wagner Free Inst. Sci., vol. 8, pt. 6, 1908, p. 1573. 342 GEOLOGY OF THE COASTAL PLAIN Fossils from Jacksonboro, Screven County. Orbitoides, small fiattish species. Cerithium n. sp. (Also Wakulla, Fla., Actaeonina ? n. sp. Tampa horizon.) Bulla petrosa Conrad. Also Tampa. Modulus turbinatus Heilprin. Also Bulla 3 other species. Tampa. Pleurotoma servata Conrad. The va- Acmaea n. sp. riety found at Chipola. Turritella tampae Dall var. (Also Pleurotoma ? sp. Tampa.) Drillia sp. Strombus albirupianaG Dall. Olivella ? sp. Calyptraea aperta (Sol.) Marginella sp. Large species, 4 Xenophora humilis Conrad. columella folds. Ampullina streptostoma Heilprin. Mitra probably new. Types from Tampa. Pyrazisinus cornutus Hpn ? Also Amauropsis ocalana Dall. Also from Tampa. Ocala limestone and Chipola. Pyrazisinus 2 other species, probably Fissuridea sp. new. Dentalium miosissippiense Conrad. Cerithium georgianum Lyell and Pecten sp. Apparently new. Sowerby. Mytilus n. sp. Cerithium playtynema Dail. (Also Chamalyelli. Dall. Tampa.) ALUM BLUFF FORMATION NAME The name Alum Bluff is applied to all the s"trata lying between the top of the Chattahoochee formation and the base of the Miocene. These strata are the equivalent of the Alum Bluff formation of Florida, as recently defined, and as the formation is physically con- tinuous from Florida into Georgia the use of the term is naturally extended to Georgia. ' The formation was' first studied on Apalachicola River at Alun Bluff, 25 miles below River Junction, Fla. The section at Alum Bluff was described in 1889 by D. W. Langdon' and the beds re- ferred to the Miocene without differentiation. The name, Alum Bluff, used for a geologic division or formation, was first employed by Dr. W. H. Dan: The succession at Alum Bluff as given by Dall' is as follows : Section at Alum Bluff. 6. Yellow, unfossiliferous sand . . . . . . 5. Lignitic sand . . . . . . . . . . . . . . 4. Ecphora bed . . . . . . . . . . . . . . . 3. Alum Bluff beds . . . . . . 2. Marl (Chipola) . . . . . . . . . . . . . . 1. Chattahoochee limestone ( ?) . . . .. Feet . 70 . 10 . 30 . 15 . 5 The Alum Bluff formation, as described recently. by Matson and 1Amer. Jour. Sci.. 3d ser., val. 38, p. 324. 2Bull. U. S. G~ol. Survey No. 84, 1892, p. 122. 80p cit., p. 113. ALUM BLUFF FORMATION 343 Clapp1 includes more strata than was originally included by Dall, as the Chipola marl is considered a member of the Alum Bluff formation. As now used in Florida, the term embraces 'all the beds lying between the Chattahoochee formation and the Miocene. The divisions of the upper Oligocene, Parachucla and Combahee, made by Sloan2 on Savannah River, are the stratigraphic representa tives of the Alum Bluff formation, and their use is not continued in the present report. DEFINITION Stratigraphic relations.-The Alum Bluff formation conformably overlies the Chattahoochee formation; the exact contact between the two is in places drawn arbitrarily, since there is neither an abrupt lithological nor faunal change from one to the other. There may b~ apparent unconformities due to solution and weathering of the Chattahoochee limestone near the contact. On Savannah and Altamaha rivers the Oligocene is separated from the overlying Miocene by an erosion unconformity, perhaps of minor importance. Throughout the greater part of the area underlain by the Alum Bluff formation n the Miocene is absent, and the Alum Bluff is overlain unconform- ably by the Altamaha (Lafayette formation, with which it may, in places, be confused on account of a similarity in appearance when weathered. Lithologic characters.-The Alum Bluff formation presents a number of different lithologic phases; these include coarse, angular sand,. co;1rse-grained, aluminous sandstone or grit, sandy clay, fullers earth, phosphatic sand, quartzites, sandstones, silicified clays, and local limestones or calcareous layers and nodules. Greenish or gray, argillaceous sands, and sandy, laminated clays, form the greater portion c1f the formation. Beds of fullers earth occur in the formation both in Georgia ancl in Florida. The fullers earth is generally a gray or drab, faintly laminated, clay-like earth of low specific gravity. The earth is usually semi-hard and brittle, and in many places silicification has gonl' on to such an extent that the earth is very hard and rock-like, and no longer has the properties of fullers earth. Segregations of silica in the form of small, round, or flattened nodules is characteristic. Th:' fullers earth beds do not attain any considerable thickness and R'? not persistent over large areas but appear to be local phases in sands and sandy clays. Greenish and drab, sticky, plastic clays, and argillaceous sands, are associated with the fullers earth beds. 1 Second Ann. P~pt. Geol. surv~y of Florida, 190!l. p. 91. 2Catalogue of Mineral' Localities of South Carolina: Geol. survey of South' Carolina, ser. 4, Bull. No. 2, 1908, p. 273. 344 GEOLOGY OF THE COASTAL PLAIN On Allapaha and Suwanee Rivers are phosphatic ~ands which are believed tD lie directly aoove the Chattahoochee formation. Sands of the Alum Bluff formation on Savannah River are also slightly phosphatic. These sands are generally unconsolidated, o,_. only slightly indurated, are sometimes coarse-grained, even containing small pebbles, and often display crossbedding. They con,ri,: largely of quartz ; the phm;phate is in the form of small, brown o!' black, slick, water-worn pieces of oones and teeth, varying in ,;i:r.c from a pin-head to one"half or three-fourths of an inch in diameter. A small amount of clay is generally present and the sands, in a number of places, are calcareous and contain calcareous, phosphatic nodules. The chemical analysis' of a sample of sand from the Suwanee River, nine miles below Fargo, showed 16.80 per cent. of phosphoric acid (P 0). The clay and fullers earth phases of the formation have in places been silicified to such an extent that they have been converted .into very hard claystones, and the argillaceous sands have become dense, virtreous, and brittle quartzites; clay breccias and conglomerates have likewise been silicified. In fact greater or less degrees of alteration of the rocks by silica carried in solution by circulating waters has been extensive. Opal and agate occur in places as a result of this silicification. Samples of the silicified clays from Withlacoochee River, seven miles east of Quitman, were examined in the laboratory. They vary from bluish to light greenish and dove color, are hard, brittl2, and break with a conchoidal fracture; the rock is dense and compact, and cracks are filled with opaline silica. Some of these rocks are slightly phosphatic. There are phases wh-ich might be termed opalized clay conglomerates or breccias; originally, this conglomeratic rock consisted of fragments of clay, either pebbles of clay or angula;_ fragments, in a matrix of very sandy, lighter-colored clay or argillaceous sand, the matrix often containing oyster shells. By the infiltration of opaline silica, the rock has become dense, rompact, and in places vitreous or glassy to such an extent that the sand grain,; are no longer recognizable. The clay is about 3 in the scale of hardness and it requires a strong blow with the hammer to break it. The lime of the oyster shells has been replaced by silica, and they ,ate opalized and agatized. In Grady, Brooks and Thomas counties thin beds of white sandstone, usually soft, were noted. These sandstones are associated with sandy clays and are often phosphatic, the phosphate forming, ir1 part, the cementing agent. 1By Dr. Edgar Everhart, Chemist Geological Survey of Georgia. ALUM BLUFF FORMATION 345 Thickness.-The maximum thickness of the Alum Bluff formation in southwe~tern Georgia is estimated to be 150 feet. At no known locality can the full thicknesll of the formation be seen in a natural exposure; the estimate here given is based upon the record of a deep well at Valdosta. Samples from the depths of 150 and 176 feet in this well bore a close resemblance to the indurated fullers earth of the Alum Bluff formation, and limestone, probably of the Chattahoochee formation, was encountered at 186 feet. No natural exposures revealing a thickness of strata more t~an 40 or 50 feet were seen. Judging from the record of the Waycross well, it is probable that the Alum Bluff formation at this point is as much as 250 feet thick.' At Lumber City, in Telfair County, there is some probability that the Alum Bluff formation is as much as 200 or 300 feet thick. The natural exposures on Savannah Rived do not exceed 25 or 30 feet. Paleontologic characters.-The formation is, on the whole, poorly fossiliferous. The clays and sands generally contain only poorly preserved casts and impres.sions. Doctor Vaughan obtained a nuaber of species, listed on a subsequent page, in the vicinity of Bainbridge, and a well preserved oyster, Ostrea mauricensis, is found at a number of localities. The formation seems to mark the disappearance of the species of Orbitoides which are so common in the Vicksburg and Chattahoochee formation. On Savannah River the rme fossil,Carolia fioridana, and Pecten sayanus have been found in this formation. Area,Z Distribution.-The Alum Bluff formation underlies a large area in Georgia, extending from Decatur County northeastward to Savannah River; the northern limit of sedimentation during the Alum Bluff period is approximately marked by Cordele, Abbeville, Dublin, Millen, and Sylvania. No evidence of its occurrence north of these points has been found. Southward or southeastward from these points it is highly probable that the whole of the Coastal Plain is underlain by this formation. Througout most of this area, however, it has been covered by later sediments, and natural exposures are largely confined to bluffs of rivers. It is the surface formation, and it influences the soil and topography over a large part of Decatur, Grady, Thomas, Brooks, Lownde-5 aJJ.d Echols counties. Exposures appear in the bluffs of Ocmulgge and Altamaha rivers from near Abbeville to Doctortown. Alum Bluff strata may occur along Ogeechee River, but this has not been proven by paleontologic evidence. On Savannah River, the Alum 'Well record Underground waters of Georgia: Bull Geol. Survey of Georgia, No. 15, 1~08. p. 172. 346 GEOLOGY OF THE COASTAL PLAIN Bluff formation is believed to extend from near Hudson's Landing to Porter's Landing in Screven County. Physiographic expression.-The area over which the Alum Bluff formation is the surface formation, is small, although a distinctive topography has been produced by its erosion and weathering in the southern part of the State. In the southeastern part of Decatur and the southern parts of Grady, Thomas, Brooks and Lowndes counties, the Alum Bluff formation, together with the Chattahoochee formation, has produced a topography more broken and hilly than that of the Altamaha region to the north. This topography is due, in part, to thr> argillaceous and sandy character of the Alum Bluff formation. The formation is easily eroded and the numerous lime sinks of the region have given an impetus to this erosion. Structure.-The Alum Bluff formation has a very low southwarci. and southeastward dip, certainly much less than the older Eocene and Vicksburg formations. On Savannah River, the dip dues no~ exceed four or five feet per mile, and near the Florida line the beds must lie almost horizontally, since the streams have cut through them exposing the underlying formations. No evidence of broad :flexures, or even minor folding and faulting was observed in the natural ex- posures of the strata. However, the probability of a broad arch ex- isting in the southern part of the State has been mentioned in con- nection with the discussion of the drainage, and general structure of the Coastal Plain strata. (See pages 63-65.) Economic geology.-The Alum Bluff formation contains beds of fullers earth which, locally, are sufficiently free from sand and siliceous concretions to be of commercial value. Fullers earth mining has been carried on at Attapulgus, Decatur County, for several year;;;, and a good quality of earth for clarifying mineral oils is produced. The Attapulgus earth is very similar to that at Quincy, Fla. Brief descriptions of the deposit at Attapulgus have been published by Vaughan' and Veatch'. The prospects are favorable for finding commercial deposits in Decatur, Grady, Thomas and Brooks counties. Sands containing a considerable percentage of phosphoric acirl (P 0) were observed along the lower courses of Suwanee and Allapaha rivers, and these may prove to be of some value in the future as low grade phosphates. The clays, while on the whole poorly adapted for burned cla,Yproducts, may be of some local value for common building brick. 'Vaughan. T. W., Bull. U. S. Geol. Surv. No. 213 1903. pp. 392-399. veatch, Otto, Clay deposits of Georgia, Geol. Survey of Georgia, Bull. 18, 1909, pp, ALUM BLUFF FORMATION 347 LOCAL DETAILS Baidbridge, Deca;tur County.-The following are notes by Dr. Vaughan on localities southeast of Bainbridge, at Roseland planta- tion, "Gastropod Gully" on the Bowers land, and on the Dickson farm, in Decatur County. Lists of fossils from the first two localities are furnished. "Gastropod Gully" was named by Dr. A. F. Foerste' who made a study of the beds and referred them to the Chipola of Florida. "Campbell Htll, Roseland plantation.-The hill is composed of reddish and yellowish, residual sands. At the northeast corner of the hill, immediately west of a small ravine, a pile of yellowish, reddish, or whitish, siliceous sandstone, rich in fossils, was found. The fossils collected here belong to the same horizon as thore in Judge Bowers' and Sam Dickson's fields. Some 20 or more species of mollusks were collected and listed as follows: List of fossils from Campbell Hill Roseland Plantation. Pleurotoma servata Conrad ? Pleurotoma Fulgur spiniger Conrad Melongena Latirus? Nassa Astyris ? Astyris ? Bittium Serpulorbis ? Crucibulum auricula Gmelin Natica alticallosa Dall. Omphalius exoletus Conrad. Fissuridea sp. Area staminata Dall ? Area sp. Spisula sp. Strigilla sp. Venus sp. Carditamera sp. Gastropod Gully, Bowers' Land. This gully is on Judge Bowers' land, east of Roseland plantation. It is 12 to 15 feet deep with almost perpendicular walls. The E>ides are composed of yellowish sands and of bluish clayey sands blotched with yellow. Bits of siliceous material are common and residual pieces of usually yellowish apparently silicified sandstones are abundant. Near the head of the gully it is shallower, and the residual sandstone is strewn promiscuously over the surface. Most of the fossils were found here. The gully is only about two hundred yards long. Gastropod Gully is therefore, according to aneroid barometer readings, 85 feet above the level of Bainbridge at Hotel Wainman. List of fossils from southeastern corner of Bowers' field, Foerste's Gastropod Gully locality. Conus (probably planiceps Heilprin) Pleurotoma Marginella Turbinella ? Fulgur spiniger Conrad Mazzalina ? Melongena Murex Nassa (Chippola species) Latirus? Bittium Turritella indenta vat. mixta Dall. Turritella alcida Dall. Turritella 2 other species Solarium granulatum var. chipo- lanum Dall. Crepidula Crucibulum auricula Gml Natica alticallosa Dall. Fissuridea (2 undetermined gastropods). Area staminata Dall. Area santa rosana Dall. Pecten chipolanus Dall. Spondylus '! Carolia (probably floridana Dall). Mactra ( Spisula) sp. Mactra ? Strigilla (related to flexuosa Say). Tellina (Angulus). 'Amer. Jour. Sci., vol. 16, October 1893, pp. 245-254. 348 GEOLOGY OF THE COASTAL PLAIN "Sam Dickson's farm, six miles southeast of Bainbridge. . In a field across a small branch, on the south side of the road, are numerous boulders containing fossils. The material was originally a limestone but has been altered to a chert; it is yellowish in color, or occassionahy reddish, and is similar to that found in the Bowers pasture. These boulders are residual masses left in yellowish or whitish sands. The fossils are poor casts or siliceous replacements and are the same as those found in the Bowers pasture. A small collection was made. The horizon is in the Alum Bluff formation." Climax, Decatur County.-In the vicinity of Climax, are anumber of exposures of gray, fine-grained, clayey sands, and greenish, plastir-, Eandy clays which are probably referable to the Alum Bluff formation. A section of much stratigraphic interest is revealed in the cuts of the Atlantic Coast Line Railroad and an adjacent gully threequarters of a mile west of Climax. The lower part of this section, from the level of the branch to the level of the track, consists of gray or greenish, laminated, sandy clays, and greenish or bluish clayey sands, considered referable to the Alum Bluff formation. They contain no fossils, and their stratigraphic position is inferred from their lithologic character, geographic position, and relation to the overlying formation. The section of this. exposure given bPluw has been furnished by DL Vaughan, and it will be further discussed in connection with the description of the Altahama (Lafayette ?) formation. E:x:posure Jn north side of railroad, one mile west of Climax, from about twenty feet below to thirty feet above the level of the railroad. Pliocene ? Feet In. Altamaha formation. 15. Soil and humus . . . . . . . . . . . . . . . . . . . 5 14. Yellow sand, some small gravel . . . . . . . . . . 5 13. Mottled sands and clay . . . . . . . . . . . . . . 5 12. Sands and some clay, showing stratification dis- tinctly, whitish, yellowish, reddish, upper 20 feet crossbeded and ferruginous sandstane . . . 25 Oligocene. Alum Bluff formation. 11. Clays blotched reddish ( a:bcut two feet below level of railroad) . . . . . . . . . . . . . . . . ...... . i) 10. Stratified sands and clay, blotched red . . . . . . . 6 9. Stiff clay, blotched red . . . . . . . . . . . . . . 2 8. Whitish sands with seams of clay . . . . . . . 3 7. Stiff blue clay, blotched red . . . . . . . . . . . . . 1 6. Finely laminated sand and clay . . . . . . . . . . . . . 2 5. Bluish clay resembling fullers earth, specimen col- lected, about . . . . . . . . . . . . . . . . . . . . . 1 4. Whitish sands . . . . . . . . . . . . . . . . . . . . . . . . . 3 6 3. Clay similar to No. 1, some of which resembles ful lers earth . . . . . . . . . . . . . . . . .... . 2 6 2. Whitish sand, a little clay . . . . . . .. . 6 9 1. Fine, sandy, bluish clay . . . . . . . . . . . . . . . 1 6 ALUM BLUFF FORMATION 349 "The lower portion of the section to No. 10, inclusive, was measured; the remainder was estimated and then checked by aneroid." At Mashburn Hill, four miles north of Climax, approximately 60 feet of clay5 and sands are exposed which are here referred to the Alum Bluff formation. The bed consists of greenish, plastic, nnd vm) sandy clays, showing little stratifi!'~tion, in planes thin interbedded layers of pure whitP sand. They are fine-grained, are free from pebbles, and contain white, irregularly-shaped, ant flattened nodules of silica. They are overlain by yellow, ll;rgillacPous sand, (('lltaining black iron oxide concrctiJns, eviaently a n product of weathering. The underlying clays and sands have been previously described by Yeatch' as the ),Jtamaha (Lafayette formation, but the detailed study of the Alum Bluff formation subsf'quently undertaken has lead to the belief that they are referable to the Alum Bluff formation. This conclusion is reached on the basis of lithologic character. Attap1tlgus, Decahtr County.-Attapulgus is located 13 miles south of Bainbridge, Decatur County. There are a number o exposures of sandy clays and fullers earth, which belong to the Aluw Bluff formation, The fullers earth is of commercial value and is being mined. It has been described by Dr. Vaughan; and the chemical and physical properties of both the clay and fullers eartb have been described by Yeatch: The pit of the Lester Clay Company, when visited in .October, 1908, showed: 8edion at pit of Lester Clay Company. Age ? Feet 4. Red; sandy clay covering slope . . . . . . . . . ? Alum Bluff formation. 3. Stiff, tenacious, structureless clay apparently residual. 6 to 10 2. Fullers earth . . . . . . . . . . . . . . . . . . . . . . . . . . 6 to 10 1. Hard, greenish or drab, argillaceous sandstone . . . 7 ' The fullers earth presents very little structure; it is faintly lami- nated, the lines of stratification appearing only when the earth is dry. It is jointed and scales of manganese oxide often appear along the cracks. When moist, the earth is dull olive green in co~or, and slick or unctuous to the touch; when dry, it is white and brittle. It is distinguished from the greenish clays of the Alum Bluff for mation by its low specific gravity, and high porosity; when dry it adheres strongly to the tongue. 'GeoL Surv. of Ga., BulL 18, p. 316. 'r. S. Geol, Surv., BulL No. 213, p. 392. 3Grol. Surv. of Ga., BulL No. lR. pp. 317-318. 350 GEOLOGY OF THE COASTAL PLAIN 'The section revealed in the public road leading east from the station Is: Section in public road east of Attapulgus station. Age? 4. Red sand, in places argillaceous, capping the ridge . Alum Bluff formation. 3. Plastic, greenish clay . . . . . . . . . . . . . . . . 2. Gray, very sandy clay . . . . . . . . . . . . . . . 1. Bluish and greenish, stiff plastic clay . . . . . . . . Feet . 15 . 4 . 15 . 15 The red sand layer, No. 4, probably bolongs to the Altamaha (Lafayette?) formation. In the railroad cut, one mile south of Attapulgus station, there is four feet of white or gray, very sandy claystone or sandstone, which contains poorly preserved fossils; this is overlain by a thin bed of shaly, brittle fullers earth and plastic clay, and probably represents the sandy bed observed in the bottom of the fullers earth pit. Whigham and Cairo, Gradry Oounty.-'The topography in the vicinity of these towns is broken and there are a number of exposures where the character of the Alum Blu:ff and its relations to the overlying Altamaha (Lafayette?) formation may be seen. The Alum Blu:ff formation consists mainly of greenish or gray, sandy, massive clays, thin beds of fullers earth, and gray and white phosphatic sandstones. In a cut one mile east of Whigham, a bed of light greenish clay, somewhat in the nature of fullers earth, is overlain by orange-colored sands, and clays and sands alternately stratified: The clay bed shows some slight crumpling. It probably represents the Alum Blu:ff formation, while the overlying sands belong to the Altamaha (Lafayette?) formation. The conformable relations of the Alum Blu:ff formation to the Chattahoochee limestone are revealed at Forest Falls, or Limesink, eight miles northwest of Whigham. The formation is mainly a sandy, compact clay and contains characteristic Alum Blu:ff fossils. This section has been described in detail on page 334. In the cuts of the Atlantic Coast Line Railroad west of Cairo, the greenish, sandy clays of the Alum Blu:ff formation rise as high as 12 to 15 feet above the track and are unconformably overlain by the mottled sands and sandy clays of the Altamaha (Lafayette?) formation. On Tired Creek, three and a half miles west of Cairo, a cut reveals fossiliferous sandstone of the Alum Blu:ff formation. ALUM BLUFF FORMATION 351 Section on Tired Creek. Feet Alum Bluff formation. 4. -Stiff, bluish or greenish clay, weathering brown . . . . 3 3. Very thinly laminated fullers earth . . . . . . . . . . 1 2. Soft, argillaceous, white sandstone, fossiliferous; contains Ostrea, Carditamera tegra, Chione, Venus. . . . . . . . 1 1. Pale-green, non-laminated clayey sand . . . . . . . . . 5 A white sandstone, locally altered to quartzite, occurs on the Ragan plantation on Buck Creek, 10 miles south of Cairo. The sandstone is overlain by a "gummy," greenish clay with laminae of fullers earth. This sandstone is quarried for local building purposes. Ocklockonee River.-The Alum Bluff formation is exposed along Ocklockonee River from the southern part of Colquitt County through Thomas and Grady counties to the Florida line. It consists of greenish or gray, compact sands, greenish clays, and gray, argillaceous sandstones. Poorly preserved fossils were found at some localities. It is often difficult to distinguish the formation, especially where weathered, from the overlying Altamaha (Lafayette?) formation. The contact between the two is revealed, howeV'er, east of Pine Park, in the cuts of the Atlantic Coast Line Railroad near the river, at mileposts 203 and 205. Near the FloridaGeorgia line the river has cut through the clays, exposing limestones which probably belong to the Chattahoochee formation. Thomasville and Boston, Thomas County.-In the hilly region south of Thomasville, and in the vicinity of Boston, the Alum Bluff formation is the main surface formation and, together with the Chattahoochee limestone, has determined the character of the topography, and to a considerable extent the character of the soil. It consists largely of gray and greenish clays, and compact, argillaceous sands, which upon weathering, produce red and brown sands and sandy clays. Layers of white, phosphatic sandstone occur which appear at the surface as brownish, both angular and rounded fragments strewn through the soil. Oyster shells are the common fossils, but associated with them are corals which were probably weathered from the underlying Chattahoochee formation. The weathered Alum Bluff materials might be easily confused with the Altamaha (Lafayette ?) formation. At the few places where the Altamaha (Lafayette?) could be recognized it consisted of crossbedded, varicolored quartz sand and mottled, sandy clays. The Alum Bluff formation is distinguished by its greenish clays, usually containing foPPils, and by its phosphatic sandstones. 352 GEOLOGY 0~' THE COASTAL PLAIN The best exposures revealing the character of the Alum Bluff formation in this part of the State are at the old Toy phosphate pit, three and one-half miles west of Boston; a hill on the Mallet plantation on the Boston-Monticello road, four and one-half miles southwest of Boston; and at the Mcintyre plantation, 11lj2 miles south of Thomasville. Sandy clays of the Alum Bluff formation overlie the Chattahoochee formation at these localities. Greenish quartzite and quartzitic conglomerate, similar to that on vVithlacoochee River, seven miles east of Quitman, appear on the Mitchell plantation, six and one-half miles east of Thomasville. This rock contains a small percentage of phosphoric acid. The underlying Chattahoochee formation also outcrops at this place. Withlacoochee River.-The Alum Bluff presents a variety of phases along the course of Withlacoochee River and its relations to the Chattahoochee formation may be seen. At Old Troupville, four and one-half miles northwest of Valdosta, about 15 feet of Alum Bluff strata is exposed in a bluff of Little River near its junction with the Withlacoochee; the rock here might be described as an argillaceous sandstone. There is a thin layer which contains poorly preserved fossils; Turritella, Area, and agatized oysters were noted. In places, the rock has a brecciated or conglomeratic appearance, and is slightly calcareous and phosphatic. At the Atlantic Coast Line Railroad bridge, seven miles east of Quitman, the channel of the stream is cut into a hard, greenish or bluish claystone. This rock is a semi-indurated or very hard rock, which was probably originally in the nature of fullers earth, but is now hardened by the infiltration of opaline silica which has form( the cementing substance of the rock. It contains knots or nodules more siliceous than the matrix, in some of which finely crystalline pyrite was observed. The rock does not show any distinct lamination or bedding. The left bank of the river, one-half mile below the railroad bridge, exposes the following section: Sect.ion left bank of river, one-half mile below Atlantic Coast Line Railroad bridge. Pleistocene. Feet. 4. Slope of incoherent, gray sand . . . . . . . . . . . . . 15 Oligocene. Alum Bluff formation. 3. Compact, clay breccia and quartzite . . . . . . 8 2. Fullers earth-like clay containng siliceous and calcare- ous nodules . . . . . . . . . . 15 Chattahoochee formation. 1. Limestone, covered by water . . . . . . . . . . ? GEOLOGY OJ.' 'l'RE COASTAL PLAIN OF GEORGIA. PLATE XXV. A. EXPOSURE OF PARTIALLY INDURATED. PHOSPHATIC, CALCAREOUS ::>AND OF THE ALUM BLUFF FORMATION. ALLAPAHA RIVER, STATENVILLE. ECHOLS COUNTY. BLUFF AND ALTAMAHA FORMATIO::\'S. ALDM BLDFF FORMATION 353 Beds 2 and 3 are referred to the Alum Bluff formation. No. 3 is in places a vitreous and brittle, amorphous silica, having imbedded in it pebbles and fragments of greenish clay; where unaltered it is a conglomerate of sand and green clay or fullers earth. The fullers earth is greenish and unctuous when moist, and drab and brittle when dry; it contains nodules of silica, often agate, and calcareous, earthy layers and nodules. No unconformity between layers Nos. 3 and 4 was noticed, although the conglomerate character of layer No. 4; suggests that the underlying clays were eroded during its deposition. The only fossils observed were oysters, which were imbedded in the silicified conglomerates. The relation of the clays to the limestone of the Chattahoochee formation was observed in the bluff on the west side of the river two and one-hal miles below the railroad bridge, near Stony T_,ake. Section near Stony Lde. Feet Pleistocene. 3. Gray and brown sand covering the upper slope of the bluff . . . . . . . . . . . . . . . . . . . . . . . 20 Oligocene. Alum Bluff formation ? 2. Greenish and drab, semi-indurated fullers earth . . 14 Chattahoochee formation. 1. Limestone . . . . . . . . . . . . . . . . . 4 The fullers earth is brittle and crumbles when dry. It contains siliceous nodules. At one point a bed was observed which was thought to be a transition layer between the fullers earth and the limestone. It consisted of one or two feet of soft clay and sandy marl, containing numerous fragments of shells, Pecten, echinoids, Orbitoides and pieces of bones. No evidence of an unconformity between the limestone and the fullers earth was observed. At Knight's Ferry, 11 miles southeast of Quitman, the Alum Bluff formation is a semi-indurated clay or fullers eartl>, partly silicified. The bed of the river at low water is strewn with fragments of chalcedony, agate, and white, rounded nodules or concretions of silica. About one mile above the wagon bridge there is a picturesque fa]] in the river caused by a bed of semi-indurated, sandy fullers earth protruding six or eight feet above the water and forming large boulders in the channel. Allapaha River.-The nothernmost exposure of the Alum Bluff formation observed on Allapaha River is near Willacoochee, Coffee County, where two feet of stratified, fine, sandy clay appears in the left bank of the rivPr, overlain unconformably by later sediments. 354 GEOLOGY OF THE COASTAL PLAIN The following section appears in the east bank of the river at the bridge two miles east of Milltown: Section two miles east of Milltown. Feet In . Pleistocene (terrace deposit) 3. Brown or chocolate-colored, compact sand . . . . . 5 2. Pebbly sand, greenish quartzite, and white phosphate pebbles . . . . . . . . . . . . . . . . . . . . . . . . . 1 6 (Unconformity) Oligocene. Alum Bluff formation. 1. Greenish, sandy clay, containing siliceous and cal careous. nodules . . . . . . . . . . . . . . . 8 Laminated, greenish or drab clays were thrown from a well near the old brick yard west of Stockton, and natural exposures of gray or greenish, sandy clays occur at Hotchkiss Mill, three and one-half miles northwest, and in the banks of the river at Milltown. On the lower courses of Allapaha and Suwanee rivers in Georgia, the greenish, sandy clays, fullers earth, and quartzites seem to be represented by phosphatic sands. The sands are unconsolidated or only slightly compacted, in places are calcareous, and are made up principally of coarse, quartz sand and black and brown, water-worn particles of bones and teeth which vary from a pin-head to threefourths of an inch in diameter. They contain only poorly preserved fossils, not sufficient to .determine their age, but they directly overlie limestone which has the characteristics of the Chattahoochee formation. The only fossils which have been secured from these sands are a Scutella, from Statenville, and a Pecten related to P. madisonius from Suwanee River, 14 miles south of Fargo, together with poor prints of an oyster, and unidentifiable casts. In the river bank and in a ravine a few rods below the wagon bridge at Statenville, Echols county, 14 feet of phosphatic sand is exposed. It is a coarse, gray, calcareous sand, full of brown and black, phosphatic particles. The sand becomes decidedly coarse, almost pebbly. Thin limestone layers occur in it, and it is strikingly crossbedded, the lines of stratification dipping 20 to 30 degrees from the horizontal. The phosphatic particles vary from the size of a pin-head to one-fourth or one-half inch in diameter. Phosphatic and conglomeratic limestone of the Chattahoochee formation appears along the river below Statenville, in places rising as high as 10 or 12 feet above low water. Exposures of phosphatic sands and greenish, laminated, sandy clays, similar to the material on the Allapaha, have been noted by Mr. S. W. McCallie' on the Allapacoochee near the State line. 1Geol. Surv. of Ga., Bull. No. 5-A. p. 82. ALUM BLUFF FORMATION 355 Suwanee River.-Suwanee River has its source m Okefenokee Swamp and flows through a low, flat, sandy plain. The river has formed no high bluffs, and exposures of strata other than surficial gray or white sands of Pleistocene age are rare and may be seen only at very low water. Beneath the railroad bridge at Fargo is a greenish, sandy, finegrained clay which appears about one foot above low water. It is overlain by brown, incoherent, quartz sand, a Pleistocene terrace deposit. The greenish clay probably belongs to the Alum Bluff formation, although it contains no fossils, and its age is inferred from its lithologic appearance. At Bony Bluff, nine miles southwest of Fargo, three feet of gray, compact, calcareous sand probably belonging to the Alum Bluff formation appears at very low \YUter. This sand is full of black, phosphatic pellets from the size of a flax-seed to one-onrth inch in diameter, and also contains large fragments of blackened bones, sharks' teeth and poorly preserved prints of shells. The phosphatic sand is overlain by eight t,) ten feet of brown and white sand of Pleistocene age. Large fraguents of silicified wood not in place occur, but they probably came from the base of the Pleistocene sand. Similar phosphatic sand was found at "The Rocks" or "Rocky Ford," five miles below Bony Bluff, and one-half mile above the Georgia-Florida State line. The bluff of the river at this point is 12 feet high at low water. The rock is in the bed of the river, but when the water is very low about one foot of it is exposed. It is a buff-colored sand, compacted by calcium carbonate; it is slightly more indurated than that at Bony Bluff and contains nodules of stone harder than the matrix, which appear to be due to segregations of calcium carbonate. Bones and prints of shells are abundant; two species of Pectens, an oyster, and a number of obscure casts occur. Dr. Vaughan has identified Pecten madisonius from this locality, and states that, although the formation here is provisionally classed as Oligocene, it may be Miocene. The phosphatic sands on Suwanee River and on Allapaha River are similar in apiJearance, and probably occupy the same geological position, namely, directly above the Chattahoochee formation, and there may be a continuous sheet of these sands between the two rivers. The greater part of Echols, Clinch, and Charlton counties is a very level, sandy plain, and only Allapaha, Suwanee, and St. Marys rivers have cut through the Pleistocene surficial sand. The smaller streams have low, sandy banks, or flow through swamps, and since they have not cut through the sands, exposures of the older formations do not appear. 356 GEOLOGY OF THE COASTAL PLAIN St. Marys River.-The occurrence of the Alum Bluff on St. Marys River is doubtful. If exposed at all, it is only along the upper 25 or 30 miles of its course after its issuance from Okefenokee Swamp. St. Marys River flows through a flat plain underlain by Pleistocene sand, and is generally bordered by low sand banks. The following section was observed at Smith Bluff, six miles north of MacClenny, Florida: Section at Smith Bluff St. Marys River. Feet In. Pleistocene. 6. White sand . . . . . . . . . . . . . . . . . . . . . . 2 6 Age? 5. Weathered clay and sand, red mottling . . . . . . . 2 6 4. Clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Brownish, quartz sand . . . . . . . . . . . . . . . . . . 1 2. Bluish, or drab clay . . . . . . . . . . . . . . . . . . . . 4 Oligocene ? Alum Bluff formation ( ?) 1. Bluish-gray sand, containing a small amount of dis- seminated clay, sufficient to make the sand com- pact, and mii).ute phosphatic particles . . . . . . . 15 No fossils were observed either in the upper or lower part of the bluff. Lithologically the lowest stratum is not wholly unlike some of the Alum Bluff clayey sands observed at localities in Georgia. Beds 2, 3, 4, and 5 perhaps belong to the Altamaha (Lafayette ?) formation. Inasmuch as younger fossiliferous beds are found at Stokes Ferry, 11 miles south of St. George, it is not probable that the Oligocene extends further than the eastern angle of the river, in southern Charlton County. Ocmulgee River.-Certain strata appearing in the bluffs from near Abbeville on Ocmulgee, to Doctortown on Altamaha River, are referred to the Alum Bluff formation. The age of these beds has been largely determined by their petrologic character and their stratigraphic relations to other formations. Conclusive paleontologic evidence of their age is wanting: They are underlain by lower Oligocene limestone and are overlain by beds of Pleistocene, Pliocene ( ?) , and Miocene age. The presence of the Chattahoochee formation underlying these Alum Bluff beds has not been demonstrated, although there is a suggestion that the Chattahoochee formation exists near Hawkinsville and Abbeville where silicified corals have been found. . A number of sections of bluffs will be given to indicate the lithologic character and the relations of the Alum Bluff formation to other formations. A.LUM BLUFF FORMATION 357 The following succession of beds appears at House Creek bluff, two miles east of Bowens Mill, Wilcox County: Section at House Creek Bluff, Ocmulgee River. Feet In. Pleistocene (terrace deposit) Okefenokee formation. 8. Thin covering of gray sand . . . . 7. Mottled, red and yellow sand or loam . 30 Oligocene Alum Bluff formation. 6. Greenish, fine textured clay containing sand pockets and siliceous nodules . . . . . . . . . . . . . . . . . . 10 5. White, calcareous sandstone . . . . . . . . . . . . . 5 4. Bed of oyster shells in a calcareous, sandy matrix . 2 6 3. Greenish, clayey sand with calcareous concretions . 3 2. Greenish, laminated, sandy clay . . . . . . . . . . . 4 1. Gray, compact sand . . . . . . . . . . . . . . . . . . . . 5 The oyster-bearing beds of this locality are mentioned by Dall' as "presenting such a petrologic character as the Hawthorne beds of Florida." The Hawthorne beds are now regarded as approximately the age equivalent of the Chattahoochee.' Certainly the lithologic aspect of the beds at House Creek is more like that of the Alum Bluff formation of southwestern Georgia than of the Chattahoochee formation of the same region. Section of Bluff at Lumber City, Telfair County. Feet Pleistocene (terrace deposit) 4. Thin covering of gray sand, level of second terrace 3. Coarse, gray and red, pebbly sand; coarse pebble layer at base . . . . . . . . . . . . . . . . . . . . . 15 (Unconformity.) Oligocene. Alum Bluff formation. 2. Interstratified layers of greenish clay, and yellow and white, unconsolidated sand . . . . . . . . . . . . 10 1. Greenish and drab, sandy clay . . . . . . . . . . . . 15 No fossils were found here except in limestone fragments at the base of the Pleistocene. In the bluff at Quinns "Fractions," four miles below Lumber City, similar sandy clays, together with a bed of vitreous quartzite, are exposed. 1U. S. Geol. Survey, Bull. No. 84, p. 81. 'Matson and Clapp, Fla. Geol. Surv. 2d Ann. Rept. 1909, p. 70. 358 GEOLOGY OF THE COASTAL PLAIN Section at Quinns "Fractions/' Ocmulgee River. Feet Age ? 5. Upper slope of bluff, strata concealed . . . . . . . 20 to 30 Alum Bluff formation. 4. Bed of quartzite, expbsed . . . . . . . . . . . . 1 3. Gray, compact sand containing clay laminae; contains poorly preserved prints of fossils . . . . . . 12 2. Gray sand slightly indurated . . . . . . . . . . . . . . . . 3 1. Greenish laminated clay with sand partings . . . . . . . 5 At Oaky Bluff, two miles above the junction of Ocmulgee and Oconee rivers, thin slabs of greenish, brittle quartzite similar to that at Quinns "Fractions" appear. This is a low Pleistocene bluff and the quartzite extends only two feet above low water. Similar rock occurs on the Altamaha and probably lies in the channel of the river at Town Bluff, and also appears in the right bank of the river just above N ayles Ferry. Oconee River.-Good exposmr of beds, questionably referred to the Alum Bluff formation, occur at several bluffs on Oconee Hiver. The materials are not typical of the Alum Bluff deposits, but differ from them only in being coarser and more irregularly-bedded; some of the coarser phases resemble the materials of the Altamaha (Lafayette?) formation. Exposures have been examined at Berry Hill Bluff, J oyces Bluff, Stallings Bluff, and other bluffs between Dublin and the mouth of the river. Berry Hill is 55 miles above the mouth of the river and 10 miles' west of Soperton. Section at Berry Hill Bluff. Age ? 3. Loose gray sand and gravel on upper slope Alum Bluff formation. 2. Gray, alluminous sandstone, forms a precipice . . . . 1. Sandstone and claystone, softer than the above . . Feet 50 15 The sandstone is an indurated, coarse, feldspathic, quartz sand with disseminated greenish clay, the whole slightly cemented by silica. The rock varies from a claystone to a coarse sandstone almost a conglomerate. No fossils \\'ere found. J oyces Bluff, t uo miles above Seaboard "1ir Line brid.r;e. Alum Bluff formation. 9. Mottled grit . . . . . . . . . . . . . . . . . . . . . . 8. Gray, fine-grained, aluminous sandstone . . . . 7. Drab claystone, containing coarse quartz grains 6. Gray sandstone 5. Hard clay . . . . . . . . . . . . . . . . . . . Feet. 10 5 3 4 1 ALUM BLUFF FORMATION 359 4. Fine-grained sandstone . . . . . . . . . . . . . 3. Greenish, massive, sandy clay . . . . . . .. 2. Gray sandstone . . . . . . . . . . . . . . . . . . . . 1. Drab, sandy clay . . . . . . . . . . . . . . .... Feet In. 2 5 6 1 6 6 Section of lower end of Joyce's Bluff. Feet Age ? 9. Upper slope, concealed . . . . . . . . . . . . . . . . . . . 20 Alum Bluff formation. 8. Fine-grained, gray sandstone . . . . . . . . . . . . . . . . 3 7. Coarse, feldspathic, conglomerate, crossbedded; pebbles an inch in diameter . . . . . . . . . . . . . . . 7 6. Fine-grained sandstone . . . . . . . . . . . . . . . . . . 1 5. Massive, drab clay . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Fine-grained, sandy clay, indurated and jointed . . . 4 3. Yellowish sand . . . . . . . . . . . . . . . . . . . . . . . 1 2. Feldspathic sandstone or grit . . . . . . . . . . . . . . . . . 1 1. Greenish and gray, friable sandstone . . . . . . . . . 8 Stallings Bluff, two miles west of Mount Vernon, is 45 feet high and is made up of rock similar to that at Berry Hill and J oyces Bluff. No fossils were found. Altamaha River.-One of the best exposures of the Alum Bluff on Altamaha River is in the bluff at Grays Landing, 10 miles below the forks. Section at Grays Landing. Feet Age ? 9. Incoherent gray sand, containing coarse gravel . . . 2 Pliocene. Al\amaha (Lafayette ?) formation. 8. Mottled coarse sand and clay . . . . . 8 7. Gray feldspathic sandstone or grit . . 20 Unconformity ( ?) Oligocene. Alum Bluff formation. 6. Gray or greenish sand, compacted by disseminated clay . 6 5. Greenish or gray sand, containing less clay than the overlying bed . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Greenish or drab clay . . . . . . . . . . . . . . . . . . . . 2 3. Massive sand containing clay layers an inch or two thick 6 2. White, jointed, and laminated fullers earth . . . . . . . 6 1. Compact sand and claystone . . . . . . . . . . . . . . 1 The fullers earth is very similar in appearance to the fullers earth of southwestern Georgia. The Alum Bluff formation is represented at Upper Sister and Lower Sister bluffs, 48 and 49 miles, respectively, below the forks. The Alum Bluff strata exposed in the bluffs reach a thickness of 360 GEOLOGY OF THE COASTAL PLAIN 30 or 40 feet and consist of gray or greenish,. aluminous sands and laminated, gray or greenish, sandy clays. The upper parts of the bluffs consist of coarse, feldspathic grit, the age of which is in some doubt. No fossils were found. These localities will be further discussed nnder the chapter on the Altamaha (Lafayette?) formation. At Fort James, 58 miles below the forks, the lower part of the bluff, consists of fine-grained, almninous, compact sand, gray or greenish in color, and is probably Oligocene. This material is overlain by coarse-grained, more feldspathic beds. The Alum Bluff formation at Oglethorpe Bluff, eight and onehalf miles above Doctortown, is exposed to a thickness of 15 feet and is unconformably overlain by unconsolidated sand and clay of the . Altamaha (Lafayette?) formation. lt consists of greenish clays, and gray or greenish, compact, aluminous sands. The Alum Bluff formation, consisting of coarse, bluish or greenish, aluminous, compact sands, occurs at Linden, Bugs, and Doctortown bluffs, where it is unconformably overlain by Miocene strata. Sections at Bugs Bluff and at Doctortown will be described under the chapter on the Miocene. The last high bluffs on the river are the Upper and Lower Sansavilla bluffs, 27 and 282 miles, respectively, below Doctortown. There is a small thickness of coarse, crossbedded sand which may represent the Oligocene. The_ section at the lower bluff is: Section at Lower Sansarilla Bl1tjf. Feet Pleistocene. 3. Fine, brown and white sand . . . . . . . . . . . . . . . . 15 2. Sand containing thin layers of white or drab, laminated clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Oligocene ? Alum Bluff formation (?) 1. Coarse, crossbedded, bluish, aluminous sand 8 Ogeechee River.-The Alum Bluff formation occurs at t\\o localities on Ogeechee River. A ;;haly, fullers earth-like clay and a greenish or gray siliceous n,laystone are exposed on the west side of the river, about one mile west of Rocky Ford. This rock rises about '20 feet above the water. No fossils were observed. At Indian Head, three miles west of Egypt, Effingham County, two and one-half feet of sandstone, containing pockets of greenish, silicified clay, occurs in a slough on the property of Carl Higgins. The rock at these localities are referred to the Alum Bluff formation pmely upon the bm:is of lithologic character and geo- graphic position. ALUM BLUFF FORMATION 361 Savannah River.-The northernmost exposure of the Alum Bluff formation on Savannah River was noted at Hudsons Landing, Screven County, 68lf2 miles above Savannah. The following section is exposed at the base of the bluff near the boat landing: Section at base C:f bluff near Hudsons Landing. Alum Bluff formation. Feet In. 3. Pale green, thin, calcareous clay containing indis- stinct impressions of leaves . . . . . . . . . . 0 1 to 2 2. Hard, sandy claystone, poor prints of fossils . . 0 3 1. To water's edge, dark green, coarse sand, argil- laceous and compact; poor prints of fossils . . . 1 About 300 yards above the landing a bed of compact sand and finegrained clay co:qtaining prints of fossils appears in the bluff 25 feet above the river; it is probably referable to the Alum Bluff formation. The presence of beds of upper Oligocene age at this locality has not been proven by fossils. The beds here lie above the Chattahoochee and Vicksburg formations, which appear at the surface to the northward and the succession of beds is similar to that at Porters Landing where beds of upper Oligocene age have been recognized by fossils; the stratigraphic position of the lower beds at Hudsons Landing is, therefore, inferred to be that of the Alum Bluff formation. The following is a section of a bluff one-half mile below Hudsons Landing: Section of bluff one-half mile below Hudsons Landing. Feet Pleistocene ( ?) 7. Gray, surficial sand . . . . . . . . . . . . . . . . . . . . . . 2 Pliocene ? Altamaha (Lafayette ?) formation. 6. Coarse sand containing a small amount of clay, mot- tled red and gray; thin line of quartz pebbles at base. 30 (Unconformity) Miocene. 5. Brown, fine-grained sand . . . . . . . . . . . . . . . 7 Miocene (?) (Unconformity) 4. Yellow and gray, unconsolidated sand; thin line of flat and discoidal quartz pebbles at base . . . . . . . . 20 (Unconformity) Oligocene. Alum Bluff formation. . 3. Light greenish, sandy clay, faintly laminated 6 2. Greenish-gray or ash-colored, compact sand . . . . . . . 11 1. Red and brown, compact sand . . . . . . . . . . . . . . 4 As no well preserved fossils were found the correlations indicated ~in the preceding section are tentative. 362 GEOLOGY OF THE COASTAL PLAIN In a bluff one mile below Hudsons Landing, Alum Bluff strata rise 30 feet above the river. They consist of greenish, compact, argillaceous sands which are massive and not laminated. No fossils were observed in these sands. The formation is separated from the overlying strata by a thin bed o.f nodular, fossiliferous, Miocene limestone containing M ytil:us conradinus d'Orbigny. The Alum Bluff formation appears in the lower part of a bluff at Porters Landing, 62 miles above Savannah. Sloan' was first to recognize the stratigraphic importance of this section and has made a careful study o.f it. The Porters Landing exposures are described in dEtail on pages 371-373 of this report. MIOCENE In earlier geological literature on the Atlantic and Gulf Coastal Plain the term Miocene included beds which are now placed in the Oligocene. For example, the Chattahoochee and Alum Bluff formations were formerly described as :Miocene. Under the Miocene were included all the beds between the Vicksburgian and the Pliocene or Pleistocene. The necessity of a division, however, was recognized, and Dr. W. H. Dall distinguished the "old or subtropical Miocene" and the "new or Chesapeake Miocene." The "old Miocene" is now referred to the Oligocene division of the Tertiary, a discrimination due largely to the studies of Doctor Dall.' The Miocene here described refers only to that portion formerly designated "new or Chesapeake," which includes the strata lying between the Alum Bluff formation, and the Pliocene or Pleistocene. A summary of correlations of Tertiary horizons, according to the new classification, has been given by Doctor Dall. The name Chesapeake was used by Dall as a general term to include all of the Miocene of the Atlantic and Gulf Coastal Plain. Dr. Vaughan' has recently made a paleontologic study of the Miocene at Porters Landing, Savannah River, Effingham County, and has correlated the late Miocene here [="Edisto" phase of Sloan, of his section] with the Duplin marl of North Carolina, and considers the older Miocenf? here [= Marks Head of Sloan] the approximate equivalent of the Calvert formation of Maryland. 'Bull. South Carolina Geol. Survey No. 2. ser. 4. p. 273. 'Eighteenth Ann. Rept.. , U. S. Geol. Survey, 1896-1897, pp. 327-34R. Proc. U. S. National Museum, vol. 19. No. llHl, 1896, pp. 303, 304. 'Science, n. s., vol. 31, No. 804, May 27, 1910. pp. 833, 8:l4. According to Doctor Vaughan the "Edisto" of Sloan in the Porters Landing section ls not his "Edisto" of the vicinity of Charleston, but is a much later horizon. MIOCENE 363 MARKS HEAD MARL NAME The }liocene at Porters Landing was differentiated by Sloan' into two phases, which he designated the "Edisto" and Marks Head phases, respectively, correlating the former with the phosphatized Miocene marl on Edisto River, S. C., and applying a new name to the latter. Later, Dr. Yaughan' has shown that the luwer of Sloan's phases, the Marks Head, is approximately synchronous with the Calvert formation of Maryland, and that the upper or "Edisto phase" is contemporaneous with the Duplin marl of North Carolina. The latter is stratigraphically higher than the Edisto marl of South Carolina. The name Marks Head is derived from :Marks Head, a small ravine one mile northwest of Porters Landing, Savannah River, Screven County, Ga. The Marks Head marl, although corresponding approximately to the Calvert formation, is separated from it geographically by a wide interval, and the different name Marks Head is therefore appropriate. DEFINITION Stratigraphic Relations.-The Marks Head marl rests upon the Alum Bluff formation of the Oligocene. The exposures on Savannah River fumish evidence of an erosion unconformity, separating the former from the latter. However, both the physical and faunal evidence seems to show that the time interval represented by this unconformity was relatively short. The formation is overlain unconformably by the Duplin marl. Since the Marks Head marl is of Ejarly Miocene age and the Duplin marl of late Miocene age, the unconformity separating therri is an important one. Lithologic Characters and Thickness.-The beds of this formation consist of gray or brownish, compact, argillaceous sands, containing large, calcareous nodules, and, in places, of friable, phosphatic sands containing shells. The phosphatic sands are mainly quartz sand with a small amount of phosphate in the form of small, brown and black, smooth or water-worn particles of bones and teeth, disseminated clay, and calcium carbonate in the form of shells and calcareous nodules. (See detailed sections, pp. 371-373.) The maximum observed thickness of this formation is 45 feet, this thickness appearing in some of the sections in the vicinity of Porters Landing on Savannah River. 10p. cit. :364 GEOLOGY OF THE COASTAL PLAIN Areal Distribution and Structure.-This formation has been differentiated at and in the vicinity of Porters Landing, Savannah River, Effingham County, Ga. It is doubtless represented in the undifferentiated Miocene occurring in sections above Porters Landing at least as far as Hudsons Ferry, and in the sections between Porters Landing and Sisters Ferry. (See detailed sections, pp. 371a75.) So far as can be determined from the natural exposures the beds lie almost horizontally, having only a very slight dip southward, probably not more than three or four feet to the mile. The formation is almost entirely concealed by later sediments, outcrops occurring only in the bluffs of streams; for this reason the beds have had little or no influenct- either upon the topography or upon the character of the soil of the region underlain by them. Paleontologic Oharacters.-The formation has yielded a relatively small fauna, the collections coming chiefly from localities in the vicinity of Porters Landing, Savannah River. The fossils have been studied by Dr. Vaughan, who furnishes the following annotated list: Table of fos~ils from the Marks Heal Marl. Localities' Marks Head, one mile west of north of Porter's Landing.-Earle Sloan and T. W. Vaughan, collectors. One-half mile above Porter's Landing.-L. W. Stephenson, collector. One-half mile above Porter's Landing,-T. W. Vaughan, collector. Porter's Landing, between the Oarolia bed below, and the Ostrea mauricensis ledge above.-T. W. Vaughan, collector. Porter's Landing, Ostrea mauricensis ledge.-T. W. Vaughan, collector. Sister's Ferry,-L. W. Stephenson, collector. MiOCENE 365 NAME Stratigraphic Range and occurrence o'd "i;t'l.l ui r.i ~:i ~ ~.,-> >'"...l _g.9 ;I: .,::::~;:~ . ;t<-,:j .: S...l -+< Turritella aequistriata Con- rad Jericho, N. J Neverita duplicata var. per- calosa Conrad Miocene to re- . cent ' Calliostoma aphelium Dall. Jones Wharf and Calvert Cliffs Md. Calliostoma sp. ' I X Yoldia leavis Say Area limula Conrad i Miocene and Plh ocene ! X Ostrea mauricensis Gabb Eocene, Oligo-, cene, lower: Miocene of Jer- Pecten marylandicus Wag- icho, N. J. X X ner. Jones Wharf, Md., etc. X X Carolia sp. (floridana Dall ?) X Mytilus conradinus d'Orb. Throughout the Astarte yo. (also in the up- Miocene per horizon at Porters) . .' X X Venericardia perplana var. I abbreviata Conrad Miocene of York~ .ruver to Plio-[ cene . I Phacoides trisulcatus Con- Oligocene to Plij rad. cene I I Phacoides crenulatus (Con- [Miocene of Jeri- 1 rad). cno, N. J., to! Duplin horizon, Phacoides sp.. .. N.C. Jones Wharf, Md. Cardium laqueatum Conrad. to Duplin hori- zon, N. c. I I Dosinia sp. Macrocallista sp. Strigilla flexuosa Say :Ib1ig~c~n~ : t~ I ! it~-~ Strigilla carnaria (Linn) cent ..... I Hitherto only Re- cent Donax n. sp. X Mactra sp. (hinge of large sp.) Spisula n. sp. Corbula n. sp. .t. X Balanus I I I X I - -- ~---~ .. :i t> ]0~ o.,; ui " ~:i ~ >'",_; .oo."S' "-,:j - "' ""j ., .s .,a,15 ..., ~~ ...l j'~> ur -,:j .. d ;...- jc3~> ~ t: .~,.~,=~:i ~H,..; <~~>t=E~,f-:o. e ~ -+< '"' ~ iii X X X X X X X X X X X X X X X X X X X X X X X X X X X ---- 366 GEOLOGY OF THE COASTAL PLAIN "Geologic Horizon.-The presence of Carolia in this bed suggests Oligocene, but every other identifiable species may be Miocene, and only three others range downward into the Oligocene; nine species are not known below the Miocene; of these nine, six are confined to the Miocene. The horizon is, therefore, in the Miocene, while the presence of Turritella wquistriata Conrad, Calliostoma aphelium Dall, Ostrea mauricensis Gabb, and Pecten marylandicus Wagner, definitely points to a horizon low in the series." Economic Geology.-From an economic viewpoint the formation contains little of interest. It contains some phosphatic marls which may prove to be of local value as fertilizers or as fillers for commercial fertilizers. DUPLIN MARL NAl\[E. The name Duplin is derived from Duplin County, N. C. It was proposed as a formation name by Dr. Dall in publications appearing from 1895 to 1903.''' DEFINITION Stratigraphic Relations.-The Duplin mal'l re~ts unconformably upon the ~larks Head marl, or, where the latter is absent, upon the Alum Bluff formation of the Oligocene. The former relations ~were observed in the various sections examined at and in the vi- einity of Porters Landing, Savannah River (pp. 371-373), and the latter relations are believed to obtain in sections on Altamaha River, at the bluff at Doctortown, at Buzzards Roost Bluff, and at Bngs Bluff (pp. 376-377.) ~ The formation is overlain unconformably by deposits referred in this report in part tentatively to the Altamaha formation, and in part to the Pleistocene (terrace deposits). Lithologic Characters and Thickness.-The formation as exposed on Savannah River is mainly a shell marl, consisting of shells in a matrix of coarse, phosphatic sand; but in places it consists of a fine, gray, or brown, quartz sand, which contains scarcely any fossils or calcareous matter. The formation probably does not reach a thickness of more than 10 or 12 feet. The Duplin marl on Altamaha River consists of friable, sandy, and pebbly shell-marl, and bluish, compact,- fine-grained, argillaceous 'Proc. Nat. Mus., vol. 18, 1895, pp. 31, 40, 46. 'Eighteenth Ann. Rept., U. S. Geol. Survey, pt. 2, 1898, p. 338. 'Trans. Wagner Free Inst. Sci., Philadelphia. vol. 3, pt. 6, 1903, pp. 1598-1603. MIOCENE 367 sand which is also fossiliferous. The formation overlies; unconformably, strata of probable Alum Bluff age and is, in turn, over- n lain by vari-colored sands and clays which probably belong to the Altamaha (Lafayette formation. The Duplin marl does not reach a thickness of over 12 or 15 feet in natural exposures. Areal Distribution and Structure.-The formation has been differentiated in the sections at Porters Landing, and at Mount Pleasant Landing, one and one-half miles below Porters Landing on Savarmah River (pp. 371-374). It is doubtless represented in nndiffercn tiated :Miocene beds recognized in bluffs above Porters Landing as far as IIudsons Ferry, and below Porters Landing perhaps as' far as Purisburg, S. C., 23 miles above Savannah. It has also been differentiated at Doctortown, at Buzzards Roost Bluff, and at Bugs Blnff on Altamaha Hiver. The formation probably underlies much of the area, beneath surficial formations, between the occurrences on Altamaha and on Savannah rivers. The Duplin beds dip to the southward at a very low angle, the inclination probably not E>xceeding three or four feet to the mile. Except as revealed in occasional stream bluffs the formation is probably concealed over the entire area of its occurrence by surficial deposits, and for this reason has had little or no part in determining the topographic features or the character of the soils of the region. Paleontologic Characters.-This formation has yielded a fairly large number of species in Georgia, although compared with the collections from the type region in North Carolina the fauna is small. The collections were made chiefly at Porters Landing on Savannah River, but a few species have been identified from Doctortown and from Buzzards Roost Bluff on Altamaha River. Dr. Vaughan furnishes the following annotated list of species identified from the Porters Landing collections: 368 GEOLOGY OF THE COASTAL PLAIN Table of fossils from upper horizon of the Miocene, Porters Landing> Georgia. L. W. S.=L. W. Stephenson, collector. T .. W. Y.=T. W. Vaughn, collector. D.=Duplin, N. C. 1 2 IUp;;: L 5w191 s endiLoJ;; end of Bluff of Bluff I . .. T.W.V. T.W.V. Scala sp. a. X Scala sp. b X Scala sp. c X Scala sp. d X Scala sp. e Scala sp. f Turritella variabilis Conrad . Turritella duplinensis Gardiner I X I X .D. I X X .D. I X Omphalius exoletus (Conrad) Calliostoma mitchelli (Conrad) . .D. I X X .D. X Calliostoma armillatum (T. & H.) .D. X Fissuridea sp. yo . .D. X Cadulus thallus Conrad .D. X X Nucula proxima Say .. .D. X X Leda acuta Conrad .D. X X Glycymeris sp. yo . Area improcera Conrad Area sp. fragment Ostrea disparills Conrad I X :I .D. X .D. X X X X Ostrea sculpturata Conrad .D. X X Pteria colymbus Bolten X Pecten eboreus Conrad .D. X X X Pecten jeffersonius Say . X X Pecten jeffersonius var. septenarius Say . . D . Pecten sp. X X X Pseudamusium sp. X Plicatula marginata Say .D. X X Anomia simplex d'Orb .D. X X X Placunanomia plicata T. & H. .D. X Astarte concentrica Conrad .D. X X Astarte distans var. fioridana Dall . X Astarte undulata Say .D. X Crassinella dupliniana Dall .D. X Venericardia granulata Say .D. X X X Venericardia tridentata Say .D. X X Venericardia perplano Conrad .D. X Phacoides anodonta (Say) .D. X Phacoides radians (Conrad) .D. X X Phacoides cribarius (Say) Phacoides multilineatus (T. & H.) :I .D. X X X X X X Chione athleta (Conrad) .D. . I X X X Venus tridacnoides var. rileyi Conrad .I X X X Venus tridacnoides Lamarck .D. X Transennella caloosana Dall X Tellina (Angulus) umbra Dall .D. X Tellina ? sp. Strigilla sp. fragment . Mulinia congesta (Conrad) Corbula inequalis Say Balanus, probably 2 species X I X :I .D. X .D. X X X X X Crab chela .. Lunulites Other Bryozoa, 2 species Echinoid spines. . .. Septastrea Astrangia ? X X X X X X X .I X X Boring sponge ? ____I X MIOCENE 369 Total number of identified species, 34 (not counting varieties), 30 of which are also at Duplin. The.four species which have not been found there are as follows: Pteria colymbus Bolten, the previously known range of which was from the Caloosahatchee Pliocene to Recent, or younger than the Duplin horizon. Astarte. distans var. floridana Dall. Miocene of Jackson Bluff, Fla., approximately the Duplin horizon. Phacoides multilineatus (T. & H.) Known range from the Miocene of Maysville, S. C., to Recent; from the Duplin horizon to Recent. Transennella caloosana Dall. Known range from Miocene of Jackson Bluff, Fla., to Pleistocene, from approximately the Duplin horizon to Pleistocene. The bed whence the fossils came is evidently the stratigraphic equiva lent of the Duplin marl of North Carolina. Economic Geology.-The formation gives but slight promise of yielding products of economic value. It contains some phosphatic marls which may prove of local value as fertilizers, or as fillers for commercial fertilizers. The terrane may be of importance as a water-bearing formation since it probably is the source of many of the flowing wells obtained in Glynn, Mcintosh, and Camden counties. UNDIFFERENTIATED MIOCENE Excepting the exposures in the vicinity of Porters Landing, at Mount Pleasant Landing, and at Sisters Ferry, it has not been possible with the available data to differentiate tho J\1.arks Head and Duplin divisions of the Savannah River sections, though doubtless both formations are represented at least from I-Iudsons Ferry in Screven County to Sisters Ferry in Effingham County. Detailed information concerning these undifferentiated J\liocene beds are given in the chapter on local details, pages 377-378. Fossils of Miocene age have been recognized in dredgings from Brunswick River at Brunswick, Glynn County, Ga., but they had been mixed by the dredging processes with la1;ge numbers of shells younger than the J\fiocene. Limestone tentatively referred to the Miocene occurs on the Livingston plantation, 18 miles west of Brunswick in Glynn Gounty, and a calcareous sand at Owens Ferry, Satilla River, eight miles west of \Voodbine, Camden County. It is believed that strata of Miocene age underlie much of the region adjacent to the Atlantic Coast beneath beds of younger age; and it is considered not improbable that such strata may reach a thickness of several hundred feet. However, confirmatory evidence is Jacking. 370 GEOLOGY OF THE COASTAL PLAIN LOCAL DETAILS Because of the limited area of the exposures, and as the different subdivisions recognized can not be definitrly identified except at a few of the better exposures, the local details of the :Miocene will be treated together. SAVANNAH RIVER Strata of :Miocene age appear in exposures on and near Savannah River at intervals from Hudsons Ferry, Ga., 681j2 ,miles above Savannah, to Purisburg, S. C., 23 miles above Savannah. Sections of a number of bluffs in which :Miocene strata occur, and which are considered stratigraphically important, are given below. Final decisions as to the divisions and the age of some of the beds exposed from Hudsons Landing southward have not yet been made, and the conclusions here presented are only tentative. Some sections of interest in connection with the :Miocene are given in the chapter on the Alum Bluff formation. Hudsons Ferry.-A section observed one-half mile below the landing, in which 37 feet of undifferentiated :Miocene is recognized, is given in the chapter on the Alum Bluff formation, page 361. The section described below occurs three-quarters of a mile below the landing. Section at Landing three-quarters of a mile below Hudsons Landing, Screven County. Pleistocene. Feet. 8. Loose, incoherent gray. sand . . . . . 2 Pliocene ? Altamaha formation ? 7. Mottled gray and red, coarse, clayey sand . . . . . . . 10 6. Interstratified, harsh sand, and fine-grained waxy clay . 10 5. Brown, ocherous, coarse sand; well-rounded pebbles at base ....................... 5 (Unconformity.) Miocene. Duplin marl ? 4. Compact, ash-colored, argillaceous sand . . . . . . . . 10 3. Drab, and brown or yellow, sandy clay containing fossils, Pecten madisonius, and other fossils poorly preserved . 2 (Unconformity.) Miocene? 2. Massive-bedded, gray and brown phosphatic sand . . 25 Oligocene ? Alum Bluff formation ( ?) . 1. Concealed by creep from upper part of bluff . . . . . 20 Division No. 3 contains prints of Pecten, poorly preserved leaf impressions, sharks' teeth, and dental plates of fish; at the base a few MIOCENE 371 well-rounded quartz pebbles appear. From its lithologic appearance and position in the section No. 2 is believed to be the equivalent of division No. 4 of Sloan's Porters Landing section which is subsequently given. Paleontologic evidence to confirm this is lacking. Similar sections were observed in other bluffs in this vicinity and the Miocene seems to be separated from both the overlying and ~nder lying formations by unconformities, which are marked by lines of small quartz pebbles. These pebbles are generally flat, oval, and discoidal, and are probably of beach origin. Marks Head.-The following is the section at Marks Head, the type locality of the Marks Head formation, adapted from that given by Sloan! Marks Head) on the western side of Savannah River) one mile northwest of Porters Landing) near head of Marks Head Run. 6. Surface sands. 5. Thin broken line of hard yellow marl. Feet. 4. Yellow-brown clayey matrix inclosing soft fossil shells 3. Partly indurated sand mass inclosing some fossil molds (2and 3 aggregate 14 feet in thickness).. . . . 10 2. Blue-green matrix inclosing many small rounded black particles, and soft shells (Pecten, Mytilus, Mytilo- concha, Area, Anomia, etc., etc.). . . . . . . . . . 4 1. Hard, sandy, brown matrix inclosing many soft shells. Extends below valley line increasing in hardness with depth . . . . . . . . . . . . . . . . . . . . 1 For a list of the fossils from this locality, see page 365. Porters Landing and Vicinity.-The best exposures of the Miocene occur in the bluffs at Porters Landing, 62 miles above Savannah, and the section is of much stratigraphic importance. It has been studied in detail by Mr. Earle Sloan,' State Geologist of South Carolina. The following section is based upon his descriptions, but the classification of the beds is changed to ~ccord with the conclusions of Dr. Vaughan from a careful study of the fossils. Section at Porters Landing, 62 miles above Savannah. Age ? Feet. 8. White, yellow, and red sands in stratified beds of both fine and coarse-grained material . . . . . . . . . . 64 7. Thin broken line of vertebrate remains, and small pieces of phosphate rock . . . . . . . . . . . . . . . . . . Miocene. Duplin marl. 6. Ledge of compact, yellowish marl enclosing Pecten ebor- eus, Ecphora quadricostata, numerous Anomias, etc . 5.9 1Bull. Geol. Survey of South Carolina, series IV, No. 2, p. 274. Bull. Geol. Survey of South Carolina, series IV, No. 2, p. 273. 372 GEOLOGY OF THE COASTAL PLAIN Marks Head marl. 5. Dun-colored mass of leached marl and indurated sands enclosing many rounded concretions of carbonate of lime encasing variable amounts of sand. Some concretions more than two feet in diameter. The basal portion is a hard concretionary layer (about a half foot thick) formed along a highly irregular surface. Stratum ( 5) appears at same level as the Marks Head marl at its type locality, one mile northwest . . . . . . . . . . 27 4. White sands enclosing a large number of one species of Pecten and numerous shell fragments, Pecten marylandicus Wagner . . . . . .. . . . . . . . . . . . . . . 1.7 3. Fine-grained, laminated shale with sand partings. The median portion appears in the form of silicified concretions. The base includes a line of rounded pebbles . 14 Oligocene. Alum Bluff formation. 2. A much leached marl enclosing Carolina floridana Pectens, sharks teeth, rib of cetaceans, and a large number of small, discoidal, quartz pebbles . . . . . . . . 6 1. Above zero water level appears 0 to 8 feet of a laminated drab shale with arenaceous partings. Enclosing molds of the Lucinidae, and at Hudsons Ferry impressions of the dwarf palmetto . . . . . . . . . . . . . . . . . Sloan recognized two divisions, the "Edisto" and Marks Head. In a subsequent study, Vaughan' correlated the upper Miocene horizon with the Duplin of North Carolina. The following sections near Porters Landing are by the authors of this report. Section 100 yards below Porters Landing. Pleistocene ? Feet. 6. Loose, gray sand . . . . . . . . . . . . . . . . . . . 5 Pliocene ? Altamaha (Lafayette ?) formation ? 5. White, yellow, and red sand 25 Miocene. Duplin marl. 4. Bed of shell marl; shells in a matrix of coarse, phos- phatic sand. Small, well-rounded, quartz pebbles at the base, resting unconformably on No. 3, Pecten eboreus, Pecten jeftersonius, Anomia simplex, Area, Phacoides, etc . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Marks Head marl. 3. Brown or gray, phosphatic sand with large calcareous nodules, as much as two feet in diameter or length . . 30 2. Drab, or dark greenish, sandy, faintly laminated clay (no unconformity observed between Nos. 2 and 3.) . . 10 1. Sandy, drab clay, partly silicified, and contains hard, round, siliceous concretions. Phosphate pebbles, but not so abundant as in No. 3. Contains Pecten mary- landicus . . . . . . .......... . 8 'Science, n. s., vol. 31, No. 804, May. 27. 1910, pp. 833, 834. MIOOENE 373 As the basal beds o the bluff were under water at the time o making the section, the Alum Bluff ormation was not studied at this locality. An exposure appears about three-quarters o a mile northwest 0 Porters Landing. Section one-half to three-quarters of a mile northwest of Porters Landing. Age ? Feet 5. Upper beds concealed . . . . . . . . . . . . . . . . ? Miocene. Marks Head marl. 4. Brownish quartz sand containing at the base a mass of shells and phosphatic sand, Ostrea mauricensis . . . 6 3. Compact, gray, argillaceous and calcareous sand, phos- phatic . . . . . . . . . . . . . . . . . . . . . . . . 18 2. White and brown sand, shells in white, phosphatic sand very abundant about the middle of the J::ed; fossils, Oarolia fioridana (?), Mytilus conradinus, Pecten marylandicus, Anomia, Area, etc. . . . . . . . 15 1. "Concealed by talus to the level of the swamp . . 6 For list o fossils rom this locality see page 366. Section about 200 yards above Porters Landing. Pliocene (?) Feet Altamaha formation ? 10. Coarse, variegated sand with line of small, quartz peb- bles at base . . 25 Miocene. Duplin marl. 9. Fine, brown sand . . . . . . . . . . . . . . . . . . . 4 8. Friable marl; shells in a matrix of coarse gray, phos- phatic sand. Contains large, ribbed Pecten, Anomia 1 Area, etc. A few scattered pebbles at base . . . . 2 Marks Head marl. 7. Brown and ash-colored, compact, argillaceous sand . 6. Compact sand; large, calcareo-phosphatic nodules . . . 5. Calcareous ledge containing Ostrea mauricensis, 20 30 feet above the river level . . . . . . . . . . . . . . 4. Poorly exposed, probably sand, (about 4 feet) . . . . . 3. Friable marl, shells in a matrix of gray sand, Ostrea mauricensis, Pecten marylandicus . . . . . . . . . . 4 2. B!'ownish, compact, sandy laminated clay, partly silicified 7 1. Greenish, sandy clay . . . . . . . . . . . . . . . . . . 4 Mount Pleasant Landing.-At Mount Pleasant Landing, one and one-hal miles 'below Porters Landing, the Duplin marl is 40 feet above the river, and consists o eight feet o friable, highly calcareous shell marl overlain by coarse, brown sand which reaches a thickness o 10 feet. The shell marl here in places approaches somewhat the lithologic character o coquina, or friable shells in a 374 GEOLOGY OF THE COASTAL PLAIN sand matrix, and is similar to some of that observed at Doctortown on Altamaha River. Beneath this upper bed is brown, phosphatic sand, similar to that at P6rters Landing. Section at M aunt Pleasant Landing, one and one-half miles below Porters Landing. Age ? Feet. 1. Sand, and white, tough, waxy, laminated clay with sand partings. Stratum poorly exposed 20 Miocene ? 2. Coarse, brown sand . . . . . . . . . . . . . . . . . . 10 Miocene. Duplin marl. 3. Friable marl and limestone, contains shells and casts of shells, Pecten, etc. . . . . . . . . . 7 Marks Heud marl. 4. Brownish, phosphatic sand . . . . . . . . . . . . . . . 25 5. Greenish, sandy clay, not well exposed . . . . . . . . . 20 At the Seaboard Air Line Railway bridge, three miles north of Clyo, there is 30 feet of fine-grained, white and yellow, sugar-like sand, the basal portion of which contains fine, brown, phosphatic grains. While this stratum contains no fossils, its lithologic char- acter and geologic position suggest that it is of Miocene age. The two Miocene divisions (Duplin and Mwrks Head) can not be dis- tinguished. It is overlain unconformably hy li'l feet of strata re- ferred tentatively to the Altamaha (Lafayette?) formation; the latter formation appears to increase in thickness westward from the bluff. Sisters Ferry.-At Sisters Ferry, Ga., 47 miles above Savannah, and two miles east of Clyo, there is a good exposure of Miocene strata. The beds consist of greenish or gray, very sandy, laminated clay in the lower part of the bluff, and of crossbedded, red and white sands in the upper part. Section at Sisters Ferry, Savannah River, Effingham County. Pleistocene. Feet. ln. 11. Thin covering of gray sand at the top of the bluff. Pliocene ? Altmaha formation ? 10. Mottled red and yellow sand with some thin clay layers . . . . . . . . . . . , . . . . . . . . . 20 Miocene ? (Undifferentiated.) 9. Coarse, crossbedded, yellow, red, and white sand . . 20 8. Poorly exposed . . . . . . . . . . . . . . . . . . 10 7. Drab, laminated clay, contains hard, sandy, calca- reous nodules, covered with a crust of fibrous calcite, . . . . . . 7 6. Hard, silicified clay . . . . . . . . . . . . . . . . 0 8 MIOCENE 375 5. Drab clay . . . . . . . . . . . . 0 3 4. HaJd, silicified, clay . . . . . . . 0 3 3. Laminated, gray, very sandy clay 2 6 2. Hard, silicified clay . . . . . . . 2 Miocene. Marks Head marl. 1. Very sandy clay, contains some black phosphatic particles . . . . . . . . . . . . . . . . . . . 3 The only :fossil which could be identified here was a Pecten marylandicus, which occurs near the base o:f the bluff. About one-hal: mile below the :ferry the dark-colored clays o:f the Miocene appear 25 :feet above the level o:f the river. Southward :from Sisters Ferry the river flows through low Pleistocene plains, and the bluffs along the river do not exceed 30 or 40 :feet in height; along this stretch o:f the river there are :few localities where satisfactory studies o:f the geological :formations can be made. Frying Pan Landing.-At Frying Pan Landing, eight miles below Sisters Ferry, greenish, ~andy clay, similar in appearance to that at Sisters Ferry, occurs in the lower eight :feet o:f the bluff. Section at Frying Pan Landing. Feet 4. Loose, gray sand . . . . . . . . . . . . . . . . 4 3. Red, clayey sand . . . . . . . . . . . . . . . . . 10 2. Brown and white, unconsolidated, rather pure, quartz sand . . . . . . . . . . . . . . . . . . . . . . . . 8 1. Gray and greenish, sandy clay . . . . . . . . . . . . . 8 There are no determinable :fossils and the divisions arc made 011 the basis o:f lithology and geologic position. No. 4 may be safely considered Pleistocene. No means are at hand :for definitely determining the age o:f division No. 3, but it is probably Pleistocene. No. 2. is probably Miocene, since the sandy clay of No. 1 is very similar lithologically to the Miocene at Sisters Ferry and Porters Landing. A similar succession o:f beds continues to Purisburg, S. C. Ebenezer Landing.-At Ebenezer Landing, 34 miles above Savannah, beds corresponding in position to the Frying Pan Landing beds, rise about 18 :feet above the river. The lower beds here are tentatively referred to the Miocene. They consist o:f brownish or yellow, compact, sandy clays, which contain poor prints and casts o:f :fossils, and white and brownish, fine quartz sand. Purisburg.-At Purisburg, S. C., 23 miles above Savannah, there is a bluff about 10 :feet high, which exposes Pleistocene and older :formations. 376 GEOLOGY OF THE COASTAL PLAIN Section at Purisburg, 23 miles above Savannah. Feet In. Pleistocene. 6. Red, sandy clay, containing small pebbles, color due to weathering , . . . . . . . . . . 1 5. Drab or white, laminated clay . . . . 3 4. Line of coarse, quartz pebbles . . . . 0 3 Miocene? 3. Gray or pale green, argillaceous sand 3 6 2. Thin line of quartz pebbles . . . . . . 0 3 (Unconformity) 1. Gray or pale green, argillaceous sand 3 Below Purisburg only Pleistocene deposits are exposed. ALTAJ\!AHA RIVER Bugs Bluff and Buzzards Roost Bluff.-In descending Altamaha River the first exposure in which Miocene strata have been certainly recognized is at Bugs Bluff, two and one-half miles above Doctortown. Except that it yields no fossils the section is essentially like that at Buzzards Roost Bluff, two miles (by the river) above Doctortown. The Buzzards Roost exposure is described in detail as follows: Section at Buzzards Roost Bluff, two miles above Doctortown. Feet In. 7. Gray sand covering upper slope . . . . . . . . . . 2 Pliocene ? Altamaha formation ? 6. Mottled, clayey sand . . . . . . . . . . . . . . . 10 5. White, crossbedded, coarse sand, pebbly at the base . 28 (Probable unconformity) Miocene Duplin marl. 4. Yellow and white, very sandy clay, pebbly in upper part, faintly laminated . . . . . . . . . 5 3. Blue, almost black, silty clay . . . . . . . . 6 2. Shell and pebble conglomerate, contains Pecten eboreus, Mytilus conradinus . . . . 1 6 (Unconformity) Oligocene ? Alum Bluff formation ? 1. Bluish gray, massive, compact, clayey sand 10 Layer No. 2 is made up of well-rounded, quartz pebbles, coarse sand and shells. The whole is in places consolidated into a conglomerate, calcium carbonate forming the cement. Large fragments of water-worn, silicified wood also occur. The horizon is the same as that at Doctortown (Duplin horizon). The remainder of the section bears.no fossils and the divisions are made upon the basis of physical differences and relations. The total thickness of the Miocene is 12 feet. It is separated from the underlying formations by an erosion GEOLOGY OF THE COASTAL PLAIN OF GEORGIA PLATE XXVI. B. CHARLTON FORMATION. T. ~~ARY RIVER. (FLO RIDA SIDE) STOKES FERRY. 11 MILES OUT H OF T. GEORGE. CHARLTO~ COUNTY, GA. MIOCENE 377 .unconformity, and probably also from the overlying formation by an unconformity. Doctortown.-At Doctortown, Wayne County, the bluff of Altamaha River is 40 feet high, and near the base of the bluff beds of Duplin marl are exposed. The following is a section of the bluff at the south end of the Atlantic Coast Line Railroad bridge. Section of Bluff at south end of Atlantic Coast Line Railroad Bridge. Feet Pliocene ? Altamaha (Lafayette ?) formation ? 6. Yellow and mottled, argillaceous sand . . . . . . . . . 10 5. White and yellow, crossbedded sand containing thin layers of small, quartz pebbles . . . . . . . . . . . 10 4. Red and yellow, stratified sand containing thin clay laminae . . . . . . . . . . . . . . . . . . . . . 10 (Probable unconformity) Miocene. Duplin marl. 3. Calcareous, fossilliferous sand, or sandy, friable marl . 1 2. Bluish sand containing Pecten eboreus, Mactra congesta, etc. . . . . . . . . . . . . . . . . . . . . . . . . . 4 (Probable unconformity) Oligocene ? Alum Bluff formation ? 1. Coarse, bluish or greenish, compact, clayey sand to wa- ter's edge . . . . . . . . . . . . . . . . . . . . . 7 The relations between layers Nos. 3 and 4 could not be determined with exactness. Layers Nos. 2 and 3 are Miocene. No. 5 is considered Oligocene, and the upper part of the bluff'is referable either to the Pliocene ( ?) (Altamaha formation) or to the Pleistocene. Below Doctortown there are no known exposures of Miocene strata, although beds at the bases of Upper and Lower Sansavilla Bluffs, 27 and 28V2 miles, respectively, below Doctortown, may belong to this series. GLYNN COUNTY Brunswick.-At the southern limits of the city at the Atlanta, Birmingham, and Atlantic Railroad terminals, a large amount of shells and rocks have been dredged 'from Brunswick River. A study of the dredged material leads to the conclusion that the :1fiocene underlies this region and is concealed by a small thickness of later formations. The material thrown from the dredge consists of shel-ls, fragments of bones and teeth, sand and quartz pebbles, compact, sandy marl or shells imbedded in a phosphatic sand matrix, argillaceous limestone, and hard clay. 378 GEOLOGY OF THE COASTAL PLAIN A study of the fossils was made by Dr. Vaughan and they wera found to range from Miocene to Recent. The dredge probably cut through a thin covering of Recent and Pleistocene deposits into. the Miocene. Dr. Vaughan furnishes the following list of fossils collected from the dredgings : List of fossils dredged from Brunswick River, Brunswick. Septastrea crassa (Holmes). Terebra dislocata Say. Conus sp. Young. Drillia abundans Conrad. Oliva Iiterata Say. Olivella mutica Say. Marginella contracta Conrad. Fulgur carcia Linn. Ecphora quadricostata Say. Nassa vibex Say. Ilyanassa obsoleta Say. Nassa acuta Say. Columbella avara Say var. Astyris lunata Say: Turritella variabilis Conrad. Turritella plebeia Say? Crepidula fornicata Say. Neverita duplicata Say. Solarium granulatum Lam. Fissuridea carolinensis Conrad. Dentalium caroll'1ense Conrad. Glycymeris parilis Conrad. Glycymeris subovatus Conrad. . Barbatia adams! Shuttlew. Area lienosa Say. Area plicatura Conrad. Area transversa Say. Area incongrua Say. Area limula Conrad. Ostrra aisparilis Conrad. Ostrea virginica Gmelin, P. & R. Pecten jeffersonius Say. Pecten septenarius Say. Pecten madisonius Say. Pecten n. sp. '! Astarte concentrica Conrad. Astarte distans var. floridana Dall. Astarte undulata Say var. Astarte undulata var. vaginulata Say. Astarte <'Uneuormis Conrad. Crassatellites undulatus Say. Crassatellites sp. t.a:aiainera arata Conrad. Venericardia granulata Say. Echinocnama arcinella Linn. Phacoides anodontus (Say). Phacoides radians (Conrad). Phacoides multineatus (Tuomey & Holmes). Phacoirle1 amiantus Dall, P. & R. Diplodonta acclinis Conrad. Cardium robustum Solander, R. & R. Chione cancellata Linn. Chione alveata Conrad. IJuione aff. cortinaria Rogers. Don ax. MJ.linia congesca Conrad. Mulinia congesta var. contracta Con rad. Mulinia cone:esta var. elongata Dall. Rangia clathrodon Conrad. Corbula inaequalis Say. "Geologic H orizons.-At least two mixed, most of the species are Miocene, those marked P. and R. are Pliocene to Recent, and not known from the Jl.fiocene; all of the others may be Miocene, and many are only in the Jl.fiocene. The dredge has cnt through what is probably Pleistocene or Recent into Miocene strata." Livingston Plantation.-This locality is 18 miles west of Brunswick. The exposure is in the bed of a small creek and can be seen only at low tide. Section at Livingston Plantation. Recent. 3. Marsh mud . . . . . . . . . . . . . . . . . . . Feet 2 PLIOOENE 379 Pleistocene. 2. Greenish gray, argillaceous sand with some smoothly- rounded quartz pebbles. Bones and teeth in the lower part . . . . . . . . . . . . . . . . . . . . . . . . . 3 (Unconformity) Miocene. 1. Yellow, argillaceous limestone . . . 2 A piece of coarse sandstone loosely cemented by lime, containing a Pecten) was obtained at this locality by Prof. McCallie. The age of the beds has not been proven by paleontologic evidence. Layers Nos. 2 and 3 should probably be referred to the Pleistocene. Layer No. 1 is tentatively referred to the Miocene; however, this rock is similar lithologically to limestones of probable Pliocene age exposed at Burnt Fort on Satilla River, and near Folkston on St. Marys River, and future investigations may prove its Pliocene age. CAMDEN COUNTY Owens Ferry.-At this locality, eight miles west of Woodbine, a compact sand and calcareous sandstone is exposed in the bed of Satilla River at low tide. This rock contains fossils, but none are very \vell preserved. It is overlain by bluish, coarse-grained, clayey sand, while the upper part of the bluff is Pleistocene sand and clay. The following fossils from this locality have been identified by Dr. Vaughan: Fossils from Owens Ferry. Pecten, probably madisonius, Carditamera arata, Cardium sp. PLIOCENE The existence of strata of Pliocene age in Georgia has not been definitely proven. However, certain deposits have been referred with greater or less degrees of confidence to this period. The socalled Lafayette formation of the Atlantic and Gulf Coastal Plain has for many years been regarded as of probable Pliocene age. A summary of the events leading up to the adoption of the name has been given by McGee.1 In a recent contribution E. \V. Berry2 has shown that the name Lafayette, as applied to a surficial formation in the Atlantic and Gulf Coastal Plai~ by McGee and others, is a misnomer, the beds exposed at the type locality in Lafayette CQunty, Miss., being in fact of Eocene age and referable to the Wilcox formation of that series. However; a surficial formation consisting of 1Twelftb Ann. Rept., U. S. Geol. Survey, pt. 1, 1892, pp. 498-502. Journal of Geology, vol. 19, 1911, pp. 249-256. 380 GEOLOGY OF THE COASTAL PLAIN sands and heavy beds of gravels r~sting unconformably upon Cretac~ous and Eocene strata, to which the name was intended to apply, is extensively developed in certain parts of the northern embayment region, especially in Tennessee and Kentucky. The so-called Lafayette formation is represented by McGee as covering the whole Coastal Plain of Georgia. Beds considered referable to this formation have been described at numerous localities in Georgia by different investigators, but on the following pages it will be shown that, assuming the formation to be of Pliocene age, many of these correlations were erroneous. Frequently the beds so referred have been found to belong to Cretaceous, Eocene, or Oligocene formations, or are the weathered, residual products of these formations. Terrace deposits -which are clearly of Pleistocene age have also been referred to this formation. The Altamaha (Lafayette?) formation, a widespread but relatively thin series of sands and clays covering much of central and southern Georgia, is tentatively referred to the Pliocene. Doubtless a part of the strata included in the Altamaha terrane is contemporaneous with the so-called Lafayette formation. However, the inadequacy of our knowledge of the age and stratigraphic relations of the Altamaha deposits is conceded. The possibility is also admitted that the beds here included in this formation may prove to be a complex embracing strata of all ages from the Oligocene to the Pleistocene. Certain fossiliferous strata exposed on Satilla and St. Marys rivers have, on paleontologic evidence, been considered as probably of Pliocene age. The beds appearing on Satilla River will be described in the chapter on the Altamaha (Lafayette ?) formation, since it is believed they are synchronous with at least a part of that formation. The exposures on St. Marys River will be described nndor tho name Charlton formation. On following pages the literature relating to Pliocene or supposed Pliocene deposits in Georgia is reviewed. HISTORICAL REVIEW In 1884 Dr. R. H. Loughridge' described beds which he considered of Pliocene age, as follows: The Savannah region along the coast, which occupies the first terrace at an elevation of from 10 to 15 feet above tide-water, is assigned to the PliO<~ene formation. Marls or shell beds of this age are found on the Savannah River near the Effingham and Chatham County lines. On Satilla River a white marl bed outcrops at Burnt Fort, the head of tidewater, which is 1'T'enth Census, vol. 6, part II, 1884, p. 16. PLIOCENE 381 mostly devoid of fossils. In the sand and clay beds of the coast region in Glynn, Chatham, and other counties have been dug up the remains of gigantic quadrupeds, such as the mastodon, and along its borders are buried stumps of cypress and other trees still standing upright. Loughridge referred strata both older and younger than the Pliocene to this period. The "marl or shell beds" on Savannah River are in part o:f Miocene and perhaps in part o:f Oligocene age. (See pp. 370-376 o:f this report.) The sands and clays o:f the coast region which bear remains o:f quadrupeds and contain buried tree stumps are believed to be o:f Pleistocene age. No :fossils have been identified from Burnt Fort, but the beds are regarded as the equivalent o:f the fossiliferous beds on St. Marys River (Charlton :formation) which Dr. Vaughan regards as probably of Pliocene age. In 1891 W J McGee1 described the deposits in Georgia which he regarded as referable to the Lafayette formation. The following are quotations :from his report with comments by the writers: "The exposures on both sides of the Chattahoochee River at Columbus are specially noteworthy, not only by reason of the clear display of struc- tural and textural features, but because the terracing which characterizes the formation at many localities is here particularly well displayed. Colum- bus is built on a terrace a mile broad, thinly veneered with "second bot- tom" (Columbia) loam near the river, but consisting generally of the orange- red loam of the Lafayette, massive above, mottled 8 to 15 feet below the surface, and more or less definitely bedded below; Phoenix, or Lively, on the opposite side of the river, is built on a higher terrace of bronze-tinted loam, here containing moderately abundant disseminated pebbles, and the many excellent exposures in the railway and street cuttings well display the stratification of its lower portion... * .. * .. (p. 478.) "On examining the materials composing the formatio:1 at Columbus, certain new feamres apppear. As usu: 1, -the upper part of the deposit is orange tinted loam, mass1ve, rock-like, undergoing suverficial cementation on weathering, and flecked or streaked with white; but the color is lighter than in Mississippi, the proportion of sand is smaller, the sand grains are coarser and more angular, and the flecks and streaks of white are no longer of siliceous clay or pt:lverulent amorphous silica but of kaolinic clay or kaolin. The lower portion of the formation displays a bedding as distinct as the stratification of Mississippi, but the bedding is simply a ser aration of the loam into heavy, rock-like ledges parted by leaves of clay, sa 1d, and gravel, quite unlike the inter-stratification (with occasional cross-.amina- tion) of sands and clays in the western part of the terrace; w, too, the materials of the intercalated clay leaves are changed, instead of the silice- ous pottery clays of Mississippi and Tennessee they are chiefly a kaolin-like material, with occasional quartz crystals and mica scales included; and the pebbles are no longer 01 chert, as in Mississippi and Tennessee, or even the mixture of cherts and siliceous dolomites found on Tuscaloosa River, but mainly of granular quartz with occasional well worn bits of quartzite. (p. 478.) ' "The exposed thickness of the formation about Columbus is generally 10 to 30 feet; and the combined exposures indicate that while the thickness is exceedingly variable it probably reaches a maximum of 50 or 70 fP<:JL * * * * (p, 478.) 'Twelfth Ann. RPpt .. L- ;;. GPol. Survey, pt. J, 18D1, pp. 4i8-4QO. 382 GEOLOGY OF THE COASTAL PLAIN "Along the Chattahoochee River about Columbus, and southward nearly or quite to the confluence of the Flint, the Lafayette deposits are not concealed by the newer Columbia formation save along the rivers, which are all flanked by the "Second bottom" loams characteristic of the rivers of the eastern Gulf slope * * * (p. 479.) "In the vicinity of Columbus, particularly on Mill Creek, between Phoenix and Girard, the Lafayette rest~;, either with or without marked unconformity, on the Potomac (Tuscaloosa) arkosic sand and clay; the materials of the terrace east of the river and north of Columbus generally lie on the eroded surface of the Piedmont gneiss; within 2 or 3 miles south of Columbus the Lafayette rests unconformably (though sometimes the unconformity is inconspicuous or even imperceptible) on the sands of the Eutaw; while still farther southward it reposes with like unconformity successively on the Ripley, the various divisions of the argillaceous Eocene (Hilgard's Lignitic), the White limestone of Smith and Johnson, and Miocene limestones. About Columbus the materials of the basal part of the Columbia, of the Lafayette, of the Potomac (Tuscaloosa), and sometimes of the Eutaw, contains certain common elements and sometimes approximate in composition so closely that they may be discriminated only by structural characteristics; and in some of the most conspicuous exposures near the mouth of the Mill Creek the Lafayette and the Potomac (Tuscaloosa) have not been certainly discriminated.:' ( pp. 479-480.) The deposits on the plains bordering Chattahoochee River in the vicinity of Columbus, and extending dow'll the valley from Colum- bus, are Pleistocene terrace sediments which rest upon Cretaceous, Eocene, and Oligocene strata. "The lower portion of Macon is bullt on a "second bottom" plain, but the residence part of the city stands on the amphitheater-like slopes semicircling the terrace occupied by the low-lying business portion; and in every street and country roadway, in every excavation on railways entering the city from the west, northwest, and even from the southeast, the orangetinted loams are well displayed, always with the prevailing color and frequently with characteristic structure; so the roads, streets, railways, ancl hill slopes of the most of Macon gleam red against the dark green background of the pine-clad hills. Here as elsewhere the material is a loam, containing a sufficient element of clay to produce considerable coherence, orange red or or sometimes brick-red above, mottled orange yellow at greater depths. Here, as elsewhere, the formation is characterized by irregular stratification and rather obscure crossbedding in its lower portion,. the structure lines being marked sometimes by ferruginous crusts and sometimes by lines of pebbles or gravel grains, but more frequently by sheets of white plastic clay, sometimes continuous, sometimes in layers of distinct pellets. Here, as elsewhere, the upper part of the deposit is massive, and diplays in an 'minently satisfactory manner the distinctive semiglazing or case-hardening by which tlre formation is generally characterized. Here, as elsewhere, the deposit is frequently pebbly, the pebbles being either arranged in lines of stratification or accumulated in pockets and in beds, sometimes assorted by size, and as usual the pebbles are commonly disseminated above and commonly bedded below; and here, as at Columbus, the pebbles consist predominantly of mederately well rounded and subangular fragments of quartzite and quartz, ranging from 3 inches in diameter downward, and there are in addition a few granitoid fragments. (p. 480.) "The relations of the Lafayette formation to the Columbia "second bottom'' are not well displayed, but the relations to the Potomac are admirably displayed in many exposures. The eminence in the western part of the -city known as Primrose Hill is a cusp of Potomac arkose only veneered with PLIOCENE 383 the Lafayette, and the street cuttings and gullies by which it is laid open .along many lines display the two formations in contact, sometimes conforniable in structure and concordant in materials to such an extent that they may not be demarked, but elsewhere strongly unconformable in structure and discordant in composition. Precisely similar relations are displayed in the half dozen or more excellent exposures on the Georgia Southern Railway in the western part of the city, in some of which the formations are quite distinct, while in others they intergrade." (pp. 480-481.) The physiographic features at Macon are: (1) terrace or "swamp" 1.5 to 20 feet ahove the level of Ocmulgee River; (2) terrace plain 40 to 50 feet above the first plain; (3) upland plain 100 to 125 feet aboye the second terrace plain. J\.IcGee does not describe this terracing in detail, hut it is inferred that he considered the Lafayette as occurring on aU three ]jlains. Both the second terrace and the higher land have gravel and red loam deposits spread over them, but these deposits are evidently of different ages since they are separated by a vertical interval of as much as 100 feet, and the deposits do not appear to form a continuous mantle over the escarpment between the two plains. Those on the lower two plains are Pleistocene terrace deposits. The red loam deposits on the high land west and south of l\facon are lithologically similar to the Eocene strata capping the hills on the east side of Ocmulgee River, and it is believed that they correspond to them. "Over the divide between the Ocmulgee and the Oconee the Lafayette appears in many exposures." (p. 481.) No localities where the exposures appear are mentioned. There are in places deposits of red sand unconformably overlying the Cretaceous which might be mistaken for surficial deposits but which have been shown by their contained fossils to be of Eocene age. At other places there are similar sands which do not contain fossils, but these can usually be traced into fossil-bearing Eocene beds. It is believed, therefore, that McGee has mistaken the red Eocene sands for the Lafaytte for- mation. The formation is mentioned as occurring in the vicinity of Millen (p. 481), but no particular locality is described. In this report these deposits are considered referable to the Altamaha formation. "* * * But on returning to the fall line the normal fall-line fea- tures recur, as in the fine exposure near Green's Cut (10 miles south of Augusta) where the usual aspect of the massive loam is well displayed. At this point the deposit is exceptionally pebbly, to the extent, indeed, that it has been largely worked as gravel for railway ballast, the pebbles ranging from 2 inches down, the most abundant dimensions being three-fourths to one and one-quarter inches; the materials are predominantly quartz and quartzite, with no chert, the prevailing form being fairly well rounded, and the pebbles are accumul~ted in layers, sometimes discontinuous, in which it is occasionally cross-bedded, though even in these layers the gravel is nowhere clean, the pebbles being simply disseminated closely throughout a 384 GEOLOGY OF THE COASTAL PLAIN matrix of loam just as the finer sand grains are disseminated through a clay matrix in the loamy parts of the formation." (p. 481.) At Greens Out on the Central of Georgia Railway, 27 miles south of Augusta (probably the locality referred to in the above description), is a deposit of mottled sands and gravels overlying the Barnwell sand of the Claiborne group. These have much the aspect of the Altamaha formation which appears to the southward and they are believed to be referable to it. "In central Georgia the Lafayette forms the surface on the Ocmulgee and the Oconee rivers, save where the "second bottoms" overlap it; but farther eastward, on the Ugechee as well as toward Savannah, the distinctive "second bottoms" proper disappear, and the coast-sand mantle stretching up from the seashore, and along the Savannah finally overlaps the Lafayette and extends upon the Piedmont gneiss, from which the orangetinted formation has been removed, if it was ever deposited." (p. 481.) Just what is meant by "second bottoms" is not clear, but here, a8 elsewhere in Georgia, the materials occupying definite plains bor dering the rivers are considered Pleistocene terrace deposits. "In southwestern Georgia, e. g., about Thomasville, the characteristic orange tinted or brick-red loams (in this direction the colors strengthen) are not concealed by the coastal sands of the Columbia epoch, except about the lower levels; but in southeastern Georgia there is a more or less continuous mantle of these sands, by which the Lafayette is commonly buried from sight. In passing southward from Thomasville the features of this formation and its relations to the Columbia are well displayed." (p. 482.) The so-called Lafayette materials referred to in the preceding quotation are in this report considered referable to the Altamaha formation; they oYerlie the Alu'm Bluff formation (Oligocene). "The Lafayette is well exposed on the southern bank of St. Mary's River, near Traders Hill. Here the upper part is orange brown or drab and massive for a few feet, but it quickly becomes regularly bedded, the heavier layers of brown or gray clayey loam separated by leaves of gray silt and brown or drab sand. It is again displayed in many railway cuttings about Waycross, where the upper massive member is better developed yet decidedly less distinctly massive, orange-tinted, and casehardened than in central Georgia, while the lower part is always stratified. It is revealed to a depth of 40 feet or more at Doctortown in a railway cutting through a natural bluff overlooking the Altamaha; here the upper member is ill developed or absent and the mass is stratified throughout, consisting of alternations of brown loam and white silt above and in the lower part of the exposure these become, respectively, blue or gray clay and light colored sand. Still farther northward the formation approaches within 10 miles of the sea islands and inlets in the Cherokee Ridge on the southern side of the Savannah. The upper massive member is fairly displayed here, though orange yellow rather than of the characteristic color, while the lower portion consists of stratified sand with fine gravel disposed in sheets." (p. 484.) A detailed section at the Atlantic Coast Line bridge near Folkston, probably the Traders Hill locality, is given on page 398 of / PLIOCENE 385 this report, and the stratigraphic relations of the beds discussed. The strata above the Charlton formation (probably Pliocene) are considered of probable Pleistocene age. The materials exposed near Waycross are, in this report, considered a part of the Altamaha for- mation. The beds above the fossiliferous Miocene marl at Doctor- town are tentatively referred to the Altamaha formation, although they may be Pleistocene terrace deposits. "Superb exposures of the Lafayette, displaying the usual fall line features, occur on Savannah River about Augusta. The characters and structural relations here represent those exemplified at Columbus and Macon, save that the "second bottom" phase of the Columbia is replaced by a series of sandy terraces running up into the prevailing coastal sands." (p. 484.) It is probable that both Pleistocene and Eocene deposits at Augusta have been mistaken for the Lafayette. The Pleistocene beds are de- scribed on page 433 of this report. Sunhill and Munnerlyn are mentioned by McGee as localities where the Lafayette may be observed. The materials at both lo- calities appear to be identical in character with those of the Alta- maha formation, which is well exposed to the southward of these localities. In 1891 J. W. Spencer' also gave detailed descriptions of sup- posed occurrences of Lafayette strata in Georgia. The following are quotations from his report, with comments by the writers: "At Rich Hill, about six miles southeast of Knoxville, the same red loam forms a capping at an elevation of 835 ( ?) feet; and near by, gravel is seen on the hills at fifty feet below. At both these localities, the loam forms a capping for both the surface and the sides of the hills, where the underlying formations were incised by former eroding streams. This condition is common to the formation, as it forms a sheet alike over the ancient hills ant'i greater valleys. The base of this loam, especially in the vicinity of the greater rivers, passes into a well marked bed of rounded quartz gravel, sometimes three inches in length. Such gravel is seen upon the hills between Knoxville and the Flint River, at elevations of 130 feet above its modern high water. South of Knoxville the red loamy surface is replaced by a belt of loose gray sand." The red loam capping Rich Hill is probably of Eocene age. The materials at lower levels in this vicinity are in part residual sands and in part Pleistocene terrace deposits. "The country south of this point is, commonly speaking, a high plain somewhat incised by streams. The surface is generally composed of the orange loam, which varies in thickness from zero to 20 feet, as shown in the railroad cuts south of Gaillard's. "At Fort Valley, this red loam or clay reaches a depth of 2 feet, as shown in the artesian well. About three miles south of Fort Valley, there is an excellent exposure in the railroad cut on the road to Americus. 'First Report of Progress of the Geological Survey of Georgia, 1891, pp. 60-72. 386 GEOLOGY OF THE COASTAL PLAIN Feet "1. Deep colored red loam or hard sandy clay, with rounded gravel in the lower two feet, resting upon an eroded surface . . . . . . . . . . . . . . . . . . . . . . . . . G-10 2. White and red mottled clay with surface eroded . . . 7- 3 3. Thin laminated sand with clay partings . . . . . . . 2 4. Laminated sand in colors from black to white exposed . 10 "No. 1 represents our Lafayette deposit, and I am inclined to place even the lower members as belonging to an earlier episode of that period. "In a neighboring washout, the red loam has a thickness of ten feet, underlaid by beds of whitish clay from 4 inches to 2 feet thick, intercalated with sand beds. Some of these sands are deep red, and others gray or white; beneath the whole are white sands. This section reaches a total thickness of about 25 feet. "From Fort Valley southward, the level plateau is covered with the red loam of argillaceous texture. West of Winchester, sections of this superficial material are well shown, where about eight feet of orange clayey sand rests upon laminated sands in white and colored bands. Upon the higher plateau, above Montezuma, the red loams prevail; but in descending to the Flint valley, the underlying gray sands form the surface soils. This is true over the lower country about Montezuma, and, indeed, for many miles in the direction of Americus. But the higher hills are everywhere capped with the orange loam. "Along Flint River, many sections of the Lafayette loam are seen form- ing the bottom lands. The best section, in its relation to other rocks, is shown about two miles south of the great bend, in the river in closest prox- imity to Everett station. That section is here given. Feet "1. Orange loam or sandy clay . . . . . . . . 8 2. Light bluish clay with irregular joints stained red 6 3. Orange and gray clayey sand, unconformable above and below . . . . . . . . . . . . . . . . . . . 5-9 4. Coarse light bluish clay, unconformable above and below . . . . . . . . . . . . . . . . . . . ... 3 5. Orange-colored quartz gravel, unconformable above . 10 6. Coarse white sand cemented with clay, exposed . . . 4 "The upper three members and the fourth member represent. two distinct episodes, as shown by the unconformity. At the ferry, between Winchester and Garden Valley, the mantle of orange loam Is well developed, reaching from near the river to the surface of the country 210 feet above it, this occupying alike the hill and the old valley. Here, the deposit is of a more sandy character than adjacent to Fort Valley, and the lower beds are cemented into occasional blocks of ferruginous sandstone." The deep red materials forming the upland surface at Fort Valley and southward to the vicinity of Montezuma are in this report considered of Eocene age, and probably referable to the Claiborne group. The materials on the low plains bordering Flint River from Montezuma up the river to Everett Station are Pleistocene terrace deposits. LAFAYETTE AND COLUMBIA MANTELS IN THE CHATTAHOOCHEE VALLEY "In the vicinity of Columbus, both the Lafayette and Columbia formations are best shown in the railway cut, and in the ravines upon the Alabama side of the river. The upper of these consists of about ten feet of red loam underlaid by from one to four feet of coarse gravel. This formation rests PLIOCENE 387 upon the eroded surface o-f the Tuscaloosa series. The C<>lumbia series rests unconformably upon the older and constitutes the plains at Columbus, which rise about one hundred feet above the river and 260 feet above the sea. This later formation is made up of bluish sand and alluvial clay. kbout five miles south of Columbus, just beyond Upatoi Creek, on the road to Cusseta, there are other fine exposures of the older deposits. Feet "1. Orange loam . . . . . . . . . . . . . . . . . . . . . . 10 2. Laminated, colored sands with a streak of whitish clay; this bed is completely cut through by the valley of an ancient branch about twenty feet wide, which is now filled with the over-lying red or orange loam . 6 3. White and stained clayey coarse sand 8 4. Gray sandy clay . . . . . . . . . . . . . . . 6 "On neighboring hills, the gravels are found at an elevation of about 350 feet above the river, which is two or three miles distant. "At many points along the Chattahoochee River, this orange loam cap- ping is characterized by drift logs at its base; these probably belong to the younger system of deposits, altl;wugh sometimes of a different color trom those at Columbus. "Steward's Hill, six miles north of Georgetown, displays the finest ex posures of the Lafayette series seen anywhere in Georgia. This hill rises 265 feet above the river; the lower 145 feet belong to Cretaceous beds; the overlying 120 feet constitute the Lafayette sand or loam. Feet 1. "First bench of loamy sand, drab or reddish; the lower three inch'es ,cemented with iron 30 2. Second bench, like tqe first, with sandstone cemented at base 10 3. Ditto of a redder color, but at base there are three feet of sandy clay 20 4. Variegated colored laminated clayey sands 40 5. Ditto partially concealed 20 6. Cretaceous deposits . 145 "The lamination is not always well marked. The sands vary from white to red. Through one of the beds there is a layer of coarse pellets, producing a fine conglomerate. In this region, the gravels occur along the sides of valleys tributary to the Chattahoochee, but are not found at Steward's Hill. The gravels appear to be characteristic of the plateau to which Columbus belongs. This condition is shown in the high terrace of Eufaula ( 125 feet above the river), where there is a thick gravel floor. That terrace is bounded on the west by hills covered with Lafayette loam. At Fort Gaines, a similar condition is found. The surface of the same terrace is covered with twenty feet of red clayey sand or loam, the lower part of which is composed of quartz gravel. "The railway cuts east of Georgetown expose excellent sections. "Along the river, about four miles above Columbia, Alabama, a fine exposure of orange loam was seen rising twenty or thirty feet above the river. In this loamy deposit, a piece of gneiss was found, in, size 8 to 6 by 4 inches, and some smaller pieces of mica schist. These transported stones could not have been brought from a point nearer than Columbus, seventyfive miles distant in a straight line. They could not have been transported by waves, but were probably carried southward entangled in the roots of driftwood. "The terrace in the extreme southwest corner of the State, near Chattahoochee village, has approximately the same altitude as at Columbus and Fort Gaines. Its surface and sides are covered, throughout a vertical range, of one hundred feet, with the same orange-colored sandy clay or loam. 388 GEOLOGY OF THE COASTAL PLAIN "From these descriptions, it will be seen that orange-colored or red sandy loam extends througnout the whole length ot the river from the highest altitudes of the country to the pre~:~ent flood plains." The Q.eposits on the plains bordering Chattahoochee River at Columbus, Eufaula, Georgetown, and Fort Gaines are Pleistocene terrace sediments which rest directly upon Cretaceous, Eocene, and Olig_ocene strata. There is question as to the age of some of the gravels on the upland east of Columbus, but since gravel beds are known in both the underlying Lower Oretact;ous beds and in the Eutaw formation of the Upper Cretaceous, it is considered probable that they are all of Cretaceous age. The section at Stewards Hill is referable in its entiretY: to the Ripley formation of the Cretaceous. "LAFAYETTE AND COLUMBIA MANTELS IN THE INTERIOR OF SOUTHWEST GEORGIA "Thrcughout the highlands of Decatur and Thomas counties conditions similar to those along the great rivers prevail. Thus, near Whigham station we see the following section: Feet "1. Orange or red loam passing beneath into a lighter and more clayey layer . . . . . . . . . . . . . . . . . . 4- 8 2. Redish and light colored mottled clayey sand with light patches of clay; only the upper portion is laminated; the lower part is somewhat snarply defined, and in other places apparently passes into . . . . . . . . . . . . . 8 3. Laminated white and purple clay with red micaceous and sandy partings. This bed shows undulations . . . . 3 4. Laminated red sand with clayey partings . : . . . . . 6 "No. 1 belongs to the Columbia and possibly to the No. 2 and No. 3 Lafayette series. In the Attapulgus Creek district, the orange or red loam varies from two to eight feet, and often passes imperceptibly into bluer clay, which occasionally graduates into banded clay. "On the Tnomasvilie road, nine miles east of Bainbridge, the orange loam is conspicuous. There, a rolling hill-country, covered with this red deposit, bounds the sand-covered plains of Bainbridge. In a washout, the lower portion of the loam, which is 8 or 10 feet thi9k, contains irregular pockets of cherty fragments derived from the adjacent rock. At one point, this loam rests upon blue clay. In some localities, this subjacent clay is seen; at others the underlying material is quicksand. The explanation of thrs condition was not obtained until the observation was made in the railway cut about a mile west of Climax, on the road to Bainbridge, showing the following section: Feet "1. Orange or red loam passing below into a red and white clayey material, with some ferruginous con- cretions . . . . . . . . . . .. . . . . . . . . . . . 4-12 2. Laminated sands, in colors from white to black, with clay film partings . . . . . . . . . . . . . . . . . 0-12 At the west end of this section the sand is traversed by two seams of white clayey matter about 8 inches thick. 'It rest upon the eroded surface of 3. Whitish sandy clay . . . . . . . . . . . . . . . . . . 4-8 4. A hand of sand from white to dark red in color with some slightly clayey seams; exposed in places 8 5. Miocene, white sandy clay, exposed . . . . . . . . . tJ-16 PLIOCENE 389 "No. 2 is wanting at the eastern end of the cut, but No. 1 rests upon from 10 to 15 feet of a sandy clay (Miocene) No. 5 which is not exposed at the western end of the section. Two unconformable depostts succeed the Miocene; but the lower of the two is sometimes completely wanting. Thus is explained the occassional absence of the sand, which is so often seen beneath the loam; namely, on account of its entire removal by erosion, before the deposition of the superficial red loam. "In many places, in these southern counties, the orange loam rests directly upon the deposits of apparently Miocene age. On the higher lands, the loam is not covered by any superficial material, but at elevations inferior to 200 feet above the sea, a superficial water washed sand (Columbia series) may be seen, at many places, resting upon the loam. This superficial sand, at the phosphate beds, west of Boston, has a depth of a foot and a half. Throughout the lower arid more level counties of MHchell, Miller, Baker, Dougherty and Calhoun, the loam is apt of itself to be sandy, and covered with a sandy soil, either directly derived from the loam, or perhaps indirectly by the waves acting temporarily in some lagoon, which may formerly have covered these counties. This last explanation appears to be sustained by the presence of duny sand ridges rising to a height of twenty feet, on the east side of the Flint River, opposite Newton. "A further characteristic of this orange or red sandy clay or loam is that its lower portion consists of a bed of gravel, in the vicinity of the ancient valleys. Thus, on the hills, above the last bridge over the Upatoi Creek, the gravel occurs at an elevation of 350 feet above the Chattahoochee River, which is two or three miles distant. These pebbles diminish in importance on going southward, and were not seen near the Florida boundary. But, as if to take their place, fragments of limestone, or in phosphatic regions, pebbles of phosphate occur in portions of the beds. In this way the character of the subjacent rocks is detected by the hillocks being covered with such loose masses, secondarily derived from the drift. "As was noted before, at one or two points along the Chatahoochee, drift boulders from the crystalline rocks far away were found. The same holds true along the Flint and in other regions. This evidence of partial transportation of the material of the loam is not needed to explain its source; for it is generally so charged with hydrated micaceous particles as to at once tell that a considerable portion of it has been derived from the decayed crystalline rocks of Middle Georgia; which had also contained the quartz veins, whence the quartz pebbles, in the gravelly portions of the formation, originated. However, their partial local origin is attested by the presence in many localities of fragments of the subjacent rocks." The deposits in southwestern Georgia referred by Spencer to the Lafayette formation are included in the present report in the Alta- maha formation. In 1898, in connection with his study of the clays of the Fall Line region, Dr. Geo. E. Ladd1 made some observations on supposed Lafay- ette strata, occurring in the Fall Line region. Following the theories advanced by McGee and Spencer, Ladd assumed that the Lafayette formation was a surficial deposit which covered the entire Coastal Plain. "THE COLUMBIA AND LAFAYETTE FORMATIONS" "The formations of the Cretaceous and Tertiary succeed each other, without any long continued land intervals, geologically speaking; and, 1Clays of Georgia : Geol. Survey of Georgia, Bull. No. 6-A, 1898. 390 GEOLOGY OF THE COASTAL PLAIN in spite of the unconformities mentioned, they rest, one on another, in a gen- erally conformable series. At the close of the Miocene Period, however, South Georgia stood for a long time high above the sea, the great rivers carved broad and deep valleys, cutting down, in places, to a depth of 350 feet below the general surface level, for a breadth of several miles, the topogr::p1>1C features of the region becoming pronounced. (p. 88.) "Following this land epoch, however, came a new subsidence, the shore- line moving inland to the present Fall Line, and, in places, somewhat beyond it. During this subsidence, when elevations, now 800 feet above the level of the sea, were washed by its waves, deposits of sand, clay and gravel were spread irregularly, sometimes to the depth of 150 feet like a huge mantle over the hills and valleys, which had been carved out, during the land epoch. The materials of this formation can be found all over southern Georgia. They rest on the hill-tops, on their slopes, and on the floors of the valleys, and greatly interfere with geological research. This formation is known as the Lafayette. (pp. 88-&9.) "After a comparatively brief subsidence, there was re-emergence, when new valleys were cut, often through the Lafayette, and penetrating the underlying strata. Then took place a final submergence and a deposition of the superficial sands and gravels, which make up Columbia formati-on. The Columbia and Lafayette formations are unconformable with reference to each other; they also lie unconformably upon the Tertiary and Cretace- ous strata; and along the margin of the Coastal Plain even upon the crys- tallines of the Piedmont Plateau. * * * (p. 89.) "The Lafayette gravels are Ctlaracterized by cross bedding, rapid trans- ition from coarse to fine material, and generally, by a deep-red color, result- ing from the oxidation of iron-bearing material. It frequently has a mot- tled appearance which is noticeable in the sides of gullies and cuts. The pre- vailing red color is frequently broken by a net-work of gray and blue tints, which mark the former position of the roots of trees and shrubs where the iron oxide has been "reduced" by the organic compounds resulting from their decay." (p. 90.) Ladd states that Rich Hill, Crawford County, is capped with Lafayette strata (p. 91). As previously stated, the red materials on this hill are probably of Eocene age. "Tne Fall Line crosses the Ocmulgee River beneath the Macon footbridge; and here are exposed boulders and outcropping ledges of the hard Piedmont crystallines. Overlying them are the Columbia terraces; and east and west mounting over, but capping, the Tertiary heights are the white, red and orange gravels and sands of the Lafayette. (p. 101.) The thought expressed is that the terrace materials belong to the Columbia division of McGee, and that the Lafayette formation is confined to the heights and rests upon Tertiary strata. As previously stated, the gravels and red loams on the upland at Macon overlie Cretaceous strata and probably belong to the Claiborne group of the Eocene. Gravel deposits occurring at Vineville and at Rutley [Rutland] are referred by Ladd to the Lafayette formation (pp. 102, 103). In the present report these are considered terrace deposits belonging to the Okefenokee formation (Pleistocene). Ladd also described sands and gravels which he considered referable to the Lafayette formation, at Griswoldville, Jones Count; PLIOCENE 391 (p. 106); at Gordon; at Mcintyre, Wilkinson County (pp. 120, 130) ; at Stevens Pottery, Baldwin County (pp. 138, 139) ; at Chalker, Washington County (p. 151); and near Belair, Richmond County (p. 161). These materials are said to form mantles over Cretaceous or Tertiary strata, or over both. After having studied many exposures in this region the present writers have reached the conclusion that Ladd has mistaken for the I~afayette formation both Eocene and Cretaceous. strata in place, and the residual creep materials derived from these strata. This opinion is based partly upon paleontologic evidence and partly upon the lithologic resemblances of the supposed Lafayette materials to the Eocene and Cretaceous strata of the region. R. :M. Harper' has discussed the occurrence of supposed Lafayette deposits in Georgia as follows: "When moroughly decomposed by atmospheric agencies the Grit can often hardly be distinguished from the Lafayette loam, and in railroad cuts and other artificial. excavations which exposes the indurated Grit it is sometimes impossible to say whether there is any Lafayette above it or not. "The Lafayette probably covers more than 99 per cent. of the Altamaha Grit region, but its presence cannot easily be proved, for the reason just stated, and also because neither it nor the Grit is fossiliferous. Little if anything is known as to its maximum thickness in this region. In composition it is a loam, containing probably as much sand as clay. Farther inland it is often ,brick-red, but in the Altamaha Grit region, and in pinebarrens generally, its color is considerably lighter and might be described as terracotta." Although assuming that the Lafayette formation is present as a surficial covering over practically all of the Altamaha reg~on, Harper admits that "its presence can not ellsily be proved." The present writers have not been able to differentiate any surficial formation .other than residual gray sands and the Pleistocene deposits which along the rivers and towards the coast rest upon the Altamaha beds as terrace accumulations. In their opinion the loams referred to the Lafayette formation by Harper are the weathered residual products of the Altamaha strata. The following description of the Lafayette is given by Professor :McCallie:' "Lafayette.-The Lafayette, whose exact position in the geologic time scale is still debated, like the Columbia formation, is a superficial deposit, covering most of the Coastal Plain. The formation consists of orange and vari-colored clays and sands, with local beds of gravel. The basal member of the formation along the Fall Line frequently becomes distinctly pebbly. These water-worn pebbles, which consist largely of quartz derived from the crystalline rocks to the north, occur irregularly distributed throughout the 'Annals New York Acad. Sci., Vol, 71. pt. 1, 1906. p. 23. 2Geol. Survey of Ga., Bull. 15. 1908, p. 30. 392 GEOLOGY OF THE OOASTAL PLAIN Vll.ri-colored sandy clays, but more often they are found in layers or pockets. They also occur in the basal member, at places, with fragments of white clay forming more or less continuous layers. These phases of the lower di- vision of the formation become less pronounced in the southern part of the State, where sandy loam and vari-colored stratified clays predominate. "The upper member of the formation differs from the lower in being more uniform, both in physical structure and lithological character. Along the Fall Line, at some points, it becomes quite pebbly; however, as a general rule, it is made up almost entirely of massive reddish or motley sandy clays. Frequently, the massive clays of the upper division are hardened into a com- pact mass, having almost the consistency of sandstone. This indurated layer resists the erosive action of surface water; and, by being undermined by the washing away of the layers below, it often stands out in high, perpendic- ular walls. Excellent illustrations of this mode of erosion are frequently met with in the vicinity of streams, which have lowered their channels into the underlying formations. "The thickness of the Lafayette formation is quite variable. At some places, near the northern margin, where it has been protected by the Colum- bia sands, it attains a maximum thickness of more than 80 feet; at other points, it has been entirely removed by erosion. These eroded areas are quite irregular in outline, and may occur at any point throughout the Coastal Plain. They are more frequently met with, however, in the vicinity of the larger streams; yet, they are not entirely absent from the level piney woods." Following McGee. and others, McCallie has referred to the Lafayette formation deposits both older and younger than Pliocene. In the opinion of the writers the existence of the so-called Lafayette formation in Georgia has not been proven. Assuming the terrane to be of Pliocene age, it is probable that at least a part of the lbeds referred in this report to the Altamaha formation are synchronous with it. Other than these the formation probably has no representatives in Georgia. CHARLTON FORMATION The name Charlton is derived from Charlton County Ga., and is applied to an argillaceou5 limestone and clay formation exposed in the banks and bluffs of St. Marys River, from Stokes Ferry, 11 miles ~:>outh of St. George, Charlton County, Ga., to Orange Bluff, near Kings Ferry, Fla. This formation, however, may also occur on the Satilla River' and the probability of limestone beds at Burnt Fort, 12 miles northeast of Folkston being equivalent, has been mentioned on a preceding page. From a study of the fossil collections from St. Marys localities, Dr. Vaughan has classified the formation as probably of Pliocene age. In previous publications there are a few scattered references to the formations exposed along St. Marys River, but the authors have w. lNOTEI.-A fossiliferous l!md of M.. Thrift, six of the marl on St. Marys marl has recently been found near the Satilla River, on miles east of Winokur, River and is of probable Charlton Pliocene Coul).ty. It or Mwcene argesee.m-0bl.esv.s the ome GEOLOGY OF 7'BE OOA T A L PL.H 1\" OF GFJO IWf.! PLA7'B XXV II. C HARLTO~ FORllA'.fJON. . T. :\IAH Y!': RIYER. AT A. C. L . R. R. BRIDGE , THREE MILE 0 THEA '1' OF FOLK TON. CHARLTON COUNTY, GA. PLIOOENE 393 made little or no attempt at correlation. The relations of the Charlton formation to other formations on St. Marys River are graphically shown in the profile, fig. 4, page 47. The relations of the Charlton formation to the Miocene are not definitely known. At Stokes Ferry, the top of the formation is perhaps 30 or 35 feet above sea level, and it descends gradually do\\n stream, reaching tide level. According to the geological m2p of Florida by Matson and Clapp' the Jacksonville formation (Mioc{lne) outcrops at elevations of 50 to 100 feet above sea level, n short distance south and east of St. Marys River. Beds, from which Dr. Vaughan has identified Miocene fossils, are exposed at low tide at Owens Ferry, Satilla River, Camden County, Ga. In view of these vccurrences of Miocene the Pliocene beds on St. Marys River, if correctly correlated, may occupy an erosion basin in Miocene strata, or, if the latter are absent beneath them, th~y may rest in a similar basin in pre-Miocene strata probably referable to the Alum Bluff formation (Oligocene). The great thickness' attributed to the Miocene at Jacksonville, 460 :eet, and the fact that the Miocene there is supposed to lie unconformably upon the Vicksburg, makes the former alternative seem the more probable one. There are no data for estimating the thickness of the formation; only 12 or 15 feet have been observed in natural exposures. The strata are poorly fossiliferous, and it is difficult to correlate the beds on the basis of their fos'Sil contents. The formation is characterized at two or three localities by an abundance of ostracods. All of the fossils which have been identified from the formation are given on succeeding pages. Regarding the age of the formation, Dr. Vaughan, in unpublished notes, says: "None of the material [fossils] between Hicks Bluff and Orange Bluff can be older than Pliocene, and although not a single extinct species was collected, it may be Pliocene. The two species of ostracods listed by Doctor Bassler from Rand Landing and Clay Landing appear to be recent. As the material from Stokes Ferry seems to be the same as that from Rand and Clay landing it is probably of the same age. [Pliocene.]" LOCAL DE!T:AILS ST. MARYS RIVER. Stokes Ferry.-The point farthest up St. Marys River at which hard rock of the Charlton formation appears is at Stokes Ferry, 11 miles south of St. George, Ga. The exposure is in a low bluff on the F~orida side, about 100 yards below the ferry. Orange-colored loam 'Second Ann. Rept., Geol. Survey of Florida, 1909. 2Idem. 394 GEOLOGY OF THE COASTAL PLAIN overlain by gray sand appears in an escarpment a short distance back from the river at a higher level than the strata described in the following section: Section at Stokes Ferry Pleistocene Feet Satilla formation. 4. Dark colored sand; contains vegetr ble matter; thickness variable . . . . . . . . . . . . . . . . . . . . . . . 4 3. Coarse, greenish, argillaceous sand, Line of rounded, flat, or discoidal quartz pevoles, some as much as two inches in diameter, along base . . . . . . . . . . . . 2 (Uncrmformity) Pliocene ? Charlton formation. 2. Greenish or urab, stiff, tenacious clay containing calcar- eous concretions; ostracods and some phosphatic parti- cles, maximum . . . . . . . . . . . . . . . . . . . 4 to 5 1. Limestone containing ostracods, small gastropods, and casts of small bivalves . . . . . . . . . . . . . 1 The limestone at the base is a hard, spongy, or cellular, siliceous rock; about one foot is exposed at low stages of the river. Beds Nos. 1 and 2 appear for about 150 or 200 feet along the river bank beyond which they are replaced by the more recent Pleistocene. Loose fragments of bones and mammal teeth were found here, and from their position on the slopes of the bluff it is inferred that they came either from bed No. 2 or bed No. 3. Hicks Bluff.-Except at one point only late Pleistocene sands and clays are exposed at this locality; however, the orange-colored, argillaceous sands, which in this region overlie the Charlton formation, appear in an escarpment leading to the higher land about 300 yards back from the river. Section a.t Hicks Bluff. Pleistocene. Satilla formation. 3. Dark-colored, thin line of quartz p,eobles at base . (Unconformity) Pliocene ? Charlton formation. 2. Greenish, sticky, sandy clay, maximum . . . . . . 1. Soft, argillaceous, fossiliferous limestone; contains Pecten gibbus, Phacoides multilineatus and Laevicardium, maximum thickness . . . . . . . . . Feet. 3 to 10 4 4 The limestone and clay appear as a small erosion dome covered by late Pleistocene sand. The limestone is richer in fossils than at any other locality on the nver. A few fragments of bones and mammal teeth were found. PLIOCENE 395 No exposures of hard rock are known between Hicks Bluff and Red Bluff. Red Bluff.-The section at Red Bluff on the Florida side of the river, two miles east of St. George, Ga;, is described as follows: Section at Red Bluff. Pleistocene? 4. Partly concealed, and in part gray sand . 3. Vari-colored sand Pliocene ? Charlton formation. 2. Drab, sandy clay . . . . . . . 1. Sandy, fossiliferous limestone Feet 10 26 7 1.5 From the limestone bed Dr. Vaughan has identified the following fossils : Fossils from limestone bed at Red Bluff. Leda acuta Conrad. Barbatia marylandica Conrad. Area umbonata Lamarck. Pecten sp. Lithophaga sp. Phacoides or Diplodonta. Schoolhouse Blnff.-A section similar to the preceding is exposed' at Schoolhouse Bluff, about four miles below the Georgia Southern and Florida Railroad bridge, and one mile below old Drewry Ferry. Sect1:on at Schoolhouse Bluff. Pleistocene. Feet. In. 7. Gray or white sand at top of blufl' . . 4 to 5 6. Orange-colored, argillaceous sand with clay at the base, and beneath the clay a thin line of small quartz pebbles . . . . . . . . . . . 12 " 1o Pliocene ? Charlton formation. 5. Greenish, fine-gra:ined, sticky clay . . . . . . 3 4. Soft limestone, and siliceous, fossiliferous ma- terial with ostracods and Rangia cuneata . 1 3. White, calcareous clay . . . . . . . . . . . 3 2. Hard, earthy, argillaceous limestone . . . . v 4 1. Chalky, argillaceous limestone with small gas- tropods . . . . . . . . . . . . . . . . . 2 6 Ramd Landing.-This bluff is located about two miles below the old Drewry Ferry, and about five miles, by land, below the Georgia Southern and Florida Railroad bridge. Section at Rand Landing. Pleistocene? Feet ln. 12. Poorly exposed orange-coloreu argillaceous sand; line of small quartz pebbles along base . . . . . . . . . . . . . . . . . . 20 396 GEOLOGY OF THE OOASTAL PLAIN Pliocene ? Charlton formation. Feet. In. 11. Clay ( ?) . . . . . . . . . . . . . . . . . } 10. Thin, nodular, limestone layer . . . . 4 to 5 9. Greenish clay . . . . . . . . . . . . . . 8. White and greenish laminated clay with poor- ly preserved prints of fossils . . . . . . . 0 4 7. Greenish, laminated clay . . . . . . . . . 1 6 6. Cream-colored, argillaceous limestone . . . 0 6 5. White, calcareous clay . . . . . . . . 2 4. Soft calcareous material containing ostra- cods, Bythocypris, Oytherella . . . 1 3. Limestone, non-fossiliferous . . . . . 0 10 2. White, calcareous clay . . . . . . . . 2 1. Rather hard, argillaceous limestone . 2 10 Stratum No. 1 is apparently arched into a small anticline. It appears at the water's edge at two points about 100 yards apart, and halfway between these two points it rises about three feet above the water. Clay Landing.-This bluff is on the Florida side of the river and about one and one-half miles northeast of Toledo, Ga. Section at Clay Landing. Pleistocene ( ?) . 5. Slope covered by gray sand; underlying strata probably orange-colored, argillaceous sand . . . . . Pliocene ? Charlton formation. 4. Contact with the above not exposed. Greenish, f.negrained, sticky or plastic clay containing small, calcareous nodules,-exposed . . . . . . . . . 3. White clay . . . . . . . . . . . . . . . . . . . 2. Soft, friable, calcareous, sandy clay or marl; contains ostracods, poor casts and prints of mollusks, fish teeth and fish vertebrae . . . . . . . 1. White, hard, argillaceous limestone, no fossils . . Feet 15 to 20 5 2 3 1 Two ostracods, Bythocypris sp. and Cytherella sp. have been identified from bed No. 2. According to Dr. R. S. Bassler these species are either Recent or close to Recent species. Nettles Landing.-There is a high bluff at an old log slide one and one-half miles by land above Cow Ford. The strata are not very well exposed. Section at Nettles Landing. Pleistocene? 11. White, surficial, quartz sand at top of bluff 10. Not well exposed, slope covered with white sand; probably an orange-colored, argillaceous sand underlies the surface, line of small, well-rounded Feet 3 or 4 PLIOCENE 397 quartz pebbles at base from which springs emerge ........... Pliocene ? Charlton formation? 9. Poorly exposed, plastic, greenish, fine-grained clay 8. Concealed . . . . . . . . . . . . . . . . . . . . Charlton formation. 7. Thin layer of hard, argillaceous limestone, probably but a few inches thick . . . . . . . . . . . . 6. Clay . . . . . . . . . . . . . . . . . . . . . . . 5. Thi~s~~:es~o~e .l~y~r. ":it~ .a .few p.o~r .p~i~ts. ~ } 4. Drab, laminated clay . . . . . . . . . . . . . } 3. Soft, sandy, argillaceous limestone, Modiolus, Oy therea?, Rangia . . . . . . . . . . . . . . . 2. White, hard limestone-no fossils . . . . . . . 1. Earthy, compact limestone . . . . . . . . . . . Feet 15 to 20 3 5 ? 4 2 5 Stratum No. 11 is a part of the gray or white surficial sand covering the upland plain. The river at this point impinges against the scarp of the Okefenokee plain or plateau, and the late Pleistocene or Satilla terrace deposits do not appear, which accounts for the difference in the height of this bluff as compared with the bluffs at Sawpit Landing and Cow Ford. Stratum No. 10 is probably the equivalent of the upper parts of the bluffs at Calico Hill and near Folkston. Cow Ford.-The next exposure of the argillaceous marl or limestone of the Charlton formation appears in the right bank of the river about one-half mile below Cow Ford and nine miles south of Folkston. Section at Cow Ford. Pleistocene or Recent. 4. Dark or chocolate-colored sand, white at the sur- face . . . . . . . . . . . . . . . . . . . Pliocene? Charlton formation. 3. Plastic, sandy clay . . . . . . . . . . . . . . } 2. Soft, yellow, argillaceous limestone; contains poorly preserved fossils-Modiolus, Pnacoiaes Oaraitamera sp. . . . . . . . . . . . . . . . 1. White, laminated, fine-grained clay . . . . . . Feet 5 4 The lowest Pleistocene terrace, which at this point IS a palmetto "flatwoods," is about three-fourths of a mile wide. It lies 10 to 15 feet above low water; at its inner margin there is an abrupt rise of about 30 or 40 feet from this lower plain to the upland plain. 398 GEOLOGY OF THE COASTAL PLAIN Sawpit Landing.-Calcareous clay and chalky limestone are exposed at this locality, two miles by the river above the ferry at ' Traders Hill. Section at Sawpit Landing. Feet In. Pleistocene. Satilla formation. 8. Stiff, greenish clay 3 (Unconformity) Pliocene? Charlton formation. 7. White, calcareous clay 1 6. Calcareous sand and sandy limestone 0 6 5. soft, white, calcareous clay, fossiliferous; con- tains Leda, probably acuta, Pecten g2bbus, Anomia simplex, Phacoides or Diplodonta, Tel- lina sp. 1 4. White or yellow limestone 1 3. Greenish clay . 1 2. Drab, calcareous clay 2 1. Soft, gray or white, chalky limestone or marl at low tide 2 Bed R o. 8 is considered Pleistocene in age; the clay forms a flat terrace about one mile wide bordering the river. Folkston.-A good exposure occurs three miles southeast of Folkston on the Florida side of the river at the end of the new bridge of the Atlantic Coast Line Railroad. The section in detail is as follows: Section of bluff on St. Marys River, at end of railroad bridge, three miles southeast of Folkston. Feet ln. Pleistocene ? 24. At top-gray, fine, incoherent, quartz sand . 2 (Unconformity) 23. Mottled clay and sand 22. Stiff, plastic clay 4 6 3 6 21. Orange-yellow, clayey sand 5 6 20. Yellow sand 4 19. Drab, sandy clay 4 18. Yellow sand 2 6 17. Greenish, stiff, sandy clay with line of quartz peb bles at base (Unconformity) 4 6 Pliocene? Charlton formation. 16. Greenish, laminated clay 1 15. White limestone layer 14. Drab, calcareous clay 0 4 0 8 13. Limestone 0 3 12. Drab clay 0 6 11. Greenish, laminated clay 1 6 10. Gray, fossiliferous, sandy clay or phosphatic marl; Pecten gibbus 1 PLIOCENE 399 Feet. In. 9. Thin layer of compact, argillaceous limestone . . 1 8. Green or drab, highly fossiliferous clay, ostracods and clay casts of fossils . . . 2 6 7. Limestone . . . . . . . . . . . 0 3 6. Green, fossiliferous clay, Pecten 1 5. Limestone . . . . . . . . . . . 0 6 4. Clay . . . . . . . . . . . . . . 0 4 3. White limestone . . . . . . . 0 6 2. Laminated, fossiliferous clay : 2 6 1. White, argillaceous limestone . 0 6 The beds from 17 to 23 inclusive lie horizontally, and are probably of Pleistocene age; from 1 to 16 the strata belong to the Charlton formation. These beds have been disturbed from their original positions and dip northward 30 to 45 degrees. Bed No. 24, the surficial sand which covers the flat, upland plain reaches a thickness of eight feet or more, and is sharply defined from the underlying, red, argillaceous sand, being quite different in lithologic appearance; it is, therefore, considered a later deposition. About 50 yards east of the bridge there is a friable, coquina-like layer, possibly the equivalent of No. 10 of the aboYc section. Of the fossils collected from the Charlton formation at this locality Dr. Vaughan has identified the following : Fossils from the Charlton formation three miles southeast of Folkston. Pecten gibbus Linnaeus Anomia simplex d'Orbigny Rangia cuneata (Gray) . Limestone or marl is reported at the base of the bluff at Calicc, Hill, two miles below the bridge; when visited this was not exp0sed. The bluff or hill is about 40 feet high and the strata exposed are the equivalents of the upper 30 feet of the section at the railroad b"!"itlge, with the possible exception of the bluish, fine-grained, plastic clay seen near the base of the hill. Bet\veen the preceding exposure and Chalk Bluff, a section of which is given below, only late Pleistocene sand and clay appea1 }n tl,c river banks. Cha,lk Bluff.-This locality is about one-half mile above Orange Bluff, described below, and exhibits a similar succession of strata. Section at Chalk Bluff. Feet In Pleistocene. Satilla formation. 5. Bluish or greenish, fine-grained, plastic, sandy clay 2 400 GEOLOGY OF THE COASTAL PLAIN Pliocene? Charlton formation. Feet In. 4. Stiff, white, chalky or calcareous clay, thin layers of limestone . . . . . . . . . 2 6 3. Greenish or drab, fullers earth-like clay . . 1 2. White, chalky clay . . . . . . . . . . . 2 1. Sticky, greenish, calcareous clay . . . 1 Stratum No. 5 underlies a flatwoods terrace, as at Orange Bluff. Poorly preserved fossils occur in the lower part of the bluff. A Pecten and probably a Modiolus were identified. Orange Bluff.-This bluff is on the Florida side of St. Marys River, about two miles above Kings Ferry, Fla. It is a low blnff,about 10 feet high at low tide. The fossiliferous limestone of the Charlton formation is not exposed on the river below this point: Section at Orange Bluff. Feet In Pleistocene Satilla formation. vard by streams. The source of the material was probably mainly from the Piedmont region, but there is evidence that the older Coastal Plain formations furnished a share of the detritus. LOCAL DETAILS The details concerning lithologic character, stratigraphic relations, etc., from which the general conclusions preceding were drawn, are given in the following sections and descriptions: ALTAMAHA RIYER The characteristic, lithologic features of the formation, its relation to the underlying Alum Bluff formation, and questionably, its relation to the Miocene, are exhibited in the bluff exposures on Altamaha River. The sections exposed at Grays Landing, 11 miles below the Fo1ks are: Section at Upper Bluff, Grays Landing. Pleistocene ? 7. At top, thin veneer of gray sand and gravel . . Pliocene ? Altamaha (Lafayette?) formation. 6. Characteristically mottled, argillaceous sand . 5. Massive bed of gray, feldspathic sandstone or grit Oligocene. Alum Bluff formation. 4. Gray argillaceous sand . . . . . . . . . . . . . 3. Interstratified sand and clay; clay layers a few inches thick; the sand has the appearance of the Alum Bluff sand in the southwestern part of the State . . . . . . . . . . . . . . . . . . . . . 2. White, minutely jointly, fullers earth, contains round, siliceous concretions . . . . . . . . . . 1. Semi-indurated, greenish argillaceous sand . . . . Feet 8 to 15 15 6 10 2 to 12 2 Section at Lower Bluff, Grays Landing. Pleistocene ? 9. Gray sand and gravel at the top, forms a , thin veneer over the surface . Pliocene? Altamaha (Lafayette ?) formation. 8. Mottled, argillaceous sand . 8 7. Sandstone and gray sand . 20 (Unconformity) Oligocene. Alum Bluff formation. 6. Fullers earth-like clay and sand . , 6 5. Greenish argillaceous sand . . . . 5 4. Greenish day . . . . . . . . . . . 2 3. Massive sand, containing thin clay layers 6 2. White fullers earth . . . . . . 6 1. Greenish, rather comnact sand . . 1 410 GEOLOGY OF THE COASTAL PLAIN The massive Altamaha sandstone or grit also appears at Fail-inRock, 18-mile post, and at Piney Bluff, at the 20-mile post. Section at Fall-in-Rock Bluff. 3. At top, reddisa sand . . . . . . . . . . . . 2. Massive bed of gray or greenish sandstone, forms a projecting ledge and a precipitous bluff . . . 1. Greenish and gray clay and sand, softer than the above rock . . . . . . . . . . . . . . . . . . Feet 25 10 It is probable that layer No. 2 belongs to the Altamaha formation; however, no unconformity appears between 1 and 2 and there are no fossils or other conclusive evidence of the age of the strata. Section at Lower End of Piney Bluff. Pliocene? Altamaha (Lafayette?) formation 3. Abrupt bluff of greenish or gray, massive sandstone or grit . . . ............. . Oligocene. Alum Bluff formation. 2. Compact, gray sand . . . . . . . . . . . . . . . 1. Sandy, fullers earth-like clay; no fossils, but ap- pears similar to the Alum Bluff deposits of soutnwestern Georgia . . . . . . . . . . . . Feet 25 3 ( ?) 6 At Tillmans Ferry, 36 miles below the Forks, the entire bluff is made up of the Altamaha formation. The bluff is 65 feet high; the lower 35 feet is more or less indurated, and is a coarse feldspathic grit; the rock above is not well exposed and the upper slope is covered with sand and gravel and a few sandstone projections appear. The sandstone is conglomeratic in places and pebbles threefourths of an inch in diameter were noted. Nothing resembling typical Alum Bluff materials appear. Lower Sister Bluff, at the 49th mile-post, presents fine exposures. The lower, softer strata are carv:ed into .a "bad-lands" type of erosion and the bluff is the most picturesque on the river. Section at Lower Sister Bluff Pliocene ? Altamaha (Lafayette?) formation 7. Beginning at the top, mottled grit . . . . . . . 6. Drab and greenish, friable aluminous sandstone . 5. Coarse grained, pebbly grit . . . . . . . . . . . (Unconformity.) Oligocene. Alum Bluff formation. 4. Greenish, argillaceous sand, finer in texture than the above ....... . Feet. 10 8 22 8 PLIOCENE 411 3. Drab, sandy clay . . . . . . . . . . . . . . . . 2. White sand, thin clay 1ayers . . . . . . . . . . 1. G;reenish and drab, compact, aluminous sand, finer in texture than No. 2. Laminated clay at the base . . . . . . . . . . . . . . . . . . . . . Feet. 10 3 25 Proof that the strata in the upper and lower parts of the bluff are of different ages is not as patent as is desirable, for the beds exhibit no striking lithologic differences, and no fossilE> were found. However, at the upper bluffs, one mile above, there is better evidence of an unconformity. The upper portions of the sections at Fort James (58th milepost), have the characteristic appearance of the Altamaha formation but here again there is some uncertainty about the age of the beds. Section at Upper Fort James Bluff Pliocene? Altamaha (Lafayette ?) formation 6. At top, pebbly mottled, argillaceous sand 5. Coarse, mottled grit . . . . . . 4. Greenish sandy clay . . . . . . . . . 3. Sandstone . . . . . . . . . . . . . 2. Semi-indurated aluminous grit . . . (Unconformity) Oligocene. Alum Bluff formation. 1. Greenish compact clay and sand mixture, perhaps finer in texture than the beds above . . . . . Feet 30 12 2% 6 4 25 Section of Lower Fort James Bluff. Pliocene ? Altamaha (Lafayette ?) formation 5. Beginning at the top, mottled sand not well exposed . . . . . . . . . . . . . . . . . . . . . 4. Coarse, gray grit . . . . . .. . . . . . . . . . . 3. Greenish or gray fine argillaceous sand, compact, massive .... 2. Sandstone or grit . . . . . . . . . . . . . . . . Oligocene Alum Bluff formation ? 1. Fine-grained, greenish, argillaceous sand . . . . . Feet 30 12 7 2% 20 At Oglethorpe Bluff (69th mile-post), the indurated phase of the Altamaha does not appear, and the formation is represented by varicolored sand and by thin lenses of clay. Section at Oglethorpe Bluff. Pliocene ? Altamaha (Lafayette?) formation. 6. Beginning at the top, red and yellow sand; contains some clay and is mottled in the upper part 5. Clay layer . . . . . . . . . . . . 4. Yellow and white crossbedded sand . . . . . . . Feet 18 2 25 412 GEOLOGY OF THE COASTAL PLAIN 3. Purplish clay lens . . . . . . . . . . . . . . . . 2. Coarse-grained, crossbedded, arkosic sand, feldspar and angular quartz gravel . . . . . . . . . . Oligocene (Unconformity) Alum Bluff formation ? 1. Greenish, compact argillaceous sand, no fossils . Feet. 5 20 15 (max.) Section at Linden Blufr 73 Mile-post. Pliocene ? Altamaha (Lafayette?) formation 6. Mottled argillaceous sand (top of section) 5. vVhite, coarse, to very coarse sand with some gravel at the base . . . . . (Unconformity J Miocene? 4. White and yellow sandy clay . . 3. Black silty clay . 2. Quartz pebbles in a matrix of bluish sandy clay (Unconformity.) Oligocene? Alum Bluff formation ? 1. Greenish compact argillaceous sana Feet. 12 25 2 5 5 18 The beds which are marked questionably Miocf!ne, occupy the same position in the section as the fossiliferous Miocene bed at the next bluff below,-Bugs Bluff. The lowest bed is referred to the Alum Bluff formation on the basis of the unconformity. Bugs Bluff is nearly a mile in length; the section given is at the lower end of the bluff, and is one mile by land from Doctortown. Section at lower end of Bugs Bluff. Pleistocene 7. Gray sand, capping bluff . . . . . . . . . . . . Pliocene? Altamaha (Lafayette?) formation? 6. Mottled, argillaceous sand . . . . . . . . 5. Coarse, white crossbedded sand, becomes coarser and p~bbly at the base . . . . . Miocene Duplin marl 4. Faintly laminated, yellow and white sandy clay 3. Bluish mud . . . . . . . . . . . . . . . . . . 2. Shell and pebble conglomerate, contains Pecten eboreus, Mytilus conradinus . . . . . . . . . (Unconformity) Oligocene? Alum Bluff formation ? 1. Greenish, compact, argillaceous sand . . . . . . Feet 2 10 28 5.! 6.! 1.! 10 PLIOCENE 413 Section at Doctortown Pliocene ? Altamaha formation ? 6. Yellow and mottled argillaceous sand, has the typical surface aspect of the Altamaha . . . . o. White and yelow crossbedded sand containing thin layers of small quartz pebbles . . . . . . 4. Red and yellow sand containing thin clay laminae Miocene. Duplin marl 3. Calcareous fossiliferous sand or sandy friable marl . . . . . . . . . . . . . . . . . . . . . 2. Bluish sand containing the Miocene fossils, Pecten eboreus, Mactra congesta . . . . . . . . . . . (Unconformity) Oligocene? Alum Bluff formation ? 1. Coarse, bluish or greenish compact clayey sand to water's edge Feet. 10 10 10 1 4 7 The Sansavilla bluffs, 27 and 28Yz mil,es, respectively, below Doc- tortown, are the last high bluffs on the river. Paleontologic evidence of the age of the beds is lacking ; the succession of beds is similar to that at Doctortown and Bugs Bluff. Section at Upper Sansavilla Bluff Pleistocene Okefenokee formation 3. Fine, brown and white quartz sand, covering a terrace plain Pliocene ? Altamaha formation ? 2. Bluish-gray sand, interstatlfied with white, thinly laminated clay; the clay layers contain small bits of plant remains . . 0 0 Miocene or Oligocene ? 1. Bluish, compact, argillaceous sand . . . . Feet. 30 5( ?) Section at Lower Sansavilla Bluff. Pleistocene. Okefenokee formation. 8. Fine brown and white, incoherent quartz sand . 10 Pliocene ? Altamaha formation ? 7o 6. W W~h\~iteey ccll~ayy.eyl~ys~ar:nd~n..e-.~r.~i.~e.~.ot.~i.~l~0 l0oa ~i ~~ te : ~ 5. Sand 0 0 0 0 0 0 0 0 18 4. Thin clay layer . 0 o. . . . . . . oo. . . a. Argillaceous sand . . . . o . 0 0 0 2. Clay, fullers earth-like . . o . . . 0 o o o . . Miocene or Oligocene ? 1. Coarse, crossbedded compact, argillaceous sand . 8 414 GEOLOGY OF THE COASTAL PLAIN EAST AND NORTH OF ALTAMAHA RIVER On the Macon, Dublin, and Savannah Railroad, between Vidalia and Dublin, various lithologic phases appear in the cuts. The formation near the surface is an orange yellow loam, beneath which is a mottled, argillaceous sand splotched with red, yellow, white, and purple. Crossbedded sands and local beds of gravel appear, and at anumber of places are drab claystones and gray, aluminous sandstones. The formation is uniformly overlain by a gray, incoherent sand, from two to six feet thick. A bed of coarse gravel consisting of pebbles and cobbles was noted in a railroad cut on the east side of Ohoopee River, two miles east of Adrian. Section in railroad cut two miles east of Adrian. Altamaha formation 4. Gray, incoherent sand . . . . . . . . . . . . . 3. Yellow, argillaceous sand . . . . . . . . . . . 2. Gravel bed, maximum thickness . . . . . . . . 1. Coarse, gritty clay and argillaceous sandstone, typical Altamaha . . . . . . . . . . . . . . Feet b 3 2.5 12 The gravel bed is not a persistent layer and soon thins out, proving that it is merely a lens in the Altamaha (Lafayette ?) formation. The pebbles are mostly quartz, but a few pebbles of decomposed feldspar and vitreous flint, which has the appearnce of Vicksburg flint, occur; unlike most of the Altamaha gravel the pebbles are smooth, well rounded, and of large size, some three or four inches in their longest diameter. The lower bed contains coarse fragments of crystalline quartz in which flakes of mica occasionally occur. This is evidence that the detritus was derived directly from the Piedmont Plain. Characteristic phases of the Altamaha formation occur at Stillmore, Emanuel County. The surface is covered with small, brown, iron oxide concretions about the size of buckshot, and the weathered part of the formation presents a mottled or "calico" appearance. The best exposure appears in the deep cut of the Central of Georgia Railway within the town limits. Section at Stillmore. Altamaha formation? 7. Gray sand residual . . . . . . . . . . . . . . . 6. Yellow loam, presenting a mottled or "calico" ap- pearance . . . . . . . . . . . . . . . . . . . 5. Yellow and drab clay layer . . . . . . . . . . 4. Mottled purplish and gray argillaceous sand . . 3. Greenish sand, containing a small amount of clay 2. Drab, "stickey", sandy clay . . . . . . . . . . 1. Aluminous grit or sandstone . . . . . . . . . . Feet 2% 6 2 3 3% 3% 2 PLIOOENE 415 At Ohoopee station, Toombs County, there is a cut about 25 feet deep in which the sands and clay beds exhibit local unconformities. On the south side of Pendleton's Creek, two miles south of Ohoopee, there is a rough, craggy bluff of Altamaha sandstone, 15 feet high. The rock is made up principally of sharp quartz sand and a small amount of disseminated clay, and is similar to the sandstone at other localities. No fossils occur. At the Jack Williams cut, four miles west of Collins, typical clay and aluminous grit are exposed. In a cut of the Seaboard Air L.ine Railway three-quarters of a mile west of the station at Collins, Tattnall County, purplish sand and gravel layers are overlain by orange-colored, sandy loam. The locality is of interest since fragments of oyster shells, which could not be specifically identified, were found in a gravel layer 10 feet from the top of the cut. These shells may have been transported with the gravel. This is the only locality in this formation where fossil animal remains have been found. The pebbles are small, not exceeding an inch in length or diameter, angular or E>Ubangnlar, and consist principally of quartz with a small percentage of decomposed feld.spar. Grits and claystones, similar to those described above, outcrop on the farm of Dr. Donaldson, on Lott Creek, one mile northeast of Register. There is a rugged bluff 10 feet high; the rock is fine- grained, and the cementing substance is opaline silica; parts of the sandE>tone are quartzitic, as at some other localties, although this is n not a charactertistic phase. It can not always be certainly deter- mined whether such materials belong to the Altamaha (Lafayette formation or to the Alum Bluff formation. At Ludowici, Liberty County, coarse, mottled sands with thin lay- .ers of clay appear in a cut at the factory of the Ludowici Roofing Tile Company. These sands and clays resemble the materials of the Altamaha (Lafayette ?) formation. Red sands resembling Altamaha materials were noted beneath the Pleistocene gray sands between Darien Junction and Ludowici, and also beneath the gray sands between Darien Junction and Darien. At Waynesboro and Greens Cut, Burke County, the formation appears in railroad cuts. It consists of mottled, argillaceous sands and loams, easily distinguishable from the red sands of the Claiborne group which it overlies. A good exposure appears in a railroad cut three miles north of Munnerlyn, Burke County. 416 GEOLOGY OF THE OOA"STAL PLAIN Section in railroad cut, three miles north of Munnerlyn. Altamaha formation 3. Mottled sand, and drab, massive clay, oxidized red 2. Coarse-grained sandstone or grit . . . . . . . . 1. Bluish-gray clay containing coarse grains of quartz and feldspar . . . . . . . . . . . . . . . . . Feet. 10 5 10 The clay is slick and unctuous, has a high air shrinkage, and when dry crumbles into very hard lumps. Similar clay occurs near Screven approximately 100 miles to the southward. On the L. L. Brasselle place, six miles south of Midville, bluish or drab claystone, and sandstones or grits, appear in a rather pictureque bluff about 12 feet high. At a lower level a white quartzitic sand bears poorly preserved fossils, and oyster shells embedded in a white, calcareous sand have been thrown from a nearby well. The fossil-bearing beds undoubtedly belong to the Alum Bluff formation. The claystones or grits observed at this locality probably belongs to the Altamaha formation. They contain no fossils. There are no exposures showing the two phases in contact. Sandstones and gritty claystones appear at Parramore Hill. . Section in railroad cut north of Parramore Hill Station Altamaha formation 4. Weathered red and yellow, sandy clay . . . . 3. Gray, coarse-grained sandstone . . . . . . . 2. Drab or chocolate-colored, semi-indurated clay 1. Very hard, massive, drab clay . . . . . . . Feet. 4 2 3 7 The sandstone is a local induration and not a persistent layer. Coarse, quartz grains are embeddt:d in the fine-grained ground-mass of the clay. There is no evidence of any overlying formation except a thin veneer of sand. Mottled, argillaceous sands, tentatively referred to the Altamaha (Lafayette ?) formation, overlie Miocene strata at Porters Landing, Trowel Landing, and at Sisters Ferry on Savannah River, and similar materials appear in cuts of the Seaboard Air Line Railway three miles north of Clyo in Effingham County. At Ebenezer Church, 30 miles above Savannah in Effingham County, a small thickness of red sand with thin, laminated clay layers overlie Miocene beds at an elevation of about 40 feet above the river; these are probably of the same age as the other Savannah River occurrences jw;t noted. These deposits may all prove to be Pleistocene terrace deposits. . North of Savannah, along the Seaboard Air Line Railway, red sands appear at a few places beneath the gray surface sand, and are similar in lithololgic appearance to the red, argillaceous sands of Effingham County. GEOI, OGl' OF THti OAS7'. 1f, l'L.II X 01-' GEORG I A PL.l7' B XXl'TJT. B. IL\RA C" I' F:RT!:iTIC' )lO'I'TLl:-\G lX WEATriER ED PHA."E J1' 'L'ITE ALTA)! .\ II.\ FOR:\IATION, UT OF .\ TLi\:-\ '1'1 COAST L l:-'cross, Ware County. The PLIOCENE 419 most instructive exposure is in a cut of the Atlantic Coast Line Railroad, two miles north of \Vaycross. Here are revealed pecularities of deposition, local unconformities, and the relation of the mottled, argillaceous sands to the less altered parts of the formation, and to the gray sands which cover the plain. Somewhat similar sands and clays appear in Red Bluff on the right bank of Satilla River, four miles east of Raybon, Wayne County, and about eight miles above the King Plantation bluff. No fossils were found. Section at Red Bluff 4. At top, light yellow, incoherent sand (Pleistocene) Altamaha (Lafayette ?) 3. Mottled sand containing a small amount of disseminated clay . . . . . . . . . . . . . 2. White, red, and yellow, fine sand , . . . . . . 1. Gray, very sandy clay . . . . . . . . . . . Feet 3 10 15 4 The only means of establishing the correspondence in age of these beds with the typical Altamaha farther west, is by tracing the beds; this is hindered by the gray sand covering and the lack of continuous exposures. Sands and clays similar to those exposed in a cut three miles southeast of Jesup occur at the brickyard at Waynesville, Wayne County. A locality of much interest in connection with the discussion of the Altamaha formation is the bluff on Satilla River at the King plantation, six miles south of Atkinson, for fossiis occur in the basal bed of the section and there is some probability that the beds are contemporaneous with the Altamaha beds exposed at Waycross and Blackshear, about 25 miles to the westward. Section at King Plantation 9. Gray sand (Pleistocene) Pliocene 8. Bluish, sandy clay, laminated; red splotches due to weathering . . . . . . . . . . . . . . 7. Gray, sharp sand; a small amount of disseminanated clay, some small quartz pebbles . . . . 6. Drab clay layer . . . . . . . . . . . . . . . . 5. Gray sand, containing clay laminae an inch or two thick . . . . . . . . . . . . . . . . . . 4. Gray, fine-grained, very sandy clay . . . . . . . 3. Gray sand . . . . . . . . . . . . . . . . . . . 2. Yellow sand, fragile molds of shells . . . . . . . 1. Bluish, laminated argillaceous sand, containing fragile shells and a few smap bone fragments Feet 1 4 8 2 8 3 2 2 2 From the shell bed No. 1 Mr. T. H. Aldrich identified several species and regards the horizon as probably Pliocene. ---- 420 GEOLOGY OF THE COASTAL PLAIN Fossils from bluff of Satilla River, King Plantation, six miles south of Atkinson) identified by T. H. Aldrich.1 Rangia cuneata (Gray) M:ulinia lateralis (Say) Mulinia congesta (Conrad) Dosinia sp? Modiolaria sp? Gemma purpurea, H. C. Lea Neretina sp? Neverita sp? New Species Potamides saltillensis Potamides cancelloides Paludestrina u.lana Amnicola saltillensis Amnicola georgiensis Amnicola expansilabris Planorbis antiquatus There is no good evidence of an unconformity between the fossiliferous bed and the upper part of the bluff. Although no definite, structural break was detected in the section there is some ground for believing that a part of the section above the fossiliferous layer, in addition to the surface gray sand, should be referred to the Pleistocene and not to the Pliocene. On the Jacksonville branch of the Seaboard Air Line Railway at Waverly, Woodbine, Colesburg, and Kingsland, in Camden County, red sands, which are probably of the same age as the red sands in the vicinity of Savannah are exposed in the shallow cuts. Although resembling the Altamaha materials, and here tentatively referred to that formation, they may eventually prove to be Pleistocene terrace deposits. These red sands are covered with a thin mantle of surficial, gray sands. WESTERN AND SOUTHERN LOCALITIES Drab claystones and gray sandstones appear near the Georgia Southern and Florida Railroad, one-half mile north of worth, Turner County. Section one-half mile north of Worth. Altamaha (Lafayette ?) formation. 6. Upper part of hill partly concealed, projecting beds of sandstone and conglomerate . . . 5. Drab, sandy claystone, massive . . . . . . . . . 4. Mottled clay layer . . . . . . . . . . . . . . . 3. Gray sandstone or grit in places very hard . . . 2. Mottled clay . . . . . . . . . . . . . . . . . . 1. Indurated gray or drab, fine textured clay; breaks with an angular, conchoidal fracture . . . . . Feet. 20 20 1.5 5 5 8 At this locality indurated sands and clays may be seen grading into non-indurated materials which have the mottled aspect so characteristic' near the surface throughout the Altamaha terrane. 1 Nautilus, vol. 24, No. 11, March, 1911, p. 131. PLIOCENE 421 In a_ cut of the Atlantic Coast Line Railroad near the bridge, one- half m1le east of Sylvester, Worth County, the following section was observed: Sedion in railroad cut one-half mile east of Sylvester. Feet. In. Altamaha (Lafayette?) formation 7. At the top of the cut, orange-colored loam con- taining small, iron oxide "pebbles'' . . . . . 3 6. Yellow, crossbedded sand containing small angular quartz pebbles; thin layers of clay in the sand 6 5. Purple sand 0 3 4. Yellow sand . . . . . .. . . . 7 3. Purple sand . . . . . . . . . 0 4 2. Yellow sand . . . . . . . . . 0 6 (Unconformity.) 1. Purplish, sandy, massive bed of clay 2 6 The. characteristics displayed here are angular, lath-shaped, quartz }lebbles and unconsolidated sands. In the vicinity of Ticknor and Doerun, Colquitt County, there are areas of typical "pimple" or "pebble" land, or land strewn with small, brown, iron oxide concretions resutling from the weathering of Altainaha materials. Pelham, Mitchell County, is located on the top of the Altamaha escarpment which parallels Flint River. Near the surface there is a red or mottled, argillaceous loam overlain l,y a carpet of gray sand. Drab and purplish, very sandy clays occur ben8ath the surface formation. "Pimple" land occurs in this neighborhood also. At Forest Falls, or Limesink, eight miles north of Whigham, Grady County, the Altamaha (Lafayette ?) formation varies in thickness from 8 to 20 feet. It overlies the Alum Bluff formation unconformably. At the base are gray and yellow sands and greenish, "gummy" clays, and at the surface red, case-hardened sands. In southern Georgia and near the Florida line the formation has a lesser thickness, and over parts of Grady, Thomas, and Brooks counties is entirely absent. The topography of this part of the State has been influenced more by the Alum Bluff formation than by the Altamaha (Lafayette ?) formation. Sandstones and conglomerates which farther to the northward characterize the Altamaha terrane, are here absent. In the railroad cuts and in an adjaoo.nt gully three-quarters of a mile west of Climax, Decatur County, the Altamaha formation overlies gray, or greenish and drab, interstratified clays and sands which probably belong to the Alum Bluff formation. Neither the upper nor lower exposures bear fossils, and there are differences -- 422 GEOLOGY OF THE OOASTAL PLAIN of opinion as to a division of the strata. A detailed section at this locality, made by Dr. Vaughan, has been quoted on page 348. All th~ beds expo~ed from the level of the track up, except the gray, sur- fiCial sands, m the second cut \vest of Climax have the lithologic characters of the Altamaha formation at other localities. The section in the second cut, not including the gully exposures is as follows: ' Section in railroad cut three-quaders of a mile west of Climax. Altamaha (Lafayette ?) formation. 6. Beginning at the top,-gray incoherent sand reaching a maximum of . . . . . . . . . . . 5. White and orange-colored, argillaceous sand, mot- tled and massive, due to weathering . . . . . 4. Thin, siliceous crusts of limonite, apparently marking an unconformity . . . . . . . . . . 3. Purplish, white and yellow, crossbedded sand . . . 2. Gray or drab clay layer with purplish splotches; appears to be a lens in the sand; varies from 6 to 12 feet above the level of the track . . . 1. White, purplish, and yellow, crossbedded, coarse sand; very small percentage of disseminated clay; sand mainly angular, quartz grains; maximum thickness . . . . . . . . . . . . . Feet. 3 7 1 15 2.5 to 4 12 The beds between the level of the branch and the track level, about 40 feet, probably belong to the Alum Bluff formation. Characteristic, mottled, argillaceous sands of the Altamaha forma- tion appear in the Atlantic Coast Line Railroad cuts near Fowltown and Recovery in Decatur County. In a cut one and one-half miles west of Recovery the contact wit_h Alum Bluff is exposed. Six.feet of mottled, argillaceous sand rest unconformably upon two to four feet of fine, gray sand containing a small amount of disseminated clay. About 10 feet below the level of the track a sandy limestone referable. to the Chattahoochee formation is exposed. In the first cut east of the station at Whigham, Grady County, the Altamaha formation appears as thin layers of red and purple sand, alternating with laminated clay. Some of the clay laminae are not more than a fraction of an inch in thickness, and the clay layers have sand partings. In a cut one mile east, light, green clays of the Alum Bluff formation appear overlain by orange-colored sand of the Altamaha formation. Fine exposures appear in the railroad cuts at Cairo, Grady County. The formation here consists of mottled, sandy clays and crossbedded, ydlow and red sands, with dull yellow loam at the sur- face. The peculiar mottling or calico effect, due to weathering, is shown in a photograph made in a cut west of Cairo. Plate XXVIII-B. PLIOCENE 423 The Alum Bluff formation is exposed in the terrace escarpments of Ocklockonee River at the 204th and 205th mileposts on the Savannahl\Iontgomery division of the Atlantic Coast Line Railroad. The overlying Altamaha (Lafayette ?) formation appears in a cut which extends from milepost 203 eastward for one-half mile; the formation here is a massive, argillaceous sand, mottled with yellow and gray. At Thomasville, Thomas County, the Altamaha is represented by a small thickness of red sand. South of Cairo, Thomasville, Boston, and Quitman, the formation appears only on the higher hills as a capping. It consists mainly of red loam and may be easily confused with the red, argillaceous sand, residual from the Alum Bluff. North of these points the formation presents topographic and lithologic characters similar to those which prevail in the northern part of the Altamaha area. One of the few exposures south of Thomasville which are considered referable to the Altamaha, occurs on the Tallahassee road, 12 miles south of Thomasville. Section twelve miles south of Thomasville. Feet. 5. At top of hill-gray, surficial sand . . . . . . . 2 Altamaha (Lafayette ?) formation. 4. Stratified sand and clay, mottled red and white, coarser in texture than the underlying materials 20 Alum Bluff formation (contact obscured by weathering and creep.) 3. Residual, red, sandy clay 30 2. Greenish, fossiliferous clay 10 Chattahoochee formation. 1. Limestone . . . . . . . . 15 The materials capping the hill on the Mallet plantation on the Boston-Monticello road, four and one-half miles southwest of Boston, Thomas County, have much the appearance of the Altamaha formation, but their relation to the underlying residual sand of the Alum Bluff formation is obscure. The A1tamaha formation appears in railroad cuts near Quitman, Brooks County, and near Kinderlou and Valdosta, Lowndes CountJ, It attains only a small thickness and is underlain by sandy clays of the Alum Bluff formation. East and southeast of Valdosta the country is a flat, sand-covered plain in which there are few natural exposures. Yellowish, mottled .sands occur beneath the gray surface sands. It is probable that there is a small thickness of the Altamaha formation underlying this region. The mottled sand in the cut one mile west of Stockton has the appearance of this formation. 424 GEOLOGY OF THE COASTAL PLAIN PLEISTOCENE The Pleistocene deposits consist of thin, fluviatile and marme terrace accumulations of sand, clay, and gravel. The only systematic description of the Pleistocene of the Georgia Coastal Plain previously given is that of W J McGee.' :lVIcGee first studied the Pleistocene in the District of Columbia, gave it the name "Columbia formation" and differentiated it into three phases, the fluvial, inter-fluvial, and low-level phases. The formation was traced southward to the Mississippi and to ~Iexico. He recognized the three phases in Georgia and gave brief, general descriptions of them. Previous to McGee's studies, Lyell had already observed successive terraces on the coast Qf Georgia, and other observers have also mentioned them, but their geological significance seems not to have been fully presented. In the present report the differentiation is based largely upon physiography, and the formations are described in greater detail than in McGee's report. The name Columbia as a group name is retained. The divisions are given in the following table: Pleistocene C 0 I bl um a { S a t i lla formation { group Okefenokee formation Marine terrace deposits { Fluviatile deposits Coastal terrace sand { Fluviatile deposits The solution of the Pleistocene problem of Georgia, and in fact of the Atlantic Coast region in general, is conditioned largely upon a knowledge of topographic details. This knowledge can not be acquired until detailed topographic maps have been made available. In Georgia the Pleistocene formations do not lie superimposed one upon the other, but occupy terrace benches at different topographic positions with respect to each other. During the Okefenokee period gray sands and other sediments were laid down on a terrace plain of probable marine origin, now 60 to 125 feet above sea-level, and contemporaneous fluviatile terrace deposits consisting of gravels, sands, and loams, were laid down .on the "second" terrace skirting the larger rivers. During the Satilla period gray sands and muds were laid down On a marine terrace, a flat plain 20 to 40 miles broad, bordering the coast at elevations of 15 to 40 feet above sea level, and corresponding terrace alluvium was deposited along the rivers. Although the available data are at present too incomplete to admit .of a positive statement it is not improbable that an older Pleistocene 'The Lafayette formation; Twelfth Ann. Rept. U. S. Geol. Survey, pt. 1, 1S90-1891, lPP 353-521. PLEISTOCENE 425 terrace plain exists to the westward of, and at a higher elevation than the Okefenokee terrace. Evidence of such a plain is to be seen in the topographic aspect of the country lying along the Atlantic Coast Line Railroad between Valdosta, Lowndes County, and Waycross, Ware County; along the Atlantic Coast Line Railroad between Pearson, Coffee County, and Waycross; and along the Southern Railway between Baxley in Appling County, to near Jesup, Wayne County. The general surface of the belt of country crossed by these railroads is a nearly level plain which gradually descends towards the coast. Along the first mentioned railroad there is a descent from an elevation of 215 feet at Valdosta to 140 feet at Waycross; along the second there is a descent from 205 feet at Pearson to 140 feet at Waycross; and along the third, a descent from 206 feet at Baxley to 155 feet at Odum. The northern part of Effingham and the southern parts of Screven and Bulloch counties, also present the aspect of a plain similar to the Okefenokee Plain. COLUMBIA GROUP OKEFENOKEE FORMATION The name Okefenokee is derived from Okefenokee Swamp, a great, swampy tract in southern Georgia covering parts of Charlton, Ware and Clinch counties. The swamp occupies a portion of the plain on which were laid down the deposits under consideration. The Okefenokee formation consists in part of coastal terrace deposits and in part of river terrace or fluviatile deposits. During this period there was probably a depression of the land, the coast line perhaps being 40 to 75 miles west of its present position. Coastal sands and probably other sediments were laid down forming a terrace, and contemporaneous fluviatile deposits were formed on terraces skirting the larger rivers as far as the Fall Line. The coastal terrace formed during this period is a flat plain 20 to 40 miles wide, which varies in elevation from 60 to about 125 feet above sea-level. It is covered with gray and white quartz sand. The river tffi'races lie 50 to 100 feet above zero water level, and form prominent topographic features along Savannah, Ocmulgee, and Chattahoochee rivers. The terrace deposits -consist of sands and gravels of fluviatile or fluvioestuarine origin. The two types of deposits will be described separately. COASTAL TERRACE DEPOSITS The coastal terrace phase of the formation is represented principally by a thin deposit of gray sand which covers the Okefenokee Plain, a topographic division which has been described in t]1e chapter 426 GEOLOGY OF THE COASTAL PLAIN on physiography. The age of the formation is determined by the physiographic position and not by the evidence of fossils since fossils. are entirely absent. The western boundary of this plain is marked approximately by a line extnding from near Sisters Ferry on Savannah River, or Clyo, southeastward through the northern part of Bryan County, to about 10 miles north of Ludowici, Liberty County; thence to Jesup, and along the Atlantic Coast Line Railroad to near \Vaycross, Ware County; and thence to the western boundary of the Okefenokee Swamp. It includes the Okefenokee Swamp, and the towns of Folkston, Jesup, Ludowici, and Hinesville are situated upon it. Its eastern boundary is marked by an escarpment 20 to 40 miles from the coast, which separates it from the first or Satilla terrace. (The approximate area of this plain is shown on the sketch map, Fig. 1, p. 28). The most conspicuous deposit on the plain referable to this period is a gray sand. Red and yellow sands ~ontaining thin clay layers and pebble beds underlie the surface sand and are doubtless in part Pleistocene, although in this report such materials are in most cases tentatively referred to the Altamaha formation. The Okefenokee formation is not in contact with any formation older than Pliocene and Miocene. On the west the sand of the Okefenokee Plain merges into the surficial sand of a higher plain and it is not always possible to draw a sharp line of demarkation between them. Swampy flats traversed by small creeks occur in the plain and probably the muds underlying these flatS' belong to this period of the Pleistocene. The gray surface sand is composed almost entirely of subangular quartz particles, probably derived from the older Coastal Plain formations. On the whole, it is, perhaps, finer in texture and lighter in color than the upland .sands to the west. At the surface the sand is loose, incoherent, and structureless, but shows faint lines of stratification and current bedding at depths. At a few localities it is white at the surface and darker-colored beneath, the white phase having been formed by leaching and not as a separate deposit. A notable occurrence of white sand lies along the railroad between Ludowici and Darien Junction. In the Okefenokee Swamp the only deposits known, aside from the recent peaty accumulations, are white, yellow, brown, and black sands,-the dark colors being due to large amounts of organic matter. The sand is in places indurated, due probably to a cement of iron oxide. This is the so-called "hard pan" of this area. The thickness of the sand is small, probably averaging less than 10 fet over the whole plain. Good exposures appear at Folkston, where the aver,age thickness is six or eight feet, with local accumula- PLEISTOCENE 427 tions reaching 15 or 20 feet; the sand is gray, almost white at the surface, and light yellow beneath. At other places over the plain the thickness varies from two or three to 10 or 15 feet. The plain which the Okefenokee sand covers is in general flat and almost featureless. Some of the larger streams vvhich traverse it have bluffs 30 or 40 feet high, but these are exceptional. The erosive power of rainwater is lessened by the porous sand, and ravines and gullies are rare. The main streams have few tributaries. The plain is dotted with cypress ponds and swamps due to original inequalities in the land surface. Locally the sand has been heaped into low ridges and hills which in certain instances were controlling factors in determining the courses of streams. The anomalous course of St. Marys River is probably due to obstructing sand ridges. As may be inferred from the lithologic description given above, little can be said regarding the structure of this formation. It conforms to the low seaward slope of the Okefenokee Plain and varies il}. elevation from 60 to 125 feet above sea-level. LOCAL DETAILS Surficial sands.-Gray, yellow, and brownish to almost black sand, reaching a thickness of 20 feet or more, occurs in and on the borders of Okefenokee Swamp. The sands are prominent at Folkston; at the surface they are gray, or in places almost white, becoming yellow at depths. A high, sand-covered scarp occurs a short distance east of Folkston and borders St. Marys and Satilla rivers on the west. Fine-grained, sandy clay or mud, which may be an Okefenokee Pleistocene deposit, underlies a broad flat through which Spanish Creek flows. East of Waycross, near the 42d mile-post on the Atlantic Coast Line Railroad, cuts on either side of Big Creek expose 10 or 15 feet of brownish sand showing stratification lines. The color is due f to organic matter. Heavy beds of gray sand occur at vVaynesville, Wayne County, which is on the scarp between the first and second Pleistocene ter- races. A considerable area in southeastern Wayne County and eastern Pierce County forms a flat, swampy, palmetto and pine covered plain, over which the gray sands ha.ve a thickness of only three or four feet. Gray sands are conspicuous on the eastern edge of the plain at J\llount Pleasant in vVayne County, and similar sands occur be- tween Jesup and Altamaha River in the same county. At Ludowici, l-iberty County, the sands covering the plain are gray to almost white, and of small thickness. This pine-clad sand plain seems to 428 GEOLOGY OF THE COASTAL PLAIN merge gradually to the northwestward into the dry, rolling, wiregrass, sandhill region covered with a scattered tree growth, which surrounds Glenville, in Tattnall County. Gray sands are conspicuous on the eastern edge of the plain at Walthourville in the same county. The sand-covered Okefenokee Plain extends northeastward from Ludowici, through Bryan and Effingham counties, to Savannah River. In Bryan County the surface gray sands and the typical topography of the plain are finely exhibited along the Seaboard Air Line Railway between Ellabell and Groveland. Here the western limit of the plain is on the west side of Cannoochee River, between Groveland and Daisy. Deposits beneath the surficial sands.-At numerous places within the area covered by this plain there are, beneath the surface sands, deposits of sand and clay the ages of which are more or less problematic. Some of these deposits probably belong to the Okefenokee formation. Occurrences of such materials, concerning the Pleistocene age of which but little doubt exists, are described or referred to below. The sands and clays overlying the Charlton formation in the higher bluffs on St. Marys River, described on pages 392-400 of this report, are tentatively referred to this formation. In a cut on the Southern Railway, three miles east of Jesup, a coarse, quartz gravel bed, which may belong to this division of the Pleistocene, is exposed. Sands and clays, probably referable to the Okefenokee formation, underly the surface sands at brickyards near Waynesville and Odessa, Wayne County. Unconformities, the significance of which could not be determined appear in these ~ections and it may be that both the Okefenokee and Altarnaha formations are represented. Red and gray, argillaceous sands probably belonging to the Okefenokee formation, appear in bluffs of Savannah River at Frying Pan Landing, Gaffney Landing, and at Ebenezer, Effingham County. Certain deposits, described in the chapter on the Altamaha formaa tion and tentatively referred to that terrane, may eventually prove to be of Pleistocene age and referable to this formation. FLUVIATILE TERRACE DEPOSITS Bordering the large rivers of the Coastal Plain of Georgia are remnants of a plain, higher than the "second bottoms" or Satilla Plain, and 50 to 200 feet lower than the general upland of the re- gion. It is believed that the deposits laid down on this plain are PLEISTOOENE 42~ contemporaneous with the Okefenokee coastal deposits. while the coastal portion o the Okefenokee terrace plain was being cut and the gray sands and other deposits were being laid down upon it, the terraces bordering the present river valleys, and their accompanying deposits, were being ormed,-either by the waves along the borders o reentrant estuaries, or by the meandering o the rivers in the parts o the valleys not submerged. The river terraces coalesce with the coastal terrace. The river terrace plains lie 50 to 125 feet above the present rivers. Immediately subsequent to their ormation the fluviatile portions of the Okefenokee plain filled the valleys rom side to side, having widths varying rom one to ten miles; into these ancient plains the rivers have intrenched themselves, forming younger plains at two lower levels,--one the Satilla plain, and the other the Recent flood plain. The cutting o these younger plains has resulted in the destruction o all but remnants o the original Okefenokee plain. The Okefenokee fluviatile deposits overlie in turn all the older Coastal Plain formations, rom the Cretaceous to the Pliocene. The materials have been derived in part, perhaps chiefly, rom these older formations, and in part rom the Piedmont Plateau region to the northward o the Coastal Plain. On account o lithologic similarity it is sometimes difficult to distinguish between the terrace deposits and the underlying older formations. However, in most cases a gravel bed is present at the base o the terrace deposits, and unconformable relations to the older deposits appear wherever there are clean cut exposures. It is probable that in the past some o these deposits have been confused with the Altamaha ormation as has been pointed out in the discussion o the Lafayette formation. The deposits consist chiefly o red, argillaceous sands, in places pebbly, and ,coarse gravels. There are but few clay beds and the ormation lacks the distinctive alluvial character o the lower terrace and flood plain deposits. Along some o the streams a gray, incoherent, rather pure sand seems to be the only deposit. Near the Fall Line the deposits show clearly that they have been derived in large part rom the crystalline rocks o the Piedmont region, but farther south the Coastal Plain formations have contributed a major portion o the materials. Along Withlacoochee, Allapaha, and Ocklockonee rivers the detritus has been derived entirely rom the Coastal Plain formations. The ormation is usually unconsolidated but in a few places there are local beds o gravel cemented by iron oxide. The pebbles are chiefly quartz and quartzite, but a subordinate percentage are limestone, flint, and limonite. At a number o localities on the Okefenokee plain there are sur- 430 GEOLOGY OF THE COASTAL PLAIN ficial, brown-gray, loose, incoherent sands differing in their physical appearance and lithologic characters from the red loams and gravels forming the terrace deposits, and resembling closely the gray sands of the upland. Conspicuous accumulations of such sands were noted at :.Montezuma, Bainbridge, Fort Gaines, Dublin, and Lumber City. Some of these deposits are in the form of hills and are probably of wind-dune origin; they may have been formed subsequent to the elevation of the terrace plain. At other localities the gray sands appear to be water-laid sediments which rest directly upon the older formations, forming a thin uniform mantle over the plain. The formation is thin, not exceeding 50 feet at any place, and nsually much less than 20 feet. The greatest thickness was noted near the Fall Line. Except for fragments of silicified wood found at Fort Gaines, and fossils in limestone and flint pebbles derived from the underlying Tertiary beds, no fossils are known in this formation. The deposits are confined to comparatively level plains paralJeling the riYers. The plains were originally one to 10 miles in width, but the deposits have been so largely removed by subsequent erosion that their total area is relatively small. They are confined principally to the courses of Chattahoochee, Flint, Ocmulgee, Oconee, Altamaha, Ogeechee, Savannah, Ocklockonee, \Vithlacoochee, Little, and Allapaha rivers. At a few localities the terrace plain forms a conspicuous topographic feature. The physiography of the terrace is illustrated in a profile accompanying this report (See fig. 2, p. 37). The business portion of Macon, a part of the residence portion of Columbus, the cities of Fort Gaines, Albany, Lumber City, and parts of Augnsta are built on this terrace. In detail the surface of the terrace is nearly level, the only undulations being due to sand heaps. The vegetation is more lnxnriant and the soil generally more fertile than on the inte,rstream uplands. The approximate elevations of the second, or Okefenokee terrace plain, above sea-level at the Fall Line are: Augusta ....... . Milledgeville . . . . . . Macon . . . . . . . . . Flint River at Fall line . Columbus ....... . River. Terrace Plain. 0 98 200 . 215 290 . 279 355 . 320 ? 380 ? . 190 300 to 325 From the Fall Line there is a gradual descent, until the river ter raceR merge into the coastal sand plains bordering the sea coast. PLEISTOCENE 431 LOCAL DETAILS Chattahoochee River.-Good exposures of the Okefenokee formation occur in the valley of the Chattahoochee at Columbus, and Omaha, Ga., at Eufaula, Ala., Fort Gaines, and at Columbia, Ala. At Columbus, :M:uscogee County, the deposits lie on a terrace approximately 100 to 125 feet above the river. They consist of bright red, highly ferruginous, clayey sands, and gravel composed of large, well-rounded quartz pebbles or cobbles. The formation is exposed at Rose Hill, Ga., and in Phoenix, and Girard, on the Alabama side of the river. It rests unconformably upon the Cretaceous and Crystalline rocks. The deposits do not exceed 30 or 40 feet in thickness. In the vicinity of Eufaula, Barbour County, Ala., the second terrace deposits appear in a bluff of Chattahoochee River, and form a level plain lying about 100 feet abme the river. Upon this plain the greater part of the city of Eufaula is built. The formation rests unconformably upon the black clay-marls of the Ripley formation. The surface materials are massive, highly ferruginous, clayey sands, slightly hardened by atmospheric agencies, resting upon heavy beds of grawl. The gravels are made up chiefly of quartz pebbles. About one mile southeast of Georgetown, Quitman County, Ga., the gravels have been mined in a pit near the Central of Georgia Railway. Here the deposits are a heterogeneous mixture of gravel and red sand, in places indurated to such an extent as to require blasting. About 15 feet is exposed in the pit. The pebbles are small and consist chiefly <) vein quartz material. At Fort Gaines, Clay County, the second terrrace deposits consist principally of coarse, red, clayey sands with quartz pebbles at the base. They rest upon Eocene strata. A thickness of 25 feet was noted in this vicinity. In places large limestone fragments, evidently derived from the Midway formation (Eocene), occur in the base of the deposits. The pebbles are composed chiefly of subangular quartz; they are poorly stratified, being arranged in oblique lines and showing crossbedding. Good exposures occur at the old Brown Mill, one mile north of town. Fragments of silicified wood were noted which probably came from this formation. In this vicinity loose, structureless, gray sands also appear on the terrace plain. At Columbia, Ala., and vicinity, the deposits consist of highly ferruginous, red, clayey sands with scatt:ered small pebbles. The sands have a distinctive bright red appearance, and, upon exposure to the atmosphere, harden in a peculiar manner. The sands form a plain about 100 feet above the river level upon which the town of Columbia is built. 432 GEOLOGY OF THE COASTAL PLAIN Flint River.-The deposits along Flint River lie 50 or 60 feet above the river and consist of coarse, red sands and gravels. The gravels, which consist of small pebbles, form the lesser part of the deposits. The sands contain some disseminated clay, and when weathered present ~ mottled appearance. li covering of gray sand is conspicuous over the second terrace from the vicinity of Newton southward; the plain here reaches a greater width than along any of the rivers. The upper part of Red Bluff on the west side of the river, seven miles north of Bainbridge, presents an exposure of Okefenokee sand lying unconformably upon a mass of residual flint and clay de- rived from the Vicksburg and Chattahoochee formations. The deposits vary from 6 to 29 feet in thickness; at the base they consist of coarse sands and small quartz pebbles with a few limestone and flint fragments; the upper part is composed of red, massive sand with sufficient clay to produce a mottled effect when weathered. On the west side of the river, and extending three or four miles northward from Bainbridge, is a conspicuous development of wind-blown sand upon the second terrace. Ocmulgee River.-Along Ocmulgee River deposits were recognized at Macon, Lumber City, and other points. At Macon they occur on a terrace 60 to 75 feet above the river, and form the plain on which the business section of Macon is built. They consist of coarse quartz gravels and red, clayey sands containing fragments of siliceous lim- onite. The deposits are kaolinic in places, the source of the kaolin being in part the crystalline rocks which outcrop in the valley just to the north of the city, and in part the underlying Lower Cretaceous deposits. The beds are heterogeneous, show very little sorting, and pre~ent evidence of rapid deposition. At one point in a cut of the Georgia Southern and Florida Railway, near H. Stevens Sons' Company's sewer-pipe plant, a bed' of sandstone and conglomerate is prominent. The terrace deposit is easily distingu,ished from the underlying Cretaceous materials by its darker color and its coarser texture. Its thickness can hardly be more than 20 or 25 feet. An ex- posure showing the relations between the Cretaceous materials and the terrace deposits occurs in the bluff a few hundred yards south of the plant of the Cherokee Brick Company; white, micaceous, kaolinic sand is overlain unconformably by 15 feet of crossbedded, vari-colored sand and gravel. Lying from 150 to 200 feet above the river are beds of gravel and red, argillaceous sands similar to those on the second terrace, but there is reason to believe that these are remnants of overlapping Eocene deposits. ' The terraces are inconspicuous at Hawkinsville and Abbeville and <'xposures are poor. The formation seems to consi&t of red sands PLEISTOCENE 433 >vith suoordinate amounts of gravel. The plain lies about 60 feet aoove the river and is covered with loose, gray sand. At Lumber City the Okefenokee terrace is present as a well developed plain about one mile wide on the north side of the river. The terrace deposits are exposed in the upper part of the river bluff. The materials are coarse, gray and red, pebbly sands with coarse quartz pebbles at the base. Among the pebbles were noted fragments of limestone derived from adjacent older formations. The formation probably does not exceed 20 feet in thickness; the surface of the plain lies 40 to 50 feet above the river. The Okefenokee plain i5' herP en\ered in part by deposits of yellowish, incoherent sand heaped up, in places, probably by wind action. Savannah River.-The Pleistocenr. terraces are well developed at Augusta, hut there are no sharp demarcations between the deposits on the second terrace and those on the adjacent upland. On the Carolina side at 80 to 100 feet abme the river, bright red, ferruginous sand overlies, unconformably, Cretaceous strata and weathered schists, but exposures of red san'ium appearing at but a few localities. At Augusta the deposits reach a thickness of 30 or 40 feet. They 442 GEOLOGY OF THE COASTAL PLAIN consist of sands, gravels, and lenticular layers of sandy and plastic clays. The clays are used extensively in the manufacture of common building brick. The business portion of Augusta is built upon the plain formed by these deposits. New Savannah Bluff, 13 miles below Augusta, affords a fine exposure of the formation. The bluff reaches a maximum height of 25 feet; the lower part consists of coarse, crossbedded sand and beds of small pebbles. A large percentage of the pebbles is composed of feldspar; the upper eight feet is red, coarse, harsh sand which contains a small amount of disseminated clay, and is sufficiently compact to form an abrupt face. At the upper end of the bluff there is a thin, non-persistent layer of bluish-white, sandy clay. The material exposed forms a level plain about one mile wide on the Georgia side of the river. Silver Bluff, 27 miles below Augusta, on the Carolina side, is the most typical Pleistocene bluff exposed on the river. It furnishes an excellent example of a fluviatile or flnvio-estuarine deposit. The materials consist of coarse, crossbedded sands and gravels of a heterogenous character, overlain' by an undulating, massive, and non-laminated sandy clay, and this in turn by red and yellow sands. The pebbles are angular and occur in lenses about three feet thick. None of the beds are indurated: The bluff reaches a height of 22 feet. Opposite, on the Georgia side, the low silty banks of the swamp or Recent flood plain appear. Other exposures of the Satilla formation occur at Cohens Bluff Landing, S. C. ; Poor Robin Landing, Ga. ; Parachuchla, and Purisburg, S. C. At Cohens Bluff, 101 miles above Savannah, a bed of massive, light greenish clay, containing lime nodules is exposed. Its lithologic character indicates that it has been derived in large part from the argillaceous Eocene marls to the northward. At Parachuchla, 55 miles above Savannah, the bluff exposes about 15 feet of structureless, gray, and light buff sand, underlain by two or three feet of mottled, sandy clay. The sand forms an oval hill produced by either wind or current action; the type of deposit is similar to that at Beards Bluff on Altamaha River described on a subsequent page. At Purisburg, S. C., 23 miles above Savannah, the formation appears in a bluff about 12 feet high in which is exposed reddish, sandy clay (color due to weathering), drab, laminated clay, crossbedded sand, and coarse gravel resting unconformably upon Miocene strata. The pebbles, which have a maximum diameter of six inches, indicate a fluviatile or estuarine deposit; the coarseness of the gravel suggests that the material was carried down during floods, or at some stage when there were strong currents. PLEISTOCENE 443 Ogeechee River.-Along Ogeechee River, dposits of the Satilla formation consisting mainly of sand form a terrace, the upper surface ' of which lies about 10 feet above the river. At Rocky Ford, Screven County, however, clay probably belonging to this formation waS' noted in a terrace which lies about eight feet above the swamp. A conspicuous development of the sand occurs at Eden, Effingham County. The highest part of the sand hill west of Eden is- nearly 20 feet above the swamp. Ocmulgee and Oconee Rivers.-The Satilla terrace along Ocmulgee and Oconee rivers rises 10 to 20 feet above the river levels. In many places the terrace is swampy, is :mb~ect to overflow, and has the aspect of a Recent flood plain deposit. Near the Fall Line, clay makes up the greater part of the deposits~ the amount of sand increasing to the southward. The general section at the Fall Line is: At the surface, sandy loam grading into brownish or yellowish clay with limonitic concretions; then bluish, plastic clay; and at the base, sand and gravel, water-bearing. Southward the plain is covered at many places with loose, gray sand, and the clays occur as lenticular beds of small extent, or in pockets in the sand. In places the clays are fine-grained, plastic, and contain lime nodules. AUamaha River.-Along Altamaha River the Satilla formation presents much the same aspect as along Savannah River. The Satilla plain originally had a maximum width of four or five miles; into this plain the Altamaha River has entrenched itself, meandered and formed an extensive Recent flood plain or swamp two to six feet above low water level. The Satilla beds appear in bluffs 10 to 15 feet high. Hillocks of wind-blown sand appear at different places over the terrace plain. Beards Bluff (see plate XXIX, B), in Tattnall County, 60~ miles below the forks, affords a good example of the fluviatile phase of the formation. The bluff is about 15 feet high and is capped by a dome of fine, gray sand; beneath the surface sand is an undulating layer of bluish, sandy clay, and beneath the latter, forming the base of the bluff, is a coarse, current-bedded sand. The surface sand seems to have been accumulated by wind action: The clay and lower sand were probably reworked from the Altamaha formation. Ohoopee White Bluff, 392 miles below the forks also presents a good section of the Satilla formation. The section is similar to that at Beards Bluff except that the wind-blown surface sand does not appear. A coarsely arenaceous clay bed, which terminates abruptly along the 444 GEOLOGY OF THE COASTAL PLAIN bluff, appears in the section. The materials as a whole are heterogenous in character and appear to have been deposited by rapid river currents. Buckhorn, Red, and Town Bluffs expose materials, mainly sand, referable to this formation. Flint River.-Near the Fall Line the first terrace above the river is broad and swampy, and is underlain mainly by brownish and bluish plastic clays. From Oakfield to Bainbridge the Satilla terrace forms a narrow plain, 15 to 20 feet above the river. The terrace deposits are exposed at a number of places. The general section is as follows: At the surface-loose, gray sand; then undulating layers and pockets of clay; at the basec--(;6arse, heterogenous, crossbedded sand with lesser amounts of graYel. Chattahoochee River.-The best development of the Satilla terrace occurs along the Chattahoochee RiveJr. Th.e river has cut a narrow trench about 40 feet deep in the nearly level plain, exposing unconsolidated sands, clays, and gravels of the Satilla formation, resting upon strata of Tertiary and Cretaceous ages. Conditions differ from those on SaYannah and Altamaha riYers in that there is scarcely any swamp bordering the river, and the plain is on the whole higher above the river level; tributary streams enter the river through narrow trenches or gorges and not through swamps, as on Savannah and Altamaha rivers. Fine developments of the terrace may be seen at Columbus, Omaha, Georgetown, opposite Eufaula, Ala., and at Fort Gaines. This terrace plain reaches a maximum width of three miles but the average is not perhaps more than one or one and one-half miles. Opposite Columbus the terrace material consists in part of brownish or yellowish, structureless loam presenting somewhat the appearance of loess. The Satilla terrace forms a level plain, approximately one mile wide and about 50 feet above the river, on which a part of the city of Columbus is built. The deposits consist predominantly of sand; clay layers occur in undula.ting beds of variable thickness and in pockets enclosed by sand, and graYel beds are common at the base of the terrace deposit. The crossbedding and the general heterogeneous character of the materials indicate rapid changes in the conditions of deposition. Southward from Columbus the deposits begin to show evidence of being derived in part from the Coastal Plain formations. Other rivers.-The deposits of this formation bordering the Ocklockonee, \Vithlacoochee, Allapaha, Suwanee, and St. :Marys rivers are composed almost entirely of gray or white sand and gravel, with subordinate clay beds in a few places. The rivers have cut narrow RECENT 445 trenches resembling canals in the sandy terrace plains of the for- mation. The terrace plains reach a width of one-half mile or more,. though usually they are much narrower; their surfaces lie about 8 to 15 feet above the rivers. Along Withlacoochee River, east of Quitman, the Satilla terrace is about 20 feet above the river and is about one-half mile wide. The sand is pure white in places and might be suitable for use in the manufacture of bottle glass. It is usually fine at the surface but becomes coarser with depth, often showing crossbedding at the base. On the Allapaha, two miles east of Milltown, the terrace is well developed and is about 15 feet above the river. The section at the wagon bridge is as follows : Section at wagon bridge two miles east of Milltown. Feet. Pleistocene. Satilla formation. 3. Brownish or chocolate-colored sand, gray or white over the surface of the plain . . . . . . . . . 5 2. Brown or yellow, coarse sanu, quartz, and quartz ite pebbles; also contains small white pebbles of phosphate . . . . . . . . . . . . . . . . . . 2 (Unconformity.) Oligocene. Alum Bluff formation. 1. Greenish; laminated, sandy clay . . . . . .. S This terrace forms a clay flat west of Stockton. At Statenville, Echols County, the Satilla formation consists of very pure, gray or white, quartz sand, in places coarse-grained. The terrace lies about 20 feet above the river. At Bony Bluff, nine miles southwest of F'argo, large, blackened bones and fragments of silicified wood are found in a bed supposed to lie at the base of the formation. On St. Marys River from near St. George up the valley the deposits of the formation may be considered of fluviatile or fluvio- estuarine origin. They form a flat sand terrace about 12 feet above the river. At Stokes F'erry, 11 miles south of St. George, the basal part of the formation consists of pebbly sand in which are embedded fragments of bones and teeth, and roots of trees. RECENT The Recent deposits, or those formed since the close of the Pleisto- cene or the uplift of the Satilla or hltest Pleistocene terrace, and now in the process of formation, consist of: (1) marsh and tide-swamp \ muds; (2) beach sand and dunes; (3) river flood plain deposits; (4) interstream swamp deposits; ( 5) certllin terrigenous deposits. semi-alluvial in character. 446 GEOLOGY OF THE COASTAL PLAIN The processes by which the Satilla terrace, with its accompanying deposits, was formed are being repeated at the present time along the coast. The Recent terrace which is thus being formed is largely submarine. Beach sands are being laid down on the ocean front, while the courses of the streams entering the ocean are drowned and converted into estuaries, and muds are being deposited in the marsh and tide-swamp land. In the absence Of any accurate maps the area of marsh and tide-swamp land along the coast may be roughly estimated at 400 square miles. While observations have not been made at a very large number of localities, the thickness of the Recent deposits in the area inundated by the tides probably does not exceed six feet. The composition of the muds is indicated by the following .analysis of a sample from St. Simons Island, made by Dr. Edgar Everhart from a sample collected by Prof. McCallie. Analysis of mud from St. Simon Island. Moisture at 100 C. . Loss on ignition Soda, Na, 0 . . Potash, K,O Lime, CaO Magnesia, MgO Alumina, Al,O, . . . . . . . . . . . . . . Ferric oxide, Fe,03 Titanium dioxide, TiO, . . . . . . . . . . . . . . . . . Sulphur trioxide, SO, . . . . . . . . . . . . . . . . . . Phosphorus pentoxide, P,O, . . . . . . . . . . . . . . . Chlorine, Cl . . . . . . . . . . . . . Silica, SiO, 4.62 9.94 3.013 1.1:: .40 1.28 13.67 4.86 1.01 .24 2' 1.77 C7.:)5 Total . . . 100.15 In places the Satilla terrace is separated from the Recent terrace by bluffs 10 to 15 feet high, while at other localities the two merge into each other. The Recent alluvium along the Coastal Plain streams consists m;ainly of sand, although along the lower courses of Altamaha and Savannah rivers some clay has been deposited. Owing to the comparatively short period that has elapsed since the close of the Pleistocene, deposits of this class are of small extent. Along some of the streams the only Receni deposits are accumulations of sand in the form of bars. In the southeastern part of the Coastal Plain' of Georgia are numerous swamps ranging in size from one to two acres to tha~ of the immense tract known as Okefenokee Swamp. Peaty accumulations {)r decayed plant matter with more or less silt and sand are being formed in these swamps. In the Okefenokee Swamp peaty accumu- SURFICIAL SAND 447 lations to the thickness of four feet are reported. Some of the E>'Wamp areas are densely wooded and have been the roosting places of birds for perhaps centuries, and a phosphatic muck is being slowly .formed from their dung and dead bodies. Sand deltas or plains of semi-alluvial character form another type of Recent deposits. In the northern, hilly part of the Coastal Plain erosion has been very active on account of the loose, unconsolidated character of the formations; and at certain localities, especially where the forests have been cut away, deep gullies have been formed. Every torrential rain moves large quantities of sand which, on acount of over-loading, is deposited along the beds of the small creeks, forming so-called "sand streams," or is spread out at the mouths of gullies forming small subaerial deltas. The best example of this type is at the huge gullies or "caves" west of Lumpkin, Stewart County. A "sand stream" is illustrated in Plate XIV, B. SURFICIAL GRAY SANDS OF THE UPLAND Surficial grayish or brownish, incoherent quartz sands cover large portions of the interstream uplands of the Coastal Plain of Georgia at elevation~'>' higher than the Pleistocene terrace plains. On account of the sterility of the soils which these sands produce and their influence on the topography and tree growth, they attract the attention even of perE>'ons who are not interested in problems of geology. The sands are not everywhere of the same origin. Much of the sand is residual and can not be referred to any one geologic period or formation. However, in places there are wind-blown accumulations, and at rare intervals the marks of ~Stratification can be detected. In this report no attempt has been made to sub-divide or to map these sands and a part of this work would, perhaps, more properly fall within the province of a soil survey. The surficial gray sands are made up almost entirely of crystalline quartz there being at no place sufficient clay to render them coherent. A number of samples were examined microscopically. In addition to the quartz grainE>', small percentages of clay, some limonite and allied iron oxide minerals, and very small amounts of minerals common to igneous rocks such as mica, magnetite, ilmenite, feldspar, ana rutile were detected. The clay content rarely exceeds three per cent; the limonite occurs as a coating over the quartz grains and gives the sand its yellowish or brownish appearance. On the whole, the sand is uniformly fine in texture; in samples tested from several localities 40 to 60 per cent. of each sample passed a 40-mesh sieve; the texture o-f the residual sands at any particular locality depends upon the {'har:wter of the sands in the formations from which they were de- 448 GEOLOGY OF THE COASTAL PLAIN rived. In all of the more notable deposits the quartz grains are for the most part subangular. In color the sands are dull gray or white at the surface, but at varying depths becomes yellowish or some darker shade; the darker basal sands grade downward into the underlying, unweathered, argillaceous, sandy formations. Pebbles are not common although at a number of localities they have been observed. They consist of t>mall, well rounded to angular, quartz pebbles, and small, brown or black, iron oxide nodules. Slight differences in the character of the sands at various localities have been noted, but on the whole they are uniform in texture, color, and composition, notwithstanding their diversity of origin. The surficial sands vary in thickness from a few inche~ to a maximum of 30 feet. The greatest thickness of \Vhat appear to be residual sands occurs at the sand-pits near Howard, Taylor County, whel'e the maximum is 20 or 30 feet. At other localities along the Fall Line 10 to 25 feet of sand has been observed, but over much of n the "sand hill' region, the thickness does not exceed five or six feet. Over the Altamaha (Lafayette terrane the average depth of the residual sands in place is probably between two and four feet,. but there are local accumulations of sands of torrential or eolian origin reaching a thickness of 10 to 25 feet, In the western part of the Coastal Plain, principally that part underlain by the Vicksburg formation, the gray sands are either absent or very thin. The,y are absent also in scattered smaller areas in other parts of the upland regwn. The surficial sands are present as a thin mantle over parts of the upland region from the Fall Line on the north to the Florida State line on the south. To the southeastward, within 50 or 75 miles of the Atlantic Coast, they merge' into the lithologically similar sands which cover the Okefenokee terrace plain. The sands are unequally distributed over the upland and are notably absent from certain areas. Their most conspicuous development is in the Fall Line region, chiefly over the area underlain by Lower Cretaceous strata; they are also welL developed over the region underlain by the Altamaha and Alum Bluff formations in the eastern and southeastern parts of the Coastal Plain. Upland areas, where the sands are nearly or entirely absent, are the following: Certain areaS' in Burke, Washington, wilkinson, and Twiggs counties which are underlain by red, ferruginous sands of the Claiborne formation; Rich Hill, Crawford County; the Fort Valley plateau, and the "red lands" in the vicinity of Grovania, Henderson, and Elko in the southern part of Houston County; the northern part of Dooly County; in the vicinity of Americus, and the southern part of Sumter County; GEOC.OGY OF 'l'IIE COASTAL Pl.d..IN OF GEORGI A.. PLATE XXX. SURFICIAL SAND 449 large parts of Randolph, Terrell, Dougherty, and other counties west of Flint River; and in the southern parts of Grady, Thomas, and Brooks counties. The sands, notwithstanding their relatively insignificant thickness, have had a very marked influence upon the topography, vegetation, and settlement of the country. The "sand hills" constitute a well known type of topography in the region of the Fall Line, and throughout that part of the area underlain by the Altamaha (Lafayette ~) formation, popularly known as the ''wire-grass" region. In the latter region the sands are mo~t conspicuous along the streams and particularly along those streams having general north-south courses. It has been commonly noted by the people living in this region that the accumulations of sands are greater on the east or left sides of the streams. Numerous exceptions to this may be found in the Coastal Plain region as a whole, but it is prevailingly true over the "wire-grass" region.. The hills perhaps antedate the present streams and may have governed their courses in part, the western front having acted as a barrier preventing the streams from pushing their courses to the eastward. The most notable examples of this type of sand hills are on the eastern side of Ohoopee River at Reidsville; on Cannoochee River at Stillmore; on Little Ocmulgee River two miles east of Helena and at Lumber City; and on the north side of Satilla River north of Waycross. These hills are well above the level of the streams and the sand is not to be confused with the alluvial sands of lower lervels. The vegetable growth over the sand hills is sparsl:l, consisting mainly of scattered long-leaf pines and stunted oaks, and the soil is poor and unproductive. The origin of the gray sands which form the "sand hills" and cover the higher interstream areas of the Coastal Plain has been a perplexing problem to geologists and other investigators. In the few references made by McGee' to these surficial sands he referred them to the "interfluvial phase of the Columbia." Also Spencer; McCallie,' and Veatch' have referred to them in a general way as "Columbia sand." Mr. R. M. Harper' has given interesting descriptions of the E>ands at a number of localities, discussing them from the standpoint of their influence upon the flora of the Coastal Plain. 'The Lafayette formation : Twelfth Ann. Rept., U. S. Geol. Survey, 1890-1891, pt. 1, pp. 388, 389. ' 2Spencer, J McCal!ie, .s.Ww., .F, irst Un Ann. Rep derground t . Progre Waters ss, of Georgia Geol. Survey, 1890-1891, Georgia: Georgia Geol. Survey, pp. 61-71. Bull. No. 15, 1908, p. 2' clay Depos A. Phytogeob ~ae!orSgika.c: Georgia h of the Geol. Survey, Bull. No. Altamaha Grit Region 18, :t909 p. of Georgia: 68. Annals N. T. Acad. Sci., Vol. n, pt. Nov., 1906. 450 GEOLOGY OF THE COASTAL PLAIN It is reasonably certain that much of the surficial sand is residual from Cretaceous and Tertiary formations, and hence should not be classed as a formation, using this word in a stratigraphic sense. The residual sand varies from one to ten feet in thickness. At many places on the slopes there are accumulations of sands transported by rainwater from higher to lowerr levels. In some cases the redeposited sands appear to rest unconformably upon the underlying strata, this relation being especially apparent where pebbles are presel).t at the base. Such deposits may show a thickness of from five to fifteen feet wher~as the residual sands on the tops of the hills may not be more than two feet. Accumulations of this nature are properly colluvial deposits. The winds may have shifted and redeposited the residual sands in places but there do not appear to be many large deposits due to this cause. The formations from which the residual, surficial sands are derived are themselves composed chiefly of quartz sand with small percentages of disseminated clay. In the process of weathering the clay is carried away in suspension by rainfall leaving the quartz grains and small amounts of other minerals, such as mica, iron oxides, etc. Wherever the formations underlying the surface are very calcareous, argillaceous, or fe,rruginous, the gray surficial sands are absent. In addition to the residual and colluvial deposits, there are gray or browish, incoherent sand deposits 10 to 30 feet thick, which lie in belts one~half mile to two miles wide, paralleling certain rivers and creeks; these accumulations appear to be at higher elevations than the fLuviatile terrace deposits of the O~e,fenokee formation. Locally, they exhibit faint stratification lines and in places seem to be sharply separated from the underlying older formations. These facts, together with their peculiar distribution and relatively great thickness are evidence of their non-residual character. Their high elevation precludes the possibility of their having been deposited by existing streams. It is suggested that they may have been heaped up as the result of combined wave and wind action along the shores of early Pleistocene estuaries, or they may have been deposited as alluvium by the rivers occupying the valleys in early Pleistocene time. This type of surficial sand is typically developed along Cannoochee, Ohoopee, LittLe Ocmulgee and Satilla rivers, and appears along other streams throughout the Altamaha upland or "Wiregrass country." One well known sand deposit,-the sand hills on the east side of Flint RiV'e'r at Albany,-dearly owes its r.resent form to wind deposition, whatever may have been the primaiy origin of the sand. SURFIOIAL SAND 451 There is some evidence of a sand-coverd, Pleistocene terrace plain higher and older than the Okefenokee plain and perhaps similar in origin, although as yet sufficient proof of its existence has not been obtained to warrant positive statements. Such a plain, if it exists, includes a part of the gray surficial sands here treated under the head of upland sands. (See pp. 424-425.) LOCAL DETAILS The more important localities where the surficial sands are developed, are mentioned below, and the topographic positions, lithologic characters, and probable origins of the deposits are indicated. Fall Line localities.-Extending southward 10 to 20 miles from the &'outhern border of the Piedmont Plain is a belt of land over much of which gray or brownish, incoherent quartz sands form a surficial covering. In a classification of the Coastal Plain from the agricultural standpoint Loughridge1 has described this region as the "Fall Line sand hills." In extent the "sand hills" were said to reach across the State from Augusta to Columbus, covering an area of about 2,950 &"quare miles. The surficial sands over this area are believed to be residual, except along the terraces bordering the rivers, where fluviatile sand deposits of Pleistocene age have been deposited. Near Hampton Terrace Hotel on the South Carolina side of Savannah River opposite Augusta, the surficial sands are gray or brownish, and mantle the upland plain at an elevation of 225 feet or more above the river; in one exposure, at the base of the gray &"and water-worn, quartz pebbles having a diameter of two or three inches, were observed. These pebbles are unmistakably in the surficial sand and suggest an unconformity with the underlying strata. The sand here overlies red, highly ferruginous sand of Eocene age. The gray sands are also exposed on the Georgia side west of AuguE>ta, at Monte Sano, at which place also a few pebbles were noted. The sands also mantle the hills and ridges westward from Augusta. Notable thin coverings of grayish or brownish quartz sands, probably residual, occur in the vicinity of Grovetown, Columbia County, and are also well developed over the hill tops and slopes southward from this place to Hephzibah, Richmond County. They attain a thickne&'s of only a few feet. In this region the sands are underlain principally by Eocene strata. At Keysville, in the northwestern corner of Burke County, the surficial sands reach a thickness of 10 to 18 feet and do not seem to be in any way connected with the drainage of the country. The 1Loughridge, R. H., Cotton Production: Tenth Census, Vol. 6, p. 38. 452 GEOLOGY OF THE COASTAL PLAIN sands are in general yellow or brownish, and, when moist, resemble oak sawdust; but in places at the surface they have beern leached almo::.t pure white. They consist almost entirely of subangular quartz, but microscopic examination reveals a few. rounded grains of opalescent silica; limonite forms a coating over the quartz grains ; there is some organic matter at the surface to which the characteristic dull gray appearance is due. No trace of stratification appears in any of the exposures. About two miles east of the town there is in these sands a circular depression which probably resulted from the irregular heaping up of the sands by wind action. The surficial sands overlie red, argillaceous sands of Eocene age. About 10 feet of brownish, incoherent sand overlies the Cretaceous strata in the railroad cut at Carrs Station, Hancock County, and similar sands appear at other localitie::. in the southern part of the same county. In a cut of the Central of Georgia Railway, about three miles west of Griswo-ldville, Jones County, 10 to 15 feet of loose, surficial sand overlies red Eocene sand from which it does not seem to be sharply separated. Although so great a thickness of sands of the residual class is not common, the nearly pure character of the underlying Eocerne sands at this locality renders this explanation of the origin of the deposit the most probable one. The gray, pebbly sands appear as a thin covering over the high level upland west of Macon, lying about 200 feet above Ocmulgee River. They appear to be residual from the underlying pebbly formation. The gray sands and gravels are mined at a small pit three miles west of Macon near the Columbus road. The gray sands are well developed southeast of Roberta, Crawford C~unty. They do not appear at all on Rich Hill, which is capped by Eocene strata, and which is probably the highest point in the Coastal Plain; over the adjacent Lower Cretaceous area to the southward they form a thick mantle covering a belt a few miles wide. In this r:egion the sands are gray at the surface, and light yellow at depths, and are composed almost entirely of qua,rtz. The thickness averages four to six feet but locally reaches 10 to 15 feet. At many places in this region the surface is dotted with numerous small, oval hillocks of sand, 8 or 10 inches high, thrown up by a burrowing pouched gopher, locally known as a "salamander." This small rodent is common elsewhere in the sand hills of the Coastal Plain. To the southward of this region in the Fort Valley area the surficial sands appear to be entirely absent. The best known development of the surficial sands occur on the high plain' stretching from three miles east of Butler, Taylor County, SURFICIAL SAND 453 westward to Geneva, Talbot County, in the region traversed by the Central of Georgia Railway. This plain reaches an elevation of 650 feet or more above sea-level. The sands are being excavated for. commercial purposes at Howard and Junction City. Near Butler the sands are only five or six Jeet thick. They extend northward from Butler to the border of the Piedmont area. At Howard, near the pits of the J. M. Brown Sand Company, the sands attain a probable maximum thickness of over 30 feet. Thirty feet of sands appear in the pits near the railroad, one mile west of Howard. They are entirely unconsolidated and show but little evidence of stratification. At the surface they are gray or light buff in color but in places at depths are' slightly darker. These sands overlie Lower Cretaceous strata apparently filling old erosion hollows; although there are these local indications of unconformity it is believed that the sands are residual from the underlying Cretaceous strata, but in places have been shifted into ravines by winds and torrents. Section in pit of J. M. Brown Sand Company at Howard. 1 Surficial sand. 5. A~s~!~ s~r~a~e-:-~n.e-~r~i~e~,. g.r~y. o~ ~~o~n.is~ 4. Light yellow sand . . . . . . . . . . . . . . 25 3. Almost white sand, showing some evidence of water stratification . . . . . . . . . . . . } 2. Ferruginous sand containing a very small per centage of clay . . . . . . . . . . . . . . . 5 1. White sand . . . . . . . . . . . . . . . . . . Microscopic examination of a sample of the surficial gray sand from this locality revealed chierfly subangular quartz grains with slight amounts of mica in fine flakes, some decomposed feldspar attaGhed to quartz grains, minute particles of black sand, and a small amount of iron oxide which forms a coating over the quartz grains; the clay content does not erxceed one or two per cent. Near Junction City, Talbot County, the sands reach a thickness of 20 feet; in color they are light bluff or dull gray; as at Howard, they are composed, of subangular quartz with minor amounts of clay, iron oxide, mica, and black sand; they are genecr.-ally fine in texture . but a few rounded quartz pebbles about the size of buckshot were observed in places. The deposits are wholly unconsolidated and reveal no stratification. Similar sands are present in the region to the southward of the above mentioned places and overlie the Upper Cretaceous and lower Eocene beds. Over a large part of the limestone region of southwestern Georgia they appear to be absent, the soils consisting of I 454 GEOLOGY OF THE COASTAL PLAIN red, argillaceous sands residual from the Eocene and Oligocene formations; they have been noted in a few places, however, as in . the region east of Americus, Sumter County; north of Shellman, Randolph County; over a large part of Lee County; in the we5tern part of Bakecr County; and in Miller County. Large accumulations of sand appear in the form of dunes 30 or 40 feet high on the east side of Flint River at Albany; the maxim11m elevations of their summits above the river is about 100 feet. Among the dunes are undrained depressions probably due in part to the collapse of solution caverns in the underlying Vicksburg limestone, and in part to the irregular heaping up of the sand by wind. The sands are gray or light buff in color and are composed entirely of subangular quartz grains; in composition and appearance they resemble the gray sands of the Fall Line region. Small, angular and fiat flint chips are scattered through the sands; since these fragments show no evidence of having been water-worn in transportation they are believed to be the chippings left by Indians in the manufacture of arrows, hatchets; etc. Similar flint chips have been observed at Dublin in sand described on a following page. The sands were probably accumulated during the' early Pleistocene period. "Wire-grass" sand hills.-Grayish and brownish sands are present as a surficial covering over nearly the whole of the "wire-grass" upland east of Flint River. Generally they form only a thin residuat covering over the mottled, argillaceous sands and clays of the Altamaha (Lafayette ?) formation. The thickness of the sand averages two to folir feet, but at a number of localities there are accumulations reaching 10 to 25 feet. A few of the more conspicuous localities are mentioned below: In the southeastern part of Burke County, and also in Screven County, are heavy beds of surficial gray sand of probable residual origin lying between Briar Creek and Savannah River. The sands reach a thickness of from 3 to 10 feet and overlie, alike, the Barnwell sand of the Claiborne group and the Altamaha (Lafayette ?) .formation. They lie on the divide between the two streams at elevations of 125 to 150 feet above Savannah River. On the east side of Oconee River, opposite Dublin in Laurens County, is a conspicuous accumulation of sand lying about 100 fee.t above the river and reaching a maximum thickness' of 20 feet. See plate XXX, opposite page 448. The sands are gray to light buff in color. Near the surface they are rather fine, incoherent, and structureless, but with depth become slightly coarser and near the base exhibit current bedding. Between this sand accumulation and the river there are gray -sands of terrace origin which are certainly of SURFICIAL SAND 455 Pleistocene age and referable to the Okefenokee formation. Quartz pebbles were noted in the upland gray sands south .and southwest of Dublin. A fine exposure of sand appears in a cut of the Seaboard Air Line Railway two miles east of Helena, Telfair County, on the east side of Little Ocmulgee River. The sand bed reaches a thickness of 25 feet; it is gray or light buff in color, becoming coarser and almost white at the bottom of the cut; very coarse sand and a few pebbles were noted near the contact with the underlying formation. The sand hill reaches a height of 75 feet above the river and extends southward to the junction with the Ocmulgee at Lumber City. On the west side of the river only a thin coating of the gray sand is present. The gray sands are well developed in the region traversed by Cannoochee River and its tributaries. A notab~e deposit occurs on the east side of Cannoochee River five miles northeast of Stillmore, Emanuel County, where it is well exposed in a cut of the Georgia and Florida Railway. The sands reach a thickne,ss of 15 feet; are gray, yellow, or light buff in color, and have the characteristics of similar accumulations at other localities. Wavy lines one-eighth of an inch thick or less, of ferruginous, darker colored sand, present the only ervidence of stratification. At one point in the cut a high percentage of iron oxide was observed, rendering the sands yellow or orange in color; a few thin, limonitic crusts were noted. This deposit is well above the river and is certainly not a Recent floodplain' accumulation. On the west side of the river there is only a very thin film of sand over the Altamaha (Ldayette ~) formation~ Similar deposits occur along the Georgia and Florida Railway on the north side of Ohoopee River, six miles southeast of Stillmore; on the north side of Pendletons Creek; and near Normantown. Near Reidsville, on the east side of Ohoopee River in Tattnall County, is a heavy sand bed covering a belt two to three miles wide. The sands are white at the surface in places and in a photograph produce the effect of snow. The deposit lies well above the river and apparently is not of river terrace origin. However, gray sands, locally termed "sand hammocks" which are probably of Pleistocene tel'race origin, occur at lower levels along the river. There is an extraordinary development of sand on the east and north side of Satilla River, and its tributary, Seventeen Mile Creek, extending from western Pierce County opposite Waycross, to Douglas, Coffee County. This deposit consists of gray, yellowish or b~ownish, incoherent quartz sands free from pebbles and clay, and for the most part structureless or showing only very faint structure. 456 GEOLOGY OF THE OOASTAL PLAIN In places the sands reach a thickness of 20 or 30 feet or more. The altitude of the sand hills above Satilla River is about 50 feet, or about the same as the general upland level of the same region. The sands lie at a higher elevation than the sands of the Okefenokee terrace plain east of Waycross, and because of their higher elevation are supposed to be older than that formation. In places in this belt there are in the sands roughly circular, shallow depressions which during rainy seasons., hold water and form sand hill ponds. It is not known whether these sands are of beach and wind-dune origin along the shore of a Pleistocene estuary or whether they were deposited as alluvium. It is certain, however, that they owe their present form in part to wind action. Considerable accumulations of surficial sand cover the high plateau on the east side of Flint River from near Faceville, Decatur County, southward to River Junction, Fla. The sands are buff or dirty gray in color, due to iron oxide and to a small amount of organic matter from growing 'vegetation. They are loose in texture and resemble the surficial sands of the Fall Line region and elsewhere. A sample from near the 255th mile-post on the Atlantic Coast Line Railway between Recovery and River Junction was examined microscopically. It was found to consist chiefly of fine, sub:angular quartz with a small percentage of well rounded, or spherical :grains, and a very small percentage of clay. INDEX Page. A Adrian, section near . . . . . . . . . . . . . . . . . . . . . . . 414 Aeolian, sand deposits . . . . . . . . . . . . . . . 442, 443 448, 450, 452, 454 Agate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337, 344, 353 Albany, artesian well at . . . . . . . . . . . . . . . . . . . 200-201, 317-319 Sand hills near . . . . . . . . . . . . . . . . . . . . . . . . 450, 454 Vicksburg formation near . . .. . . . . . . . . 316-319 Albion Kaolin Co. section at mines of . . . . . . . . . 105 Aldrich, T. H., fossil determinations by . . . . . . . .. . . . . . . . . 420 Alexanders Landing, Chattahoochee R. section at . . . . . . . . . . . 178-179 Allapaha River, sections along . . . . . . . . . . . . . . . . 340, 353-354 Altamaha (Lafayette) formation . . . . . . . . . . . . . . . . . . . 400-423 Altamaha River, course of . . . . . . . . . . . . . . . . . . . . . . 41 Detailed sections along . . . . . . . . . . . . . 359-360, 376-377, 409-413 Altamaha Upland . . . . . 31-34 Alum Bluff formation . . . . . . . . . . . . . . . . . . . . . . . . 342-362 Alum Bluff, section at . . . . . . . . . . . . . . . . . . . . . . . . 342 Americus, geology near. . . . . . 267, 314 Andersonville, geology near . . . . . . . . . . . . . . . . . . . 235, 267, 313 Anticlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41, 63 Appalachian Mountains . . . . . . . . . . . 26 Appalachian Valley . . . . . . . . . . . . . . . 26 Appalachicola Group . . . . . . . . . . . . . . . . . . . . . . . . . 324-362 Arkose . . . . . . . . . . . . . . . . . . . . . . . 84, 104, 269, 403, 404, 417 Arlington, Vicksburg near . . . . . . . . . . . . . . . . . . . . 313 Atkinson, Wayne County, section at King plantation . . . . . . . . . 419-420 Attapulgus, fullers earth and sections near . . . . . . . . . . . . . . 349-350 Augusta, Cretaceous near . . . . . . . . . . . . . . . . . . . . . . 103, 105 Pleistocene at . . . 433, 441 Surficial sand at . . . . . . . . . . . . . . . . . . . . . . . 451 B Bainbridge, geologic notes and sections near. . . . 320-322, 329-332, 347-348 'Barnwell sand .. . . . . . . . . . . . . . . . . . . . . . . . . . 285-29() Barrows Mill, Houston County, section at. . . . . . . . . . . . . . . 197, 217 Basin, Claiborne, along Savannah River. . . . . . . . . . . . . . . 239 Bassler, R. S., fossil determinations by . . . . . . . . . . . . . . . . 260, 396 Bauxite . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72, 75, 96, 2~~ Bays, definition of . . . . . . . . . . . . 3~ Beach pebbles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371, 435 Beach deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446 Beards Bluff, Pleistocene at. . . . . . . . . . . . . . . . . . . . . 44:\ Berry, E. W., on fossil plants in Georgia . 73, 87, 119, 123, 128, 144, 163, 171, 173, 209-210, 246 Bibb County, Lower Cretaceous in . . . . . . . . . . . . 90-91 Claiborne in . . . . . . . . . . . . . . . . . . . . . . . . 283, 295-29!i Big Pond, Appling County . . . . . . . . . . . . . . . . . . . . . . 49 Blakely, log of well at . . . . . . . . . . . . . . . . . . . . . . . 201, 312 Blue Bluff, Savannah R. section at . . . . . . . . . . . . . . 249-256 Blue Spring, Decatur County . . . . . . . . . . . . . . . . . . 325, 330, 331 Blue Spring Dougherty County . . . . . . . . . . . . . . . . . . . . 50 Blufftown, Chattahoochee River, section and fossils . . . . . . . . . 134-137 Boston, formations near . . . . . . . . . . . . . . . . . . . . . . . 338, 351 Boyd Farm, Burke County, fossil collection at . . . 289 Broken Arrow Bend, section at . . . . . . . . . . . . . . . . 117-119 457 458 INDEX Brunswick, Miocene at . . . . . . 377-378 Pleistocene at . . . . 436 Buena Vista, sections near . 163, 196, 217 Log of well at . . . . 190 Buffalo Swamp . . . . . . 37, 49 Bugs Bluff, Altamaha River, section of . 412 Buhrstone formation . . . . . . . . . . . 238, 262 Burke County, Claiborne in . 242-251, 287-290 Surficial sand in . . . . . . . . . . . . . . . . . . . . . . . 451-452, 454 Burnt Fort, marl at . . . . . . . . . . . . . . . . . . . . . . . . . 380, 381 Pleistocene near . 439 Byron, sections near. . . . . . . . . . . . . . . . . . . . . 169-171 c Calico Hill, St. Marys River . . . . 399 Camden County, Pleistocene in . . . . 439-440 Cannoochee River; sand hills along . 455 Cape Fear beds . . . . . . . . . . 109 Carrs Station, geology near . . . . . 79, 99, 452 Chalk Bluff, St. Marys River, section at . 399-400 Chalker, Claiborne near . . . 276 Charlton formation. . . . . . . 392-400 Chattahoochee formation . . . . 324-342 Chattahoochee River, map of . 79 Pleistocene along . . . . . . . . . . . . . . . . . . . . . . . . 431, 444 Sections along . . . . . . 78-83, 117-123, 131-138, 172-181, 231-232, 262-264 Structure along . . . . . . . . . . . . . . . . . . . . . . . . . 63, 64 Chimney Bluff. section . . 122-123 Fossils from . . . . . 132 Claiborne group . . . . . . 235-296 Historical summary. . 235-237 Divisions of . . . . 236 Clark, W B. . . . . . . . 111, 179, 341 Clay Landing, St. Marys River, section . . 396 Clays, of commercial value . . . . . . . . . 72, 75, 88, 231, 284, 346 Clays, silicification of . . . . . . . . . . . . . . . . . . . . . . . . 272, 344 Climax, Decatur County, sections near . . . . . . . . . . . . 348-349, 421-422 Section near, by J. W. Spencer. . . . . . . . . . . . . . . . . . 388-389 Coastal Plain, area of . . . . . . . 27 Elevations of above sea level . 27 Elevations, list of . . . . . . . . 50-57 Geology of, general statement . 58-G5 Physiography of . . . . . . . 27-50 Colerain bluff, St. Marys River . . 435 Collins, Altahama (Lafayette) at . 415 Colluvial sand deposits . . 450 Columbia formation . . . . 424 Columbia group. . . . . . . . 425-445 Columbus, sections near. . 78-86, 124-127 Wells near . . . . . 80-81 Pleistocene near . . . . 382, 431, 444 Congaree clay member . . . 2G7-284 Conrad, T. A., cited . . . . . . . . . . . . . . . . . . . . . . . 68, 236, 243 Copperas Bluff, section at . . . . . . . . . . 226 Cordray Mill, geology near. . . . . . . . . . . 266. 267, 299 Correlation, Cretaceous . . . . . . . 108-111, 140-149, 204-215 Cowford, St. Marys R., section at . 397 Cox property, section on . 242 Cox spring, sections near . . . . . . 287-288 INDEX 459 Crescent, Mcintosh County, Pleistocene at . . . . . . . . . . . . . 438 Cretaceous . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 66-215 Historical review . . . . . . . . . . . . . . . . . . . . . . . 67-73 Crystalline Area of Georgia . . . . . . . . . . . . . . . . . . . . . . 58 Crystalline floor, slope of . . . . . . . . . . . . . . . . . . . . . . . 62, 74 Cumberland Plateau . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Cusseta, Cretaceous near . . . . . . . . . . . . . . . . . . . 139-140, 162-163 Cusseta sand member . . . . 152 Cuthbert, geology near. . . . . . . . . . . . . . . . . . . 234, 266, 311 D Dall, W. H . . . . . . . . . . . . . . Danville Ferry, Flint River, section at . . Dawson, Vicksburg formation at ..... Demeries Ferry, Savannah R., section at. Diabase dike . . . . . . . Doctortown, section at . . . . "Lafayette" at . . . . . . Dougherty Plain . . . . . . . Drainage of the Coastal Plain. Drainage in relation to structure . Drybranch, sections and geology near Dublin, Vicksburg near . . . . Sand hill opposite . . . . . Dune sand and aeolian deposits Duplin Marl . . . . . . . . . . . . 243, 247, 307, 342 260 312 248 28Q . 377: 413 384 30-31 39-43 . 63 . 9294, 255-256, 294, 304 . . . . . . . . . 323 . . . . . . . . . 454 . 37, 389, 430, 432, 441, 454 . . . . . . . . . . 366-369 E Ebenezer, Effingham County, Miocene at . . . . . . . . . . . . . 375 Economic geology . . . . . . 220, 283-284, 298-299, 311, 328, 346, 366, 369 Eden, sand hill near . . . . 443 Elevations in Coastal Plain 50-57 Ellaville, formations near . . 191, 224, 235 Euchee Rapids, section at . . 119-121 Eocene ........... . . 216-306 Eufaula, Alabama, list of Cretaceous fossils from . 176-177 Pleistocene at 43.1 Sections near . . . . . . . 173-181 Eutaw formation . . . . . . . . 111-149 Everhart, Edgar, analysis by . 446 Exogyra ponderosa zone 154 Exogyra costata zone . . . . . 154 F Faceville, section at . . . . . . . . . . . 333-334 Fall Line, definition of . . . . . . . 27 Fall Line Hills . . . . . . . . . . 28-30 Feldspar in Coastal Plain formations . 403, 404, 405, 417 Flint of the Vicksburg formation . . . 308-309 Flint River, course of 63 Pleistocene along . . .. . 432 Sections along . . . . . 225-226, 260-262, 314-322, 328, 332 Foerste, A. F. . . .. . . . ... . . . . . . 34 7 Folkston, formations near . . . . . . . . . 398-399, 426, 427 Forest Falls, sections at . . . . . ..... . . . 334-336 Florence, section of Cretaceous at . . . . . . . . . . . . . . . . . . . 155-156 460 INDEX G Fort Gaines, log of well near . . . . . . . . . . . . . . . . . . . 202 Pleistocei).e at . . . . . . . . . . . . . . . . . . . . . . . . . . . 431 Sections at . . . . . . . . . . . . . . . . . . . . . . 220-221, 231-233, 263 Fort James, Altamaha River, section at . . . . . . . . . . . . . . . 411 Fort Val~ey, notes on geology near . . . . . . . 154, 168-169, 171, 386 Sectwn of well at . . . . . . . . . . . . . . . . . . . . . 171 Fossils, value of in stratigraphy . . . . . . . . . . . . . . . . . . . 61, 66 Fullers earth . . . . . . . 268, 269, 278-279, 283, 284, 343, 346, 349, 359, 409 Geologic formations, detailed description of 66-456 General statement about . . . . . . . . . 58-65 "'Iap of . : . . . . . . . . . . . . . 58 Tables of . . . . . . . . . . . . . . . . . . . . . 48, 60-61 Thickness of_. . . . . . . . . . . . . . . . . . . . . . . . . . . 59-62 Georgetown, formations near . . . . . . . . . . . . . . . . 181-184, 222, 431 Georgia Kaolin Company, sections at mines of . . . 93, 256, 304 Gibson, sections near . . . . . . . . . . . 272-274 Gidley, J. W., fossil determinations by . . . . . . . . . . . . . . . 208-436 Gilmore, C. W., fossil determinations by . . . . . . . . . . . . . . . 175, 208 Girard, Vicksburg near . . . . . . . . . . . . . . . . . . . . . . . . 323 Glauconite beds . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 Glynn County, Pleistocene in . . . . . . . . . . . . . . . . . . . . . 439 Gosport greensand formation . . . . . . , . . . . . . . . . . . . . 236, 287 Gravel beds . . . . . . . . . . . . . . . . . . . . . . . . . . . 90, 431, 452 Grays Landing, Altamaha River, sections at . . . . . . . . . . . . . 409 Greens Cut, Burke County, formations at . . . . . . . . . . . . . . . 384 Greer Cave, Midway formation at . . . . . . . . . . . . . . . . . . . 223 Griffin Landing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 Griswoldville, formations near . . . . . . . . . . . . . . . . . 94-95, 282, 452 Grit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403 Grovetown, section and geology near . 102, 103, 269-271, 451 Gullies . . 29-30 Gypsum . . . . . . . . . . . . . . . . . . . . . . 435 H Hamburg beds, Cretaceous . 109 Hammocks .. . . . . . . . . 34, 455 llancock Landing, section at . 248-249 Harlem, sections at . . . . . . . 271-272 Harper, R. M., quoted . . . . . . . . . . . . . . . . . . . . . . . 44-46, 391 Harris, G. D., cited . . . . . . 270, 279, 282 Hawkinsville, section near . . . 305, 322-323 Helena, sand hills east of . . . . . . . . . . . . . . . . . . . . . . . 455 Hephzibah, geology near . . . . . . . . . . . . . . . . . . . . . . 105, 290 Hershman .Lake . . . . . . . . . . . . . . . 43, 324 Hicks Bluff, St. Marys River. section at . . . . . . . . . . . . . . . 394 House Creek bluff, section at . . . . . . . . . . . . . . . . . . . . . 357 Howard, Taylor County, surficial sand near . 453 Hudson's Landing, sections at . . . . . . . . . . . . . . . . . . . 361, 370 Ideal, section near . . . . . . . . . . . . . . . . . . . . . . . . . . 192 Igneous and crystalline rocks . . . . . . . . 73-74, 78, 84, 101, 104, 106, 280 Illustrations, list of . . . . . . . . . . . . . . . . . . . . . . . . 20-24 Iron ore . . . . . . . . . . . . . . . . . . . . . . . . . 164, 218, 220, 286 Irwinton, Lower Cretaceous near . 96 Islands, area and origin of . . . . . . . . . . . . . . . . . . . . . 37 INDEX 461 J Jackson formation . . . . . . . . . . . . . . . . . . . 296-306 Jacksonboro, Screven County, limestone near . . . . . . . . . 341-342 Jamestown P. 0., section of Cretaceous at . . . . . . . . . . . . 138-139 Jefferson County, Claiborne in . . . . . . . . . . . . . 251-253, 272, 291-292 Jeffersonville, section near. . . . . . . . . . . . . . . . . . . . . . . 294-295 Johnsons Hill, Stewart County, section . . . . . . . . . . . . . . . 187 Johnsons Landing, formations at . . . . . . . . . . . . . . . . 306, 324 K Kaolin . . . . . . . . . . . . . . . . . . . . . . . . . . . 72, 75, 92-95 Keysville, surficial sand at . . . . . . . . . . . . . . . . . . . . . . 451-452 King Plantation, Satilla River, sections and fossils . . . . . . . . . 402, 419 Kittrells, section near . . . . . . . . . . . . . . . . 305 Kramer, Wilcox County, Altamaha (Lafayette) at. . . . . . . . . . 417 L Ladd, Geo. E., quoted . . . . . . . . . . . . . . . . . . 277-278, 389-390 Lafayette formation . . . . . . . . . : . . . . . . . . . . . . . 379, 380 Review of literature on . . . . . . . . . . . . . . . . . . . . 381-392 Relation to Altamaha formation . . . . . . . . . . . . . . . . . 392-407 Lakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41-43 Langdon, D. W., cited . . . . . . . . . . . . . . . . . . . . . . 70, 227, 262 Lignite . . . . . . . . . . . . . . . . 116, 122, 270-271, 284 Lignitic group . . . . . . . . . . . . . . . . . . . 227 Lime, rock suitable for . . . 221, 250, 254, 299, 311, 314, 328 Limesink, Forest Falls . . . . . . . . . . . 42 Sections at . . . . . . . . . . . . . . . . . . 334-336 Limesinks . . . . . . . . . . . . . . . . . . . . . . . . 31, 33, 34, 42 Limestone, silicification of . . . . . . . . . . . . . . . 222, 292, 308, 313, 326 Linden Bluff, Attamaha River, section at . . . . . . . . . . . . . . . 412 Lithology, as a basis for mapping . . . . . . . . . . . . . . . . . . 61, 66 Little, Dr. George. quoted . . . . . . . . . . . . . . . . . . . . . . 69 Livingston plantation, section at . . . . . . . . . . . . . . . . . . . 378-379 Loughridge, Dr. R. H., cited . . . . . . . . . . . . . . . . . . . 49, 380, 451 Louisville oil well, log of . . . . . . . . . . . . . . . . 76, 100, 107-108, 252 Lower Cretaceous . . . . . . . . . . . . . . . . . . . . . . . . . . 73, 111 Lumber City, Pleistocene at . . . . . . . . . . . . . . . . . . . . . 433 Section of Alum Bluff formation at . . . . . . . . . . . . . . . 357 Lumpkin, sections near . . . . . . . . . . . . . . . . . 187, 194-195, 216-217 Lyell, Sir Charles, cited . . . . . . . . . . . . . . . . . 67, 243, :t41, 436-437 L7ell gullies . . . . . . . . . . . . . . . . . . . . . . 30 Me McBean, fossils near . . . . . . . . . . . 239-240 Sections near . . . . . . . . . . . . . 242-243 McBean formation . . . . . . . . . . . . . 237-284 McBride Ford, section of Cretaceous at . . . . . . . . . . . . . 86 McCallie, S. W., sections and notes by . . . . . . . . 71, 253-254, 283, 295, 305 Quoted on Lafayette . . . . . . . . . . . . . . . . . . . . . . . 391-392 McDuftl.e County, Lower Cretaceous in. . . . . . . . . . . . . . . . 101 McGee, W. J., cited on Pleistocene . . . . . . . . . . . . . . . . . . 424 Quoted on Lafayette . . . . . . . . . . . . . . . . . . . . . . 381-385 Mcintyre plantation, rocks at . . . . . . . . . . . . . . . . . . . . 337 462 INDEX M Macon, formations near . . . . . . . . . . . . . 90-91, 283, 383, 390, 432 : Terracing at . . . . . . . . . . . . . . . . . . . . . . . . . . 383, 432 Mammalian remains . . . . . . . . . 394, 435, 437 Map, geologic, opposite . . . . . . . 58 Marll:s Head, section at . . . . . . . 371 Marks Head marl . . . . . . . . . . . . 363-366 Marl, description of at Shell Bluff . . . . . . . . . . . . . . 247 Marls and limestone for fertilizer . . . . . . ~ . . 220, 231, 247, 284, 328, 366 Mars~ and tide swamp . . . . . . . . . . . . . . . . . . . . . . ' 38 Area of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446 Marshallville, log of weir' at . . . . . . . . . . . . . . . . . . . . . 197 Matson, G. C., and Clapp, F. G., cited . . . . . . . . . . . . . . . . 306, 393 Midville, formations near . . . . . . . . . . . . . . . . . . . . . . 289, 416 Midway formation . . . . . . . . . . . . . . . . . . . . . . . . . 216-226 Millen, formations near . . . . . . . . . . . . . . . . . . . . . . . 341, 433 Miocene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362-379 Montezuma, sections near : . . . . . . . . . . . . . . . . . . . . . 224-225 Well at . . . . . . . . . . . . . . . . . . . . . . . . . . 202-203 Morris Landing, Chattahoochee River, Eocene at . . . . . . . . . . . 181, 220 N Names of formations . . . . . . . . . . . . . . 61 Narrows, Pataula Creek, section and fossils . . . . . 184-185 Nettles Landing, St. Marys River section . . . . . . 296-397 New Savannah bluff, Savannah River section at. 442 Norwood, Lower Cretaceous at . . . . . . . . . . . . .. . . . . . 101 0 Oakfield, Vicksburg formation near . . . . . . . . . . . . . . . . 314-315 Ocean Pond, Lowndes County . . . . . . . . . . . . . . . . . . 34-35 Ochille, section at . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Ocmulgee River, sections along . . . . . . . . . . . . . 305, 356-358 Pleistocene along . . . . . . . . . . . . . . . . . . . . . . . . 432, 443 Oconee River, sections along . . . . . . . . . . . . . . . . . . . 305-, 358-359 Ogeechee River, Alum Bluff formation along . . . . . . . 360 Oglethorpe Bluff, Altamaha River, section at . . . . . . . 411-412 Okefenokee Plain .., . . . 35-36, 46, 425, 426 Okefenokee Swamp . . . . . . . 44-49 Map of, opposite . . . . . . 44 Okefenokee formation . . . . . . 425-434 Old Town, list of fossils from . . 292 Oligocene . . . . . . . . . . . . 306-362 Adoption of the term . . . .,. . . 307, 362 Olympia, section near . . . . . . . . . . . . . . . . . . . 339 Omusee Creek, Alabama, Claiborne at . . . . . . . . . . . . . . . . 263-264 Orange Bluff, St. Marys River, section at . . . . . . . . . . . . . . . 400 Pleistocene at . . . . . . . 440 Orbitoidal limestone . . . . . . . . . . . . . . . . . . . . . . . . . 310 Original Pond, formations at . . . . . . . . . . . . . . . . . . . . 336-337 Ostracods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396, 399 Ostrea georgiana bed . . . . . . . . . . . . . . . . . . . . . . . . . 240, 244 Ostrea georgiana, description of . . . . . . . . . . . . . . . . . 243, 247, 250 Owens Ferry, Miocene at . . . . . . . . . . . . . . . . . . . . . . 379 INDEX 463 p Paleozoic area of Georgia . . . . . . . . . . . 58 Parramore Hill, Altamaha (Lafayette), at . . . . . . 416 Pataula Creek, fossils and sections . . . . . . 1'79-180, 184-186 Peat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 "Pebble" land . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405, 421 Penny Bluff, Flint River, section at . . . . . . . . . . . . . . . . . . 261 Perry, Cretaceous near . . . . . . . . . . . . . . . . . . . . . . . . 198-199 Sections south of . . . . . . . . . . . . . . . . . . . 258-260, 301-303 Phosphate . . . . . . . . . . . . . . . 326, 337, 338, 340, 344, 346, 354, 355, 363 Physiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25-50 Piedmont Plain . . . . . . . . . . . . . . . . . . . . . o . . . . . 26-27, 58 Pikes Peak station, sections at . . . . . . . . . o . . . . . . . . . 278-279 Plant remains (see also Berry, E. W.) . . . . . 99, 269, 270, 271, 290, 370, 372 0 Pleistocene . . . . . . . . . . . . . . . . . . . . . . . 0 424-445 Pliocene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379-423 Ponds . . . . . . . 33, 34, 41-43 0 0 Porters Landing, Savannah River, sections at . . . . . . . . . . . . 371-373 Fossil collections at . . . . . . . . . . . . . . . . . . . . . . . . 365, 368 Potholes . . . . . 0 0 0 o . . . . . . 221, 233 Potomac formation . . . . . . . . . . . . o . . . . o . . . . . . . 70, 71 Powell Umesink . . . . . . . . . . . . . . 332-333 Preston, Midway near . . . . . . . . : . 0 223 rrov1aence gullies . . . . . . . . . . 30, 19" Providence, Lumpkin County, section at. . 19! Providence sand member . . . . 152-153 Sections of . . . . . . . . . . . . 0 0 192-198 Pumpelly, Raphael, cited . . . . . . . . . 325 Purisburg, S. C., section at . . . . . . . . 375-376 Pyles Marsh, reference to plate illustrating . 37 Q Quaternary . . . . . . . . . . . . . . . . . . . . . 424-445 Quitman, geology near . . . . . . . . . . . . . . . . . . . . o . . 339; 352 Quitman County, Cretaceous in . . . . . . . . . . . . . . 181-183, 192-193 Eocene exposures in . 222-223 Pleistocene in . . . . . . . . . . . . . . . . . . . . . . . 431 R Racepasses, Chattahoochee River, section at . 123 Rand Landing, St. Marys River, section . 0 395-396 Recent deposits . . . . . . . 445-447 Red h1lls . . . . . . . . . . . . 29 Reidsv1lle, sand hill near . . . . . . . 455 Renfroe& marl formation . . . . . . . . . . . . . . . . . . . . 72 Rept1Uan remains . . . . . . . . . . . . . . . . . . . . . . 151, 208, 215 Reynolds, well at . . . . . . . . . . . . . . . . . . . . . . . . . 76 Rich Hill, Crawford County, formations at . . . . . . . 30, 88-89, 299-300, 385 Richland, Midway near . . . . . . . . . . . . . . . . . . . 223 Richmond Coo,mty, geology of . . . . . . . . . . . . . 103-105, 251, 290-291 Ripley formation . . . . . . . . . . . . . . . . . . 149-215 Rivers of the Coastal Plain . . . . . . . . . . . . 40-41 Road metal . . . . . . . . . . . . . . . . . . 311 Rock House, Crisp County, section at. . . . . . . . . . 0 340 Roods Bend, Chattahoochee River, section and fossils . . 159-160 Roberts Station, section and fossils . . . . . . . . . 279-282 464 INDEX Rose B,luff, Fla., fossils and section . . . . . . . . . . . . 436 440 , Rors Hill, section of Jackson formation at. . . . . . . . . . . . . . ' 301 Rotten limestone formation . . . . . . . . . . . . . . . . . . . . . 69, 71 Rutland, Bibb County, section near . . . . . . . . . . . . . . . 90 s Sal.amander, in sand hills . . . . . . . . . . . . . . . . 452 Sandersville, sections near . . . . . . . . . . . . . . . . 253 Sand hills . . . . . . . . . . . . . . . . . . . . . . . . 29, 33, 77, 449-451 Origin of . . . . , . . . . . . . . . . . . . . . . . . . . . . . . 34, 77 Sand hill ponds . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Sand pits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453 Sand streams . . . . . . . . . . . . . . . . . . . . . . . . . . . 30, 164, 447 Sandersville, geologic formations ne~r . . . . . . . . . . . . . . 253, 274-275 Log of well at . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Sansavilla bluffs, Altamaha River, sections . . . . . . . . . . . . . . 413 Satilla Coastal Lowland . . . . . . . . . . . 36-39 434 Satilla formation . . . . . . . . . . . . . . . . . . . . . . . . . . 434-445 Satilla River, course of . . . . . . . . . . . . . . . . . . . . . . . . 41 Formations along . . . . . . . . . . . . . . . . . . . . . . . . 379, 392 Sand hills along . . . . . . . . . . . . . . . . . . . . . . . . 455-456 Savannah, Altamaha (Lafayette) near . . . . . . . . . . . . . . . . 417 Pleistocene near . . . . . . . . . . . . . . . . . . . . . . . . . 437-438 Savannah River, sections along . . . . . . . 105-106, 243-251, 361-362, 370-376 Pleistocene along . . . . . . . . . . . . . . . . . . . . . . 433, 441-442 Savannas . . . . . . . . . . . 37 Sawpit Landing, section at . . 398 Second bottoms . . . . . . . . . 39 Sellards, E. H., cited . . . . . . . . 440 Selma Chalk . . . . . . . . . . . . . 69-71 Shell Bluff, description of strata at . . . . 243-247 Silver Bluff, Savannah River, Pleistocene . . . 442 Sister Bluff, Altamaha River, section of . . . 410-411 Sisters Ferry, Savannah River, section at . . . . . . . . . . . . . 374-375 Slick Bluff, Chattahoochee River . . . . . . . . . . . . . . . . . . 71, 120 Sloan, Earle, cited and quoted . . . . . . . . . . . . . . . 236, 239, 267, 371 Smith, E. A., cited . . . . . . . . . . . . . . . . . . . . . . . . 69, 112, 177 Smithville, Claiborne near . . . . . . . . . . . . . . . . . . . . 267 Soils . . . . . . . 29, 32, 35, 238, 269, 287, 309, 345, 351, 364, 367, 405, 430, . 447, 453-454 Southern Limesink region . . . . . . . . . . . . . . . . . . . . . 34-35 Spencer, J. W., on Cretaceous geology . . . . . . . . . . . . . . . . 71 Quoted . . . . . . . . . . . . . . . . . . . . . . . . . 261-262, 385-389 Section by . . . . . . . . . . . . . . . . . . . . 387 Springs . . . . . . . . . 49-50 Stanton, T. W. . . . . . . . 23 Fossil collections by . . 178-180 St. Marys River, course of . . . . . . . . . . . . . . . . . . 41 Detailed sections along . . . . . . . . . . . . . . . . . . . . 356, 393-400 St. Stephens limestone formation . 306 Stephenson, L. W. . . . . . . . . . . . . . 22-23 Stevens Pottery, sections at . . . . . . . . . 97 Stewarts Hill, Chattahoochee River, section Section of by J. w. Spencer . . 174-175 387 Stillmore, sand hills near . . 455 Stokes Ferry, section . . . . . . . 393-394 Stony Bluff, section at . . . . . . 290 Stony Lake, section at . . . . . . . . . . . . . . . . . . . . . . . . 339 INDEX 465 Structure of the Coastal Plain . . . . . . . . . . . . . . . . . . 62-65 During deposition of Claiborne . . . . . . . . . . . . . . . . . . 239 Submergence, coastal . . . . . . . . . . . . . . . . . . . . . . . . . 37, 38 Surficial sands . . . . . . . . . . . . . . . . . . . . . . . . . 402, 447-456 Suwanee River, formations along . . . . . . . . . . . . . . . . . . 355, 445 Swamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43-49 Sylvester, Chattahoochee formation near . . . . . . . . . . . . . . . 327 T Talbot County, Lower Cretaceous in . 87 Taylor County, Lower Cretaceous in . . . . 87-88 Tennille, Sections near . . . . . . . . . . 254 Log of well at . . . . . . . . . . . . . . . . . . . . . . . . . 107 Terraces . . . . . . . . . . . . . . . . . . . . . . . . . . 35-38, 39, 424, 441 Elevations of . . . . . . . . . . . . . . . . . . . . . . 424, 425, 430, 441 Terrace deposits, described in sections (see under Pleistocene) . . . . 424-445 (See also various sections along Chattahoochee, Flint, Ocmulgee, Altamaha and S'avannah Rivers). Tertiary . . . . . . . . . . . . . . . . . . . 216-424 Thickness of . . . . . . . . . . . . . 61 Thickness of Coastal Plain strata . . . . . 61-62 Thomas Bluff, Chattahoochee R., section at . 82 Tide Swamp . . . . . . . 38 Tivola, section at . . . . . 303 Tombigbee sand member . . 112 Correlation of . . . . . 145-149 Sections of . . . . . . . . . . . . . . . . . . . . . 131-138 Turtles, fossil . . . . . . . . . . . . . . . . . . . . . . . . . 151, 219 Tuscaloosa formation . . . . . . . . . . . . . . . . . . . . . . 70, 109, 112 Twiggs County, Claiborne formation in . . . . . . . 255-257, 278-279, 293-295 Jackson formation . . . . . . 304 Lower Cretaceous in . . . . . . . . . . . . . . . . . . . . 91-94 u Underwood Ferry, formation near . . . . . . . . . . . . . . . . 165, 217 Upatoi Creek, sections along . . . . . . . . . . . . . . . . 126-127 Upper Cretaceous . . . . . . . . . . . . . . . . . . . . . . 111-215 Unio, in Lower Cretaceous . . . . . . . . . . . . . . . . 77 United States Geological Survey, co-operative work with . 22 v Vaughan T. Wayland, supervisory and paleontologic work. . . . . . 22 Notes and sections by . . . . . . . 242-243, 258, 259-260, 261, 273, 281-282, 315, 321-322, 328, 333, 393 Veatch, Otto, work of . . . . . . . . . . . . . 22-23 Vicksburg formation . . . . . . . . . . . . . . . . . . . . . . . . 306-324 w Washington County, Claiborne in . . . . . . . . . . . . . 253-255, 274-276 Waycross, Altamaha (Lafayette), near . . . . . . . . . . . . . . . 418-419 Waynesboro, formations near . . . . . . . . . . . . . . . . . . 288-289, 415 Westlake, Jackson formation near 304 Weston, section near . . . . . . . . . . . . . . . . . . . . . 235 Wilcox formation . . . . . . . . . . . . . . . . . . . . . . . . . . 226-235 466 INDEX Wilkinson County, geologic formations of . . 95-97, 276-278, 293 Winokur, Charlton County, marl near . 392 Wiregrass . . . . . . . . . . . . . . . 32 Wiregrass region . . . . . . . . . . . . . 449 Wiregrass sand hills . . . . . . . . . . . . . . . . . 454-456 Woolridge Landing, Chattahoochee River, sections . . 157-158 Wylie Landing, Decatur County, section at . . . . . . . . . . . 334 X YZ Zenith, sections near . . . . . . . . . . . . . . . . . . . 167 Zeuglodon . . . . . . . . . . . . . . . . . . . : . . . . . . . . . ~ 298, 300