THE GEOLOGICAL SURVEY OF GEORGIA DEPARTMENT OF MINES, MINING AND- GEOLOGY J. H. AUVIL JR., Director ! STRATIGRAPHY, PALEONTOLOGY, AND # ECONOMIC GEOLOGY OF PORTIONS OF PERRY AND COCHRAN QUADRANGLES,- GEORGIA BY S. M. PICKERING JR. ATLANTA 1970 DEPARTMENT OF MINES, MINING AND GEOLOGY 19 Hunter Street, S. W. Atlanta, Georgia, 30334 404/522-7076 August 15, 1970 His Excellency, Lester G. Maddox Governor of Georgia and Commissioner Ex-Officio State Division of Conservation Atla:nta, Georgia 30334 Dear Governor Maddox: I have the honor to submit herewith Bulletin 81 of the Department of Mines, Mining and Geology entitled, "Geology of Portions of Perry and Cochra.11. Quadrangles, Georgia," by Samuel M. Pickering, Jr., a member of this staff. ------------------------------------"--------------- ----------------------- The report is an expansion of work done for a Master's thesis at the University of Tennessee and was partially supported at small expense by this Department. The report covers work on rocks in middle-central Georgia just below the fall line in an area previously unreported in detail and should serve as an excellent guide to future workers in this area. Deposits of commercial interest such as cement-grade limestone, iron ore, high-silica sand, fullers earth clay, chemical-grade limestone, and road material are described, located and analyzed in this report. The stratigraphy developed in this work will be of inestimable value to water research in this area. Very respectfully yours, 'c . CONTENTS page INTR0 DUCTI0 N---------------------------------------------------------------------- 1 L ocation-------------------------------------------------------------------------------- 1 Purpose--------------------------------------------------------------------------------- 2 Previous Work----------------------------------------------------------------------- 2 Acknowledgements--------------------------------------------------------------- 4 STRATIGRAPHY--------------------------------------------------------------------- 5 General Discussion---------------------------------------------------------------- 5 MeBean Forrnation--------------------------------------------------------------- 6 Clinchfield Sand-------------------------------------------------------------------- 7 Ocala Lirnestone-------------------------------------------------------------------- 9 Twiggs Clay--------------------------------------------------------------------------- 11 Cooper Mar1----------------------------------------"--------------------~------------- 13 Byram Forrnati-on------------------------------------------------------------------ 14 Flint River Formation----------------------------------------------------------- 16 Neogene Clastics-------------------------------------------------------------------- 19 BI0 STRATIGRAPHY--------------------------------------------------------------- 20 General Discussion-------------------,-------------------------------------------- 20 MeBean Formation---------------------------------------------------------------- 25 Clinchfield Sand-------------------------------------------------------------------- 25 Ocala Limestone-------------------------------- 26 Twiggs Clay-------------------------------------------------------------- 27 Cooper Marl-------------------------------------------------------------------------- 27 Byram Formation----------------------------------------------------------------- 28 Flint River Formation----------------------------------------------------------- 29 Neogene Clastics-------------------------------------------------------------------- 29 _______________________________ ____ _ ----------------------PA1EOEGOtUGY=-~-:.-=:-.-=:.-:.~-===::~-.:::: :==::=~::--3o McBean Formation---------------------------------------------------------------- 30 Clin._, ~ r a r r r r c c c r vr r r r c r vr r r r c c r r c c c c a c c r r c r c c a r r a Geology of Portions of Perry and Cochran Quadrangles, Georgia 23 TABLE I BIOSTRATIGRAPHY (cont.) vr - very rare r - rare c - common a - abundant va- very abundant '0 (J) -- I~~:::1:: .:2s 1 ~~o i FORAMINIFERA (cont.) Siphonina jacksonensis Cibicides americanus Cibicides mississippiensis Cibicides lobatalus Cibicides planoconvex us I I r I c I c 1r c c r 'I 1 I c r I 1 r a r c c rI Cibicides westi r ,. j Planulina byramensis 1 c Planulina cocoaensis j \vr /r J __________ .- __ Planulina cooperensis \ I . Jc / f:~:r~~~~~;~::n=-----------~-~~ ~ ~~-~~ Lepidocyclina mantelli Nummulites flpridensis Robulus alato-limoatus Robulus alatolimbatus Marginulina cocoaensis Dentalina jacksonensis Dentalina cocoaensis Nodosaria latejugata Lagena laevis Lagena hexagona Guttulina problema Globulina gibba globosa Nonion advenum Nonion inexcavatum Nonion vicksburgensis Hantkenina alabamensis Bulimina jacksonensis Bolivina jacksonensis vrl I Ja / / j- /r r 'c Jr 1 ' r1 1' c rJ / rc ( C c vr r r c r c a vr r rr c vr c r cr _ Geological Survey of Georgia Bulletin 81 24 TABLE I- BIOSTRATIGRAPHY (cont.) vr - very rare r - rare c - common a - abundant va- very abundant FORAMINIFERA (cont.) Reusella eocena Reusella oligocenica Reusella byramensis Asterigerina subacuta Alabamina mississippiensis :... '"0 -s:: (]) <;: C\S fJ (]) ...c::: <:,.) .5 1):1 .5 <:,.) ;;s - ~ u 0 C\S ~ <:,.) 0 ~ "o.ll (]) > :... (]) ~ 0.. 0 0 :... :>. 1):1 -1-'> ~ c r r ca c c . . ';;. ': : Geology of Portions of Perry and Cochran 'Quadrangles, Georgia 25 McBean Forma~i9n The oyster, Ostrea sellaeform is, occurs near the top of the McBean Formation at the only outcrop observed. This oyster is regarded -as being characteristic of Middle Eocene sediments wherever found (Veatch and Stephenson, 1911) (Cooke, 1943). The foraminifer Cibicides westi was found in drill cuttings from several of the Clinchfield Penn-Dixie Cement Company test holes by Herrick. It was found in material from the outcrop in the ditch at locality 11 by the author. Cibicides westi is regarded as 'being characteristic of Middle Eocene sediments wherever found (Herrick, 1961; Herrick and Vorhis, 1963). Clinchfield Sand The Clinchfield Sand in the area U:nder consideration contains a megafauna very similar to that of the Ocala Limestone. The echinoids Periarchus lyelli, P. lyelli pileus-sinensis, and Laganum /loridanus have been observed in this unit, generally in the limy beds at the top. The characteristic Ocala pecten Chlamys spillmani clinchfieldensis is common locally in the Clinchfield, generally in -- - --- . -------- --------- the more calcareous portions. An oyster- which Stenzel (personal communication) identified as Crassostrea gigantissima occurs at the top of the Clinchfield but not in the overlying Ocala. Shark, stingray, porpoise, whale, and sawfish teeth, along with whale and manatee bones are abundant in the Clinchfield at localities 9 and 10. The microfauna of the Clinchfield Sand is presently being studied by S. M. Herrick, U. S. Geological Survey, from samples provided by the author; a Moodys Branch equivalence for the Clinchfield Sand has been suggested by Herrick (personal communication, -1966). The presence of -Periarchus lyelli indicates possible correlation_ with the Periarchus lyelli zone of the Moodys Branch Marl of peninsular Florida (Toulmin, 1955). As noted in a previous- section, ClinchfieldjS~pd ha~ been regarded without proof as being of Claibo:rne age, the equivruent Geological Survey of Georgia Bulletin 81 26 of the Gosport Sand of Alabama (MacNeil, 1946; LeGrand, 1962; Herrick, 1961). However, both the similarity of the megafossils observed in the Clinchfield to thos~ of the Ocala Limestone of Jackson age and the resemblance of the microfauna to that of the Mo~dys Branch Marl indicate a Jackson age for the Clinchfield. Ocala Limestone Fragments of a regular echinoid resembling Phyllacanthus mortoni have been observed at locality 11 near the base of the Ocala. This echinoid has also been observed in the Ocala at Lee County, Florida (Cooke, 1941). Periarchus lyelli pileus-sinensis is very common in the Ocala at many outcrop localities (fig.12). This echinoid is common in the Ocala Limestone of Florida, Alabama, and Georgia (Cooke, 1941). Figure 12. Periarchus lyelli pileus-sinensis in Ocala Limestone at locality 11. The echinoid Wythella eldridgei was found at locality 11. It has not previously been found in Georgia north of Dougherty County. It is considered to be characteristic of the Ocala Limestone (Cooke, 1959). Typical Ocala pelecypods encountered at many Geology of Portions of Perry and Cochran Quadrangles, Georgia 27 localities in the study area are Chlamys spillmani clinchfieldensis and Amusium ocalanum. The large foraminifer Lepidocyclina ocalana is abundant at most outcrops and has frequently been mentioned in the literature as being characteristic of the Ocala. The very large irregular echinoid M acrop neustes m ortoni is relatively common in fragmented form at most Ocala outcrops; one intact individual was recovered at locality 11. This echinoid has been found only in the Ocala Limestone of Florida, Georgia, and Alabama (Cooke, 1959). Twiggs Clay Foraminifera found in the Twiggs Clay in the study area differ from those in -the underlying Ocala Limestone and the overlying Cooper Marl. The presence of the Twiggs Clay of Nonion advena and Textularia hockleyensis is the chief difference. The irregular echinoid Periarchus lyelli pileus-sinensis occurs in limestone beds in the Twiggs Clay at localities 6, 12, and 24. This ______ _ ______________ echinoid_has .been noted by the author from-limestone bedsc;in the--------Twiggs Clay at outcrops across the eastern part of Georgia. Cooper Marl The foraminifera assemblage of the Cooper Marl is very distinctive. Some of the representative forms common at most outcrops of the Cooper Marl sampled are: Planulina cooperensis, Marginulina cocoaensis, Siphonina jacksonensis, Dentalina jacksonensis, Bolivina jacksonensis, Liebusella byramensis, Uvigerina jacksonensis, and Bulimina jacksonensis. Cooke and MacNeil (19.52) based a change in age of the Cooper Marl in South Carolina from Eocene to Oligocene on the presence of the pelecypod Chlamys cocoana. This pecten is abundant at most outcrops of the Cooper Marl in the area studied and is present in the Red Bluff Formation of early Oligocene age in Alabama (Cooke, 1952). Geological Survey of Georgia Bulletin 81 28 The echinoids Periarchus quinqu,efarius and P. quinquefarius kewi occur in the Cooper Marl at localities 7, 13, and 25. These echinoids are known otherwis~ only from the Sandersville Lime- stone of east .G~orgia. The exact age of the Sandersville is not , I. '. < 1 ~ ) ~ known, and the pre$ence of this unusual echinoid may provide a .means of establishing correlation with the Cooper Marl. The echinoid Paraster am ericanus may be found at localities 16 and 17. This speCies has not been previously encountered in the Cooper M~rl; it occurs in Vicksburg (Middle Oligocene) sediments of Mississippi (Cooke, i942; Clarke and. Twichell, 1915). The echinoid Brissopsis blandpedi also occurs at localities 16 and 17 and has not been noted from Georgia before. It is known only froni the Glendon Limestone of Middle Oligocene age in Mississippi (Cooke, 1942), : BYRAM FORMATION The first biostratigraphic evidence for the presence of the Byram Fo~mation .in Georgia was obtained from the west bank of the Ocmulgee River at locality 33 (Herrick, Pickering, and Sachs, 1966). The correlation of these sediments with the Byram Formation in Mississippi w~s based primarily on this work. Of the 77 species of foraminifera identified from these sediments at locality 33, 58 are listed in the literature as occuring in the Byram Formation in Mississippi. Also the irregular echinoid Parast~r americanu.s, which was found in Unit B, occurs in the Mint Spring member of the Byram Fonnation in Mississippi. The writer has noted a similar suite of fossils from the type locality of the Jacksonboro Limestone of Screven County, Georgia (Dall and Harris, 1892), and correlation with this unit is here suggested. Geology of Portions of Perry and Cochran Quadrangles, Georgia 29 .- : " ~' Flint River Formation Foraminifera assemblages of the Flint River Formation may be distinguished from those of the Cooper Marl and the Byram Formation in the area studied by the. presence of abundant miliolids (Quinqueloculina and Pyrgo) and Pararotalia mexicana var. These forms are characteristic of the Flint River Formation in Georgia (Herrick, .personal communication, 1966). -- Pecten poulsoni, present in most Flint River Formation -outcrops in the .area mapped, is also found in Flint River Formation outcrops at Bainbridge, Georgia (Dall, 1916). Glycymeris cookei and G. suwannensis are present at all major outcrops of the Flint River Formation in the area studied and have been noted from the Flint River Formation of southwest Georgia (Dall, 1916}. ; .. The regular echinoid Gagaria mossom i was observed at localities 16 and 17. This echinoid has previously. been found in Florida.!P:___________ -- -------------- .~ ---------- --------- . ------ - -- ". -- .. ------ .. -- the Upper Oligocene Suwannee Limestone (Cooke, 1941). The .irregular echinoid Cassidulus gouldi is common at almost all outcrops of the Flint River Formation. The Flint River Formation of central and west Georgia and the Suwannee Limestone of Florida contain Cassidulus gouldi in abundance (Cooke, 1943). Neogene ClastiGs . The Neogene clastic sediments of the area mapped are not generally fossiliferous; but a few fragments of oysters were found in the purpl~ clay included in these rocks at_locality 31. The fragments cannot be further identified. Since they are stained and enclosed in sandy clay near the base of the unjt, it can be concluded that they are fossil remains rather than recent exotic material. Geological Survey of Georgia Bulletin 81 30 PALEOECOLOGY McBean Formation The carbonaceous nature of the top of the McBean Formation and the presence of plant fossils and oysters indicate that the environment of deposition was probably quite near shore, and very possibly, in brackish water conditions. The abundant glauconite .encountered further down in the formation in the test holes drilled at Clinchfield is an indj.cator of reducing conditions. Clinchfield Sand The environment of deposition of the Clinchfield Sand is one of high energy. The quartz grains are abraded and rounded and are and rather well sorted. Fossil fragments in the sand are 'likewise broken abraded. Tlie less resistant minerals of the heavy mineral' suite, such as feldspar and hornblende, have been weathered and somewhat altered. The formation is more limy near its upper contact, and there are beds of limy sandstone neat the base of the overlying Ocala Limestone. These beds are characterized by their extensive large oyster assemblages, indicating a shallow water environment. Many of the oysters are scattered at random through the sediment with little orientation of the separate valves. Broken shells are more common than whole ones. At locality 10, on the west side of the Clinchfield Penh-Dixie Portland Cement Company silica pit, "reeflike" accumulations of articulated oysters in their growth positions are encountered. Associated with these oyster beds are abundant small pelecypods (Cardium, Venericardia ., Glycymeris, and others). These pelecypods are also often articulated. The fauna of the limy sandstone beds represents a benthonic biotic community with few exotic elements. Some individuals have been drilled by boring gastropods. A general Geology of Portions of Perry and Cochran Quadrangles, Georgia 31 killing of the fauna appears to have resulted from the silting episode which provided the succeeding sedimentary cover. Where a lithologic change indicates the introduction of more favorable environmental conditions, as at the base of the limestone beds, an abundance of species is present. Ocala Limestone The Ocala varies from a calcisiltite to a calcirudite and is composed predominantly of broken bryozoan fragments. This sort of clastic accumulation represents a high energy environment of strong bottom currents. Some portions of the calcirudite are quite winnowed and well sorted, and there is no fine matrix surrounding the coarse fossil fragments. Commonly, however, a matrix of siltsize carbonate particles occurs in the Ocala. No unfragmented bryozoa have been observed in living position in the Ocala. Almost all the fossil material in the formation appears to have been transported from original living positions by strong bottom in large-- --------- currents. The large, flat echinoids occur in sedimentary concentra- ------ -------------------- tions imriihers- in -3lroilentations --- -TJ:ie- --- -:Peete~;---- ~~- seldom articulated and are buried at all angles to bedding. Their hinge areas are seldom unbroken. The coin-sized, large foraminifera have been winnowed into helter-skelter masses and are often fragmented. Large manatee, whale, and crocodile bones are usually whole, probably due to their greater strength. Usually, the faunal elements observed in the Ocala Limestone are clearly exotic. The remains seem not to have moved a great distance for they are little abraded. Possibly the Ocala in the area studied represents a region of accumulated animal debris from nearby banks and reefs. The Ocala is a very extensive formation, and paleoecological work on a larger scale is needed. Twiggs Clay The typical argillaceous portions of the Twiggs contain no Geological Survey of Georgia Bulletin 81 32 megafossils, but articulated ostracod and unfragmented foraminiferal shells are common. Small pelecypods were observed at locality 11 with bright color patterns, indicating a photic, shallow water environment. The clay is .thick-bedded and indicative of quiet, low. energy, bottom conditions with rapid sedimentation. Such conditions do not favor prolific bottom life. Some of the microfossils may represent forms whose remains accumulated as sediments from water zones above the bottom. For others, death probably resulted from silting and rapid burial. Cooke (1943), LeGrand (1962), and King (1962) stated that the Twiggs Clay is a bentonite or a weathered volcanic ash. The clay is a mixture of the clay mineraJ. montmorillonite with silt-size particles of calcium carbonate, mica, and quartz. Foraminifer tests, which are abundant in the sediment, are generally remarkably well preserved. The writer finds it most difficult to believe that the sedifuent was once fl. volcanic ash embedding consistently abundant benthonic foraminifers or that the ash could have weathered so completely as to. destroy any glass and volcanic minerals and leave the deiic~te hyaline foraminifer tests intact and shiny. No textural or structural features suggesting ash deposition were observed in the field or the laboratory.. Numerous samples of Twiggs Clay from many localities were washed, screened, and examined by the author for microfossils; no glass shards were' observed. In the writer's opinion, the Twiggs Clay was precipitated as colloidal particles formed by the action of salt water on normal terrestrial clay minerals. There are limestone beds in the Twiggs Clay which represent a;: reef-like . environment. Echinoid shells encountered in these beds .lie ;upright in a life position. Corals occur attached to each other and to pelecypod masses. Pelecypods are articulated, and the .larger f()raminifera. lie flat. No fragmentation of fossils in these. beds has. bee;n observed..These reef-like beds of limestone may end abruptly in massive Twiggs Clay. Geology of Portions of Perry and Cochran Quadrangles, Georgia 33 Cooper Marl The Cooper Marl shows more facies change in the area studied than any other exposed formation. Thus, the fauna of the Cooper is more varied than the fauna of other formations studied. The echinoid Periarchus quinquefarius is found in the Cooper Marl at its updip edge, at localities 7 and 13. The formation at locafity 5 is a very glauconitic silt with white calcareous clay pockets which are highly fossiliferous. The echinoid tests occur as broken and whole individuals in the pockets and in the silt. At locality 13, Periarch us quinquefarius is found in sandy limestone with little clay. Six miles downdip at locality 25 there is another occurrence of this echinoid, in rock similar to that at locality 6, but just off the flank of a calcarenite reef-like structure. Periatchus quinquefarius has been observed in the Cooper Marl of central Georgia and east Georgia and the Sandersville Limestone of east central Georgia in fine-grained calcarenite. The occurrence of this form in such varied lithology, and the fact that it has not been found in any other formation, indicate that Periarchus quinque- farius may be a good fossil for correlation between the Sanders- --------------------ville-and-the - ------- Cooper~------- - - - - - ~--- - -------- --- ---- ----- - --- --------------- Chlamys cocoana, a small pelecypod, is common at most outcrops of Cooper Marl throughout the area, regardless of facies. Since it is also found in the Red Bluff Clay of Alabama and is restricted to the Cooper_ and Red Bluff, this fossil may offerreasonable correlation with the Alabama section. The coral Flabellum cuniformae, which has been cited often as a guide fossil to the Late Eoce;ne, is found in the Cooper Marl at all outcrops of rather pure calcarenite. Apparently it could tolerate no silt or clay suspended in the water. Flabellum cuniformae occurs throughout the Upper Eocene-Lower Oligocene of the Southeast wherever clean calcarenite occurs. For this reason the use of this fossil for correlation seems unsupported by field evidence. Geological Survey of Georgia Bulletin 81 34 Bryozoans occur abundantly in the Cooper Marl north of a line between locality 19 and Elko but pave not been observed south of this line. The echinoids Paraster americanus and Brissopsis blanpiedi occur in large numbers (fig. 13) in the Cooper Marl at localities 16 and 17. They seem to have preferred a soft, somewhat sandy Figure 13. Brissopsis blanpiedi in place in Cooper Marl at locality 16. bottom and are generally found just beneath a zone of abundant worm borings. The worm workings may indicate a sediment unusually rich in organic matter. The pelagic, deep water foraminifer Globigerina sp. is absent in the updip Cooper Marl but present at downdip exposures. This is thought to be due to deeper water conditions downdip. Agglutinated foraminifera such as Textularia sp. are more abundant in more clastic lithologies, no doubt owing to the greater availability there of test construction materials. Byram Formation Unit B of the Byram Formation consists predominately of medium- to fine-grained carbonate fragments and abundant tests of smaller foraminifera. The carbonate fragments are rather Geology of Portions of Perry and Cochran Quadrangles, Georgia 35 angular and the foraminifer tests are not abraded or broken indicating their deposition was probably in rather guiet water. The coin-shaped large foraminifera~ Lepidocyclina mantelli, occurs most abundantly in a well defined bed approximately three feet in thickness in which it is scattered helter-skelter at all orientations, but the fragile test is generally unbroken. It is not known whether the random orientation of the tests of Lepidocyclina mantelli represents their mode of life in the bottom sediment or whether they were carried in by a gentle bottom current which did not fragment them. As the bed of concentration of these larger foraminifera is remarkably continuous over 200 yards distance the former hypothesis seems more tenable. The massive nature of Unit B and the lack of apparent bedding indicates that deposition was probably continuous and the environment rather similar through the entire unit. Echinoids, gastropods, and corals are generally found in their living positions throughout the unit. The rhythmic alternating nature of the lithology of Unit A suggests that environmental conditions fluctuated regularly dU:riilg- -------deposition, probably due to varying availabilities of clastic silt and clay. The base of each of the tan clay beds of Unit A contains a very great abundance of fossil material indicating that probably the influx of silt and clay killed large numbers of organisms by clogging their breathing apparatus. Most of the fossil remains observed in Unit A were in their approximate living pos!tions, indicating a probable life assemblage rather than a sedimentary accumulation of miscellaneous fossil material. Corals were observed to be considerably more abundant in the lower bed of limestone than in any other part of the unit. This limestone bed is also the thickest bed probably indicating that deposition occurred over a longer period of time during which corals could become more fmnly established. Flint River Formation The Flint River Formation is sandy in the northwestern Geological Survey of Georgia Bulletin 81 36 exposures but contains no sand to the southeast. This feature may indicate a major source of terrestrial clastic sediments from a northwest direction, possibly a large river. The presence of large oysters in chert-cemented sands in the Flint River Formation may indicate brackish water. There is a definite association between the echinoid Cassidulus gouldi and various types of ostracods. Casts of this echinoid are often filled with ostracods, which are quite rare in the Flint River as a whole. Apparently these echinoids died unburied, and ostracods entered their tests and fed on the interior soft parts until burial rendered their escape impossible. Thus casts of Cassidulus g ouldi often show abundant ostracods on the surface (fig. 14 ). Figure 14. Ostracods preserved on the silicified mold of the interior of Cassidulus gouldi Large foraminifera, mainly Lepidocyclina undosa and Lepidoi:yclina fauosa, are common at most outcrops of the Flint River Formation. At locality 26 there is a large boulder illustrating an Geology of Portions of Perry and Cochran Quadrangles, Georgia 37 unusual assemblage of vast numbers of these large protozoans (fig. 15). The tests are scattered helter-skelter at all angles in a volume of two to three cubic yards. This assemblage may be the result of rapid burial of an unusually productive bottom community, or it may represent a preserved "swash line" concentration of individuals. The tests are not broken or fragmented. Figure 15 Foraminifer tests concentrated in Flint River Formation chert. Pelecypod shells in the Flint River Formation are disarticulated and broken in local, lens-like concentrations of spectacular numbers. This may indicate "swash line" beach type deposits. The abundance of Quinqueloculina, Pyrgo, and Reussella tests also seems to indicate near-shore conditions. Alga-like masses with associated small solitary corals, gastropods, and regular echinoids, indicate that shallow, clear water conditions with high associated energy may have produced true reef development. The fauna of the Flint River Formation appears to have tropical to subtropical affinities, further substantiating this premise. Geological Survey of Georgia Bulletin 81 38 MINERAL RESOURCES Iron There is a zone, 0 to 10 feet thick, of limonite-hematite enrichment in the residuum of the Flint River Formation. This zone is near the top of the residuum and is a mappable horizon (Pickering, 1961). The iron concentration is intermittent and, where present, generally overlies the chert of the Flint River Formation. Where there are good concentrations of iron in the residuum, chert is usually not as prominent as where there is no iron enrichment. Figure 16. Limonite occurs as large spherical concretions, such as at this outcrop 3 mi. west of Hawkinsville on Old Pinehurst Road. As discussed earlier, limonitic enrichment, in the form of concretions, geodes, dornicks, and iron-cemented sandstone, apparently was produced by the replacement of limestone during solution and silicification (Haseltine, 1926; Pickering, 1961). Limonite geodes line chertified solution cavities at localities 28, 30, 32, and 33. It is suggested the iron was not derived from iron minerals originally present in the limestone but from iron-rich ground Geology of Portions of Perry and Cochran Quadrangles, Georgia 39 water solutions derived from rocks of the piedmont area. Iron mining, in the area studied, began in 1961 (Pickering, 1961) and was almost continuous to 1965 at localities 29, 30, 31, and 39. Average ore grade has been 51 percent iron, with desirably low phosphorus. It is shipped to Birmingham, Alabama, to raise the quality of the low-grade Clinton-type hematite ore. Mining was accomplished by a small (%-yard) power shovel and front-end loader. It was trucked about 5 miles to a single log washer, cleaned, and trucked 7 miles to the railhead at Unadilla. Limestone The Ocala Limestone has been quarried in the area mapped since 1912 (Brantley, 1916). For many years all of the stone was used for agricultural lime, for road metal, and for aggregate. In 1941 Penn-Dixie Cement Company began production of Portland Cement from the Ocala Limestone, Twiggs Clay, and Clinchfield Sand. Production has been continuous since that time, and ______________________ localities 10 and 1-1 have been -quarried for- this purpose; Georgia:-----Lime Rock Company is quarrying the Ocala for agricultural limestone at locality 23. The Ocala Limestone has been reported to be 89 to 97 percent calcium carbonate (table III) in the outcrop area studied (Brantley, 1916). Thickness is generally about 40 feet along the Big Indian Creek valley; but locally, solution or erosion has reduced thickness to less than 15 feet. The Cooper Marl has been quarried for agricultural limestone at localities 16, 17, 21, and 25, where the formation is a soft calcareous marl. Small operations should be able to compete favorably for local lime requirements, as the rock is easily worked and overburden is negligible. Production could be resumed at many places along the banks of the Ocmulgee River. Geological Survey of Georgia Bulletin 81 4U Fuller's Earth Twiggs Clay throughout the area mappe~ consists of a plastic gray-blue to green fuller's earth in the area of Pike's Peak in Twiggs County and Wrens in Jefferson County, Georgia. Fuller's earth)s mined and sold for a variety of purposes. As a part of the D~partwent of Mines, Mining and Geology Georgia Minerals :Expl()ratio~ Program test holes are being cored in the Twiggs Clay throughout its area of outcrop in South Georgia and tests are being mad~ to determine economic feasibility. Several test holes have been cored for areas underlain by Twiggs Clay in the Perry and Cochran quadra11gles;, test "results will be published when available. The Twiggs Clay may also be well adapted to the manufacture of r~~k wool insulation or light weight aggregate; tests for these commodities are presently being made. Th~I,Twiggs Clay, which is b~ing removed as overburden in large tonnag~s _fr.<>:m limestone quarrying. operations in the area studied, is presently being used in only sma1:1 q~antity as an additive in the manufactur~ pf Portland Cement. It is hoped that additional .... :research by ~h.e Department of Mines in cooperation with the Georgia Institute of Technology will reveal some use for this . product which is now being discarded. High Silica Sand ''The Clinchfield Sd:hd in its area of outcrop is generally highly iron stained and would be very difficult to beneficiate to an acceptable high silica sand product. However, where the formation has been protected from staining by the overlying Ocala Limestone it is relatively free from objectionable iron, and attrition scrubbing will produce a silica product which is quite low in iron. Large acreages of Ocala Limestone have been removed by quarrying operations in the area south of Big Indian Creek. In these quarry areas Clinchfield Sand is in a relatively unstained Geology of Portions of Perry and Cochran Quadrangles, Georgia 41 condition with very little overburden and is readily accessible to available mining and loading equipment and to rail transportation facilities. The Clinchfield Sand does contain from two to six percent calcium carbonate in the form of coarse- to fine-grained organic debris. Most of this carbonate material is very fine-grained and can be removed by screening. In order to produce a salable high silica product, however, the remaining carbonate would have to be removed by some method, probably froth flotation. Only a portion of the Clinchfield Sand is sufficiently coarsegrained to be used as a raw material for glass manufacture; however, the remaining fine-grained quartz sand would have a considerable market potential for the manufacture of sodium metasilicate and the making of silica-lime bricks. This fine-grained sand could also be crushed and sold for silica flour. It may be readily calculated that if the average thickness of the Clinchfield Sandis-only fifteen feet there is a minimum of more-------than 325,000,000 tons of silica sand availaJ?le for mining in presently active quarry areas in Houston County. Construction Sand There are very large tonnages of construction grade sand available in Pleistocene high terrace deposits along the east bank of the Ocmulgee River throughout the area studied. This material has been mined from several small pits along Georgia Highway 126 about three miles north of Hartford but is not presently being used in any way. If the building industry in the area should require the production of large quantities of construction sand, these deposits should be of great use. Geological Survey of Georgia Bulletin 81 42 SUMMARY AND CONCLUSIONS The exposed Tertiary rocks of the area studied may be divided and mapped lithologically and paleontologically as seven distinct formations overlain by a s~ries of undivided Neogene clastics. These formations are, in ascending stratigraphic order: McBean Formation, Clinchfield Sand, Ocala Limestone, Twiggs Clay, Cooper Marl, Byram Formation, and Flint River Formation. Regional dip is f!om ten to fifteen feet per 1riile to the southeast. Study of the paleontology in the area mapped reveals that the sand under the Ocala Limestone has a late Eocene fauna. Further it has been concluded that this sand should be referred to as the Clinchfield Sand Formation. The Alabama term "Gosport Sand" is not applicable to this unit. The Ocala Limestone is a distinctive formation and is not a ridge-forming unit as has been previously assumed by some authors. The Flint River Formation holds up the "Ocala Escarpment" just south Qf Clinchfield. Formational status. has been suggested for the Twiggs Clay. The Twiggs has been shown not to exist beneath the Ocala; it .. was thete. !!COnfused iri the past with the McBean. The Cooper Marl is present in central Georgia and is the lithologic equivalent of the Cooper Marl of South Carolina. Examination of fossils encountered in the Cooper Marl shows possibilities for correlation with the Sandersville Limestone .of east central Georgia, a unit of previously undetermined age. Detailed study af the paleontology of the Cooper Marl has shown the presence o:f a number of forms regarded as Oligocene in other states. Further substantiation is therefore given to recent is suggestions that the Cooper Marl of Early Oligocene age. The Cooper is not present along the "Ocala Escarpment" where it has beeh previously mapped. Updip, the Cooper Marl is indeed a Geology of Portions of Perry and Cochran Quadrangles, Georgia 43 typical marl containing about equal proportions of sand, clay, and carbonate but downdip, this formation is represented almost entirely by limestone. The Byram Formation has been mapped and described along the Ocmulgee River south of Hawkinsville. The Flint River Formation is represented by the residual products of an Oligocene limestone. It is the approximate updip faunal equivalent of the Suwannee Lime_stone of Florida and south Georgia. The Flint River Formation is sandy and conglomeratic to the northwest. South of this area there is a belt of calcarenite to calcirudite which has been silicified to loose, porous tripoli. South of this belt much of the chert in the formation is compact, nonporous chalcedony and jasper. The interstream divides are capped with a blanket of sand, clay, and conglomerate which cannot be subdivided. The age of this material can be only assigned to the undivided Neogene. RepOrted for the first time as a result-or-this-study--are: ______ Periarchus lyelli, P. lyelli pileus-sinensis, Laganum floridanum, Chlamys spillmani clinchfieldensis, and Crassostrea gigantissima from the Clinchfield Sand; and the echinoids Paraster am ericanus, Periarchus quinquefarius, P. quinquefarius kewi, and Brissopsis blandpiedi from the Cooper Marl. Paleoecological study has shown that the Clinchfield Sand was deposited in shallow water under high energy conditions. Change in environment to lower energy conditions led to deposition of sandy limestone beds near the top of the Clinchfield. The number of species present at this change of environmental conditions is relatively large, and all onen appear in living position. The Ocala Limestone is shown to be a high energy bioclastic accumulation of transported organic debris. Geological Survey of Georgia Bulletin 81 44 The Twiggs Clay has a shallow water pelecypod fauna and no indication of volcanic ash accumulation as previously thought. The, Cooper..Marl .shows .clear facies change from more clastic clay marl updip to fine-grained limestone downdip. The Flint River Formation shows a sandy facies at the north- .~est edge of the area studied, a coarse bioclastic facies across the central portion, and a compact, fine-grained facies along the south- west edge. Areas resembling true :reefs are present with a typical a l g a - c o r a ' l-ga ,' ) ~ .. st . r o p o d - r e. g u l a r echinoid assemblage. The youngest sediments of the area are a complex blanket of sands, clays, and conglomerates of Neogene age. The sedimentary features of this material indicate a terrestrial or deltaic origin. High silica sand from the Clinchfield Sand in the Perry and Cochran quadrangles was sampled by drilling at Clinchfield, and an analysis of this material is included. Measured sections of limestone from the Ocala Limestone and the Cooper Marl in the area have present or future economic potential as agricultural lime and for cement manufacture. Iron mining in the area is described, and other possible economic mineral resources are enumerated and described~ Geology of Portions of Perry and Cochran Quadrangles, Georgia 45 Adams, G. I., Butts, Charles, Stephenson, L. W., and Cooke, C. W., 1926, Geology of Alabama: Geological Survey of Alabama, Special Report 14, 312 p. Boynton, R. S., 1966, Chemistry and technology of lime and limestone: John Wiley & Sons, New York, 520 p. Brantley, J. E., 1916, A report on the limestone and mat1s of the Coastal Plain of Georgia: Georgia Geological Survey Builetin .21,, 300 p. Carter, R. L., and Giddens, Joel, 1953, Soils of Georgia: University of Georgia College of Agriculture Bulletin 2, 68 p. Carver, R. A., 1965, Brick clay resources of Pulaski County, Georgia: University of Georgia Press, 32 p. _ __, 1966, Facies relationships in the Jackson Group of central and eastern Georgia [abstract]: Geological Society of America, Southeastern Section. Clark, W. B., and Twichell, M. W., 1915, The Mesozoic and Cenozoic Echinodermata of the United States: U.S. Geological Survey Monograph 54, 341 p. Connell, J. F. L., 1955, Stratigraphy and Paleontology of the Jackson Group of Georgia: Ph. D. Dissertation, University of Oklahoma, 348 p. ---------~-----------------cooke-;-c W., 1915~ The age of the Ocala limestone: U. S. Geological Survey Professional Paper 95, pp. 107-120. ___., 1935, Notes on the Vicksburg Group: American Association of Petroleum Geologists Bulletin, vol. 19, pp. 1162-1172. ___., 1936, Geology of the Coastal Plain of South Carolina: U. S. Geological Survey Bulletin 867, 196 p. ___., 1939, Equivalence of the Gosport sand to the Moodys marl: Journal of Paleontology, vol. 13, no. 3, pp. 337-340. ___., 1941, Cenozoic regular echinoids of eastern United States: Journal of Paleontology, vol. 15, no. 1, pp. 1-20. ___, 1942, Cenozoic irregular echinoids of eastern United States: Journal of Paleontology, voL 16, no. 1, pp. 1-62. ---:, 1943, Geology of the Coastal Plain of Georgia: U.S. Geological Survey Bulletin 941, 121 p. ___., 1945, Geology of Florida: Florida Geological Survey Bulletin 29, 339 p. _ __, 1959, Cenozoic Echinoids of Eastern United States: U. S. Geological Survey Professional Paper 32, 106 p. Geological Survey of Georgia Bulletin 81 46 ___,and Shearer, H. K., 1918, Deposits of Claiborne and Jackson age in Georgia: U. S. Geological Survey Professional Paper 120, pp. 41-81. ___, Gardner, J. A., and Woodring, W. P., 1943, Correlation of the Cenozoic formations of the Atlantic and Gulf Coastal Plain and the Caribbean region (Correlation Chart): Geological Society of America Bulletin, vol. 54, pp. 1713-1723. ____,and MacNeil, F. S., 1952, Tertiary stratigraphy of South Carolina: U. S. Geological Survey Professional Paper 243-B, pp. 19-29. Cushman, J. A., 1945, A foraminiferal fauna from the Twiggs Clay of Georgia: Contributions from the Cushman Laboratory for ,<~::Foraminiferal Research, vol. 21, part 1, no. 205, pp. 1-11. Da11, W. H., 1916, A contribution to the invertebrate fauna of the Oligocene beds of Flint River, Georgia: U. S. Natl. Museum Proc., vol. 51, pp. 487-524. ___ and Harris, G. D., 1892, Correlation papers-Neocene: U. S. Geological Survey Bulletin 84, 349 p. Deboo, P. B., 1965, Biostratigraphic correlation of the type Shubuta Member of the Yazoo Clay and Red Bluff Clay with their equivalents in Southwest~rh, Alabama: Geological Survey of Alabama Bulletin 80, 84 p~ Fischer, A. G., 1951, The echinold fauna of the Inglis Member of the Moodys Branch Formation: Florida Geological Survey Bulletin 34, Part 'II; 101 p. Furcron, A. S., 1944, The Jackson Group of Georgia: Southeastern Geological Society, Field Trip Guidebook no. 2, Southwestern Georgia, 63 p. ___, 1961, Geolegic age of the tektite shower and its associated rocks of the Georgia Coastal Plain: Georgia Mineral Newsletter, vol. XIV, no. 4, pp. 115-123. Grant; U. S., IV~ 1938, The West American Cenozoic Echinoidea: University of California Press, 225 p. Harris, G. D., and Palmer, K. V. W., 1946-47, The Mollusca of the Jackson Eocene of the Mississippi Embayment (Sabine to Alabama River): Bulletins of American Paleontology, vol. 30, no. 117, part I, Bivalves; part II, Univalves, 563 p. _.;...._,._, 1951, Preliminary notes on Ocala bivalves: Bulletins of American Paleontology, vol. 33, no. 138, 55 p. Geology of Portions of Perry and Cochran Quadrangles, Georgia 4 7 Haseltine, R. H., 1924, Iron ore deposits of Georgia: Georgia Geological Survey Bulletin 41, 222 p. Hedgpeth, J. W., 1957, Treatise on marine ecology and paleontology: Geological Society of America Memoir 67, vol. I. Ecology, 1296 p. Herrick, S. M., 1961, Well logs of the Coastal Plain of Georgia: Georgia Geological Survey Bulletin 7 0, 421 p. ------,.-, and Vorhis, R. C., 1963, Subsurface stratigraphy of the Coastal Plain of Georgia: Georgia Geological Survey Information Circular 25, 76 p. Kellogg, A. R.,. 1936, A review of the Archaeoceti: Carnegie Institute, Washington, pp. 20, 104, 256. King, P. B., 1950, The tectonic framework of southeastern United States: American Association of Petroleum Geologists Bulletin, vol. 34, pp. 635-671. King, E. A., Jr., 1962, Field investigation of Georgia tektites and description of new specimens: Georgia Mineral Newsletter, vol. XV, nos. 3-4, pp. 84-89. Ladd, H. S., 1957, Treatise on marine ecology and paleontology: Geological Society of America Memoir 67, vol. 2, Paleoecology, ---------- 1077 p. ------ ---- - --- -- -- --------- -------- -------- -- ----------- -- LaForge, L., Cooke, C. W., and others, 1915, Physical geography of Georgia: Georgia Geological Survey Bulletin 42, 189 p. LeGrand, H. E., 1962, Geology and ground-water resources of the Macon Area, Georgia: Georgia Geological .Survey Bulletin 72, 68 p. MacNeil, F. S., 1947, Geologic map of the Tertiary and Quaternary formations of Georgia: U. S. Geological Survey Oil and Gas Investigations Preliminary Map 72. Mansfield, W. C., 1937, Mollusks of the Tampa and Suwannee Limestones of Florida.: Florida Department of Conservation, Geological Bulletin 15, pp. 46-62. Murray, G. E., 1961, Geology of the Atlantic and Gulf Coastal Province of North America: Harper & Brothers Publishers, New York, 692 p. Owen, V., Jr., 1963, Geology and ground-water resources of Lee and Sumter Counties, southwest Georgia: U. S. Geological Survey Water-Supply Paper 1666, 67 p. Geological Survey of Georgia Bulletin 81 48 Palmer, K. V. W., and Brann, D. C., 1965, Catalogue of the Paleocene and Eocene Mollusca of the Southern and Eastern United States, Part I, Pelecypod~;. Amphineura, Pteropoda, Scaphopoda, and Cephalopoda:. :S1;1.lletins of American Paleontology, vol. XLVIII, 466 p. ___, 1965, Catalogue "of the Paleocene and Eocene Mollusca of the Southern and Eastern United States, Part II, Gastropoda: Bulletins of American Pal~ontology, vol. XLVIII, 1057 p. Pettijohn, .F. J., 1957, Sedimentary rocks: Harper & Brothers, New .. ' Yo.rk, 718 p. Pickering, S. M., Jr., 1961, Iron ore deposits of the Perry Quad- rangle, Georgia: Georgia Mineral Newsletter, vol. XIV, no. 4, pp. 83-90. Pierson, R. E., 1951, Possible stratigraphic relationships of the Sandersville Limestone to the Ocala Limestone of west Georgia: M. S~ ~~esis,.:~mory University. Potter, P. E., and Pettijohn, F. J., 1962, Paleocurrents and basin analysis:_ Academic Press, I~c., New York, 296 p. Richard$, H. G., 1955, The Oligocene of Georgia: Georgia Mineral Newsletter, vol. VIII, no. 1, pp. 60-64. ...____, 1955. The Paleocene and Eocene of Georgia (Part 2: l!ppe:t; Eocene): Georgia Mineral Newsletter, Vol. VIII, rio.4, pp. 151-156. Sever, E. W., 1965, The Chattahoochee Anticline in Georgia: Georgia Mineral Newsletter, vol. XVII, pp. 39042. .Shearer, H. K., 1917, A report on the bauxite and fuller's earth of the Coastal Plain of Georgia: Georgia Geological Survey Bulletin 31, 340 p. Stose, G. W., Cooke, C. W., Crickmay, C. W., and Butts, Charles, 1939, Geologic map of Georgia: Georgia Geological Survey and 0. S. Geological Survey. Toulmin, L. D., Jr., 1955, Cenozoic geology of southeastern Alabama, Florida, and Georgia: American Associatiop. of Petroleum Geologists Bulletin, vol. 39, no. 2, pp. 207-235. ___, 1969, Paleocene and. Eocene guide fossils of the Eastern Gulf Coast Region: Transactions Of the Gulf Coast Association of Geological Studies, pp. 465-487. Geology of Portions of Perry and Cochran Quadrangles, Georgia 49 Tuomey, M., 1844, Report on the Geologic and Agricultural Survey of the State of South Carolina: Geological Survey of South Carolina; 63 p. Veatch, J. 0., 1909, Clay Deposits of Georgia: Georgia Geological Survey Bulletin 18, 453 p. ___, and Stephenson, L. W., 1911, Preliminary report on the geology of the Coastal Plain of Georgia: Georgia Geological Survey Bulletin 26, 466 p. Vorhis, R. C., 1965, Jackson stratigraphy of central Georgia [abstract] : Geological Society of America, Southeastern Section. Weller, J. M., 1960, Stratigraphic principles and practice: Harper & Brothers, Publishers, New York, 725 p. Geological Survey of Georgia Bulletin 81 50 TABLE II Chemical Analysis of Typical Channel Samples of Outcropping Formations Locality, '- s:: sro:::0oro ~, ~& . "0 Q.l' <;:::; ....cg.-.:.o:sroo::' U.Cf.i sQ:.:l .e8n".0- st;:; Q.l Q.l ..... .c: ~g ..r...o.......-.. ~u 0~ 11 10 10 '0 C-;r>,"o.),.-aC-'): ~oto:,:::-~J Ur:n oS. ~ ro f:-!E-t ....., ..,.r....o.... :;rog.;.:: ,.... Q.l cQ.l .u~ ooo.....o. Qj:Q 19 32 Loss on ignition 7.57 --- 41.29 18.91 11.23 37.02 Lime (CaO) 7.14 --- 52.32 20.16 10.64 43.87 Magnesia (MgO) Trace --- 0.40 0.30 0.30 0.40 Alumina (Al203) 17.64 2.36 1.88 16.52 14.36 7.00 Ferric Oxide (Fe203) 6.00 0.40 0.64 3.57 2.86 1.60 Phosphorus Pentoxide (P205) 0.06 --- 0.06 0.11 0.19 0.37 Silica (Si02) 61.52 91.00 3.32 40.42 60.42 9.64 TOTAL 100.00 Calcium Carbonate (CaC03) Magnesium Carbonate (MgC03) 12.74 Trace Total Carbonates CaC03 equivalent theoretical 12.74 12.75 BPL 0.13 99.81 5.42 --------- 99.91 100.00 100.00 93.38 35.98 18.99 0.84 0.63 0.63 94.22 36.61 19.62 94.37 36.72 19.73 0.13 0.24 0.42 -~ -- 99.90 78.30 0.84 79.14 79.28 0.81 --- Geology of Portions of Perry and Cochran Quadrangles, Georgia 51 TABLE II Chemical Analysis of Typical Channel Samples of Outcropping Formations Locality Loss on ignition I 0 ~Q ~r.ef ~~ ;!..< ell Cll~ 0~=Cll o0 o0.. 34 I 38.72 c :0c sO'<:l )....< 0 ~ s~ ell...., )....< ....... ;>.C ~~ I c Cll ...0....:::0:: -+->_.., I s s O'<:l 00 Cll o;!..< ..... I ~...:I s< O'<:l-+-> ;;;!..,.:<:::-: i::Q~ I ::::: ..8., sO'<:l ;;., o,;!..< _O',<:l ~Q s< O'<:l-+-> ;l;-.,<::::-: ~~ I I g;;!..< ::::: 0 ~~ ...,S :.=::::: ;!..< 0 ~~ I 37 38 I 38 I 15 43.22 42.93 33.22 0.86 Lime (CaO) 48.60 55.14 52.74 39.20 --- Magnesia (MgO) I 0.40 Trace 0.50 0.50 --- I _Alumina _(Al203)- _ --- ___4.24_,I___0.20________1.80._. --8.7L ----1.05- I Ferric Oxide (Fe203) 0.90-1 I Phosphorus Pentoxide I (P205) I 0.14 I 0.22 0.20 --- 0.02 2.29 1.00 0.23 --- Silica (Si02) I 7.08 1.18 I 1.60 14.78 97.86 TOTAL Calcium Carbonate (CaC03) Magnesium Carbonate (MgC03) 100.08 86.74 0.84 99.96 98.41 Trace Total Carbonates CaC03 equivalent theoretical 87.58 98.41 87.73 98.41 BPL 0.30 --- 99.79 94.13 1.05 95.18 95.37 0,04 99.70 100.00 69.96 --- 1.05 --71.01 --- 71.20 --- 2.18 --- Geology of Portions of Perry and Cochran Quadrangles, Georgia 53 APPENDICES Illustrations of selected fossils Illustrations by Carl Varrlaman APPENDIX A Pelecypods 54 Glvcvmeris cookei 3X Flint River Formation \' Glycymeris suwaneensis 2X Flint River Formation APPENDIX A Pelecypods 55 Chlamys spillmani clinchfieldensis lX Clinchfield Sand, Ocala Limestone, Twiggs Clay Chlamys cocoana 1.9X Cooper Marl APPENDIX A Pelecypods 56 Phacoides wacissanus 1.5X Flint River Formation Gryphostrea plicatella 4.5X Cooper Marl APPENDIX B Echinoids 57 Clypeaster rogersi lX Byram Formation APPENDIX B Echinoids 58 Clypeaster cotteaui lX Flint River Formation APPENDIX B Echinoids 59 Periarchus lyelli .95X McBean .!:<'ormation, Clmchfield Sand, Ocala Limestone APPENDIX B Echinoids bU : . I fo ,~,2~~;/ Periarchus lyelli pileus-sinensis l.lX Clinchfield Sand, Ocala Limestone, Twiggs Clay APPENDIX B Echinoids 61 Periarchus quinquefarius l.lX Cooper Marl APPENDIX B Echinoids 62 Periarchus quinque{arius kewi 1.3X Cooper Marl APPENDIX B Echinoids 63 Wythella eldridgi .85X Ocala Limestone APPENDIX B Echinoids 64 Macropneustef) mortoni .7X Clinchfield Sand, Ocala Limestone APPENDIX B Echinoids 65 Paraster americanus .BX Cooper Marl APPENDIX B Echinoids 66 Cassidulus gouldi 1.35X Flint River Formation APPENDIX C Corals 67 Trochocyathus sp. 1.7X Flint River Formation PLATE I GEOLOGICAL SURVEY OF GEORGIA BULLETIN 81 GEOLOGIC MAP OF PORTIONS OF PERRY AND COCHRAN QUADRANGLES, GEORGIA Geology by S. M. Pickering , Jr. 1970 ,... r~