GEOLOGICAL SURVEY OF GEORGIA S. W. McCALLIE, State Geologist BULLETIN NO. 34 REPORT ON THE SLATE DEPOSITS OF GEORGIA BY H. K. SHEARER Assistant State Geologist Atlanta, Ga. BYRD PRINTING COMPANY, State Printers 1918 SLATE DEPOSITS OF GEOBGIA FRONTISPIECE-PLATE I OLD DEVER QUARRY, ROCKMART, POLK COUNTY, WHILE OPERATED BY THE GEORGIA SLATE COMPANY, BETWEEN 1893 AND 1900. LETTER OF TRANSMITTAL GEOLOGICAL SuRVEY OF GEORGIA, ATLANTA., November 20, 1918. To His Excellency, HuGH M. DoRSEY, Governor and President of the Advisory Board of the Geological s~wvey of Georgia. SIR: I have the honor to transmit herewith the report of Mr. H. K. Shearer;-Assistant State Geologist, on the Slate Deposits of Georgia, to be published as Bulletin No. 34, of this Survey. Very respectfully, S. W. McCALLIE, State Geologist. PREFACE AND ACKNOWLEDGMENTS The preparation of a report on the slate deposits of Georgia was begun in 1912 by Dr. T. Poole Maynard, formerly Assistant State Geologist. The work was again taken up in 1914, when Dr. Oliver B. Hopkins s:pent some time in field work. These men both resigned from the G~orgia Survey before writing up the material on slate. They had, however, done detailed field work in the Rockmart1 and Fairmount districts, the Cartersville district being a more recent discovery. Their notes, together with photographs and coilections of specimens, have been of much assistance in my work, although I have re-examined all of the important deposits and have made additional collections. For helpful information in regard to slate deposits, tests, and methods of working I am especirally indebted to the report of T. Nelson Dale and others, "Slate in the United States," Bulletin 586 of the United States Geological Survey. All of the analyses used in this report, unless otherwise accredited, ;were made by Dr. Edgar Everhart, Acting Chemist of the Geological Survey of Georgia. A number of these analyses were made for private individuals and corporations, who have kindly given _permission to publish them. In January, 1916, when the sericite deposits first attracte1. attention as a possible source of potash, I spent two weeks examining the Pickens .County deposits. Since that time I have made several brief visits to note the progress in development. A description of the sericite deposits is included in this report as an appendix, in order to have all information on the potash-bearing deperty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1601 Johnson property ........................................ 1-60-161 Other exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 Deposits near Grassdale ...................................... 161-162 Carpenter property ....................................... 161-162 Other exposures .... : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 Oass Station and localities farther west........................ 162-163 APPENDIX ............................................ 0 0 0 .165-188 'rhe sericite schist deposits of Pickens Gounty ........................ 165-188 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Location and general relations .. : ................................ 167-169 Character of the material ......................................... 169-176 Physical characteristics ........................................ 169-172 Chemical and mineralogical composition .......................... 172-176 Mode of occurrence ............................................. 176-177 Origin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . ... . . 177 Uses .......................................................... 177-178 Descriptions of individual depos:ts ................................ 178-188 Lot 9-6 ....................................................... 178-179 Lot i21 ....................................................... 180-182 Lot 120 ............................................. .......... 182-185 Lot 119 ...................... : ............................ ... 185-186 Le~s 97 and 98 ................................................. 186-187 Lot 99 .......................................... , . . . . . . . . . . . . . 187 Lot 84 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 viii ILLUSTRATIONS PLATE FACING PAGE I. Old Dever Quarry, Rockmart, Polk County, while operated by the Georgia Slate Company, between 1893 and 1900 ................. .Frontispiece II. A. Showing method of weathering of the Rockmart slate, Seaboard Railroad cut % mile southeast of R.ockmart, Polk County. . . . . . 8 B. Conspicuously ribboned slate in the Ollie Davis opening on the Southern States Portland Cement Company property, Rockmart, Polk County ... : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 III. A. Brown's North quarry, property of the R.ockmart Shale Brick & Slate Company, Rockmart, Polk County. . . . . . . . . . . . . . . . . . . . . . . . 36 B. Dump of slate waste, Brown's North quarry, R.ockmart, Polk County ............................................ ......... 36 IV. A. Old Dever quarry, Rockmart, Polk County, while worked by the Georgia Slate Company. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 B. Splitting shanties of the Georgia Slate Company, Rockmart, Polk County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 V. A. Old Dever quarry, Rockmart, Polk County, showing a secondary calcite vein and joints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 B. Old Dever quarry, Rpckmart, Polk County, showing prominent joints almost perpendicular to the cleavage ........... _...................78 VI. A. Black Diamond slate quarry, 3 miles northeast of Rockmart, Polk County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 B. Ollie Davis opening on the property of the Southern States Portland Cement Company, Rockmart, Polk County. . . . . . . . . . . . . . . . . . . . . . 90 VII. A. View of the foothills belt of green slate near Fairmount, Gor- don County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 B. View of the green slate belt near Bolivar, Bartow County. . . . . . . . 102 VIII. A. Exposure of green slate east of Bolivar, Bartow County, showing a fold and a small fault in the cleavage ........................ 120 B. Exposure of green slate in the L.ouisville & Nashville Railroad cut near the Cartersville Poor Farm, Bartow County. . . . . . . . . . . . . . . . 120 IX. A. Quarry of the Georgia Green Slate Company near Bolivar, Bartow County, showing jointing ..................................... 134 B. Sawing shed of the Georgia Green Slate Company near Bolivar, Bartow County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 X. A. Exposure of green slate on the property of the Southern Green Slate Company, Bartow County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 B. View of the green slate ridge on the M'cCoy property, Bartow County 148 XI. A. Looking east from the Tennessee Road near the Cartersville Poor Farm, Bartow County, showing the Cartersville shale and slate belt 160 B. Shale mine of the American Potash Company near White, Bartow ix !.'LATE FACING PAGE County ..................................................... 160 XII. A. Sericite schist, "pit No. 7," lot 120, Pickens County. . . . . . . . . . . . 168 B. Seric~te schist, "pit No. 81 " lot 120, Piekens County ....... . . . . . . 168 XIII. A, B, C, and D. Microphotographs of sericite sehists from Piekens County ..................................................... 170 FIGLJRES PAGE 1. Sketches of the eleavage surfaces of slates from Rockmart . . . . . . . . . . . . . . . 10 2. Sketeh showing the relations of ribboris and. eleavage in a bloek of slate from the J?rown quarri~s, Roekmart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3 . Sketeh showing the relations of bedding and eleavage in slate folded . between harder .beds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4. Map of Roekmart and vieinity, showing land lots and the prineipal slate quarries .... ...... .. .- . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6 5. Sketeh showing the relations of bedding, grain, and eleavage in slate from the Bl9-ek Diamond quarries ....................... ,................ 90 6. .Plan and section showing potash explorations, Yaneey property. . . . . . . . 145 7. .Pla:n and ~e~tions showing potash explorations, MeMillan property . . . . . . 147 8. Map of the Piekens County sericite schist area, showing land lots and loca- tions of the prineipal mines and prospeet pits .... 166 1 MAPS PAGE r: Irrdex map' showing the distribution of slate-bearing formations in Georgia ........................ ; : ...... ; . . . . . . . . . . . . . . . . . . . . . . . 42 IL. Map of the Rockmart district, showing 'the areal distribution of the Rockmart slate formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 III. Map of the Cartersville and Fairl?lount districts, showing the areal dis- tribution of the Cartersville formation and the slate-bearing portion of the Conasauga formation ......................................... 132 X SLATE DEPOSITS OF GEORGIA HISTORY OF THE SLATE INDUSTRY Little is known of the beginnings of the slate industry. The peculiar properties of slate must long ago have been recognized as making it desirable for a structural material, but at first it was quarried only for local uses, and was not mentioned in literature. .According to the Century Encyclopedia, slate was worked in Wales as early as the twelfth century, and it is probable that the French deposits were also known and opened during the Middle .Ages. In the United States, according to local tradition, slate was quarried in Harford County, Maryland, in 1750; and slate from that area is known to have been used for roofing a church built in 1805.1 W. B. Rogers called attention to the slate deposits of Buckingham, Flu~ vannah and Fauquier counties, Virginia, in annual reports of the Virginia Survey from 1835 to 1841, stating that a quarry was first opened to procure slate for roofing the State CapitoP .A. slate quarry was opened in .Arkansas as early as 1859, but the product was found unsuitable for roofing, and no more work was done in that area for many years.3 The first to recognize the value of the Rockmart slates in Georgia was Joseph G. Blance. He owned the property now controlled by the Cherokee Slate Company, where he made the first opening about 1850; although the oldest _real quarry is said to be one on the property of the Southern States Portland Cement Company, lot 925. Blance was the grandfather of J. F. Dever, and members of the Dever family were interested in the slate industry until the greater part of their property was sold to the Cherokee Slate Company in 1907. 1 Maryland Geol. Survey, vol. 6, p. 189, 1906. 2 Quoted by Watson, T. L., Mineral resources of Virginia: Virginia Jamestown Exposition Commission, p. 42, 1907. 3 Purdue, A. H., The slates of Arkansas: U. S. Geol. Survey Bull. 430, p. 317, 1910. 2 GEOLOGICAL SURVEY OF GEORGIA Lot 925 was owned by Colonel Seaborn Jones, who started development at a.bout the. same time as Blance. The quarries were operated from 1850 until the outbreak of the Civil War. Work was stopped during the war and for a number of years after. About 1880 the quarries were reopened, and from that year until1900 was the period of greatest development. The largest reported production was in 1894, with 5,000 squares, valued at $22,500. Until 1883 the slate was hauled in wagons to Rome and Cartersville, but in that year the East Tennessee, Virginia & Georgia Railroad, now the Southern Railway, was completed, and two years later the East & West Alabama Railway, now the Seaboard Air Line, rwas built. The total production of slate in Georgi~ reported i:q. the United States Geological Survey Mineral Resources from 1879 to 1917 was 38,097 squares, valued at $165,918. Besides this amount there ha.s been the production of the years when no statistics were published on account of there being less than three operators, and the unreported produetien of slate urvey Bull. 586, p. 37, 1914. 14 GF;OLOGICA.L SURVEY OF GEORGIA. prefers the term slip cleavage.; Luckily, it is a structure more common to schists than to. slate, since it entirely destroys the utility of slate for roofing and most other purposes. False cleavage is a capacity to part along parallel incipient joints, although there is usually no actual fracturing of the mass. The planes may be closely spaced, but the cleavage does not pervade the entire mass, as does true cleavage. In slate it is generally due to minute monoclinal folding of the particles of cleavable minerals, without faulting.. Such cleavage is produced by minor stresses and movements after the development of the platy minerals under ro~k flowage conditions. GRAIN t~j; Slates break more readily in one than in the other of~fuJtt:e two planes perpendicular to the cleavage. This direction. of easy br~~age is called the ''grain,'' and usually shows itself in more or less obscure striations of the cleavage surfaces in a directi0n nearly parallel to the cleavage dip. Th'e grain is utilized in breaking down la:rge blo:ck~ of slate to workable propurtions, and roofing slates are airways cut with their long ' , > sides~paraH:eFto: 'tJi~ grarri: T1~; eas~:of'fi~aetur~ a::i:ong 'th~ 'gra1~ varies greatly in slates from different qU'ar,ries; and some show scarcely any gram. Grain may apparently be due to two causes; Most commonly it is developed contemporaneously with the cleavage arid perpendicular tQ the direction of i:q.termediate pressure (the intermediate axis of the strain ellipsoid). It may also be prqduced by slight secondary pres- sure, in which case it is related to false cleavage. In the first case the ' mineral particles, which have their flat surfaces perpendicular to the direction of greatest p;ressure, have developed with their longest axis in the direction of least pressure. Naturally, the direction of easiest relief of pressure is upward, so the longest axes of the crystals, which deter- mine the grain, are about parrallel to the cleavage dip. It has: also been found that some crystals of chlorite and many small scales of muscovite lie perpendicular to the cleavage, with their flat faces in the d~rec tion of the grain, and distorted octahedra of magnetite, distorted cubes of pyrite, erysiJals of staurolite, etc., which are larger than the crystals SLATE DEPOSITS OF GEORGIA 15 of the slate-forming minerals, are all elongated in the grain direction. Crystals of this sort are prominent in some of the Georgia green slates. Some of the Rockmart slates, especially those from the Black Diamond quarries, have a very conspicuous grain of the type related to false cleavage. In a thin section parallel to the grain the cleavage is straight, but in a section perpendicular to both grain and cleavage it shows fine wrinkling, with bending of the individual muscovite flakes. Grain of this sort must have been produced by a slight second~ry move-' ment. In other slates with only normal grain there is little difference observable in such sect1ons. Large :&akes of chlorite and small scales of muscovite flattened in the grain direction are noticeable in some cases, and sections parallel to the grain may polarize more brilliantly than those across it. JOINTS Joints are ruptures in continuity of a rock mass, in general with little or no movement. They may be produced by either tensile or compressive stresses, and the same stress may produce several sets of joints. Joints, especially in.slate, are classified as strike joints (parallel to I the strike), dip joints (parallel to the dip), diagonal joints (diagonal to the strike and dip), and horizontal or fiat joints; according to their relations to cleavage or bedding. Occasionally joints are curved or plicated. Gently curved joints may have been so formed, but closely folded or plicated joints are due to secondary movements. Very commonly joints are filled by films or veinlets or guartz or calcite, and occasionally other minerals. Many of the joints in the slates of Georgia seem to be merely incipient fractures or planes of weakness, along which the slate breaks when weath ered. Thus the slate at the surface is broken into very small pieces, but most of the joints disappear at a depth of a few feet. Joints are of great economic importance in slate quarrying. If few. and widely spaced they facilitate quarrying, but joints too close to. gether or at inconvenient angles to the cleavage cause an undue amount of waste. 16 GEOLOGICAL SURVEY OF GEORGIA FAULTS F.aults of small ~agnitude are common in slate re~io~s, but the *ork .in the Georgia quarries has not been extensive enough to show their abundance and importance. Faults have-been noted in the de, posits. near Bolivar. Both the Rockmart and Conasauga slate belts follow the great Cartersville fault, one of the major thrust faults of the southern Appalachians. The available evidence indicates .that the pressure caused minor disturbances which have rendered the slates useless for a distance of about a mile from the outcrop of the fault plane. SHEAR ZONES AND CLEAVAGE BANDS Shear zones are defined as angular plications, or series of such plications, due to shearing pressure on somewhat rigid material, where the pressure was insufficient to produce more than slight faulting. Although not usually affecting any large mass of slate, they cause the slate to break into irregu1ar blocks,. produ~ing much. waste. Shear a zon'es may be pr~duced{b~'force~ littf~ ni:dre.intense 'th~h those pro- ducing false cleavage of the monodj'nal fold type. If th~ pressure is stili more intense, cleavage banding is pr~duced; consisting of alt~r n:tting bands with ;and without cleavage. This prenomenon is of common occurrence in the Vermont and New York slate belt, but has not been noted in Georgia. VEINS Quartz veins, or ''flints,'' are common features m most slate quarries, and a cause of great difficulty in mining. Veins m:ay cut the slate in any direction, and commonly they ramify irregularly, spoiling large masses of slate. The vein-filling material is chiefly milky quartz often with associated C'alcite, chlorite and biotite. The veins are the result of openings produced by various secondary stresses, and the fillings have been deposited from solution, consisting of material dissolved from the slate itself or from associated rocks. SLATE DEPOSITS OF GEORGIA 17 DIKES Volcanic dikes are not uncommon in some slate deposits, but none are known in the Georgia slate belts. CHEMICAL COMPOSITION The chemi0al composition of roofing slates varies rather widely. The .average compositions of slates from New York, Vermont and Pennsylvania and the principal varieties of Georgia slates are shown in thefollowing table : Average analyses of slates from New York, Vermont and Pennsylvania, and Georgia. Constituents. 1. I I 2. 3. . 4. - - - - ' - - - - - - - - - -- - - - Silica ( SiO ) . 2 Alumina (A1 0 ) ................. . 2 3 Ferric oxide (:F'e 2 0 3 ) .. Ferrous oxide (FeO) ............. . 61.51 15.39 2.21 4.34 56.74 17.65 1.10 4.58 55.39 21.-15 1.58 5.64 56.73 19.27 5.57 1.89 Magnesia (MgO) ..................- 3.23 2.89 2.55 1.93 Lime (CaO) ..................... . 1.47 3.18 1.64 .01 Soda (Na20) ... : .... . Potash (K20) ...... - .... Ignition (less CO) ............... . 1.22 3.90 3.53 1. 66 3 .42' 3.81 1.33 2.96 4.83 .49 8.85 3.77 Moisture ......................... . .67 .21 .22 .38 Carbon dioxide (C0 ) 1. 55 2.64 1.59 .00 2 Titanium dioxide (Ti0 ) .75 .94 .74 .88 2 Phosphorus pentoxide (P 0 ) .08 .15 25 Sulphur trioxide (SO) ........... . .18 Sulphur (S) ..................... . .22 .68 .31 Manganous oxide (MnO) ......... . .02 .06 Barium oxide (BaO) ............... . .00 ----------------J-----~------------- 99.99 I 99.78'1 . 100.14 99.77 1. Average of 15 analyses of slates from New York, Vermont and Pennsylvania. U. S. Geol. Survey, Bull. 586, p. 51, 1914. 2. Average of 5 analyses of slates from the :R.ockmart formation, Polk County, Georgia. 3. Average of 8 analyses of green slates from the Conasauga formation, Bartow and Gordon counties, Georgia. 4. Average of 6 analyses of slates and shales from the Cartersville formation, Bartow County, Georgia. 18 GEOLOGICAL SURVEY OF GEORGIA Silica and. alumina, the most abUlil.dant oxides in all slates, va'i-y from 55 to 67 and from 11 to 22 pe/cent, respectively, in .American and European slates which have been successfully used for roofing.1 After these, the mos.t essential constituents are magnesia, ferrous oxide and potash, which enter into the platy minerals~ chlorite and mica, and must be present in considerable amounts in order to give adequate slaty cleavage to the rock. The relative proportions of these three oxides very greatly, but it is notable that in almost all analyses of roofing slates the tot~l of the three is between 10 and 12 per cent. As ~ rule, the ferrous oxide and magnesia are high in green slates, while potash predominates in gray slates, although carbonaceous coloring matter may hide the green color of chlorite. Thus, in the Georgia green slates the ferrous oxide is high and the ma,anesia moderately high, shorwing a high percentage of chlorite, which accounts for the color. The Rockmart slates also have rather high ferrous iron and magnesia:, but the green color of chlorite is obscured by the car. bonaceous matter present. The light gray Cartersville slates have low contents of ferrous iron and magnesia, with correspondingly highpotash. Ferric oxide ,i~ slates oceurs chiefly in the minerals hematite and magnetite. These .minerals'ha'Ve little effect on the stre11~th or working qualities. Hematite in large proportion gives to the slate a red or purplish color, which may add to its desirability-and value. Magnetite is undesirable in slates for electrical uses, on account of its high conductivity. In all American and in practically all European slates the potash is considerably in excess of the soda. The potash occurs chiefly in muscovite mica (sericite), 'which is in most slates much more important than chlorite in giving cleavage. Soda may also enter into the mica, taking the place of a part of the potash moJecules. Both soda an1. potash occur in detrital or recrystallized grains of feldspar, which is present to some extent in all slates. Li:tne occurs to a small extent in silicate minerals, but is chiefly in the form of carbonate. The carbonate present, however, is not pure 1 U. S. Geol. Survey Bull. 586, pp. 5051, 1914. SLATE DEPOSITS OF GEORGIA 19 calcite, but contains more or less ferrous oxide, magnesia and manganous oxide as an isomorphous admixture of siderite, dolomite and rhodochrosite molecules. The determination of ca.rbon dioxide in slates is of great importance, because it gives a measure of the quantity of minerals which cause disintegration and fading. Any slate containing a high percentage of carbonates will be weak and liable to rapid disintegration under the influence of weather and acids present in the atmosphere of cities. Ferrous carbonate is an easily oxidizable mineral, and is known to be the principal cause of fading and staining of slates. Unfortunately, it is not possible to determine by chemical ana1ysis the proportion of calcium, magnesium and iron combined in the form of carbonate in slate, because of the complex mineral composition of the rock and the fact that each of these elements may enter into several different minerals. The three average slates which contain carbon dioxide all have a small excess over the amount combinable with the lime presenti showing that some magnesium or iron carbonate must exist. The sulphur in slates occurs chiefly in the iron sulphides, pyrite and marcasite, and the small amount of sulphur trioxide sometimes found is probably an oxidation product. In the analyses as stated in this report, the iron combined with the sulphur is included with the ferrous oxide. The figures for ferrous oxide, therefore, include a small amount of oxygen not actually present. After ferrous carbonate, the iron sulphides are believed to be the principal causes of fading and staining. Marcasite is more easily oxidizable than pyrite, therefore it is more undesirable. When the sulphide mineral is pyrite, occurring in relatively large crystals tightly enclosed by leaves of mica, as is generally the case in Georgia slates, it weathers very slowly and is not likely to c~use trouble unless it makes up several per cent of the rock. This is shown by the fact that fresh, bright crystals of pyrite are found in slate which has been exposed to the weather for many years. Titanium dioxide is present in all slates, generally constituting a little less than one per cent. The usual mode of occurrence is in minute rutile ''needles.'' 20 GEOLOGICAL SUEVEJ[ OF GEORGIA Loss on ignition represents principally combined water, but includes also carbon and a;ny volatile matter that may be present. It has been found in calculating the mineral compositions of a number of slates that if the loss on ignition is assumed to be entirely combined water, there is usually a slight excess over that theoretical1y combin- able _!n the minerals likely to be present. Other elements generally present in slates are phosphorous, manganese, barium, chromiunl., vanadium ap.d zirconium. The amounts are scarcely more than traces, and are not usually determined. Summing up the chemistry of slate, Dale1 calls attention to the fact that the chemical analysis of a slate is not sufficiently characteristic to pl.'love t~at it is not a shale, a clay, or a schist. Ex-cept for the low soda and high combined water content of sla;fies, many granites syenites, porphyries, diorites and basalts could pass chemically as roofing slate. He says : "It follows . . . that while considerable scientific interest attaches to the chemistry of slate there is little correJ.a;tion between its chemical; cCOTIJ;p;0sitio:a an:d its p.hysica1 p.mperties. These. d.epend primarily on its te~ture; and seconda:rlly on its, mineral, comp;osition, and both :o:f these ar.e.hest. <;lete'rmine.d..hy, II\icr~sco.pic examination. ''That there should be chemical similarity between slate, shale and clay results primarily from the fact that the slate here considered is simply metamorphosed shale and that shale is compressed clay. What: ever mineralogic changes metamorphism brought about, the same elements persisted. In some mica slates the grains of quartz, feldspa' r, zircon and other minerals are the identical ones of the original cl,ay sediment.'' CHEMICAL CHANGES IN WEATHERING The changes in the Rockmart sl:3,te in weathering are illustrated by the following pair of analyses. The first is a:q. average of five fresh samples from various quarries in the Rockmart district; the second is an average of two samples of partly weathered slate or '' crenstone'' from the Rockmart Shale Brick & Slate Company property: 1 U. S. Geol. Survey Bull. 586, p. 52, 1914. SLATE DEPOSITS OF GEORGIA.. 21 Analyses of Rockmart slates showing changes in weathering. Constituents. Fresh slate Partly weath ered slate Silica (SiO ) .............................. . 2 - Alumina (A1 0) ................ 2 Ferric oxide (Fe20 3 ) . Ferrous oxide (FeO) ..... .................. . Magnesia (MgO) .......................... . Lime (CaO) ............................... . Soda (Na20) ............ Potash (K20) .......... Ignition (less CO2 ) ........ ~ .. Moisture ................................... Carbon dioxide (C0 ) 2 Titanium dioxide (Ti0 ) .................. .. 2 Phosphorus pentoxide (P 0 ) .... 25 Sulphur trioxide (S0 ) .. 3 Sulphur (S) ............................... . Manganous oxide (MnO) ................... . Barium oxide (BaO) ....................... . 56.74 17.65 1.10 4.58 2.89 3.18 1. 66 3.42 3.81 .21 2.64 .94 .08 .1'8 .68 .02 .00 I .. 99.78 62.40 19.74 5.38 1.00 1.22 .05 1.02 3.07 4.98 .44 .00 .89 .06 .03 - 100.28 The black slate weathers first to soft, shaly '' crenstone,'' which is light red or yellow in color. This finally breaks down to a bright red or yellow, ocherous clay. The change to '' crenstone'' is the result of many centuries of weathering, and is not to be compared to the slight changes which may take place while the slate is on the roof of any building. The final change to clay is extremely slow, and the clayey soil covering the slate is never more than a few feet thick. The stages of weathering shown by these analyses are as follows: 1. Complete loss of carbonates of lime and magnesia, with oxidation of ferrous carbonate to limonite. 2. Oxidation and loss of carbon. 3. Oxidation of pyrite; sulphur lost, part of the iron remaining as limonite. 4. Decomposition of chlorite ; magnesia lost, ferrous iron oxidized to limonite. 22 GEOLOGICAL SURVEY OF GEORGIA 5. Kaolinization of feldspars, with loss of a large part of the soda and some _potash. The results, chemically, are: ' 1. Relative increase in the stable oxides; silica, alumina and total Iron. 2. Actual increase in combined water and ferric iron. 3. Total loss of carbon dio;:x:ide, lime, carbon, sulphur and ferrous . iron; considerable loss of magnesia and soda; slight loss of potash. The potash mica is a very stable mineral under ordinary weathering conditions, and is one of t'he Jast to go. In the :final cbange to clay the mica also i~ kaolinized, with loss of the potash, and free silica is leached out, leaving essentially a mixture of kaolin and limonite. The Conasauga, and Carrtersville slates show weatheriJig phenomena of the s.ame character, but on account of their higher percentage of mica; these slates weather even more slowly than those of the Rockmart formation. In the Conasauga green slate area slightly weathered fragmental material from the formation covers the, S)l'r&~ce over l~rge ( areas. The Cartersville shales and slates, with their hjgh potash content, sh~w t1t:e sta:biliity of the micas even when: S'lihjected to weathering for an enormous period of time. MINERALOGICAL COMPOSITION Slate, being formed from the debris, of granitic or other ingeous rocks, may contain any of the common rock-forming minerals. Most important in producing texture, cleavage and working qualities, however, are a small group of secondary or authigenous minerals formed during metamorphism. These metamorphic minerals are of comparatively simple and uniform composition, and are formed at the expense of any of the original fine-grained clastic minerals which happen to contain the proper elements. Dale's1 classification of the principal minera.l constituents of slates is here quoted. "A.s the min.eral constituents were either (1) derived from older rocks and dep_osited either as mechanical sediments or chemical precipitates, or (2) formed 1 Dale, T. N., U. S. Geol. S'urvey Bull. 586, p. 22, 1914. SLATE DEPOSITS OF GEORGIA 23 during metamorphism, or (3) derived from marine organisms, they are to be classified as follows: '' Classification of mineral constituents of slates. Clastic Clastic or authigenous. Authigenous. Organic. Quartz grains Feldspar grains. Zircon grains. Muscovite scales. Kaolin. Apatite. ' Magnetite ( ~). Carbonates, gran- nlar. Rutile needles. Tourmaline. ~~ ~ I Quartz, chalcedonie. Quartz, vein. Muscovite (seri- cite). Biotite. Chlorite, inter- leaved with muscovite or biotite. Pyrite, pyrrhot i t e. Magnetite. Hematite. Carbonates of lime, iron, magnesia, manganese. Andalusite. Barite. Gypsum. Tale. Carbonaceous matter. Graphite. Calcite (fossils). - Because of the complex mineralogical composition of slates and the fact that most of the elements present may enter into a number of different minerals, the calculation of the quantitative mineral composition of a slate from the chemical analysis can not be made with great accuracy. Determination with the microscope presents even greater difficulties. While most of the minerals present may be identified, the intergrowth and extreme fineness of grain prevents quantitative meas- 24 GEOLOGICAL SURVEY OF GEORGIA uremeiits such as can be made on sections of 'more coarsely crystalline rocks. The rn.ineral compositions of the four average slates (see analyses 2 p. 17) have been calculated by a rather arbitrary method, which gives the percentage of the principal minerals, mica, chlorite, feldspar, and quartz, with a fair degree of accuracy. Some interesting facts concerning the mineral compositions of various types of slates are brought out by/these figures. Mineral composition of average slates. Co;nstituents. 11 2 3 4 _ _ _ _ _ _ _ _ _ ___...:.___1------- Cale.ite OaO C0 2 2.62 5,68 2.92 .00 Magnesite MgO CO 2 .76 .28 .59 .00 Magnetite FeO Fe 0 23 3.19 1.59 2.29 6.10 Hematite Fe 0 .. 23 .00 .00 .00 1.36 Pyrite Fe8 2 Magnesia chlorite- 5Mg0 A\ 0 .41 1.27 .57 .00 3 3Si.02 4H20 .................. . 7.91 7.63 6.29 5.35 Iron chlorite 5Fe0 A1 0 3Si0 2 3 2 4H 0 .................... .... . 6.21- 6.56 9.14 .00 2 Sericite K 0 3A1 0 6Si02 2H 0 26.59 29.0.0 25.07 30.82 2 23 2 Paragonite Na 0 3A1 0 6Si0 2 .2 3 2 .2H 0 ........................ . .00 5.44 16.39 .00 2 Orthoclase K 0 .A:1 0 6Si0 2 23 2 Albite Na 0 A1 0 6Si0 2 23 2 Kaolin A1 0 2 3 2Si0 2H 0 ........ . 2 2 Quartz SiO 2 Excess water H 0 ................ . 4.52 10.37 .00 35.26 .68 .00 10.37 .00 29.77 .59 .00 .00 6.31 29.00 .32 30.87 4.15 .00 18.17 1.69 2 Sundry minor minerals ........... . 1.42 1.43 1.17 1.26 _ _ _ _ _ _ _ _ _ _ _ _ _ _____:__ - - - - - - - - - r - - - - - f - - - - - Total . . . . . . . . . . . . . . . . . . . . . . . 99. 94 99. 61 100. 06 99. 77 ---- -----r------f----- Total chlorite .................... . 14.12 14.19 15.43 5.35 -~-------------- --~r-----r-----f----- Total miea .. . . . . .. .. . . .. .. . . .. .. .. 26.59 34.44 41.46 30.82 -----'----------~- - - - - - - - - - r - - - - - - - 1 - - - - Total feldspar . . . .. .... . . .. . . . .. .. . 14.89\ 10.37 .00 35.02 1. Average slate from New York, Vermont, and Pennsylvania. 2. Average Rockmart slate. 3. Average Conasauga green slate. 4. Average Cartersville slate and shale. SLATE DEPOSITS OF GEOBGI.A 25 These compositions were computed by the following method: 1. All lime was computed as calcite. 2. The excess of carbon dioxide was computed as magnesite. 3. The ferric oxide was combined with enough ferrous oxide to form magnetite. Any excess of ferric oxide was computed as hematite: 4. The sulphur was combined with enough ferrous iron to form pyrite. 5. All remaining magnesia and ferrous iron were computed as chlorite. 6. Potash and soda were computed as mica and feldspar, the ratio being de~,,.rmine.d by the amounts of alkalies and alumina available. The order of calculation was (1) potash mica, (2) soda mica, (3) potash feldspar, (4) soda feldspar. 7. Any alumina remaining was computed as kaolin. 8. Remaining silica and water were stated as quartz and excess water. 9. Titanium dioxide, moisture, phosphorous, sulphur trioxide, manganese oxide and barium oxide were grouped under ''sundry minor minerals.'' Errors are introduced into this computation because of the im- possibility of making allowance for the clastic grains of original silicates. The relative proportions of hematite and magnetite can not be determined, so all ferric oxide is allotted to magnetite, which reduces the amount of ferrous oxide available for chlorite. Soda mica and potash feldspar can not be computed in the same analysis, because the potash is all allotted to mica when there is enough alumina to combine -with it. Simila.rly, feldspar and kaolin can not be computed together, for kaolin is stated only when there is an excess of alumina over that necessary to combine with all alkali as mica. Nevertheless, these error~ do not affect the general relations shown for the principal minerals. These figures show that the Rockmart slate is very similar to the average of the New York, Vermont and Pennsylvania slates, containing only a little more mica and a little less free silica than the latter. The Conasauga and Cartersville slates are of more unusual composition. 26 GEOLOGICAL SURVEY OF GEORGIA The Conasauga green slates are more micaceous than the ot:Q.ers, and have a high per cent of iron-bearing chlorite, although the total chlorite is not much higher than usual. In this slate no feldspar is indicated by the analysis, as the percentage of alumina is more than enough to form mica with all the potash and soda. In the average Conasauga slate there is enough combined -water to form kaolin with the excess of alumib.a, but in some of the ib.dividual analyses there is a deficiency of water, indicating that some alumina occurs in the form of aluminum silicate, andalusite" sillimanite or cyanite. The Cartersville slates, in spite of their high percentage of potash, can not run extremely high in mica because of the low alumina content. .Ail of the soda and more than half of the potash must occur as feldspar molecules. This indicates a total feldspar percentage greater than that of mica, while the excess of free snica is much less than in any other slate. Micro~copic examination of thin sections shows a grea;t deal' of feldspar, but the visible amount is not nearly as large as that indicated by calculation from the molecular ratios. The percentage of hem?-tite shown in the sections is greater than that indicate.cil:~c by-, ~h~ttyOJI!;piUJted tC:Q:0.1]~Jo;;;itiqn; te::JE~irt:g;:;.SOJilile'. ferrous [ron to enter ib.to chlorite, but even with this addition the percentage of chlorite r.emains~ urrRsually low. AGE AND GEOLOGIC RELATIONS Most, if not all, slates of commercial value are found in formations of Paleozoic age. In general, the pre-Cambrian rocks have been too intensely metamorphosed, while those of Mesozoic and Cenozoic age are 1hot sufficently consolidated. The Georgia slates, as well as those of other states in 'the Appalachian province, belong to the Cambrian and Ordovician systems of early Paleozoic age. Slates can occur only near the borders of granitic land masses which served as sources of supply of the original materials. Thus, t~e ' slate deposits of Georgia, although they belong to three geologic formatio:ns, all occur just northwest of the old continental mass of preCambrian rocks. SL.A1'E DEPOSITS OF GEORGIA 27 After deposition the sediments must have been subjected to dynamic metamorphism, during which the pressure must not have been too intense and must have come mainly from one direction.. Two major periods of metamorphism, Ordovician and Carboniferous, occurred in the Appalachian province. The latter metamorphic period had little effect on the Georgia formations west of the Cartersville fault, but east of that fault the earlier Cambrian formations, the Nantahala slate and parts of the Brasstown schist and Valleytown formation have been too much metamorphosed to serve as commercial slates, although their chemical composition is suitable. ORIGIN1 ''With the exception of the rare slates of igneous or1gm, slates originate in marine deposits of clay and sand. TJ;.e common occurrence of angular grains of feldspar and of quartz in slate im- plies the nearness of shores or land masses of granitic rocks to such deposits. The alternation of beds of slate with beds of quartzite or grit ("ribbons," "hards," altered sandstone) corresponds to the al- ternation of extremely fine clayey sediments, derived from the waste of such granitic land masses with sandy sediments consisting of coarser material from the same source. The repeated alternation of such fine and coarse sediments is attributed to the alternation of calm water, favorable to the deposition of fine material, with strong cur- rents that brought coarse sediments more rapidly from the shore. These materials consisted largely of quartz, feldspar and mica, but included also zircon and other silicates, various compounds of iron, lime and magnesia, and kaolin arising from the decomposition of feldspar. Where the slate is interbedded with fossiliferous limestone, it is evident that periods of such changing conditions in the water also alternated with periods when marine life abounded and the sediments were entirely calcareous. Black slates owe their blackness to carbonaceous matter, probably derived from the decom- position of marine organisms on the sea floor. Red slates owe their color to the access of ferruginous matter from the land, and purplish 1 Quoted from Dale, T. N., U. S. Geol. Survey Bull. 586, pp. 11-14, 1914. 28 GEOLOGICAL SURVEY OF GEORGIA slates to an admixture of such matter and a green. magnesian mineral (chlorite) o.f secondary o;rigin. In both the reddish and the.purplish sll:!-tes.. the iron is supposed to have been originally precipitated in the fo;rm of the rust-colored limonite (2Fe2 0 3 3H20) from iron-bearing solutions and to have been afterward altered by loss of water (H 20) to the reddish hematite (:Fe2 0 3 ) 1 ''An:. accumulation of several hundred feet of such clayey and sandy. sediments when buried under several thousand feet more of other sediments of like origin on a gradually subsiding sea bottom must have been subjected to sufficient vertical pressure, in connection with a small amount of moisture, to be cemented together and hard- ened-the clay into shale and the sand into sandstone. During this process the particles in thBse sediments retained the .general horizon- ~ I ' \ tal and parallel arrangement which they had received from their dis- tribution by sea water, but became :firmly compacted and thus ac- quired a bedding foliation. ''The next stage_in the formation of slate is attributed ultimately to the radiation of heat from the earth's interior into sp_ace., resulting in.~ a conina:ction; o th-e inter:ior .and .cons~quentl~ in ..a corruga-.. , ~- , .. - \ ,,. . " "" . . ,. -,~ ._ , ' . ..:: . r . ,t!,- . ,_.. . .. tion of the outer portion. This corrugation, for reasons not yet per- fectly, evident; took. p1aee, so-ar as:,obserw.ation ex,te:ads, chiefly with- in certain belts in. which the mountain systems were formed from the lateral compression of a great mass of parallel strata. The :first effeet of this compression was to bend at least the lower portion of the strata into wavelike folds, and thus to shorten its horizontal area in one direction and increase its vertical thickness. But another effect of this compression was to metamorphose the shale into slate. This metamorphism probably did not take place until the folding was . . . ~ well initiated. The transformation included two processes, and it is uncertain which preceded. Each individual sedimentary. particle rwas rotated ~rom. its original horizontal position in the bedding foliation into one forming' a considerable angle to the direction of pressure. The~e was also, under th~ combined presence of moist~re and the effect of pressure and heat, both the heat which must have been gen- 1 See on these changes VanHise, C. R., A treatise on metamorphism: U. S. Geol. Survey Mon. 47, pp. 225, 232, 1904. SLA1'E DEPOSITS OF GEORGIA 29 erated by the pressure and that which pervaded the strata at the depth at which they were bu:J?ied, such a chemical recombination of the silica, alumina, potash, iron and water of the feldspar, kaolin and ferro-magnesian minerals of the shale as to generate new potash mica in amount sufficient to constitute, in the mica slates, over 33 per cent of the resulting slate. This muscovite was formed in scales of in-. finitesimal thinness and generally of longish, tapering, or ribbonlike outline. Most of these scales arranged themselves with their flat sides parallel to or overlapping one another, but facing the direction from which the pressure came and also with an angle of inclination governed by that pressure. .A small but variable proportion, however, of these scales took such a position that their flat sides became parallel to the direction of the pressure. .As mica crystallizes in columnar crystals, and as the plates or scales due to its molecular structure are to transverse the crystal column, and as a slab of slate consists largely of parallel scales of mica it may be said to correspond when held horizontally to such a crystal held vertically. When a mica slate is cut in thin section across the cleavage its optical behavior under polarized light is like that of a mica crystal cut across its crystal cleavage. Yet as not only a considerable number of the mica scales in slate lie across the cleavage, but as some scales of chlorite and crystals of other minerals do also, the texture of a mica slate combines some of the features of a crystal with some of .those of a tissue. Extremely thin sections of slate transverse to the cleavage may show this interlacing of the two sets of scales on their attenuated edges. It is to this microscopic texture that the slate largely owes its peculiar properties. ''This crystalline fabric may inclose in its meshes any sedimentary particles of quartz, zircon, feldspar, kaolin, or other minera1s which were not or could not be made over into mica or secondary quartz, but whose alignment became more or less parallel to that of the major part of the new mica. During this metamorphism other chemical combinations were formed by the constituents of the shale, which crystallized in isolated scales or crystals of chlorite, biotite (magnesia mica), various carbonates, pyrite, magnetite, graphite, tourmaline, andalusite, etc. These arranged themselves variously-some in the 30 GEOLOGICAL SUEVEJ! OF GEORGIA cleavage direction, some in the grain direction. Lenses consisting of or some one: mineral surround.ed by one two others were also formed and concentrically or radiately arranged. The limonite became hematite._ During these changes in the fine sediments the intercalated beds of sandstone passed into quartzite and metamorphic grit by the formation o'f siliceous and micaceous cement between their particles. "The general microscopic texture of slate is such as to warrant the assumption that the compression which produced it operated not only rwith great uniformity, but also very gradually. "Alter the s1a,te was formed the mass was subjected to various stresses (tensions, shears, contractions), which resulted in several systems of joints, in faults, slip cleavage ("false cleavage"), shear zones ("hogba~ks"), and irregular openings in which veins 6f quartz and calcite were forll1ed by infiltration. Some masses- were also traversed by fissur:es penetrating to the molten zone and thus permitting the exudation of lava-like material which formed dikes. "From the foregoing stateme:mits it may be seEm that a piece of slate is in itself a record of a long series of complex geographic, geologic, chemii<:~all; mine:r:alogic a;:B1d. physical processes of gi!Jeat 13cientific interest." METHODS OF TESTING The usual tests of slate, as outlined by Dale1 are as follows: Sonorousness.-Slate of good molecular structure yields a distinct ring when tapped. OleaJtHilbiW:y.-This test must be made on a block of moist, unfrozen, freshly quarried slate by an experienced workman. "ScuLping. "-The test to determine the character of the fracture along the grain should be made by an expe,rienced workman. It is also an advantage if the slate will "betel break" across both cleavage and grain without shattering. 1 U. s. Geol. Survey Bull. 586, pp. 172-181, 1914. SLATE DEPOSITS OF GEORGIA 31 Character of Cleavage Surface.-.Examination with a hand lens will show the grain, false cleavage, ribbons, coarse crystals producing roughness of the surface and micaceous leaves indicating good cleavage. Presence of Lime.-Test for effervescence with hydrochloric acid on the edge of a block or on powdered slate. Color and Discoloration.-Comparison of fresh slate with that exposeO. to the weather for some years. Presence of Clay.-Slate containing clay has an argillaceous odor when breathed upon. Presence of Marcasite.-Marcasite upon exposure forms a yellowish-white film and rusty spots. Pyrite in small quantity is not detrimental. Presence of Magnetite.-May be determined quantitatively by powdering the slate and extracting the magnetite with a strong magnet. Electric Resistance.-Determined by comparison with a standard resistance.1 This test is important if the slate is to be used for electric switchboards. The resistance depends largely on the scarcity of magnetite. Strength.-This test is made with Merriman's apparatus.2 The piece to be tested is supported upon knife-edges 22 inches apart, and the load is placed upon another knife-edge midway between. The nodulus of rupture of the best slate ranges from 7,000 to 10,000 pounds to the square inch. Toughness or Elasticity.-Measured by the ultimate deflection when placed on supports 22 inches apart. The deflection of certain Pennsylvania slates tested by Merriman ranges from 0.270 to 0.313 inch; that of the Rockmart, Georgia, slate is 0.160 inch. 1 Purdue, A. H., The slates of .Arkansas: U. S. Geol. Survey Bull. 430, pp. 329330, 1910. Bristol, W. A., High tension testing of Vermont slate and marble: Report of the Vermont State Geologist, 1911-1912, pp. 196-219. 2 Merriman, Mansfield, Am. Soc. Civil Eng. Trans., vol. 27, nos. 3 and 6, 1892; vol. 32, pp. 529-539, 1894. 32 GEOLOGICAL SIJ1WEY OF GEORGIA Density or Specific Gravity.-Determined in the usual manner, by weighing a piece in air and- in water, after air is expelled by boill.ng in dfstilled ::water. Porosity.-Determined by the amount of water absorbed in the pores. May be determined roughly by observing the ascent of water by capillary attraction in a.' piece partly immersed in water. H ard1tess or Resistance .to Abrasion.-Relative hardness is determined by the weight removed by a definite number of revolutions of a sta;ndard grindstone under a constant pressure. Corrodibi~ity.-Tested.by solubility in dilute acid. Merriman used a solution with one per cent each of hydrochloric and sulphuric acids. Mic1~oscopic .A.nalysis.-Determination of minerals present and their textural relations by examination of thin sections under the microscope. Sections should be cut both parallel and perpendicular to the cleavage, and should be cut much thinner than the usual sections of igneous rocks, in order that very high magnification may be used. ChermricaL AnaLysis.-Ohemical analysis of slates should be consid- ered in connection with the microscopic examination and other tests, because the analysis alone gives little evidence as to the value of a slate. In order to be worth anything at all an analysis must be complete, show:i:ng especially soda, p6tash, ferrous iron, sulphur and carbon dioxide. Merriman~ concludes that: ''The strongest slate stands highest in weathering qualities, so that a flexural test affords an excellent index of all its properties, particularly if the ultimate deflection and the manner of rupture be noted. The strongest and best slate has the highest percentage of silicates of iron and alumina, but is not necessarily the lowest in carbonates of lime and magnesia. Chemical analyses give only imperfect conclusions regarding the weathering qualities of slates and do not satisfactorily explain their physical. properties.'' 1 Op. cit. SLATE DEPOSITS OF GEORGIA 33 TESTS OF GEORGIA SLATES The follo:wing tests of Rockmart slate were made by the United States Bureau of Standards in December, 1917. The samples were collected by T. N. Dale. Physical Tests of Rockmart Slate Laboratory Number 22035, U. S. Bureau of Standards. Transverse testsModulus of rupture (ave1age of 2 tests)........ 7,589 lbs. per sq. in. Modulus of elasticity in bending .............. 14,280,000 Maximum deflection at center of 12in. span. . . . 0.026 i:ti. Equivalent deflection for 22in. span.......... 0.160 in. Absorption testsPercentage of water absorption by weight (average of 3 tests) ......................... . Percantage of water absorption by volume ........ Apparent specific gravity (average of 3 tests) ..... . Weight per cu. ft. of dry slate ................... . 0.25 0.70 2.766 173 lbs. These tests compare favorably with those made by Mansfield Merriman on slates from Pennsylvania, Virginia, Maine and Vermont, and by A. H. Purdue on slates from Arkansas.1 The modulus of rupture of the Rockmart slate is a little below the average of the Pennsylvania, Virginia, Maine and Vermont slates, but higher than that of the Arkansas slates, and any figure above 7,000 pounds per square inch indicates a strong slate. The maximum deflection is below the average, but some other strong slates are not highly elastic. The figures for absorption and specific gravity are about the average. The comparative characteristics of Georgia slates are tabulated by Dale as follows2 : 1 U. S. Geol. Survey Bull. 586, pp. 181-187, 1914. ' U. S. Geol. Survey Bull. 586, p. 188, 1914. GEOLOGICAL SURVEY OF GEORGIA Comparative characteristics o{ Georgia slates. Locality Color Bolivar, Bartow -- County Light blue-greenishgray Cleavage surface Smooth to roughish Luster Slight Magnetite Extremely little Microscopic texture Crystalline, fine Grade of :fissility (4 grades) Second grade Ohief minerals (probable descending order of abundance) Muscovite, quartz, chlorite, carbonate Class Mica slate, sJightiy '.'. . fading .. Carbonate .,, . Littie I, ' Rockmart, Polk County Very dark bluish gray Slightly roughish None Very little Crystalline, . lenticular, coarse Third grade Muscovite, quartz, carbo;nate, c;;trbon Mica slate, fading Much .It would seem obvious that the first requisite mopening a slate quarry is careful exploration to-determine both the quality and quantity of slate available. This, however, is not always done. The steps in exploration in an unglaciated region such as Georgia should be as follows: 1. Refer to a geologic map, if one is available, to determine the areas of slate formations, strike of beds, large faults, etc. 2. Search for favorable surface indications. 3. Open a pit large and deep enough to determine the thickness of weathered ''topping,'' strike and dip of bedding and cleavage, relation and abundance of faults, joints, veins, shear zones, etc., and to obtain samples of fresh slate for testing. 4. Out trenches across the strike at promising localities to expose as large a thickness as possible. 5. Make borings with a core-drill. The larger the cores and the more drilling done, the better; because liberal use of the drill may avoid many costly mistakes. SLATE DEPOSITS OF GEOEGIA 35 6. Make a topographic map, as accurately as practicable, of the area where quarries, buildings, ~umps, etc., are to be located. 7. From the topographic map and drill records construct struc ture sections. These should show the dip and thickness of workable slate, and from them estimates of the quantities of waste and workable slate should be made, especially an estimate of the slate above the lowest level at which natural drainage can be secured. Topography, drainage, and quantity of overburden are important considerations. The Georgia slate deposits occur in hilly, or even mountainous areas, and the slate formations are resistant enough to form hills, so that the topographical features are generally favorable for quarrying. Quarries may be opened in the lower slopes of the hills, and large amounts of slate may be quarried without hoisting the rock or pumping out water. In some cases it may be necessary or desirable to drive tunnels for drainage, as was done at one of the old quarries near Rockmart. Waste dumps should be placed on the lowest ground available, and great care should be taken that they do not cover slate which it will be desirable to quarry in the future. In Georgia, as in any area where the mantle of decomposed rock has not been removed by glaciation, the fresh, solid slate is covered by a considerable thickness of overburden, generally called "topping" in slate quarries. There js a gradation downward from the superficial soil or clay to the fresh slate, so that no sharp line can be drawn, but the thickness of waste material is usually from 10 to 30 feet. The partly weathered slate from the Rockmart formation may be utilized for making "shale" brick or portland cement. That from the Conasauga formation will not do for cement manufacture, because of its high content of alumina. Relations to transportation, markets, fuel, and labor, and climatic conditions are also important. The Georgia slate belts are well supplied with railroads, so that all. deposits are within a few miles of transportation. However, a deposit on a railroad line, or one which can be reached by a short spur track is much more valuable than one from which the slate must be transported several miles by road. Not only is transportation by 36 GEOLOGICAL SURVEY OF GEORGIA t .'1 i wagon or truck expensive, but slate is likely to be lost by breakage at each handling. A. market exists or could be developed in the Sot1thern States for a considerable amount of roofing and structural slate. A.t present there are no operating slate quarries closer than those of Pennsylvania and Virginia:, so that the advantage in freight rates ~lone should in- sure a profit to a quarry in Georgia in supplying several of the South- eastern 'States. It is true that not much roofing slate has been used in Southern cities in recent years, but it is likely that the demand will increase as ordinances requiring fireproof construction are passed, and no material has been found superior to sl~te fqr fireproof roofing on dwelling houses and other small buildings. The Georgia slates, on acco.unt of their small percentage of magnetite, should also be adapted to use in electrical apparatus, although the requirement for such uses in the territory suppliedis small at pre~ent. Co.al is available in the Georgia slate districts at moderate prices, being shipped 0ver the L.ouisville & Nashville Railroad from Tennes- see and over the Seaboard A.ir Line from .Alabama. There are also coal ~eposits. aBd _a :few operating mines iB northwestern Georgia, witbjn 50 miles. o the slate deposits. Large areas in the slate belts are wo., oded,. so the ne~essary 'timber and fuel for heating. may be obtained easily. Th~ supply of labor i~ starting a new industry will naturally prese~t difficulties. Under normal conditions there is plenty of common labor in the slate belts of Georgia, but slate quarrying and manufac- turing pr?cesses require a considerable number of highly skilled work- men. It will be necessar;r to import SOJ?.e skilled laborers from the slate quarrying districts of the Northern States. ..'P4e; climate of_ the ~eorgia slate region is such as to permit out- side work throughout the year.. The rainfall is between 40 and 50 inches p_er year, and aver~ges about the -saw~ for a~l months. Snow falls occasionally during.December, January and February, but rarely covers the ground. for m1 LEGEND ~ Cona.sa.u,ga. (Fo..irmount) .slo.+e Rock mo.rt slo.te Map I. Index map showing the distribution of slate-bearing formations in Georgia. Scale: 1 inch-approximately 11 miles. SLATE DEPOSITS OF GEORGIA 43 SLATE DEPOSITS OF GEORGIA The deposits of commercial slate in Georgia all occur in the Appalachian Valley physiographic province, but they are in three distinct geologic formations. (See Map I.) After a brief discussion of the general features of the area, the slate belts and individual deposits w.ill be described in detail. GENERAL FEATURES OF THE APPALACHIAN VALLEY IN GEORGIA PHYSIOGRAPHY The Appalachian Valley is a well defined physiographic division, extending from New Jersey southwestward into Alabama. The valley in Georgia is about 40 miles. wide, extending across the northwestern c10rner of the State, and is mostly drained by Coosa River and its tributaries, Etowah, Oostanaula, Conasauga and Coosawattee rivers, although a portion is drained by tributaries of Tennessee River. The valley belt is made up of several parallel valleys separated by narrow ridges. The topography is entirely dependent on the character of the underlying rocks. The valleys are underlain by limestone or soft shale, while the ridges are formed by harder beds of sandstone or chert. The altitude varies from about 600 feet above sea level where Coosa River crosses the Alabama line to nearly 2000 feet at the summits of the highest valley ridges. These ridges, however, are not quite so high as the mountainous areas lying east and west .of the great valley. The Appalachian Valley is bounded on the east by the Appalachian Mountains and Piedmont Plateau provinces, and on the west by the Cumberland Plateau. North of Chatsworth, Murray County, the Cohutta Mountains rise abruptly from the valley, with an escarpment over 2000 feet high. South of Chatsworth the boundary between the Appalachian Valley and the Piedmont Plateau is marked by a less abrupt change in topography although a1ong this line is one of the most rugged portions of the Piedmont, with Pinelog Mountain 44 GEOLOGICAL SURVEY OF GEORGIA and Dugdorwn Mountain rising 200 to 300 feet above the level of the valley. West of the valley lies a dissected and mountainous section of the Cumberland Plateau, with the escarpment of Lookout lVloUlltain forming the boundary. STRUCTURE The rocks of the Appalachian Valley have the typical Appalachian structure, characterized by folding and faulting on a large scale. The pressure acted from the old continental mass which existed to the southeast, throwing the strata into great anticlines and synclines, some of which are hundreds of miles in length. At many places the folds developed into faults, and great masses of rock were thrust northwestward over the younger formations. The folds and faults are in general parallel to each other and to the old shore line, but mi- nor disturbances have been produced by later mo:vements. The east- ern ind southeastern bbundary of. the Appalachian Valley division is formed by the Cartersville fault, which extends more than 100 miles across Georgia and far into A1ahama and Tennessee. This is one of .-." '" i.' -": ', .: . -.:' j . .:.. . ' . j . -, .. . the largest fault~ in the Appalachlan region, both in length and amount of throw. The rocks of the Valley division, as well as those of the Appalachian province as a whole, are progressively less folded aJ?-d metamorphosed from east to west. In the eastern part of the Valley the folds have heen so closely compressed that the beds on both limbs are almost parallel, and in most cases nave been overturned so that all beds dip Steeply to the east or southeast, and there are evidently many minor thrust fa~ts with the same dip, besides the major thrust faults, which dip to the east at low angles. In the western part of the Valley the folding is much more open. However, the beds gener~lly dip at an- gles of 10 degrees or more, while farther west in the Cumberland Plateau division the strata lie almost horizontal. The degree of metamorphism corresponds closely with the amount of folding and faulting. In the Appalachian Mountains and Pied- mont Plateau all o~ the rocks have been intensely metamorphosed and recrystallized into schists and gneisses, while in the Cumberland SLATE DEPOSITS OF GEORGIA 45 Plateau there is practically no metamorphism aside from that due to the weight of overlying 'beds. The rocks of the Valley division are intermediate in character. The western Valley rocks are little altered shales, sandstones, and limestones, and it is only along the eastern border, within a few miles of the Cartersville fault, that metamorphism and recrystallization have progressed far enough to give to the originally shaly beds the hardness and cleavage necessary for commercially valuable slates. GEOLOGY .The geologic formations of the Appalachian Valley and Cumberland Plateau areas of Georgia are shown in the accompanying table. Table of Geological Formations of the Appalachian Valley and Cumberland Plateau Areas of Georgia Era or System Period or Group Formation Thickness feet General character. Walden sandstone 93.0 Sandstone and shale. mfl>. Pennsylvanian Lookout formation 500 Massive sandstone at base succeeded by sandstone and shale with heavy conglomerate and sandstone at top. Unconformity Pennington shale 780+ Carbonaceous shale with sandstone in upper portion. \ Carboniferous UnCOI\formity 900 Heavy-bedded, high-calcium limestone with some Mississippian Bangor lime':ltone Prob:;tbly time Floyd formation fequiv"i'ts 1,500+ magnesian limestone. Carbonaceous shale with so:n;te heavy-bedded, dark-blue limestone. g ~ a Fort Payne chert -------I I Unconformity Upper I Chattanooga black shale Devonian Middle (absent) --Unconformity Frog m't'n sandstone and Lower Armuchee chert 200 Chert an,d. cherty limestone. ~ I 20 Black shale. S2 t-1 ------,------------------'-- 40 Sandstone and chert. ~ ~ Silurian Upper (absent)-1--- Unconformity Middle Niagrian Rockwood formation Lower (absent) UnconformitY. 1,600 ~ Oliv&-green shale with many thin beds of brown f-<:j. and grem sandstones. ~ Ordovician r---------..,,-1 (West'n basin) (East'n bsn) 2,500+ Brown and olive-green shale, with sandstone and ~ Rockmart limestone conglomerate in upper portion. a Upper Chickamauga sla-te Dark bluish gray slate. !?;;j Middle formation tJnconf'rnrrtyChick'mauga limestone ----------------------------------------------- 200 Dark-blue and gray limestone. ~ ~ Unconformity ----~-t---------- -------'--------------'-------------------- Lower 5,000 Largely crystalline, heavy-bedded, gray dolomite Knox dotomite with much chert. Upper Cambrian or Sarratogan 2,000 Yellow and brown argillaceous shale with some blue limestone containing argillaceous intercal- Middle Cambrian Conasauga shale and ations and veins of secondary calcite. or Acadian limestone Green slate. Cambrian Lower Cambrian or Georgian Rome formation Apison shale Cartersville formation Beaver limestone 8,500 1,000 1,000 1,100+ Variegated shale and sandstone. Vari-colored argillaceous shale. High potash slate, shale and sandstone. Heavy-bedded, gray magnesian limestone. Weisner quartzite 2,500+1 Quartzite. SLATE DEPOSITS OF GEOEGIA 47 CAMBRIAN The Cambrian rocks of Georgia consist of sandstones, quartzites, conglomerates, shales, slates, schists, dolomites, limestones, and marbles. To the east of the Cartersville fault the lower Cambrian rocks make up the semi-crystalline or metamorphosed Paleozoic area. These formations correspond with the ''Ocoee group'' of Tennessee, and have not been correlated with the formations west of the fault. Metamorphism has been so intense that no slates of possible commercial value exist, so the geology need not be further considered. WEISNER QUARTZITE The Weisner quartzite, of lower Cambrian age, is the oldest of the Appalachian Valley formations. It outcrops in two areas in Georgia, making up Indian Mountain which extends from Alabama into northwestern Polk County, and a belt about 15 miles long just east of Cartersville. The formation consists of vitreous quartzite, quartz-sericite schist, beds of fine conglomerate, and considerable beds of softer, siliceous shales. Hayes1 estimates the thickness at 2000 to 3000 feet. The fragmental and poorly assorted character of the materials of the formation, together with the great variations in thickness in a small area indicate that it consists largely, of delta deposits. BE.A.VER LIMESTONE The Beaver limestone overlies the Weisner quartzite, occupym.g several belts and irregular areas in an area about 18 miles long, chiefl.y in and north of Cartersville. The relations are complicated by much folding and faulting, and on account of the deep weathering and similarity of composition the Beaver limestone can hardly be distinguished from the limestone of the higher Conasauga formation, since the two may have been brought into contact by faulting at some places. .Another area of Beaver limestone extends along the southeast side of Indian Mountain. in Polk County. 1 Hayes, C. W., Geological relations of the iron ores in the Cartersville district, Georgia: Trans. Am. Inst. Min. Eng., vol. 30, p. 404, 1901. 48 GEOLOGICAL SURVEY OF GEORGIA The .Beaver consists of argillaceous, dolomitic limestone. On account of its solubility it generally forms valleys, and is covered by thick deposits of da~k-rea residual clay and fragmental material derived from the Weisner quartzite, so that few exposures of fresh rock occur. The formation is of economic importance, because most of the deposits o brown iron ore, manganese, and barite of fue Cartersville district are found in the residual clay derived from it. Hayes estimates the thickness at 800 to 1200 feet. The Beaver limestone is believed to correspond to the Shady limestone of Tennessee and Virginia and to the Murphy marble of the more highly metamorphosed Cambrian area east of the Cartersville fault. The correlation with the Shady limestone is strengthened by a fossil, Ethmoph4Jnum? p1:ofJtndum (Billings) Walcott, recently found in the barite of this formation by J. P. D. Hull. CARTERSVILLE FORMATION .In .the Cartersv~lle district the Beaver limestone is overlain by a formatioiJ. of sla-te, shale; ,and feldspa.:thic sandst0ne, most of which is characterized by an unusually high content of potash. This formation outcrops in a belt about 15miles long and half a mile wide, extending from Cartersville northeastward to Martins Mill, and probably also underlies the alluvial deposits of the Etowah bottom to a point south of the river. The formation is repeated by folding or faulting, so that outcrops occur almost as far west as Cassville. The formation can. probably be correlated with the Apison shale or the Rome formation of the Rome, Ringgold and Cleveland quadrangles, and the Watauga shale of the Roan Mountain quadrapgle. However, as the exposures near Cartersville are not really continuous with these formations, .and as the lithologic character is very different, the local name ''Cartersville formation'' has been adopted, after consultation with Laurence La Forge1 of the United States Geological Survey. l. The geology of the Cartersville quadrangle was mapped by C. W. Hayes about 1900. Later La Forge revised the mapping of the area of the Cartersville Special sheet, but the time of publication of the folio is uncertain. SLATE DEPOSITS OF GEOBGI.A 49 The distribution and character of the Cartersville formation is discussed in more detail in connection with the description of the slate deposits (Seep. 128). APISON SHALE The .Apison shale underlies the Rome formation in the Ringgold quadrangle, and is the lowest formation exposed in that quadrangle. In the Knoxville quadrangle it is mapped as underlying the Beaver limestone. This formation consists of argillaceous shales of various colors. Exposures in Georgia, so far as known, are confined to two small areas in Catoosa and Whitfield counties. .Although the .Apison shale is evidently approximately equivalent to the Cartersville formation in age, the exposures are in the western part of the .Appalachian Valley, where the formation has not been sufficiently metamorphosed to produce slate. The thickness is estimated by Hayes as not less than 1000 feet. ROME FORMATION The Rome formation consists of sandstone and shale, occupying a place above the .Apison shale wherever that formation is found. The belt of high-potash shale and sandstone near Cartersville, here called the ''Cartersville formation,'' was included in the Rome formation by Hayes, on the basis of stratigraphic position. With this belt excluded, the exposures of the Rome formation are confined to the central and western portions of the .Appalachian Valley, where metamor- phism has not been intense enough ta- change the shale into slate. CONASAUGA FORMATION 'rhe Conasauga formation of middle Cambrian age covers a larger area in the .Appalachian Valley of Georgia than any other formation except the Knox dolomite. Hayes estimates the thickness as 1500 to 2000 feet in the Ringgold quadrangle, but in the area east of Dalton it may be even thicker. 50 GEOLOGICAL SUEVEY OF GEORGIA In southern Whitfield and Murray counties the belt of continuous outcrop of the Conasauga formation is 17 miles wide, from east to west. Northward the formation is split into four belts, with areas of Knox dolomite between. Southward there are three belts. The eastern, with an average width about 10 miles, extends south to Cartersville. The central belt extends down the valley of Oothkalooga Creek past Adairsville, and the western swings southwestward past Rome and widens to 13 miles in the Coosa Vailey along the ..c\J.abama line. There are also several narrower belts in the western part of the Appalachian Valley. The Conasauga formation consists of interbedded limestone and shales. Limestones occur chiefly near the bottom and top of the formation, while the middl~ beds consist chiefly of shale. J'he s~ales of the formation are fine-grained argillaceous rocks characterized by their color, which varies from yellowish-green to bluish-green. Although the entire mass of shales have approximately the same chemical composition, it is only in the eastern part of the belt, within 4 or 5 miles of the Cartersville fault, that they have been metamorphosed into a sufficiently hard and cleavable condition to 'serve as commercial slate. The geology of the slate-beaning. portion of the formation w:ill.be more fully discussed under the descr.iptions of slate deposits. (Seep. 99). CAMBRO-ORDOVICIAN KNOX DOLOMITE The Knox dolomite is shown by paleontological evidence to include both the upper part of the Cambrian and the lower part of the Ordovician; The formation attains a thickness of 4000 to 5000 feet, being the thickest and areally the most extensive formation of the Paleozoic group in Georgia. The principal area is the broad valley between Cartersville and Rome, extending from southern Murray County southwestward to the Alabama line, but there are a number of other extensive areas farther northJWest. The formation consists entirely of dolomite, and all except the lower part contains abundant chert. The chert in the residual ma- SL.A1'E DEPOSITS OF GEOBGI.A 51 terial makes erosion of the formation, in general, slower than that of the Conasauga formation, so the Knox dolomite areas are characterized by low, irregular hills and ridges. ORDOVICIAN CHICKAMAUGA FORMATION The Chickamauga formation, representing middle and upper Ordovician time in Georgia, consists of sediments of two distinct types, deposited in separate basins. The rocks of the western part of the Appalachian Valley consist of interbedded limestones and shales, having a thickness of about 1800 feet, and outcropping in a number of long, narrow areas. Along the southeastern border of the Appalachian Valley._ the formation covers two large irregular ar:eas south of Rockmart and Cedartown, and is divided into the Chickamauga limestone and the Rockmart slate members. CHICKAMAUGA LIMESTONE The Chickamauga limestone member forms the lower part of the Chickamauga formation in the eastern area. It is 100 to 200 feet thick .and consists of both high-calcium and magnesian limestones. In the area north of Rockmart the high-calcium limestone is used in the manufacture of portland cement. ROCKMART SLATE The Rockmart slate member consists of dark-colored slate and slaty shale, weathering olive-green or yellow, with only minor beds of sandstone, limestone, and conglomerate. According to Hayes the thickness may be 2500 to 3000 feet, but it is repeated by folding, so that any accurate estimate is impossible. The distribution and geology will be discussed more fully under the descriptions of slate deposits (Seep. 54). 52 GEOLOGICAL SURVEY OF GEORGIA SILURIAN Silurian deposition in Georgia is represented by the Rockwood formation, corresponding to tlie Clinton iron-bearing formation of New York. It consists of sandstones, shales, conglomerates and limestones, !With a thickness of 600 to 1600 feet. All exposures are in the central and western portions of the Appalachian Valley, where metamorphism has not been intense enough to form slates. DEVONIAN The Devonian rocks of Georgia consist of the Armuchee chert, Frog Mountain sandstone, and Chattanooga black shale. All these formations are thin, and the outcrops are of small extent. CARBONIFEROUS The Carboniferous formations of Georgia are the Fort Payne chert, Floyd formation, Oxmoor sandstone, Bangor formation, Lookout formation and Walden sandstone. Of these the first four belong to the Mississippian period; the last two to the Pennsylvanian. The total thickness is about 4000 feet, and the formations outcr0p in extensive -areas in the central and western parts of the Appalachian Valley, besides forming the greater part of the Cumberland Plateau area. GEOLOGIC HISTORY Early in Cambrian time the Appalachian region sank and the sea intruded from the northwest, while a continental mass remained at the southeast, probably extending far beyond the present Atlantic Coast line. Deposition started with beds of sand and gravel, then under changing conditions beds of conglomerate, sandstone, shale and limestone were laid down. The Weisner quartzite, the oldest of the Valley formations, is of ea:rly Cambrian age, although probably not as old as some of the metamorphosed Cambrian formations east of the Cartersville fault, with which no correlation is possible in the present state of knowledge. SLATE DEPOSITS OF GEORGIA 53 This formation consists of coarse, poorly-assorted materials, indicating continental or shallow water conditions of deposition. With the gradual transgression of the sea the Beaver limestone was laid down, but this impure limestone was evidently deposited in comparatively shallow water. A slight rise in the land must have occurred at the close of Beaver deposition, for the character of the Cartersville formation shows deposition in very shallow water. Thin alternating beds of widely different composition show changing conditions. The high potash content of the shale and feldspathic sandstone beds shows that the materials were transported rapidly from the granitic mass:es to the east, and were deposi..ted without opportunity to suffer much chemical change by weathering. At approximately the same time that the Cartersville formation was being fomed along the shore the Rome . formation and Apison shale were being laid down in the slightly deeper water farther west. In middle Cambrian time the sea transgressed over a larger area, but the water still remained shallow, and a number of oscillations occurred, while the alternatinglimestones and shales of the thick Coria:. sauga formation were deposited. A gradual submergence continued during middle and late Cambrian .and Ordovician time, when the Appalachian sea reached its greatest depth and the enormous Knox dolomite formation was deposited. Before the close of the Ordovician a great upheaval of the land occurred, and the greater part of the Appalachian Valley was temporarily above sea level, so that a part of the Knox dolomite was eroded away before the Chickamauga formation was laid down. It is probable that the pressure producing the upheaval of the land caused some folding, so that the Valley was divided into separate basins by narrow land ridges. In the southeastern basin or bay the Chickamauga limestone was deposited, then after a brief upheaval which caused an erosion uncomformity, the land sank and the Rockmart slate was laid down in shallow water close to the shore line. Periods of uplift occurred in Silurian and Devonian times, with comparatively brief int'ervals of submergence during twhich the Rock- 54 Gl[rOLOGIC.AL SVEVEY OF GEOEGI.A wood formation and the thin Devonian formations were deposited. In late Devonian a period of transgression by the sea started, and persisted during: the Mississippian, followed by an uplift. Shallow waters covered the western .part of the Appalachia,n Valley during the Pennsylvanian, when sandstones, shales, and coal beds were deposited . ..At or near the close of the Carboniferous period uplift and compression were renewed, the deformation resulting in the final withdrawal of the sea from the entire Appalachian province and the up-heaval of a great mountain system. The folded and faulted structure . of the V:alley formations is due principally to this period of deforma- +u'iOn. . The great Cartersville fault was evidently formed by the postCarboniferous deformation, and movement alon~ this plane probably continued for a long period. The fault was a controlling .factor in the formation of the deposits of commercial slate, a:p,d those in all three of the slate-bearing formations are found within a few miles west of the fault plane. Farther west the shale formations were not metamorphosed enough to produce strong slates with good cleavage, while east of the fault the metamorphism was too intense, prodncing mica schists or slates with distorted and ''false'' cleavage. THE ROCKMART DISTRICT GEOLOGY OF THE ROCKMART SLATE The Rockmart slate member of the Chickamauga formation was named by Hayes1 from its typical development in the vicinity of Rockma.rt, Polk County. Areal distribution.-The Rockmart shales and slates occupy two areas in Georgia, which may be described as the Rockmart and Cedar-town areas. (See Map II.) The Rockmart area starts with a very narrorw belt at a point 7 miles southwest of Cartersville and 12 miles northeast of Rockmart. 1 U. S. Geol. Survey Geologic Atlas: Rome Folio, No. 78, 1902. SLATE DEPOSITS OF GEORGIA 55 From this point the belt extends west to Posco and Portland (Davitte), widening gradually until it covers an area 3 miles in width southwest of those places. Then the direction of strike swings to the south and the belt splits into two divisions, one of which terminates in the prominent hill about a mile southwest of Red Ore. The other or main belt continues south through the town of Rockmart, then swings to southwest and extends a total distance of 9 miles southwest of Rockmart. At Rockmart the width of the belt is 2 miles, but it narrows to less than half a mile 8 miles farther southwest. At the extremity the belt doubles back and an area a mile wide and 5 miles long extends northeast almost to Fish. The Cedartown area is irregular in shape, and evidently represents an eroded syncline. It extends from the southern part of the city of Cedartown southwest to the Alabama line near Esom Hill, a distance of 9 miles. The maximum width from northwest to southeast is about 4 miles, but where it crosses the Alabama line it is only a few hundred yards in width. Stratigraphic relations.-The Rockmart slate is of Ordovician age, and probably represents the middle and upper parts of that system. Its stratigraphic position is immediately above the Chickamauga limestone which in the Rockmart district is only about 200 feet thick. The relations between the slate and limestone are unconformable in at least a part of the area. The observed contacts near Rockmart show that the bedding of the slate does not always dip at the same angle as that of the limestone, that in places a band of red clay separates the two formations, and that the upper surface of the limestone is more or less irregular. Conglomerates with fragments of limestone occurring in the slate show that at least a part of the Chickamauga limestone was subjected to erosion while the slates were being deposited. In the Cedartown area no evidence of an unconformity between the limestone and slate has been found. In and north of Rockmart and in the vicinity of Fish and Cedar' town the Chickamauga limestone is exposed immediately below the Rockmart slate, but south of Rockmart, Fish and Cedartown, the slate 56 GEOLOGICAL SURVEY OF GEO:RGIA lies upon the K.nox dolomite. The thin Chickamauga limestone m these area$ may. have been entirely eroded awa;y, or may never have been deposited; or the, slate may have been thrust into contact with the dolomite along :raults. ireas underlain by Knox dolomite are easily distinguishable from those underlain by Chickamauga limestone, even rwhere there are no outcrops, because of the abundance of chert in the soil derived from the Knox. The Chickamauga formation in the western Appalachian Valley is overlain by the Rockwood formation of Silurian age. That formation, h6wever, is absent i:n the Rockmart a:rea. Some of the hills within the slate area south of Cedartown are capped by chert with fossils showing that it belongs to the Fort Payne chert of Devonian age/ but the southern bnl1rl,dary of both slate a~efls is formed by the Carters- vi11~ falilt, and any yoti.llger fo~matio~s wh1ch ma;Y- have existed over the greater p~t of the slate .area have been eroded away. .Along the fault .line the Rockmart Slate com'es in contact with mica schists and phyllites of the highly: metamorphosed early Cam:brian.fo:rmations. ,.. ,.JJ"jtfiplqgib phar>ct~~;s.:-;:;::-,W}J:e Jo;w;e:~?.115Q~~Lfe,e,t, {>f .t:b!e,r;J;i()q)x:rrva;;rt. slate f'' ''~~.t:-, ';_;. ,'(:.-.~:,:. :..:.Ji '>'.:;y:..'~,, < -.;; .:l''\ .~.:;_. ,, ~ :~-~--. ,". ,,.,__:::_ --:;1 :;.) . &_:';-'';C.~ ,cr. ,, ;."' dl-''-.' -l,. ":.--: - -~~,., _. ,.. .''' ,,_~~~~ ~ <~ .._ <.c <. \_,," , --~ -.o~ ' <,-''-"'><'l-" .<. ' ~ I v cqqsists of fine-grained _CI._?-!J.r. ~olq!'~~sl~te, a11d sha~: remar.J~_~l:>ly uni- :fg~jJ:!. ,lithologic Gh~1'ac:t.~:t;" ,a:g;,d :chemieaL..eo~Ro~1i~o;p,.- ~bo:ve the unifor.J;ll slate in the area near Rockmart occurs a bed -of lin;testone' Col:\:glomerate, gen~rally 15 feet or more in tP,ickness. 'The Mnglom- erate coiLSists o-f fragments derived from the underlying Chickamauga limestone, imbedded in a siliceous matrix. The conglomerate is over- lain by a bed of brown sandstone about 4 feet thick. About 3000 feet east of' the lower limestone conglo:p:te:rate is found a bed of simi- lar conglomerate with sandstone below. It seems probable that the two conglomerate and sandstone exposures belong to the same beds, re- pe/lted in revers:ed .sequence by an o;verturned fold. Proceeding eastward and stratigraphically upward across the Rockmart slate formation the sediments b'ecome less uniform i:n com- position, with thin layers of conglomera~e and siliceous or calcareous beds. This upper part of the formation was deposited in very shallow 1 Spencer, :r. W.: The Paleozoic group, Geol. Survey of Ga., 1893. SLA1'E DEPOSI1'S OF GEOEGiil 57 water under rapidly changing conditions. The rocks for a distance of half a mile from the Cartersville fault plane have also been more intensely and irregularly metamorphosed than those farther west, developing crumpled cleavage or schistosity. For several hundred feet from the fault the Rockmart slate has been. metamorphosed into a true schist, which is hardly distinguishable from the older crystalline rocks on the.,east side of the fault, so the exact location of the fault plane is not easily determined. On account of the varia.bility of the upper beds of the formation and the effects of proximity to the fault, the slates of probable commercial value in the Rockmart area are confined to a belt about half a mile wide in the lower or northwestern part of the main area of outcrop, and to a belt near the base of the formation at Portland (Davitte), where the formation is repeated and the outcrop widened by folding. Westward from Rockmart, in the Fish and ,Cedartown areas, deposition evidently took place in slightly deeper water. The slate in these areas is interbedded with impure limestone, and is much softer and more calcareous than that near Rockmart. While some of the slates of the Cedartown area are of good appearance and have excel- lent cleavage it is unlikely that they have the strength ~nd resistance to weathering necessary for roofing slate. Structure and thickness.-The structure of the Rockmart slate is known in a general way, but the details are difficult to determine. The occurrence of the slate just northwest of the Cartersville fault has subjected it to peculiar dynamic and metamorphic conditions. The clays after original deposition in a long narrow basin were consolidated into shales, and after being lifted above sea level were subjected to the great lateral pressure which accompanied the faulting. .As a result of this metamorphism the shales were transformed into slates and the original bedding planes were obliterated to a large extent. The present apparent strike and dip of the rocks represent cleavage rather than bedding. At those places where the bedding is still determinable and not greatly contorted its dip is to the southeast at , -'.~ ,~ , -- ' ... - ... I I ' ' MAP II. Rockmart slate MAP OF THE ROCKMART SLATE DISTRICT SHOWING THE DISTRIBUTION OF THE FORMATION AND LOCATIONS OF QUARRIES fROM THE ROME. TALLAPOOSA, CARTERSVILLE AND MARIETTA TOFOGRAPHIC MAPS OF THE U . S. GEOLOGICAL SURVEY SCALE 1 : 125.000 CONTOUR INTERVAL 100 FEET 58 GEOLOGICAL SURVEY OF GEORGIA a smaller angle than .the dip of the cleavage. The original bedding is best represented by quartzitic laminae and conglomerate beds, ..... which rep'resent differences in the character of sedimentation. The strike of the cleavage in all of the slate areas is approximately parallel to the long dimension of the belt of outcrop. South of Rockmart the strike is northeast, but east of the town it changes to almost north. The strike of the bedding is parallel to the strike -of the cleavage, except for local variations. The dip of the cleavage is always southeast or east, at an average angle of about 45 degrees, and dips of less than 40 degrees are of rare occurrence. The angle of dip of the bedding is generally from 5 to 30 degrees less than that of the cleav;:tge, as may be s:een by reference. to t~e descriptions: of individual proper.ties. The repetition of apparently similar conglomerates and the great width of the belt of outcrop, especially north of Rockmart and south of Cedartown, indicate a thickening of the formation by folding and faul'tmgv'but .on .account. o the difficu1ty: irr..determmirrg:,the bedding the e;x:actlocation of folds and faults is not dete:mnin:able., The width .@f~thie~rbe-~t-o o1il:1mrop, which at!somepla:ees;~J:s,a;Sgmeaitras;;3, or 4 miles, indicates. a thick formation. The most" reliable~estimates, of the total thiek:rl:ess a:re ..from 2500 to 3000 feet) but iti may be even thicker. Physiographic expression.-The Rockmart slate is an important " factor in the general physiographic expression of the area in which it outcrops. In its resistance to weathering the slate is intermediate between the soluble Chickamauga limestone and Knox dolomite which lie to t:he northwest and the hard crystalline schists southeast of the Carter-sville fault. Therefore, it forms a b_elt of foothills to the low mountains of the metamorphic area. In the Rockmart area t:he main belt of slate forms a high ridge dissected into a number of separate hills by streams !Which have cut through it. In Signal Mountain, where the formation contains a number of siliceous beds, the ridge reaches a height of 1,3r6 feet, which is higher than any of the Piedmont hills of the vicinity. Northwest of the ridge, Euharlee Creek has cut its valley down into the I SLATE DEPOSITS OF GEOBGI.A 59 limestone and dolomite to an elevation of less than 800 feet above sea level. Many hills in the eastern portion of the valley are capped by the slate. Northeast of Rockmart the slate comes into contact with the ''mountain rock'' without any decided break in topography, but southeast of Rockmart a number of short streams have cut valleys along the contact, so that the fault line passes through valleys and across low divides, with the prominent slate ridge to the north and the escarpment of Dugdown Mountain to the south. In the Cedartown area the valleys of Lime Branch and Cedar Creek are cut down in an area of Chickamauga limestone, while the slate underlies a large hilly area south of the city, with summits reaching an elevation of over 1200 feet. In this area also there are small valleys in the southern part of the slate belt, and the Cartersville fault passes near the foot of the slope of Dugdown Mountain. Paleontology.-The rocks of the Chickamauga formation m the western part of the Appalachian Valley contain an abundant fauna. In the Rockmart slate no fossils are known to have been found, although no careful search has ever been made. The character of the sediments is such that not many fossils could be expected, and any which were .present have probably been destroyed by metamorphism. The Chickamauga limestone near Rockmart and Cedartown is also practically barren of fossils. Correlation with the western areas is on the basis of stratigraphic position. TYPICAL SECTIONS Sections across the entire outcrop of the Rockmart formation are exposed along the Southern Railway and the Seaboard Air Line Railway, running east and southeast from Rockmart. Seaboard Air Line section.-The Rockmart slate is exposed along the Rockmart and Atlanta branch of the Seaboard Air Line Railway from a point near Rockmart station, about 6163,4 miles by the mileposts, southeastward to 613% miles. 60 GEOLOGICAL SURVEY OF GEORGIA The Cartersville fault, the contact of the Rockmart slate and the Cambrian rocks, crosses the railroad in the valley a quarter of a mile east of the 614 milepost. A small cut at the 614 milepost shows practically the stratigraphic top of the Rockmart formation. This cut is mostly in weathered material, apparently derived from calcareous shale. A hundred and fifty yards east of the milepost is a 10-foot bed of slaty limestone conglomerate, striking N. 50E., and di!f.Ping 35SE. The limestone pebbles are flattened and elongated. The conglomerate is fresh, but is associated with weathered soft sandst.one and arkosic shale. The poorly developed cleavage in the conglomerate is parallel to the dip, but in the softer material the cleavage dips a little steeper than the bedding. About 400 yards west of the 614 milepost is another bed of limestone conglomerate; strike N. 30E., dip 90; with cleavage striking N. 50E., dipping 45SE. Like the other conglomerate bed this rock is fresh, while the surrounding sandstone and shale are weathered. I:ti this ease the pebblesare not so much elongated, asthe pressure was notnormal to the bedding. F~.Om thispoint,nor.tliwest to the crossitig.of the Rockmart-Yorkville public road, a distance of almost half a mile, the exposures are of mixed~ sandstone ami!:, shale, en.tire1ywea:the'red\ to a red or yellow clay. Both bedding and cle:avage are' much distorted, and the residual material is cut by occasional quartz veins up to 6 inches thick. The fresh material is not vi~Sible, but there was no hard slate in this part of the formation, because the good slate does not weather so deeply and so completely. Northwest of the road the railroad passes through a cut over 3000 feet long. The 615 milepost is at the middle of the cut, at the top of unit 14 in the following section. The measurements given are horizontal distances, and the direction of traverse is stated for each group of units, the direction being, on the average, nearly at right angles to the strike of the beds. SLATE DEPOSITS OF GEOEGIA. 61 Section inS. A. L. Rat7way cut at 615 maepost, 2 miles southeast of Rockmart.1 Unit No. DESCRIPTION Feet -------------------------------------------------- Concealed interval 50 21 Shale with sandstone layers. . . . . . . . . . . . . . . . . . . . . . . . . . 200 20 Slate, dark blue, weathering yellowish and :fissile. Com- position is uniform except near the top, where lime- stone layers occur. Weathered to a depth of 30 feet. Cleavage strikes N. 58E., dips 55SE. Prominent joints N. 10W., 63SW. Beds dip east at lower angle than cleavage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 19 Arenaceous shale with quartz veins. . . .. . . . . . . . . . . . . . . . 150 18 Concealed interval, in small valley .................... ~ 100 17 Slate, dark-blue, weathering yellowish and fissile, decomposed to a depth of 25 feet. Near the base -this unit shows well folds in the bedding, with cleavage and joints cutting straight across. Cleavage N. 55E., 60SE., joints N. 70 to 90E......................... 157 16 Slate, dark blue, in part highly calcareous. The upper part is more calcareous than the lower, with irregular calcite veins. Weathered to a depth of 25 feet, wea th-' ering hackly. Cleavage wavy; bedding not always distinguishable, but- is in part intensely crumpled; prominent joints N. 30W.,52SW......................... 278 15 Shaly slate, weathering yellow and :fissile, badly jointed, with numerous quartz veins up to 1 foot thick. Weathered to the bottom of the cut, which is 20 feet deep. 228 14 (615 milepost) Slate, dark blue when fresh, weathering olive green. Much jointed and weathered to a depth of 15 feet. Cleavage N. 5E., 40SE........ . . . . . . . . . . . . . 172 13 Concealed interval .................. _. . . . . . . . . . . . . . . 150 12 Same as unit 11. Much weathered. Small fold in upper part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 1(Measured by 0. B. Hopkins, description revised by R. K. Shearer). GEOiiJGIOAL SURVEY OF GEORGIA Section in S. A. L. Railtway cut at 615 milepost, 2 miles southeaSt of Rockmart-.1-.( 0 ontinued.) "1-1 0 ~ a) ::P ~ <:>CD .!<::DI~> A..., . '' Unit i N o. DESCRIPTION Feet. ---------------------------------------------------- 11.- . .Slate, weathering oliv:e green and :fissile. Weathered to a .... .depth .of. 30. f.eet ..................................... . 60 10 Slate 'with poorly dElveloped cleavage. Limestone con- glomerate at top and bottom, .thin beds of limestone and sandstone scattered through the unit. Weathered entire , :depth :of the cut, 30 feet. : B:edding' N. 45E., 34SE., cleavage a little steeper . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 . 9 ... Slate, :weathering .fissile... Small fault at top of unit ... . 78 . g ... Limestone .conglomerate, with pebbles~elongated parallel - ..... to. the-bedding. Beading N. 48E., 36SE.............- 5 7 Shaiy slmte interbedded with sandsto:ne and limestone .. 40 6 Slate, dark blue, weathering :fissile. Bedding N. 70E., 36S:EJ............................................. . 110 5 ; Oo:rueeale.d interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 .i. S.late :w,:i:t4 J~Eld,S. pf ~andstone and limestone conglomerate, weathered yeHo:w . . . . . . . . . . . . . , . . . . . . . . ~............. 175 3 Slate, weathering greenish yellow and :fissile. Contains some thin sandstone beds. Two faults shown in the unit 125 Slate, fresher and more massive than that below, calcar- 2 eous, contains numerous veinlets of calcite l:tnd quartz, some san_dstone and limestone beds. Bedding N. 68-80 E., 51-54 SE. Beds show some folding ..... ; . . . . . . . . 175 1 Shaly slate with thin sandstone beds, much weathered.. 150 --~----------------~--------------------------- Total .. - .............. . 3195 In this .entire .section. there is no commercial slate. The cleavage is poor,: the rm~k variable- in composition, jointing prominent, and quartz and calcite veins abundant; There is, 1?-owever, more sandstone and conglomerate above this section than in or below it. . . ' . '. l(Measured by 0. B. Hopkins, description revised by H. K. Shearer.) SLATE DEPOSITS OF GEOEGIA 63 Northwest from the measured section to Van Wert, the suburb southeast of Rockmart, a distance of a little more than a mile, the railroad crosses a valley, where there are no rock exposures. A good section is again exposed along the Seaboard Air Line where it follows the east fork of Euharlee Creek in the trench cut through the slate ridge, just southeast of Rockmart station. The first cut southeast of the station is about 600 feet long, showing bluish-black slate, weathering yellowish. The cut is not deep enough to show perfectly fresh slate, but the prospects for commercial slate :ln the hill to the northeast are good. From the southeast end of this cut the Old Dever quarry, Tunnel quarry, and the small quarry in the center of lot 926, all on the property of the Cherokee Slate Company (see locality descriptions), show the section across the belt, about 1000 feet wide, which carries the best slate. Southern Railway section.-The Cartersville fault crosses the Southern Railway about half a mile east of. the northeast corner 0f the Tallapoosa quadrangle; that is, 3.2 miles due east of the Rockmart station. The upper part of the Rockmart formation, for a diRtance of a mile west of the fault, consists of shaly slate with interbedded sandstone and conglomerate, without any prospect of commercial slate. Just west of the second railroad crossing on the road leading east from Rockmart, 2.3 miles from the station, is an exposure of limestone conglomerate. The bed dips to the east, and measures 130 feet across the strike. To the west, that is, underlying the conglomerate, is a heavy-bedded brown sandstone. For 0.8 mile west of this road crossing the railroad runs along the base of Signal Mountain (Carnes Mountain), and the slate beds worked in the Sibley quarries are cut. This part of the section contains a considerable amount of sandstone and hard, rough slate. Just east of the overhead bridge, the first railroad crossing of the road leading east from Rockmart, 1.5 miles from the station, is a section showing a bed of limestone conglomerate. 64 GEOLOGICAL SU.RVEY OF GEORGIA Section in Southern .Rali~waty cut east of bridge over public road, 1.5 mile east of Rockma1t station. (Measured by 0. B. Hopkins.) Thickness in feet. 14. Slate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Fault. 13. Sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 12. Slate with sandstone layers. . . . . . . . . . . . . . . . . . . . . . 10 il. Sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. 5 10. Slate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 9. Sandstone ....... ~. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0. 7 8. Slate . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 3 .7. Sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6. Slate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Fault. 5. Slate with sandstone layers. . . . . . . . . . . . . . . . . . . . . . . 30 Fault. 4. Sandstone ....................... . . . . . . . . . . . . . . . 2 3. Slate, dark blue, weathering yellow, with sandstone layers neat the top ........... , . . . . . . . . . . . . . . . . 35 / 2. Sandstone and fine conglome:mte.................. 8 1: Limestone conglomerate; containing pebbles of Cliick:amauga'1im.es:tiotrre3is\ large as4 inches' in diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158. 7 The heavy conglomerate bed dips 32E. Sandstone l:)eds higher in the section strike N. 17E. and dip 15SE., while the cleavage in the slaty layers dips 28; that is, the cleavage abuts against the sandstone beds at an angle o.f 13. The conglomerate and sandstone in this section are similar to those exposed at the other road crossing, 0.8 mile farther east, except that their relative positions are reversed. This may indicate a repetition of the beds by an overturned fold. A. cut west of the overhead crossing shows a thickness of 15 feet of shale and slate: Most of the exposure has very poor cleavage, but about 5 feet stratigraphically has exceptionally good cleavage. There are fragments accidentally broken off as large as a foot square and only an eighth of an inch thick. The best cleavage strikes N., dips 22E. SLATE DEPOSITS OF GEORGIA 65 The Rockmart slate area extends about 0.8 mile west of this bridge, or within 0.7 mile of Rockmart station. The contact with the Chickamauga limestone here crosses a valley, and exposures of the lower beds of the slate are not good, but there is a possibility that commercial slate will be found. DESCRIPTIONS OF INDIVIDUAL DEPOSITS POLK COUNTY THE ROCKMART SHALE BRICK & SLATE COMPANY PROPERTY (Map locality 1) The Rockmart Shale Brick & Slate Company owns lot 865, 18th. district, 3d. section, Polk County, consisting of about 40 acres, situated just southeast of the business section of Rockmart. On this lot are three abandoned slate quarries, besides the quarries from which the weathered slate or '' caenstone'' us.ed in the manufacture of vitrified brick is obtained. The quarry locations in the immediate vicinity of Rockmart are shown and lettered on the map of Rockmart (:fig. 4), others are numbered on the general map of the Rockmart area (Map II.) The slate quarries were worked by Robert H. Brown, from rwhom the lot was purchased by the brick company. Brown is said to have lost much money in the work, but the loss was due largely to inefficient working methods. The quarries were worked in such a manner that the slate was badly shattered by blasting, thus causing an unreasonable amount of waste. The sawing and splitting shed was at the top of the ridge south of the brick plant, so all of the slate had to be raised over 100 feet, although a good location for the shed could have been selected down the valley south of the quarries. Lot 865 is crossed by a prominent east-west ridge rising about 120 feet above the level of the brick plant. It lies entirely within the area of outcrop of the Rockmart slate, but the material shows considerable 849 850 Cl'l Cl'l 79~4 854 92.3 N I o 300 bOO qoo 1 SCALE IN FEET' 927 Lime~tone ~ Q.u.a.ny E ~ a t; a ~ ~ l:"L.l QSawi11g Shed b ~ E oO 1-<:j c('> ~ 865 8.66 ~ a ~ ~ 936 935 Fig. 4. Map of Rockmart and vicinity, showing land lots and locations of the principal slate quarries. SLATE DEPOSITS OF GEOEGIA 67 variations in perfection of cleavage and depth of weathering. Of course, all of the slate exposed at the time of examination had been repeatedly frozen and thawed, so the cleavage in none was as good as in the fresh slate. The openings are described in detail below. Brick plant quarries (A) .-The Rockmart Shale Brick & Slate Company was started with the intention of quarrying slate and utiliz- ing the overburden and waste in the production of brick. No slate, however, has been produced, and the only product of the plant is vitri- fied paving brick. The brick are made from the much weathered slate near the base of the Rockmart. formation, . and. . it has been found that brick made from the fresh or slightly weathered slate such as slate quarry waste and topping rwould provide are not hard and tough enough to stand the required rattler test for abrasion of paving blocks. For this reason the fresher slate is avoided. The brick plant quarries are near the base of the ridge on the north slope. The old quarries have been worked to a distance of 200 feet south and 300 feet east of the plant, and in October, 1916, the face being worked was just west of the plant. The latter opening had a face 200 feet long with a maximum height of 30 feet. .All of the material is weathered to a yellow, red or greenish color except a small mass of gray but soft slate beneath the highest part of the face. In the south end of the large quarry south of the brick plant com- paratively fresh slate is exposed, with cleavage, bedding and joints at unusual angles, as follows: Cleavage: Strike N. 70E., dip l5SE. Bedding: Strike N. 40W., dip l0SW. (Marked by conspicuous groups of ribbons.) Joints: Horizontal. (Most prominent series, at 2 to 3 foot intervals.) At other points in the quarry the cleavage and bedding are more nearly normal, as shown by the following measurements: Cleavage: Strike N. l5E., dip 68SE. Bedding: Strike N. 82E., dip l7SE. Strike N. 49E., dip l2SE. Strike N. 55E., dip 25SE. 68 GEOLOGICAL SURVEY OF GEORGIA The material used in brick-making grades from gray slate through soft, partly weathered slate, usually of red or yellow color and locally knorwn as'' caenstone, '' in.to yellow or red ocherous clay. The average composition of the caenstone is shown by the following analyses, one of. a sample taken by T. Poole Maynard while studying the cement materials Qf north Georgia; and S-267, an average S!lmple of the working face in October, 1916. Analyses of weathered slates used for nt(JJJ1,~~tacture of vitrified brick. M-31 1 'Silica (Si0 ) ........................... 66.32 2 Alumina (..8..1 0 ) .. .. .. .. .. .. 19.79 2 3 Ferric oxide (Fe 0 ) .................. 3.91 23 Ferrous oxide (F'eO) ................. . Magnesia (MgO) ...................... . .40 Lime (OaO) ........................... . .10 Soda (Na~p) ,, ......................... . 1.23 Pot~~h. (K2 0) ..................... - .. ,. 1.94 Ign1t1on .............................. . 5.20 Moisture ............................. . .30 Carbon dio:x;id:e ('00 ) 2 1 . .00 :'JP:'ithabnspioh~,;rm;;<_;,dipoeJn!itido;xeid~(,"'.'J:(~i:0 2p.),0 ) .. , . . ....... . .82 . . . . 25 Siilphlif trioxide (S0 ) 3 Sulphur (S) ....... :. ::................... Manganous oxide (MnO) ............... . .06 Barium oxide (BaO) ................... . Sc267 58.4:7 19 .. 68 6.84 2.01 2.05 .00 .82 4.20 4.76 .59 .00 .!)6; .00 .00 .11 .00 .00 100.07 100.4:9 Old q~~arry on the slope above the brick plant (B) .-This quarry is an opening about 50 feet square in the hillside south of the brick plant. The maximum height of the opening is 40 feet, but the sides slope toward the center, so that the v'ertical height does not exceed 25. feet and the quantity of splitting slate available is small.. The topping amounts to 10 to 15 feet of weathered slate, and 10 or 12 feet (stratigraphically) of fresh slate is exposed i:ri the bottom of the pit. The sJ.ate is very much ribboned, and the cleavage not particularly good. It is said that only thick, hard slates were made here. Measurements of strike and clip are as follows : 1 Geol. Sl!rvey of Ga., Bull. 27, p. 133, 1912. SLA1'E DEPOSITS OF GEOBGI.A 69 Cleavage: Strike N. 16E., dip 29SE. Strike N. 18E., dip 32SE. Strike N. 22E., dip 33SE. Strike N. 33E., dip 32SE. Bedding: Strike N. 52E., dip 21 SE. Strike N. 54E., dip 28SE. Strike N. 57E., dip 21 SE. Strike N. 47E., dip 25SE. Strike N. 46E., dip 23SE. Joints: (1) Strike E.-W., dip 78N. (2) Strike N. 26:lh 0 E., dip 81 SE. (3) Strike N. 88E., dip l3SE. (4) Strike N. 51E., dip 481h 0 SE. Joints of series (1) are most prominent. Those of series (3) and (4) give rise to wedge shaped blocks. .A.s the cleavage of the slate dips into the hill, the quarry is situated on the wrong side of the hill for convenient working. Brown's So~rth q~wr-ry (C) .-The opening is in the south slope of the ridge, 150 yards southwest of the splitting shed. It is irregular in shape, measuring 180 feet from east to west, and 130 feet from north to south. The deeper parts of the pit, in the southeast and southwest corners, were filled vvith water when examined. The maximum height of the north face above water level was 60 feet, but the highest vertical face was 35 feet, in the east end of the pit, and the water was al;>parently 10 feet or more in depth. In the upper part of the pit the face is not vertical, hut follows the slope of the hill. The topping of slate too much rweathered for use varies from 15 to 25 feet, so the amount of splitting slate exposed is only about 10 feet stratigraphically. The strike and dip of cleavage and bedding vary considerably in different parts of the quarry, and the slate is cut by a number of systems of joints, which evidently caused a great amount of waste in working. Ribbons are conspicuous at some places, but at others are absent for 4 to 6 feet across the bedding. The ribbons consist of groups of thin layers of material varying in composition from the 70 GEOLOG;ICA.L .SURVEY OF GEORGIA rest of the slate. A specimen taken from the splitting. shed measures 12 by 12 by 13/z inches and contains four groups of ribbons, which make an angle of 35 to 40 with the cleavag~. The groups of ribbons average half an inch in thickness, spreading out to an inch or more on the cleavage surface, and the cleavage is deflected 13 from its normal direction where it crosses the bands. (See fig. 2, p. 11). Brown's North quarry (D) .-This quarr:y is another large opening about 200 feet northwest of the South quarry. The pit is about 100 feet in diameter and the height from the level of the water which filled the bottom of the pit, when examined, to the top of the north face was 85 feet. All sides of the pit except at the entrance are vertical for 40 or 50 feet above water level, so most of the slate was inaccessible for measurement or sampling. Near the entrance the cleavage strikes N. 50E. and dips 38SE. The slate is of about the same quality as that in the Sou~h quarry, and in. the highest part of the face the upper 40 feet appears -to be too much weathered for splitting slate. The slate from the -Brown quarries is of a dark bluish gray color, with a roughish, lusterless cleavage surface. It is sonorous and effervesces with acid. An average sample (S-265) from the South quarry was taken for analysis, and slides were cut from a typical ribbonded specimen obtained from the splitting shed (S-2SI). ' Ana~ysis of slate from Brown's South quarry. S-265 " Silica ( SiO ) ................ , 56. 54 2 Alumina (A1 0 ).................................. 17.75 23 Ferric oxide (Fe 0 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 2 3 . Ferrous oxide (F"eO) .. .. .. . .. .. . .. . .. . . .. . . .. .. .. . 4. 90 Magnesia (MgO) .................... : . . . . . . . . . . . . . 3 . 26 Lime (CaO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.28 Soda (Na 0)...................................... 2 Potash (K 0) .......................... . . . . . . . . . . . 2 Ignition (less CO ) 2 Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.91 3. 20 4. 28 .16 Carbon dioxide (C0 ).............................. 2 Titanium dioxide (Ti0 ) :................... 2 2.10 .96 SL.A1'E DEPOSITS OF GEORGIA 71 Phosphorus pentoxide (P 0 ) .. .00 25 Sulphur trioxide (S0 ) . .34 3 Sulphur (S) ...................................... . .47 ldanganous oxide (ldnO) .......................... . .00 Barium oxide (BaO) .............................. . .00 99.71 Sections perpendicular and parallel to the clea.vage were cut from one of the ribboned bands of specimen S-25I. The ribboning is conspicuous in both sections. In the section perpendicular to the cleavage the ribbons are fine and make an angle of 30 with the cleavage, while in the other section the light and dark bands are broader, owing to the smaller angle of intersection. The structure is rather coarsely lenticular, consisting of an aggregate of fine-grained mica and chlorite stained by carbonaceous matter, surrounding colorless lens-shaped areaJs. This lenticular structure produces the roughness of cleavage surfaces, as other finer grained slates from the same district have much smoother cleavage. The lenses consist of quartz, sometimes granulated, with some feldspar, and finely crystalline, irregularly oriented sericite scales, evidently due to alteration of feldspar. The quartz occurs as rounded or angular grains, usually arranged rwith. their longest dimensions parallel to the cleavage. .A few grains have maximum dimensions as great as 0.1 mm. The aggregate or ground mass surrounding the lenticular areas shows aggregate polarization, which is somewhat obscured by the carbonaceous matter present, but is made easily visible by the use of a mica or gypsum tint plate. The aggregate consists of finely crystalline mica with a subordinate amount of interleaved greenish ~scales of chlorite, much fine carbon, and abundant spherules and isometric crystals of opaque pyrite. The opaque grains range up to 0.015 mm. in diameter, but are mostly much smaller. Extremely fine rutile needles up to 0.01 mm. in length are very abundant. The dark ribbons contain more of the finely divided graphitic carbon than the light ones, but otherwise the composition apparently does not differ greatly. 72 GEOLOGICAL SURVEY OF GEORGIA Carbonate grains and rhombs, with maximum dimensions of 0.09 mm. are abundant and about equally distributed through both light and dark ribbons. The constituents, in descending order of abundance, appear to be mica, quartz, chlorite, car:bonate, feldspar (largely detrital plagioclase), carbon, pyrite, magnetite, and rutile. I THE SOUTHERN STATES PORTLAND CEMENT COMPANY PROPERTY, LOT 925 Lot 925, 21st district, 3d. section, belonging to the Southern States .Portland Cement Company, lies west of lot 865 and south of the business section of Rockmart. This lot formerly belonged to Colonel Seaborn Jones, one of the originators of the Rock:fuart slate industry. From Jones the property was purchased by the Georgia Slate Company, which was the parent of the Southern States Portland Cement Company. The latter company was organized for the purpose of using the oveTburden and refuse from the slate quarries in the manufacture of cement, but in the development of the property north of Rockmart, where the limestone quarries were located, an ample supply of partly weathered slate or shale was :Eound, more sati~factory for cement manufacture than fresher waJSte slate from the quarries. Therefore this company has confined its operations to the manufacture of cement, and, like the Rockmart Shale Brick & Slate Company, has never started the production o.f -slate on a commercial scale. The oldest slate quarry in the district is on lot 925, beside-s a small opening made by Pritchard and Davis in 1912. The lot also includes a portion of the old Dever quarry, -which is mostly on the property of the Cherokee Slate Company. These openings are described in detail below, the numbered locations being shnwn on the map o.f Rock~ mart (fig. 4). Pritchard & Davis opening (E) .-This opening, made in 19J 2, represents the most recent attempt to work the Rockmart slate on a commercial scale. The quarry is near the center of lot 925, and about SLATE DEPOSITS OF GEORGIA 71 Phosphorus pentoxide (P 0 ) ....... 2 5 .00 Sulphur trioxide (S0 ) . .34 3 Sulphur (S) ...................................... . .47 Manganous oxide (MnO) .......................... . .00 Barium oxide (BaO) .............................. . .00 99.71 Sections perpendicular and parallel to the cleavage were cut from one of the ribboned bands of specimen S-25I. The ribboning is conspicuous in both sections. In the section perpendicular to the cleavage the ribbons are fine and make an angle of 30 with the cleavage, while in the other section the light and dark bands are broader, owing to the smaller angle of internection. The structure is rather coarsely lenticular, consisting of an aggregate of fine-grained mica and chlorite stained by carbonaceous matter, surrounding colorless lens-shaped areaJs. This lenticular structure produces the roughness of cleava.ge surfaces, as other finer grained slates from the ~same district have much smoother cleavage. The lenses consist of quartz, sometimes granulated, with some feldspar, and finely crystalline, irregularly oriented sericite scales, evidently due to alteration of feldspar. The quartz occurs as rounded or angular grains, usually arranged rwith. their longest dimensions parallel to the cleavage. A few grains have maximum dimensions as great as 0.1 mm. The aggregate or ground mass surrounding the lenticular areas shows aggregate polarization, which is somewhat obscured by the carbonaceous matter present, but is made easily visible by the use of a mica or gypsum tint plate. The aggregate consists of finely crystalline mica with a subordinate amount of interleaved .greenish 'scales of chlorite, much fine carbon, and abundant spherules and isometric crystals of opaque pyrite. The opaque grains range up to 0.015 mm. in diameter, but are mostly much smaller. Extremely fine ruti}e needles up to 0.01 mm. in length are very abundant. The dark ribbons contain more of the finely divided graphitic carbon than the light ones, but otherwise the composition apparently does not differ greatly. 74 GEOLOGICAL SURVEY OF GEORGIA "The'slate 'is of very dark bluish-gray color and of slightly roughisli, lusterless surface. It is sono:rous and ~ffer:vesces: with aCid test. The--sawn face shows minute magnetite; the powder shows. very little magne~ite 'buij?irithch~ carbon ana' effervesces very freely' with jacidtest: ''Under the r~.icr.:oscope aggregate polarization is somewhat ob- s.cu:tediby carbonacBous irratter.' The general te:xtu~e is-'ili'eritieUlar and Some~hat coarse, the quartz grains measuring. up- t? 0~047 mm; Small bed~ :(L'();wu to o:i2': rom. thick, Wit!{ quartz gt:aifig:'>t~r 0:09 mm: and . " much ca;.rbo:ri.ate, intersect the cleavage at 14 degrees. The matrix contailis~-ln.uch :fine carbon, much carbonate, chlorite scales inter- leae.d with muscovite,. abundant spherules and grains of pyrite, and- rutiie need1~s. The section para1ler;to ~leav~ge is ~rowdea 'With car- bonate; . - ,_ ..- , 1n .~ .:.~. .-~ .!;;;. '''The c6nst1tuents, .na~ed ; '-' descending o-rder of abundance, ap- pear to be mt~;E;co~tej_ quartz ((letri~al}, ca~:t>utJ;~te;: carbon, chlorite, kaolin, pyrite, magnetite, rutile, and plagioclase (detrital). ''This is a mica slate of the fading series, although some obtained from a tunnel at .one of ~he quarrje-sjs :ueported to have kept its color 0-r ,rriairi;yJ~ai-8. 1:ts,-fiss11:t:t'is''1ia1~!'1' ,'_ , - - -'" :;-.' , CJt'itest q~r,arry (F) .-The 6ia~' st quarry 1n tli~tRiYckina~t d ' i s t ric t is > situa;t..~~ near the center of lot 925, just over the crest of t];le ridge froili ~Rbckma.rt, and 150 feet northeast of the Pritchard a'nd Davis op'i:nri:ilg., ~he. pit is almost circular and about 100 feet in diameter. rrl.ie ! most extensive work was done in the northeast corner of the pit, where there is~- vertical' fa~e of 3o 'feet above the water which :fills the bot- tGJtt: ,: A't this poirit the topping is lightest, from 10 to 12feet. {)'n the other sides of the pit the overburden is heavier, and no splitting slate is exposed. The quarry is 'lai'gely :filled with_ d~ht-ls from abbve . and waste -:Erom the splitting of slate from the recent openi'ng. The quarry ''worked itself out,'' an illustration of 'poor management in quarry development. The pit wasworked' into a 'funnel~shape, in which the slate was necessarily much shattered by bla.Sting, result- ing in heavy loss. If the overburden had been removed over a larger SLATE DEPOSITS OF GEORGIA PLATE IV A. OLD DEVER QUARRY, ROCKMART, POLK COUNTY. PHOTOGRAPH TAKEN WIDLE THE QUARRY WAS BEING WORKED BY THE GEORGIA SLATE COMPANY, BETWEEN 1893 AND 1900. B. SPLITTING SHANTIES OF THE GEORGIA SLATE COMPANY, ROCKMART, POLK COUNTY. PHOTOGRAPH TAKEN WHILE THE OLD DEVER QUARRY WAS BEING WORKED. SLATE DEPOSITS OF GEORGIA 75 area and the slate worked out along the cleavage the production could have been much larger and more economical. The cleavage has an average strike of N. 42E., dip 43SE. Ribboning is conspicuous, and the ribbons are often arranged in groups. The quality of slate is about the same as that in the Pritchard and Davis quarry, previously described. CHEROKEE SLATE COMPANY PROPERTY (Map locality 2) In 1907 the Cherokee Slate Company, of rwhich A. G. Rhodes and C. J. Haden, of Atlanta, are president and vice-president, respectively, purchased from the heirs of Mrs. Sarah J. Dever, lot 936, 18th district, 3d. sectio;n, lots 926, 927, 928, 929, the north half of lots 995 and 996, and four acres in the southeast corner of lot 924, 21st district, 2d section, besides several other small pieces of property. All of these lots are nominally 40 acres, and the total holdings of the company amount to a little more than 250 acres. This property extends for a distance of 1}i miles from east to west along the slate ridge south of Rockmart, including the quarries which produced the greater part of the slate quarried in the Rockmart district and many of the best and most accessible prospects. The old Dever quarry, the largest in the district, is principally on this property, and the Tunnel quarry, the second largest and one of the best, is on lot 926. It is the intention of the company to open the quarries again with improved methods as soon as the war is over and machinery obtainable. Old Dever quarry (G).-The quarry north of the Seaboard Air Line tracks, 200 yards southeast of the station, commonly known as the Old Dever quarry, is the largest in the Rockmart district. Most of the work has been done on lots 924, 926, and 927, the property of the Cherokee Slate Company, but a part of the quarry extends onto lot 925, the property of the Southern States Portland Cement Company. The quarry has a maximum length from west to east of nearly 500 feet. In outline it followed a curve in the east fork of Euharlee 76 GEOLOGICAL SURVEY OF GJJORGTA. Creek, which was straightened when the Rockmart to Atlanta branch of the Seaboard Air Line was built. The quarry was worked back into the hill almost 200 feet, and the face has a maximum height (not / vertical, however) of 125 feet from the level of the road at the base. The following section was measured and the units described as ac- curately as possible under the conditions of difficult accessibility.. The traverse starts in the northern part o-f the quarry and run-s southeast, across the average strike of the bedding, and the units are numbered from lowest to highest, stratigraphically. The measurement-s stated are horizontal distances, and are therefore greater than the strati- graphic thickness of the beds. ' Section in o~d Dever qua1ry. Feet 7. Slate, thin bedded and contorted, containing nmb.erous veins, and of no commercial value. Exposed over the pond in the east end of the . quarry .............. ~ ............ ! ............... , ...,. . . . . . . . . 15 6. Slate, dark, bh~e, massive. J 6ints are less prominent than in the un- derlying unit, and are :filled with calcite. Overburden about 15 fee't. Expose'd mbove pond.... ; . ~ .. : .. / ..... : ~ .... :... '.,,.... 40 5. Splitting slate; with few ribbons but very ptominent jointin.gs. Contains short, disco.nnected stringers in a north-south dh;ection, and most of the joints are :filled with calcite. Measurements of strike and d:i.p are as follows: 1 Cleavage: Strike N. 45E., dip 47SE. Joints: (1) Strike N. 56W., dip 84SW. Strike N. 60W., dip 82SW. (2) Strike N. 00S., dip 51W. (3) Strike N. 45E., dip 67SE. (4) Strike N. 35W., dip 82SW. The joints of series (1) and (2) are very prominent, those of series (1) .being closer together but not as continuous as (2), and both are filled by sheets of calcite one-eighth to one-fourth inch thick. These joints cause a part of the slate to break up into pieces 8 to 10 inches wide, 3 to 4 feet long, and up to 1 foot thick ............................... :. . . . . . . . . . . . . . . . . . . . . . . . . . . 66 4. Slate, badly jointed and much weathered to a depth of 35 feet. On weathering the slate breaks down to small rectangular platy pieces. Measurements of strike and dip are as follows: Bedding: Strike N. 44E., dip 36SE. Strike N. 40E., dip 30SE. SL.A.1'E DEPOSITS OJ!' GEORGIA 77 Joints: (1) Strike N. 30W., dip goo. (2) Strike N. 10E., dip 70NW. (3) Strike N. 85E., dip 60SE. 50 3. Slate cut by many calcite veins, very little splitting slate .... , . . . . . . . 18 2. Slate with sandstone layers, intimately intersected by calcite veins.. 18 1. Dark blue-gray slate, with good cleavage and almost no ribbons. Some joints have calcite fillings, and there are a few calcite stringers near the upper part of the unit. Measurements of strike and dip are as follows: Cleavage: Strike N. 56E., dip 41 SE. Bedding: Strike N. 58E., dip 38SE. Strike N. 52E., dip 38SE. Strike N. 54E., dip sgosE. Joints: (1) Strike N. 20W., dip goo. Strike N. 80E., dip 80SE. Strike N. l4E., dip 74NW. Strike N. 70E., dip 69SE. Strike N. 62W., dip 80SW. This unit apparently contains the best splitting slate in the quarry. The overburden is 10 to 15 feet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 The portion of the quarry extending from the north point about 400 feet southwest to the railroad is at about the same horizon as the lower unit of the section, but extending a little lower. Good splitting slate is exposed in this portion of the quarry, and the relation of the cleavage direction to the slope is favorable for working. In working the higher units there would be much waste on account of jointing and calcite stringers. The overburden is greatest near the middle of the quarry, above unit No. 4, and decreases to east and west. Samples were taken from the lower 46-foot unit, which represents the best s:late in the quarry. S-264 is an average sample taken for analysis, and S-257 a typical specimen from which sections were cut. The analysis is as follows : Analysis of slate fTom old Dever quarry. Silica (Si0 ) 2 Alumina (A1 0 ) ................. Ferric oxide 23 (F e 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 S-264 56.32 17.24 1. 36 78 GEOLOGICAL SURVEY OF GEORGIA Ferrous oxide (F'eO) .... , . . . . . . . . . . . . . . . . . . . . . . . . . Magnesia (MgO) .. . . .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. Lime (CaO) . . . . . . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Soda (Na 0)...................................... 2 Potash (K 0) .......................... , . . . . . . . . . . Ignition 2 (less CO .J . .. .. . . . .. .. .. ... .. .. .. .. .. .. .. . Moisture ...... :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carbon dioxide (00 ).............................. 2 Titanium dioxide (TiO ) " .. .. .. .. 2 Phosphorus pentoxide (P 0 ). .. 2 5 Sulphur trioxide (SO ).. 3 Sulphur (S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manganous oxide (MnO) ............... ~.......... . Barium oxide (BaO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 5. 04 3.10 3.27 1.64 3 . 72 3 . 83 .10 1. 75 1.15 00 .14 . 66 . 00 . 00 99.32 Mega:scopically, this slate is darker in color and :finer in texture than the slate from the Brown quarry on an adjacent lot. It has slightly smoother and better cleavage, and shows no ribbons. The analysis indicates a little more magnetite and .pyrite, but less carbonate. : Under the microscope t'he slate shows :finer teoctuwe and. much more fi.nelylen.ticular structure than the slate,from thE} Brown quarry. Aggfe~kte poTI.arizat1on. i~ the section perpendicular t0 cleavage is not bri1liant; but distinct, while the section parallel to cleavage also shows a slight aggregate polarization, detectable with the :first order red gypsum plate. The aggregate polarization in the latter section is evidently due to the orientation of some of the mica flakes with their long axes parallel to the grain of the slate. Quartz and calcite are scattered through the slides, no grains havi:rig maximum dimensions :over 0.1 mm. Rutile needles and small opaque isometric crystals of magnetite and pyrite are abundant. Chlorite is J?-Ot definitely determinable, but fine scales of greenish mineral are scattered through the mica ground mass, and must be chlorite, as the magnesia shown by analysis evidently exists in that form. The scales of chlorite and of dark carbo:p.aceous material or graphite are more conspicuous in the section parallel to cleavage, as they are so SLATE DEPOSITS OF GEORGIA. PLATE V A. OLD DEVER QUARRY, ROCKMART, POLK COUNTY, SHOWING A SECONDARY CALCITE VEIN CUTTING THE CLEAVAGE DIAGONALLY. THE HAMMER HANDLE IS PARALLEL TO A JOINT PLANE. B. OLD DEVER QUARRY, ROCKMART, POLK COUNTY, SHOWING PROMINENT JOINTS ALMOST PERPENDICULAR TO THE CLEAVAGE. THE NOTE BOOK STANDS PARALLEL TO THE PRINCIPAL JOINT PLANES. SLATE DEPOSITS OF GEORGIA 79 i finely interleaved with the mica that they do not show up strongly in the other section. The minerals, in order of abundance, seem to be mica, quartz, chlorite, feldspar, carbonate, magnetite, pyrite, carbon, and rutile. . Tunnel q~&arry (H) .-The Tunnel quarry is on the property of the Cherokee Slate Company lot 926, south of the east fork of Euharlee Creek, and opposite the large quarry described above. The quarry was started on the north slope of the hill and rworked in the direction of the strike, with increasing depth to the southeast. The opening is about 200 feet long, and the face has a height of 100 feet, but as the face slopes with the hill the vertical depth is hardly 50 feet at any point. There was a tunnel from the bottom of the quarry, opening lower on the slope near the creek, but this is now :filled with debris. The topping of weathered slate is generally 10 to 15 feet thick normal to the slope of the hill, amounting to about 25 feet vertcially. The cleavage is wavy at places, and some of the slate in the upper part of the quarry presents a gnarled appearance. This secondary folding led to a great deal of waste, but some of the best slates in the Rockmart area were quarried here, being of uniform color, free from ribbons, and having good straight cleavage. Quartz veins are prominent locally, and there are some calcite veins up to an inch in . thickness. There is only one prominent and persistent serieS; of joints, but there are numerous other minor and irregular joints. Measurements of strike and dip are as follows: Cleavage: Strike N. 49E., dip 52SE. Strike N. 54E., dip 42SE. Strike N. 49E., dip 45SE. Prominent joints: Strike N. 45W., dip 86NE. There is a small opening between the above described quarry and the creek. It is 25 feet wide, 50 feet long, and 25 feet deep at the south end. Jointing is as in the other quarry, quartz occurs abundantly in pockets at certain places, and rwavy cleavage is found. 80 GEOLOGICAL SURVEY OF GEORGIA These openings are stratigraphically at a higher horizon than the old Dever quarry north of the creek. There is also a good exposure of slate in the cut made by th~ Sea. board Air Line to straighten the course of the creek. The cut is about 100 yards long, all in slate. The rock has suffered so'me folding since the development of the cleavage, causing locally wavy and gnarled cleavage planes. Calcite joint fillings and. quartz veins are also present. There is one very prominent series of joints, strike N. 8W., dip 56SW.; and a less prominent series, strike N. 64E., dip 72SE. The west (lorwer) part o the exposure in the cut is at about the same horizon as the oid Dever quarry north of the creek. Sample S-266 is an average of a number of samplings from the Tunnel qi:rarry, and S-259 is a typieal specimen of the good slate The analysis is as follows : Analysis of slate from the Tunnel quarry. Siliea (Si0 ) :................................. 2 kllliiima (Al20 3 ) , -...... . ]'er.rie oxide (Fe 0 ).............................. 23 Ferrous oxide (F'eO). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Magnesia (MgO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lime (CaO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Soda (Na 0)....... . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 2 Potasli. (K 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Ignition (less CO ) .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .Mo1. stu. re .I.....2............................... , . . . Carbon dioxide (CO).............................. 2 ' Titanium dioxide (Ti0 )........................... 2 Phosphorus pehtoxide (P 0 ) 2 5 Sulphur trioxide (S0 )............................ 3 Sulphur (S)....................................... Manganous oxide (MnO) . . . . . . . . . . . . . . . . . . . . . . . . . . . B'arium oxide (BaO). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S-266 57. oo 17 .'88 .64 5. 04 3.05 2.62 1.60 3. 78 3. 76 .18 1.98 1.05 00 .12 .56 . 00 . 00 99.26 Specimen S-259 is a very dark blue-gray slate, with good straight cleavage and no ribbons. It resembles the slate from the old Dever SLATE DEPOSITS OF GEOEGIA 81 quarry, having :finer texture and smoother cleavage than the slate from the Brown quarries. Under the microscope the slate is almost identical in texture and general appearance with that from the old Dever quarry. The aggregate polarization is rather strong in the- section perpendicular to the 'cleavage, and the section parallel to the cleavage shows slight aggregate polarization and elongation of the mineral particles in the grain direction. The ,structure is :finely lenticular, the lenses consisting of shattered quartz or feldspar grains and mica scales in irregular orientation, surrounded by a ground-mass of parallel-oriented mica, chlorite and graphite :flakes. Carbonate grains and rhombs are scattered through the section. Most of the carbonate grains measure less than 0.05 mm., and the quartz grains are on the average even smaller than the carbonate. The order of abundance of the minerals present is apparently mica, quartz, chlorite, feldspar, carbonate, magnetite, pyrite, carbon, and rutile. Small q~larry on lot 926 (1).-There is a small quarry in a west- ward sloping draw near the center of lot 926. About 10 feet, stratigraphically, of splitting slate is exposed, with 15 feet of overburden. The overburden would be likely to increase on working into the slopes, and the situation of the quarry in a narrow valley with the cleavage dipping into the hill is unfavorable for working. The slate is extensively ribboned, with ribbons less than a quarter . of an inch apart. The cleavage is good, but the slate has a tendency to break along the ribbons. There is only one series of prominent joints, which are :filled with calcite. The slate has a pronounced grain, and when partly weathered it tends to break into regular rhombs, the faces of which are cleavage, bedding and grain. Measurements of strike and dip are as follows: Cleavage: Strike N. 40E., dip 30 to 35SE. Bedding: Strike N. 45E., dip 10 to 20SE. Joints: Str.ike N. 3<0E., dip 75 to 850 SE. The fresh slate is dark gray-blue, and shows no sign of stain or fading since the quarry was worked. 82 GEOLOGICAL SVEVEY OF GEOEGIA ELLIS DAVIS & SON QUARRY (Map LocaLity 3) The property of Mrs. Ellis Davis consists of a part (28 acres) of lot 866, 18th district, 3d section, lying within the city limits of Rockmart and just east of the Rock:J;nart Shale Brick and Slate Company property, lot 865. The abandoned quarry (J) is near the northwest corner of the lot, and at the northeast end of the Rockmart slate ridge. The quarry consists of a large opening in the hillside, 100 feet in length, 50 feet in depth from front to back, and 50 feet in height, with three cuts through the overburden to the s:lope on rwhich the waste was dumped. Steel rails 'for cars lead through the middle cut to the dump. The quarry is now so filled with debris that no splitting slate is exposed. The visible pa,rt of the working face consists of weathered slate, form.ing the overburden, which was exceptionally thick, at least 30 feet, at this locality. The bottom of th~ qua,rcy- is about 30 feet .above the -valley to the rrortJi. On theslope' ber6w Ute quapFloadnpe.'ceeid/.:b.y . 'mll:!:ute w.rin.kling. Analysis _of slate from the Black Diamond quar.ries. S-263 Silica (SiO ) ..................................... . ' . 2 . .A.lmnina (Al20 3) ................................. . . F' er,.ric" oxid.e (Fe20 3) .. ............................. . Ferrous oxide (F'eO) ............ , ................. . 58.40 17.;62 1.28 3.88' Magnesia (MgO) ............... , ................. . 2.54 :Cim.e (GaO) ~ ................................. , .... . . ~oda (~a20) .............................. " ...... . Po1tash . .:. '!':'"; ". ' ' Ignitio n GK.-20) (less c.o.~. ..). ............ ........... . . . . . . . . .. .. . . . . . . . . . . . . . :.~ 3.14 1.66 3.34 2.9'0 . Moisture .......................................... .14 G~~bon . dioxide (CO ) 2 Titanium dioxide (TiO ) .......................... . . j ~.._ ~ ' ' ' Phosphorus . pentoxide 2. (P o ) ........................ . ,. ' 2 5 Sul]?nur trioxide' (S0 ) ..' :. . 3 Sulr>hur (S). : ...................... ; .. .. .... . 3.35 .94 .00. .-10 .44 Manganous oxide (MnO) ........................... . .00 Barium oxide (BaO) .............................. . .00 99.73 SLATE DEPOSITS OF GEORGIA PLATE VI A. BLACK DIAMOND SLATE QUARRY, 3 MILES NORTHEAST OF ROCKMART, POLK COUNTY. B. OLLIE DAVIS OPENING ON THE PROPERTY OF THE SOUTHERN STATES PORTLAND CEMENT COMPANY, ROCKMART, POLK COUNTY. SLATE DEPOSITS OF GEORGIA 91 This analysis indicates a higher percentage of carbonates and somewhat smaller percenta,ge of chlorite than the other analyses of slates from the Rockmart district. Three mutually perpendicular sections were cut from specimen S-26I, a typical ribboned slate from the largest of the Black Diamond quarries. Under the microscope the section perpendicular to cleavage and parallel to grain shows finer texture and more finely lenticular structure than any of the other Rockmart slates. The lenses consist of colorless masses of quartz, carbonate, feldspar and irregularly oriented sericite crystals, and are more elongated than similar structures in other Rockmart slates. The lenses are surrounded by a ground mass of parallel oriented sericite scales, in which aggregate polarization is distinct, interleaved with dark carbonr.ceous matter. The ribbons are marked by lighter bands about 0.16 mm. thick and 0.5 mm. apart, crossing the cleavage at an angle of about 15. F~w of the quartz and ca.rbonate crystals or fragments exceed 0.05 rum. in maximum dimensions, but there are several scales of greenish chlorite up to 0.1 mm. in diameter, with curved cleavage planes, lying across the rock cleavage. In the section perpendicular to cleavage and grain the ribbons are conspicuous and parallel to the cleavage. In the section parallel to grain the cleavage is perfectly straight, but in that perpendicular to grain the cleavage sho"Yvs fine wrinkling along planes perpendicular to the bedding. This wrinkling is not enough to produce false cleavage in the specimen, but it shows that the strong grain is related to false cleavage, which is present in some parts of the quarry. In this section the light ribbons, 0.1 to 0.5 mm. thick, are coarser than the intervening darker bands, and contain more quartz and carbonate. Some chlorite scales crossing the rock cleavage were noted, the largest measuring 0.11 by 0.02 mm. The section parallel to cleavage shows ribboning strongly. Ag. gregate polarization pa.rallel to the grain can just be detected with the first order red plate. The strong grain is due to cross wrinkling of the cleavage rather than to elongation of mineral particles. The 92 GEOLOGICAL SURVEY OF GEORGIA section shows much opaque material,. both finely divided graphite or carbonaceous material and isometric crystals Of pyrite and magnetite up to 0.06 mm. in diameter. The constituents, in descending order of abundance, appear to be mica, quartz, chlorite, carbonate, feldspar, pyrite, magnetite, carbon, and rutile. .On the Black Diamond property the. fresh slate seems to occur principally below water level in the small valley in which the quarries are located. The ove~urden increases rapidly to 25 feet in the. large quarry, and is likely to become e:ven heavier on working back into the hills. The west slope of the ridge north and south of the ...-Black Diamond quarries is eo;vered with frag:paents of weathered slate, a large part of which is very ~ile, and it is evident that much splitting slate could be found. However, the exposures in the quarries show that portions of the slate have inadequate cleavage, or are ruined by false cleavage, while joints would cause a great deal of waste. Any development work should be. preceded by core drilling to determine the thickness of o;verburden and the character of slate to be obtained below. COLUMBIA QUA~RIES (Map locality Io). The prospects of the Columbia Slate Company are on the west slope of the same ridge, half a mile south of the Bla.ck Diamond quarries; and geologie conditions are very similar. There are nine openings in the bottom of a small hollow, extending over a distance of about 100 yards. The largest pit is 10 by 12 feet and 12 feet deep. .A. small amount o. splitting slate is exposed in several openings, and the slate is quite fresh at a depth of 8 to 10 feet. .All of the slate is conspicuously ribboned; but the cleavage is eomparative~y smooth and straight. Measurements of strike and dip are as follows: Cleavage: Strike N. l2E., dip 31SE. Strike N. 25E., dip 37SE. Strike N. 6E., dip 38SE. SLATE DEPOSITS OF GEOBGIA 93 Strike N. 16E., dip 34SE. Strike N. 12E., dip 34SE. Strike N. 20E., dip 36SE. Bedding: Strike N. 18E., dip 24SE. Strike N. 25E., dip 25SE. Strike N. 15E., dip 21 SE. Strike N. 11 E., dip 27SE. Joints: (1) Strike N. 75E., dip 67SE. (2) Strike N. 65W., dip 63SW. Strike N. 60W., dip 64SW. (3) Strike N. 3E., dip 74SE. (4) Strike N. 35E., dip 59SE. PORTLAND QUARRY (Map locality II). There is an old slate quarry a quarter o.f a mile east of Portland (Davitte on the Rome topographic sheet), on the Seaboard .Air Line, 5 miles north of Rockmart.. The quarry is in the north side of a narrow V-shaped valley, and measures 100 feet across the front, worked in 30 feet, and the maximum height of the face above the water in the bottom of the pit is 45 feet. All of the slate above water level is more or less weathered, and the splitting slate, of which four or :five carloads are said to have been shipped, must have come from the part of the pit :filled with water. Measurements of strike and dip are as foUorws: Cleavage: Strike N. 22E., dip 25SE. Strike N. 15E., dip 32SE. Strike N. 19E., dip 30SE. Bedding: Strike N. 23E., dip 21 SE. Strike N. 20E., dip 27SE. Joints: (1) Strike N. 95E., dip 68SE. Strike N. 75E., dip 47SE. (2) Strike N. 28E., dip 48NW. Joints of series (1) are very prominent. Those of series (2) are less prominent, but carry disconnected stringers of calcite. The fresh. sJ.ate from the old splitting shed is dark gray-blue in color, has good straight cleavage, and the ribbons are inconspicuous. 94 GEOLOGICAL SURVEY Olf' GEORGIA Apparently slate of good quality could be obtained, but the situation of the quarrry is not convenient for working, and the overburden is heavy. The quarry is near the base of the Rockmart slate formation, as there is an outcrop of the. Chickamauga limestone . 400 feet west of the pit. FISH CREEK AREA. . A narrow synclinal area of Rockmart shale and slate extends from a little southwest of Fish, a station on the Seaboard Air Line 5 miles west of 'Rockmart, southwest to the contact with the crystalline rocks along the Cartersville fa.ult, which passes a little south of Shades. The area is connected by a narrow belt of slate with the Roclrrriart area, but is not conti:i:mous. with the Cedartown area. When viewed from the east this area sh01ws little difference in topography from the area underlain by Knox dolomite; from the west, owing to the valley o,f Fish Creek, it stands up as an almost continuous belt of low rounded hillS. The' s:tr'iitigr:'iiiE}liy o:tli~.';b\~]t is v~ry ;sjmilar to that p;f, the Rock- mart area, but some rather promii).en,t layers. of quartzite and con- gl9meriie are present. As a whole .the material is less metamor- phosed than in the Rockmart area, a.nd the resulting slates are less crystalline and consequently weaker. Mos.t of .the rock of the belt is a shale with slaty cleavage and not a slate from a commercial standpoint. The rocks of the belt are closely folded and s.ta.nd almost vertically, while the cleavage dips at high angles to south and east. The . cleavage generally cuts the bedding at considerable angles. Toward the southwestern part of the belt weathering has progressed much faster than to the northeast, b.ut .fresh rock is not seen in any natural exposures throughout the entire belt, and at many places the rock is s0 badly weathered that it is not possible to determine the strike and dip. SLA1'E DEPOSITS OF GEORGIA !:!5 HOLLAN SLATE PROSPECTS (Map locality I2). The only prospecting for slate in the Fish Creek area was done about 1885 or 1890, on the D. Hollan property, 1;6 miles south of Grady. There are three prospect pits, extending over a distance of 100 yards along the north slope of Camp Creek. The eastern pit is the largest, measuring 12 feet square and 15 feet deep on the up-hill side. All slate in sight is somewhat rweathered and very weak. A part has fair cleavage, part is gnarly. The slate is finely ribboned, ribbons making various angles with the cleavage. The cleavag~ strikes N. 28E. to N. 36E., dips 81 to 86SE., and there are two prominent series of joints, one N. 39E., 82SE., the other N. 58W., 79SW. The joints of the first series are closely spaced and make a small angle with the cleavage, causing fracture into wedge-shaped pieces. The other pits show slate similar in character, but with poorer cleavage. Two hundred yards west of the western pjt there are outcrops of sandy shale with almost no cleavage. Although this seems to be one of the most favorable localities in the Fish Creek area, it is not likely that the slate has any commercial value. The overburden would be very heavy, and the fresh slate when reached can not be expected to be very strong, "'i'lhile the poor and distorted cleavage and joints i"VIrould cause much waste. CEDARTOWN AREA South and southwest of Cedartown is a synclinal area of the Rockmart formation, discontinuous with the Rockmart and Fish Creek areas. This area extends from just south of Cedartown southwest to Esom Hill, a distance of 9 miles, and has a maximum width of about 4 miles. To the south the b8lt is cut off by the Cartersville fault, and to the west it narrows down until at Esom Hill, . where it crosses the State Line into Alabama, the outcrop of the Rockmart formation has a width of only a few hundred yards. 96 GEOLOGICAL SUEVEY OF GEOEGIA The Rockmart shale and slate fu this area resembles that of the Fish Creek area. The material appears to have been much more calcareous when originally deposited than that of the Rockmart area, and cousists in general of deeper water deposits. Thus sandstones and quartzites are not so abundant, conglomerates are almost absent, but highly calcareous shales, shaly and cherty limestones predominate. Throughout the greater part of the Cedartown area, metamo:rphism has been less intense than in the Rockmart area, consequently the sJ.ates are weak with poor cleavage and a large proportion of the shale we3Jthers hackly or penciliform rather than fissile. The contact o.f the Rockmart shales with the crystalline rocks of the Ocoee .series, however, is always accompanied by much wrinkling and folding of the former, with the consequent development of a semi-crystalline structure and very irregular cleavage. It is almost impossible to map the Rockmart shale separately from the Chickamauga limestone in the Cedartown area. The limestone underlies the relatively flat area of 5 or 6 square. miles in and surroUn.ding Cedartown, and a tongue extends southwest for seveT-al In. ... rriiles up the valley of Lim,;_,e.. . B..r.ar'w.;]l..,., . . the .area,..o..f .R..o..e..k.mart foT- mation farther_ south t'.Q.ere are numerous mino~ beds of limestone. The high hill 3 miles south Of Cedartown ana th.e. ;ri~9-ge extending southwest from Berry are caused by resiSitant beds Of cherty limestone and sandstone in the shale. Structurally, the limestone and shale of the Cedartown area has the form .of a closely folded syncline in rwhich the beds stand vertically or dip to the southeast at high angles. The shales dip to the west at only a few places on the east side. To the south the syncline is interrupted by the Cartersville fault, which has thrust the rocks of the Ocoee series upon thos:e of Ordovician age. From an economic standpoint, slates are best developed' in a narrow belt along the western edge of the area, parallelling the Seaboard Air Line from CedartoiWTI. to and beyond Berry. This belt.is limited on the west by the Knox dolomite, and on the east by the cherty and sandy beds of the Roekmart formation. To the east the cleavage of the shales is less developed and the composition of the beds is SLATE DEPOSITS OF GEOBGIA 97 less uniform. However, even in the western belt the slates are highly calcareous and very weak. CORNELIUS QUARRY (Map locality 13) The only quarry in the Cedartown area which produced slate commercially was that operated by W. 0. Cornelius, on the property now OIWIJ.ed by J. W. Phinizy, 3 miles southwest of Cedartown. The quarry is in a level meadow several hundred yards south of the Seaboard .Air Line, and was worked vertically. The pit is 65 feet square, and is said to be 75 feet deep, but when examined it was :filled with water to within 3 feet of the top. The soil covering is little more than a foot, and the slate .is fresh. a few feet below the surface. Measurements of strike and dip are as follows: Cleavage: Strike N. 30E., dip 70SE. Strike N. 29E., dip 71 SE. Bedding: Strike N. 50E., dip 38SE. Strike N. 50E., dip 39SE. Strike N. 48E., dip 39SE. Joints: (1) Strike N. 52E., dip 59SE. (:) Strike N. 51E., dip 40NE. The slate is very dark gray in color, darker than most of the Rockmart slates. It is ribboned throughout, and the ribbons, which make an angle of a:bout 30 with the cleavage, are not segregated into bands. It is extremely :fissile, 1with :finer texture and smoother cleavage than the Rockmart slates. It effervesces strongly with acid, and calcite :fills joints and forms veins. Some large masses seen on the dump are cut by parallel, discontinuous veinlets of calcite :filling joints spaced only a fraction of an inch apart. .An analysis of slate from this quarry (specimen H-29) is as follows: ' 98 GEOLOGICAL S!JRVEY OF GEO.Lui.HA AnaLysis of slate from Gorneli~ts quarry. Silica (SiO ) 2 Alumina (A1 0 ) .. 23 Ferric oxide (Fe 0 ) 2 3 Perrous oxide (FeO)........ . . . . . . . . . . . . . . . . . . . . . Magnesia (MgO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Li;m.e. (CaO) ... ; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Soda (N.a 0) ..... ,. . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . - 2 ' , Potash (K 0) ._.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Ignition (less CO ) . . . . 2 Moisture ..... .-.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carbon dioxfde (00 ) . . . . . . . . .. .. 2 Titanium dioxide (Ti0 )................. .... .. 2 Phosphorus pentioxide (P 0,,) .................. ~.... 2 Sulphur (S) ......... : ............................. Manganous oxide (111n0) ................... , ..... ,. ':"I ' H-29 55 .43 17.78 1. 68 4. 03 2 . 49 3. 60 1.47 3. 04 4. 28 .-49 4. 00 .58 .38 1.26 . 09' 100.60 This analysis indicates about twice as la,rge a percentage of car- bonate and pyrite as the slates fr0-m, the v:iciu:ity .of Rock:rnart, which accounts !or the weakness andd<~a:pid d~~integratium of the slate. Sections parallel 3illd peii'petr,liiinestone. is."blne or:gwaycin. color an:cL.contains bedded argillaceous impurities which stand out as conspicuous ribs or ridges on weathexed surfaces. Chert, which is so characteristic of the Knox dolomite and Beaver limestone, does not occur in the Conasauga limestone. Commonly the dark colored limestone js cut by small veins of white caleite which run in all directions, where fractures formed in the comparatively rigid limestone during folding were filled by calcium carbonate dissolved and redeposited by percolating solutions. The Consauga shales and slates are very :fine-grained argillaceous rocks, of fairly uniform composition over great areas and through a great thickness. The shales have the composition of ordinary mud deposits such as would be derived from the thoroughly weathe:red granitic and gneissic rocks of the crystalline area to the east. Beds of sandy shale are rare, owing to the lack of CO'arse sediments. Prac- . tically all of the shale is more or less c. alcare.ous, and even the hard SLATE DEPOSITS OF GEORGIA 101 slates contain enough calcite to effervesce slightly with acid. The most notable characteristic of both slates and shales is the green color, caused by the abundance of chlorite. Generally the perfectly fresh material has a blue-green color, which fades to a yellowish green in the :first stage of weathering. As weathering proceeds farther the rock breaks down into platy or hackly fragments, and the color becomes some shade of brown, pink or maroon by oxidation of the iron, but the shale is very resistant to complete disintegration. Little clay is formed, and the soil over the shale ~reas contains much fragmental 'r ' material. This shaly soil forms gock;l, hard road surfaces, which are easily kept in condition and nevj-'~ 'become muddy, contrasting strongly with the sticky red clay ft)fmed from the limestones of the same formation. The distinction between shales and slates is based solely on the degree of metamorphism, as both have the same chemical character. West of a line from Chatsworth to Folsom most of this material may properly be called shale, while east of that E:cP a large part has hardness and cleavage sufficiently developed to be called slate, although only locally are there good prospects for slate of commercial splitting quality. Structure and thickness.-On account of the great mass of similar sediments making up the Conasauga formation, it is very difficult to determine the structure. The limestones, which might serve as horizon markers, are not sufficiently continuous to be correlated across any great areas. In the eastern, slate-bearing belt of the Conasauga formation both the bedding of the limestone and the cleavage of the slates dip to the east at an angle averaging about 45 degrees. Generally the bedding in the slate is invisible, but where it can still be distinguished it is highly contorted and is cut by the cleavage at all angles. During the period of folding, the limestones acted as competent layers and yielded by fracture, while the slates gave way by :flowage, thus greatly disturbing the original bedding. 102 GEOLOGICAL SURVEY OF GEORGIA 'The uniform: eastward -dip o-f all structures may be explained by overturned folds and thrust faults, both o.f wh1c.h almos.t ce~tainly occur. On account o-f the lack of structural knowledge, any estimate of the total thickness of the Conasauga formation is little better than a -gUess,: but: the extensive exposures indicate a great thickness. Hayes .es:timates'the thicknes1s from 1000 to 4000 feet in variousparts of the Rome' quadrangle.1 In southern Gordon and Iior.therr1 Bartow coun- ;ties the,thickness niay even e ""it~, a the larger figure. .. ~ . . Ph:ysiogra:phic expressio ~outltern extremity of the green ,slate belt, between Fairmo , :X}?inelpg, wher~ the ,best s:tate de- posit~ ~ccur, may be divide;GJ. j,Jift~, s~veral well~define_a. pi;hyE?~ogr~phic beltf;l, 'rhe bdts, from east,tid'M~~t.;are as.fdll0Ws:.. . ' ;. ' t ,.. , .. . : (~1; ..~h~. m,?un.~ain belt, ~Gl,~:in,g. th~ J:li!fY. Pi~dmont are~ extend- _ing. north from .Pinelog Mountain.. The rf' mus:e0vite: fseri- eiteJ with ma:rked a:ggregate pora;rizatian and a fine and regullar 1 Dale, T. N., Slate in the United States: U. S. Geol. Survey Bull. 586, p. 3"9", 1914. 2 Analysis. of average sample taken over: enti.Fe quarry expos.ure. Maynard,, 'F. P., Geol. Survey of Ga. Bull. 27, p. 270, 19'12. a Analysis made by Dr. Edga:r Everhart :!!OiL" W. W. Griffin. 4U. S. Geol. survey Bull. 586, p. 71, 1914. SLATE DEPOSITS OF GEORGIA 107 cleavage, also abundant rutile needles. It contains a little carbonate in fine particles or rhombs and a little pyrite in spherules and irregular grains. There are lenses of chlorite up to 0.34 by 0.009 mm. "J.lhe chlorite scales measure as much as 0.009 mm. and the qua.rtz grains 0.047 mm. ''The constituents, named in descending order of abundance, appear to be muscovite, quartz, chlorite, carbonate, pyrite, magnetite, and rutile. . ''This is a mica slate with a fair fissility and attractive color. Although the amount of carbonate is not so large as in the sea.-green slate of Vermont, it is probably sufficient to produce in time some discoloration. The slates about the quarry, exposed not over two years, show but slight discoloration.'' The quarry equipment consisted of two saw tables, one overhead carrier in the splitting shed, one channel drill, three squaring machines, one car with dumping attachment, and two cable conveyors with towers 80 or 90 feet high for conveying refuse to the dump and splitting slate to the mill. At first one saw table was used in the hollow, later the mill was moved to the top of the hill southwest of the quarry and additional machinery was installed. In 1916 there was a stack of good roofing slates near the mill, estimated to contain about 30,000 pieces. These slates range from 6 by 10 to 10 by 20 inches and from 0.2 to 0.25 inch in thickness. They are of good quality, but for some reason were not shipped after operations ceased in 1913. J. R. Smith states that the quarry could have been operated successfully if experienced managers and workmen had been available. The final closing down was caused by a strike, after which work was not resumed. Other disadvanta.ges were the inconvenier1t location of the quarry, distance to the railroad, and the great amount of waste caused by false cleavage, jointing, veining, and irregular character of the slate. The property seems to be too close to the Cartersville fault at the eastern boundary of the slate belt, and more uniform slate could be found at many localities farther west. 108 GEOLOGICAL SURVEY OF GEORGIA BOLIVAR STATION (M' ap looality.2) The slate property controlled by W. 0. Watson, of Charlottesville, Virginia, consists of 30 acres, more or less., just west of 'the Louisville & Nashville Railroad at Bolivar station. The property parallels the railroad for about 1,000 feet. A report on this property was prepared for Mr. Watson in 1912 by Dr. T. Poole Maynard, of Atlanta. The following description is partly abstracted from that report. . Prospecting has been done in the east slope o.f the hill opposite Bolivar station and just north of Pinelog Creek. At the foot of the bill directly west of the station is a pit 6 feet long and 6 feet deep, showing somewhat weathered,' very fissile slate. The slate has a good green color and has not. faded in sever~l years since the openiri.g was' made. The cleavage is slightly m:i.rved: with average strike N. 70E., dip 20SE. A little farther north is a series of step-like pits up the slope Show- ing slate with good Cleavage, but all is weathered red and yellow. At the southwest end of the hill, near Pinelog Creek, is an exposure of white quartzite, probably 20 feet thick, and quartz fragments are ;abundant on the north slope. Natural exposures on the property are nbt goo.d, and the: knowledge of the quantity and quality of slate present depends l~rg.ely on drill holes. Four holes were bo:red with a core dr,ill. T'Wo holes near the north end of the hill did not sho:W slate of sufficient thickness for commercial development. The sections in the southern. holes are as follows : Section of green slate, d1~'LZ hole No.3. Inches. 1. Yellowish to bluish green slate, cleavage and texture o. k........... 20 . 2. Bluish green slate, cleavage and texture o. k ............. ; . . . . . . . . . 20 3. Bluish green slate, cleavage and texture o. k.; an inch or two of sec- ondary quartz at bottom ..... ................................ 20 4. Bluish green slate; drill hung,. core largely lost by grinding........ 20 5. Upper 8 inches badly weathered, lower 12 inches weathered, but shows good cleavage and texture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 6: Bluish green weathered slate, with some loose quartz in crevice at bottom .... . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 7. Bluish green slate, o. k., with lh inch of quartz at bottom............. 20 8. Blue green slate, ci. k ..... , ~...................................... 20 SLATE DEPOSITS OF GEOBGIA 109 9. Upper 6 inches contains many blue streaks which are ;o.ot seriously objectionable. Lower 24 inches o. k., but on account of drill hanging the cores were largely ground up ........... - . . . . . . . . . . . . . . . . . . 30 10. Upper 12 inches o. k., lower 12 inches quartz and rough slate. . . . . . . . 24 ll. Upper 12 inches intercalated quartz and green slate, lower 12 inches o. k . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . . . . . . . 30 12. Good green slate ............................. - . . . . . . . . . . . . . . . . . . 60 13. Some quartz in upper few inches of unit, while lower 5 inches contains much quartz-between the top and bottom occurs good slate. . . . . . 66 370 Section of green s"late, drill hole No. 4. Inches. 1. Yellow and reddish yellow topping, good cleavage . . . . . . . . . . . . . . . . . . 72 2. Yellowish green slate, containing :;4, inch of quartz at bottom, all good slate ........................i);; . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 3. Bluish green slate, o. k............ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 4. Bluish green slate, o. k........................................... 48 5. Bluish green slate, o. k., with about 6 inches of quartz at the bottom 60 360 The drilling was undertaken to determine the size of a quarry which could be opened. Maynard states that a stratigraphic thickness of 100 feet of slate, with fine texture and good cleavage, and without false cleavage, has been shown. At leas:t 75 per cent of the core shows slate of e:xlcellent quality, while about 25 per cent will result in waste consisting of quartz (secondary silica deposited in open fractures after . the slate was formed) and some slate in contact with the quartz, which will not make good commercial slate. Slate underlies the entire property, and is weathered to an average depth of about 20 feet, that is, about 20 feet of topping must be removed to secure good commercial slate. The average dip of the cleavage seems to be toward the east at a low angle. However, in the railroad cut and along the wagon road just east of the station the slate is thrown into synclines and anticlines, 50 to 100 feet across, with limbs dipping about 30 degrees (steeper dip on east side) and pitching south. It is likely that this disturbance of the cleavage persists in the hill west of the station, and would cause difficulty and loss in 110 GEOLO'GICAL SURVEY OF GEORGIA working. .Altho'Etgh there is no limestone on the Wats-on property, a massive bed outcrops- a quarte1 of. a mile east of the station. The slate is of a greenish-gray color, bluish when perfectly fresh, yellowish when weathered. It is sonorous.,. giving a good ring when struck with.a hammer.. The cleavage is-good, and micaceous leaves are seen on fresh cleavage surfaces.. The surface is slightly lustrous. There is little effervescence with acid test, and the amount of magnetite is shown by physical tests to be practically nil. A chemical analysis is as follows : Analysis of slate j1mn Bolivar. M-502 Silica (SiO) ............ , ............... : ........ 55.57 Alumina (Al 0.) .................. ...... : ....... .. 21.64 .. , ' 2 3> ' Ferric oxide (Fe 0 ) ............................. . 1 ..64 23 . . . Ferrous o:ifde (:E eO) ........................... 6.48 Magnesia (:M:go) .. : .......... : .................. . 2.52 Lime ccaO) .............. : .......................... 1.00 Soda (Na20) ............... Potash (K 0) .................................... . 2 Ignition (less CO ) . . . . . . . . . . . .................... . 2 Moisture ......................................... . gely of sericite scales, but in irregular orielllta;tion. Quatt"tz rund :EEHdspar are not determinable threugh6ut most of the area of the sections. The analysis indicates little or no feldspar, but quartz in micrc:.rystalline form is evidently present in the micaceous matrix. The ribbons show up in the slide perpendicula;r to cleavage by slightly coarser ~.:..ture, and contain quartz grains up to 0.03mm. Carbonate is rare in the slides, but is mo-st abundant in the quartzose. ribbons. It occurs as rhombs and irregular grains, mostly under 0.03 mm. The opaque mineral present seems to be all ma,O'Jletite, occurring as small isometric crystals, mostly less than 0.01 mm., scattered through the slide and more abundant in the quartzose ribbons.. Rutile needles are very abundant, and are mostly arranged with long axes parallel to cleavage, so they are more conspicuous in the section parallel to cleavage. Porphyritic greenish crystals of chlorite are scattered through tile mass, with irregular orientation. In the section perpendicular to SLATE DEPOSITS OF GEOEGIA 115 cleavage they measure up to 0.05 by 0.09 mm., and in the se-ction parallel to cleavage one 0.2 by 0.3 mm., was noted, with mineral cleavage almost at right angles to the slaty cleavage. The minerals, in descending order o1 abundance, appear to be mica, quartz, chlorite, carbonate, magnetite, rutile, and pyrite. The situation of the prospect is very satisfactory for working, as the overburden and waste are apparently not excessive and a great deal of slate could be obtained above water level. The principal disadvantage is the distance of about 3 miles over hilly roads to Rydal, the nearest railroad station. On the Long property (Map Zoca.rity 6), about a mile northwest of the Tilly prospect, green slate with very good cleavage and only slightly weathered is exposed on the banks of Little Pinelog Creek. The cleavage strikes N. l0E. and dips 30 to 40SE. SOUTHERN GREEN SLATE COMPANY PROPERTY (Map locality 7) The Southern Green Slate Company, R. L. Proctor, of College Park, Georgia, president, owns 238 acres of land lying east of the Tennessee Road and 100 yards east of the Louisville & Nashville Railroad, just north of the Georgia Green Slate Company property and 3 miles south of Fairmount. This property lies in the foothills belt of green slate. Dr. T. Poole Maynard, of Atlanta, explored the property by calyx-drilling and prepared a report from which some of the following information has been obtained. Two hills have been tested, one on the Tennessee Road and one just north of the Georgia Green Slate Company property. On the latter there are two small test pits showing beds of slate, fissile but partly wrinkled, and other beds of crumpled, knotty material. As a whole this part of the property is about the same as the Georgia Green Slate Company property, but the slate has a somewhat lighter and grayer green color than that worked by the latter company. The principal prospects are in a hill just east of the Tennessee Road, % mile northwest of the Georgia Green Slate Company quarry. The hill is elongated in a northeast-southwest direction, that is, parallel to the strike of the cleavage, and rises 130 feet above the valley 116 GEOLOGICAL SURVEY OF GEORGIA I bottom to the north. The bes.t exposures are along the -road, at tJ:ie southwest end of the hill. The following is the section in a direction N. 57W., the distances being measured horizontally. Section along Tennessee Road, Southern G1een Sl(J)te Company property. Feet. 6. Limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ' 5. Slate, largely concealed, cleavage not so good as in underlyillg material 50 4. Slate, weathered and partly concealed ................. ,....... ..... 40 3. Best. slate ...................... .-................................. ~. 160 2. -w;eathered slate .................. ........ . .................... ~. 30 1. Lim~stone ......................... ,......... ... : .............. . . . ' The 160-foot unit is largely good'slate. It contains some limestone nodules and rough slate, and is extensively jointed, but no'wrinkling 'go nor false cleavage was noted. Theunit has a thickness of eet, meas- ured at right angles to the !cleavage, and it exte:J?-dS through the long dimension of the hill. Almost 40 feet above the road exposure 'is a test pit 6 feet deep, sho'Wing~fresilii, 'iiglrt::eolor<~a, blmsh;;g;ref3n slate ill th{bottom. A part of the' slate in' the pit is :finely wrinkled, and a part shows knotty or ''augen'' structure, due to calcite nodUles: Measurements of strike and dip in the ex:posures at the southwest ehd of the hill are as follows : . ' Cleavage: Strike N. 37E., dip 43SE. Strike,.N. 26~E.,- dip 32S;EJ. Bedding (limestone): Strike N. 45E., dip 50SE. Joints (most prominent series): Strike N. 64W., dip 79SW. Strike N. 40_E., dip 78SE. A small pit at the northwest end of the hill shows only weathered slate. The cleavage there strikes N. 47E., and dips33SE. Maynard states .in his .report that drilling and other exploration work --showed up a bed of slate estimated to be 75 feet thick and 1400 feet long. The slate 'has a good greenish-gray color and e:XJcellent cleavage. The cleavage seems to be about parallel to the bedding; no ribbons SLATE DEPOSITS OF GEOBGI.A 117 could be detected. Partial analyses of average samples from drill cores are as follows : No. 1 Silica ( SiO ). . . . . . . . . . . . . . 54.95 2 Alumina (A1 0 ) ................... 22.71 23 Ferric oxide (Fe 0 )................... .56 23 Ferrous oxide (FeO) . . . . . . . . . . . . . . . . . . . 7. 20 Carbon dioxide (CO Q). . . . . . . . . . . . . . . . . . . 1. 30 Titanium dioxide (TiO )..... . . . . . . 60 2 Sulphur (S) .......... ,................. 1.08 No. 2 53.87 23.26 1.20 5. 90 1. 34 . 72 .93 These analyses show that the percentage of carbonate is about the average for the district; some green slates carry considerably more, and some considerably less. The content of pyrite, as shown by the sulphur determinations, is unusually high, and might cause spotting and staining on long exposure to the weather. The magnetite content is very lorw, and the slate takes a high polish, which makes it suitable for electrical purposes. The situation is very favorable for quarrying, as the deposit is not over 1,000 feet from the railroad, the overburden is apparently not heavy, there is a great deal of slate above water level, and the level valley bottom to the north affords ample room for buildings and dumps. The bed of slate exposed on the Southern Green Slate Company property also extends through the smaller and lower hill west of the Tennessee road, on the property of Monte Dooley. McCOY PROPERTY (Map locality 8) The property of Mr. Gus McCoy, of Fairmount, is commonly known as the Hughes pla.ce. It is situated near the northern boundary of Bartow County, 2V2 miles south of Fairmount. The slate deposits are in the hills belt west of the Louisville & Nashville Railroad. Development work consists of two small prospect pits, about 200 yards west of the Louisville & Nashville Railroad and 25 feet above the track level. The pits are at the lower end of a small V-shaped valley whose sides rise 50 to 100 feet above the bottom. 118 GEOLOGICAL SVEVEY OF GEOEGLA The lower pit measures 10 feet across the front, extending hack 8 feet, and showing a vertical face of about 10 feet. Moderately fresh slate is exposed in the bottom, but it is hardly of splitting quality. The soil cov<:>ring is only about a foot thick, but the UP,per part of the slate is weathered. The upper pit is about 60 feet northwest of the other, and also exposes a vertical face of 10 feet. The weathered slate is covered by scarcely 6 inches of soil, and the lower 2 feet of the exposure is almost fresh . The cleavage is straight and clean, and no wrinkled or knotty slate is seen in either pit. The average strike is N. 45E., dip 35SE. In parts of the exposure the slate .shows contorted ribbons, which indicate that the cleavage does not correspond with the bedding. The ribbons are faant, and do' not interfere with the cleavage. Joints are prominent, but pro'bably not to a detrimental degree. The most conspicuous seri~ of joints st:rik.re about N. 70E. and dip northwest at high angles,. These joints are spaced 10 inches to 2,% feet apart in the weathered material, hut they may be expected to be less numerous at greater depth. The-fresher sJ.ate has: a good blue.:.green:coler; Where pa;r,tl;y: wea.thered it changes to yellowish or olive green, but the change is uniform, without spotting or bad staining. The cleavage is straight and clean, and false cleavage is absent. The grain is not extremely strong, but is pronounce.d enough to make '' sculping'' easy. A part of the slate contains small "porphyritic" crystals of some chloritic mineral, up to 1 mm. in length, and elongated in the direction of the grain. These crystals produce a slight roughening of the cleavage surfaces, but would probably not be objectionable. The analysis of a specimen collected by 0. B. Hop1cins is as follows: Analysis of slate from MoOoy property. Silica (SiO ) ' 2 Alumina (.A.l 0 ) ........................ . . . Ferric .oxide 2(F3e 0 ) ..' ........ .- .................. . ' 2 g Ferrous oxide (F'eO) ............................. . Magnesia (MgO) ................................. . Lime (CaO) ...... ................................ . H-30 54.40 21.34 .88 6.77 1.78 2.65 SLATE DEPOSITS OF GEORGIA 119 Soda (Na 0)...................................... 9 Potash (K 0)..................................... 2 Ignition (less CO2 ). . Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carbon dioxide (UO).............................. Titanium dioxide (TiO) . . . . . . . . . . . . . . . . . . . . . . . . . . . Phosphorus pentoxide (P 0 )....................... 2 5 Sulphur (S)....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manganous oxide (MnO)........................... 1.23 2.45 4. 38 . 31 2.40 . 52 .24 .43 .18 99.96 This analysis indicates no objectionable qualities. The content of carbon dioxide and pyrite is a little higher than the average, indicating some fading on long exposure, but the quantity is smaller than in some slates extensively used for roofing. Microscopic examination of sections from the specimen analyzed (H-3o), shows a matrix of sericite with fine texture and slightly lenticular structure, having brilliant aggregate polarization. A slight aggregate polarization in the direction of the grain is also noticeable. The section perpendicular to cleavage shows ribbons of coarse material intersecting the cleavage at small angles, and the section parallel to cleavage cuts a ribbon in such a way that it shows an irregular triangular area, 1.5 by .5 em., consisting largely of carbonate and chlorite. The coarser ribbons contain more quartz, chlorite, carbonate, and opaque minerals (magnetite and pyrite) than the micaceous groundmass. The ribbon cut by the section parallel to cleavage consists of over half carbonate, in grains up to 0.1 mm., with a few quartz grains nea:dy as large. The spaces between are filled by very fine pale green scales of chlorite. Opaque, isometric crystals of magnetite and pyrite are scattered through the sections, and rutile needles are present. The minerals, in descending order of abundance, appear to be mica, quartz, chlorite, carbonate, magnetite, pyrite, and rutile. Since the amount of exploration work is so small, little can be said as to the quantity of workable slate available and as to conditions of quarrying. However, the property is centrally located in the extensive slate belt, and the indications are that a large area is underlain by good slate. The overburden is probably light, as the slate at a depth of 10 120 GEOLOGICAL SURVEY OF GEORGIA feet is practically fresh. In regard to transportation the property could not be more favorably situated, and the level vall~y between the slate hills and t~e railroad .aE~rds ample ~pa~e for splitting sheds, dumps, etc; ' .. BAGWELL. .PROPE. RTY (Map locality 9) The property of W. H. Bagwell consists of 42 acres on lot 218, 23d district, 2d section, Bartow County, half a mile north of Bolivar sta- tion and a quarter of a mile west of the Louisvi~le & Nashville Railroad. It H~s ~h the western _hills belt, and theprospect~ are in the gentiy sioPing' ridge which parallels the railroad at this point. There are two small openings, one .east and one west of the crest of the ridge. The e~st pit is 6 feet deep and 7 feet square, and within 4 feet of the surface the slate has a good c,olor and appears quite fresh. The west pit shows moderately fresh .and very fissile, hut soft slate at a depth of 7 feet. Between the two openings are only small expos- ur:es and scattered fragments of. slate, most of which is wrinkled and not a1tr'active in In a small branch to the of the '' ,',: -~--"' ,, l ., ! .~'~' __ , appea~ance. ~~-- .-.~{;,~: ~.~--~~-- --.:~ l '-:-~--,t . . . . ~~outh western open~g there is an expqsur~. of slate fo:r.a distadce of several hundred !~et, ending in ~ loc~ f~Id i~ which large masses of quartz are'developed and the cleavage is badly wrinkl~d.. On the: east side of the .ridge slate is exposed in a small draw ~lmo~t continuously for a d. i st an " c e .... of '550 feet in a . direction N. 85 W. . Measurements of strike and dip are as follows: East slope: Oleavage: Strike N. 11 E., dip 59SE. Joints: (1) Strike N. l1E., dip H 0 SE.. Strike N. 2W., dip H 0 NE. Strike N. 89W., dip 80NE. West pit.: . <;Jle~vage: Strike N. 16~E., dip42 6 SE. The altn.ost horizontal strike jbints of series (1) are mcist promi- nent, cutting the slate into blocks 20 to 5 feet long. The bedding is much distorted, and fine ribbons in various directions are present. SLATE DEPOSITS OF GEORGIA PLATE Vlli A. EXPOSURE OF GREEN SLATE ALONG THE ROAD JUST EAST OF BOLIVAR, BARTOW COUNTY, SHOWING A FOLD AND A SMALL FAULT IN THE CLEAVAGE. B. EXPOSURE OF GREEN SLATE IN THE LOUISVILLE & NASHVILLE RAILROAD CUT NEAR THE CARTERSVILLE POOR FARM, ONE MILE NORTH OF WHITE, BARTOW COUNTY. SLATE DEPOSITS OF GEORGIA 121 The slate from this property, in general, is grayer with less of a green tint than most slates of the belt. Most of it is soft, evidently containing more calcite than the average, and would therefore be likely to fade and disintegrate. A great deal has false cleavage or incipient jointing a'lt a small angle to the true cleavage, which would make splitting impossible, and wrinkled slate with calcite and quartz stringers is abundant. Small, porphyritic, dark colored crystals of chloritic mineral, elongated in the direction of the grain are present, as in most slates from this portion of the belt. The beds of slate on this property have suffered considerable disturbance subsequent to the development of the cleavage. This secondary movement has rendered a large part of the slate unsuitable for Commercial use. Careful prospecting would be necessary to determine the location and extent of workable slate. WOODY PROPERTY (Map loe-ality 10) The property ofL. D. Woody is on lot 145, 23d district, 2d section, on the northern boundary of Bartow County. There is a pit 20 feet square and 10 feet deep on the west s.ide of a small branch which :flows north. Good slate was found in the bottom of the pit, which was filled with water when visited. Slate is also exposed in the branch, where it preserves its green color in spite of the effects of the weather, but red specks, probably due to oxidation of pyrite, are abundant. The bed of splitting slate can not be very thick, and the location is not favorable for quarrying. The valley bottom, where the slate is ex.: posed, is 100 yards wide, with a hill of limestone to the west and a hill of knotty, wrinkled, calcareous slate to the east. GORDON COUNTY STARKWEATHER PROPERTY (JJiap locality 11) J. W. Starkweather, of Knoxville, Tennessee, owns lot 249, 6th district,. 3d section, 160 acres, and 20 acres at the northwest corner of lot 122 GEOLOGICAL SURVEY OF GEORGIA 264. The property is situated on :Pinelog Creek, on the southern boundary of Gordon County, and 4 miles in an air line southwest of FairmoUJ1t. The exploration pits a:re along Pinelog Creek south of the public road. Pit No. 1, the southernmost west of the creek, is th~ largest. It is 40 feet long and worked in 6 to 8 feet, showing about 25 feet of slate at right angles to the cleavage. The bottom of the pit is at creek le:v:el. ;Most of the slate shows excellent straight cleavage, but some is knotty and finely wrinkled. The bedding is obscure but there are some indistinct ribbons making angles of 15 to 20 with the cleavage. Pit N(). 2 !s 14 feet north of No. 1. It' is a small opening exposing 8 feet of slate which is very fissile, with clean, straight cleavage. No ribbons nor w.rinkling were seen. Pit No.3, about 150 feet north of No.2, is a small opening in a draw about 15 feet above creek level. It shows some good splitting slate about 8 feet below the surface. Pit No. 4, 75 feet north of No. 3, is a.small opening about 8 feet above creek level. The slate does not appear so good as in the former op-enings: Pit No. 5 is a...small o:peni.g jn a ~uciace outcrQ]) _about 150 feet north of'No. 4. Fit N-o; 6 is a s:inali opentng,on the e~:~st side of the .cr~ek at about the same horizon as the southern pits rwest of the creek. It shows some good slate. The cleavage is fairly uniform and a number of measurements show a variation in strike from N. 20E. to N. 32E., dip 27 to 53SE. The bedding in the slate is hardly distinguishable, but limestone beds strike N. 25E., and dip 40SE. at the bridge ovef Pinelog Creek, and strike N.3E. and dip 11SE. at Worley's mail box, 500 yards east of the creek. The most prominent joints in the slate are dip joints, varying in strike from N.55W. to N.76W. and in dip from 75 to 80NE. Several other series of joints are also present, but probably would not cause much loss in the fresh material. Calcite is searce, but quartz is deposited along some of the joint planes. The slate has a good gray-green color, and the cleavage is good, but surfaces are slightly roughened by ''porphyritic'' crystals of dark colored, ehloritie mineral, elongated in the direction of the grain. It is SLATE DEPOSITS Oli' GEORGIA 123 sonorous, and effervesces only very slightly with acid. A few roofing slates have been prepared by G. W. Davis, sho~ring that the working qualities are good, and some of these have remained on a roof for severalye.ars rwithout noticeable fading. There is evidently a workable bed of slate on the property, but exploration to a greater depth by pits and borings is desirable to form an estimate of the quantity. The situation on the steep slope near the creek is not ideal, but the slate and waste could be transported by aerial cable to the fiat area east of the creek mthout great difficulty. A serious handicap, as compared with other properties nearer the railroad, is the haul to F:;Lirmount, more than 5 miles by road. The slate bed, which has been tested on the Starkweather property, also underlies a part of the remaining 140 acres of lot 264, belonging to A. Worley. NEEL PROPERTY (Map locality 12) The property of Mrs. J. W. Neel consists of about 600 acres lying along Pinelog Creek north of the Starkweather and Worley properties, and about 4 miles, air-line distance, southwest of Fairmount. The entire property is underlain by green slates and limestones of the Conasauga formation, but prospecting has been done only on lot 250, 6th dis-: trict, 3d section, near an old mill on Pinelog Creek. Several blasts have been made in the dip slope west of the creek, above the old mill and half a mile north of the Fairmount-Adai:rs.ville public road. These openings show fresh green slate with good cleavage, at a depth of 5 feet. The cleavage strikes N. 40E. and dips 48 SE. The only prominent joints are strike joints at wide intervals, which rwould assist in working. Half a mile down stream, below the saw mill site, there are exposures in the steep banks of the creek. At this point all of the slate is knotty or contorted, with poor cleavage, and much calcite along joints and in the form of nodules and stringers, and some thin beds of limestone. A well at the saw mill brought up fresh green slate, but it is of no value on account of poor cle~vage and calcite nodules. 124 GEOLOGICAL SURVEY OF GEORGIA The cleavage of the slate from the best exposures is good, showing micaceous leaves on fresh s"W'faces.. A part has strong enough grain to be worked by sculping, but some beds show little grain, and must be sawed. .As in most other slates from this part of the green slate belt, there are crystals of a chloritic mineral large enough to he visible to the naked eye. These crystals are elongated in the direction of the grain, and cause a.little roughness on cleavage surfaces. The amount o n1agp.etite, 3.$ revealed by physic~l and microscopic analyses, is very small. Maynard1 gives the following description of microscopic examina- tion: ''Two slides were studied-one cut parallel to cleavage and one perpendicular .to cleavag~. The three principal mineral constituents are muscovite mica (sericite), chlorite, and quartz;. the accessory constituents are pyrite, rutile, calcite, siderite, and a few other minerals which are so rarely found that they do not affect the slate commer- cially. ''The sections s~ow the cleavage to he good and no false cleavage or ribbons were observed. The calcite anq. siderite are very difficult to di~tin,g~~s:J;t,;; hew;~~erlj .~er;(j ~~,~~~9tr~,\~"tt:~di~~e~t s 1n 10'eor@a in Oetober, 1'917. I . THE CARTERSVILLE SLATE'? AS A SOURCE OF POTASH A g;reat many processes for the extraction of po~ash from silicate rock-s and minerals have been devisea: and patented. Abstracts of .anumbel' of the patents are given in a.. previous ;publication of the Geological 'Survey o Georgia.8 The shales and slates of the Cartersville formation are as suitable for these processes of direct extraction of potash .as any other rocks of equal potash eontent. The American Potash Company is now treating this slate on a sma,ll srcale for the extraction. of pDtash alone, but evi- dently themo'st prb:fitable I;ha:t;i::il~r df ;haaid11fig such material would be the manuf'acitt~~ of porti~na eement with recovery of the potash as a hyprouuct. The following riotes on the recovery of potash from dust from ce- ment works were supplied by Mr. A. W. Stockett, of the United States Bureau of Mines: 1Erom ~' Pt~fea,:sJi \i'S:;nf>w 'beln;g 'Iie~t:Jv-ereil if-Tom ~'tlie'\aust-~ ;eem'ent kilns m: ai a l1'11mlBe:r ef,];)ian't~,. rrhe priudipal on:e the east 1:s -a;tthe J)lant of t-he .JSBcuii:'ity 0em~n%,;&lliiim!~ fDo'mrpinyLnBa~r~!Ht:ligerst{l)WD:;' 1Macyland. I At thi~ plant the dlitiSt' is 'r-eeov.er.ed hy meaELS of t'fi-Oentre11 e'i:eetrie pT.ecipiilator. .Sittll:!liaall! p'lan:ts a'X~ ijjcing instllilled. flit,.: N21za:'re'i}n, PJeiln:- sylvania; Ironton, Ohio ; Newa:go, Michigan; and Kingsport, Tennes- s'ee~ 'ilrhe r.eBuilts oibta:ined at Se:eurrity- have been vecy sat:i~fa>etory !ffi:El:'an:~ dally, :as the entlire cost of tlae plant was :vetrurned from the pr:olfits o ti!w &st year's i()J)).eiration. It is estimated th.:at p.otash ellill b:e produeed at less than 60'cents per unit (20 pounds) of K 2D, which is less than the pr,e-waf' price. ''It would be very useful tL W4. B.G.. 10, .P i>Ml,. Oct. 1\3,, 1.917. 2 The term "slate" as used in t:lie followi.ng descriptions, refers in general to b0th .SJa!f:e and Shaie of thie Carter,sviiH:e formation, a-s d 56':'73 . .:.A:1umirra :ci.iuQ'J ~ ... ; ...:..... ~ ......... -...... .'... . 19~27 ..... , t ~"~~trf;r~Mi,~~i):(%~,~ffi?),;r._.,,.,...... .. ...; : 5.:5'7 ...... . Fer.rous, oXide (F~o J .............. ......... :1,.89 . ,~~~f~.si~----~~go) ..... :~ ..... ~ ._. ........ :......... . 1.9? ":"' , B1-me : (~0ru0 )~ ................ ; ...................... . .OI- So:da (Na20}............ . ~HotasJi . (~ 2~ )............................... ; ..... . .49 8.85 , .Los13 on Ignition., .................................. 3.77 iv.r'oisture ........................ : ................ . c'arboh ctioxid~ (co,) . ~ ........................ , .. . .38 .oo , T.itaninnt dioxide ( T.iO ) : .88 2 Total ..... ........................ , ............ 99. 77 This analysis meets tb.e. requite~ents of a slate for cem~nt manu- to. facture, having an alurilina siliER.TIES (M:aplocality 19) . The American Potash Company controls thB Pyr~n pr<:>p13:rty of 20 acres,4mil~snorth:of'Gartersville; and the T.: A .. Bennett p:roperty, 8 acres, harlf a: mile SOl,]}trhwres.t .of. White; M:i!ruirig:;has: been done only on the Bennett property. The Bennett property, a part of lot 298, 5th district, 3d section, lies along the Louisville & Nashville Railroad, and. a g~od section of the beds is shown in a railroad cut.. There are 16 beds of purplish, slaty shale totaling about 60 feet, in a total stratigraphic thickness of 250 or 200 feet. The strike varies from N. 45E. toN. 72E., and the dip from 40 to 70SE. The beds o~ bluish slaty shale, which contain the most potash,. are interbedded with light-colored, weathered shale and feldspathic sandstone. There is only one thin bed of true quartzite, which outcrops at the north end of the section. The quarry is in the hill just west of the railroad cut, .where the surface is about 20 feet above the railroad level. The .quarry was opened in April, 1918, and in June the opening was about 200 feet long, 50 feet i The section and a number of ilnalyses were given by Mr. M. W. Hayward and Mr. G. B. Corless, geologists for the American Metal Comp:;~.ny. All analyses were made by Dr. Edgar Everhart. " SLATE DEPOSITS OF GEORGIA 151 wide, and 15 feet deep. Since that date work has continued at an increasing rate. The beds worked are near the center of the section exposed in the railroad cut. The material shipped is selected so as to keep the content of potash above 9 per cent, although it is probable that the average of all beds exposed in the quarry would be about 8 per cent. In the southwest corner of the quarry eight distinct beds are shown. The lowest is feldspathic sandstone, overlain by four beds of good shale (shipping material) with a total thickness of 10.5 feet, and three beds of poorer, - sandy shale (waste) with a total thickness of 8 feet. The remainder of the section across the beds to the railroad is of the same character with beds of purplish, high-potash shale from 1 to 5 feet thick alternating with sandy beds of lower grade. None of the material in the quarry or railroad cut has sufficient hardness and :fissility to be called slate. The following analyses are typical. One is an average of the material shipped, the other is an average sample of the 5-foot bed of hard, feldspathic sandstone exposed in the railroad cut north of the quarry. Several samples analyzed for the company contained over 10 per cent potash. Analyses of shale and sandstone from the American Potash Company property. Constituents. S-511 S-512 Silica (Si0 ) 2 Alumina (Al 0 ) 23 :F'erric oxide (Fe20 3 ) Ferrous oxide (FeO) ................. . Magnesia (MgO) ..................... . Lime (CaO) ................ ." .. ...... . Soda (Na9 0) ... Potash (K 0) ....................... . 2 Ignition ........................ ... Moisture ...................... .... Titanium dioxide (TiO) ............. . Manganous oxide (MnO) .............. . 68.40. 14.44 1 3.58 .56 .20 .00 ) .47 7.77 2.48 . .23 .96 . 62 56.38 17.14 6.56 1.44 3.20 .00 .53 9.57 3.40 .70 .86 tr . 99.71. 99.78 S-511. Feldspathic sandstone, average of 5-foot bed exposed in railroad cut. S-512. Average of material being shipped, Jun.e 10, 1918. 152 GEOLOGICAL SURVEY OF GEORGIA Mining has been done by hand, with horse-drawn drags to move the waste, and the shale hauled to White for loading. The deposit is favorably situated for steam-shovel work, as there is a thickness of several hundred feet 'of high-potash beds, dipping steeply, and forming hills 20 feet or more above railroad level. However, it is questionable whether the cheaper mining method would counterbalance the somewhat higher potash content obtainable byhand working and selection. With soluble potash valued at four or five dollars a unit, and while working on a small scale and selling the product without leaching and concentration. of the potash salts, a considerable additional mining cost is justified in keeping the potash content of the raw material, and hence of the finished product, a per cent or more higher than the average. .BELT BETWEEN CARTERSVILLE AND WRITE .Along the belt of outcrop of the Cartersville formation between' Cartersville and the .American Potash .Company mine almost no exploration rwork has been done, but a number of samples showing the general character of the formation have 'been analyzed. In and near Cartersville the formation is made up of _sandy material and weathered shale, with.little.prospect of hig}f.-po:tash materiaL Going north from Cartersville, the first high-potash sample was taken at a point one mile north of the city limits: From this point northeastward to White the formation becomes more slaty, and the sandstone beds have determined the location of a number of prominent hills. .Analyses of all samples from the Cartersville-White belt are given first, foll01wed by brief notes on the localities. Partial anal;yses of samples from the slate b~lt befnv.~en OartersviUe and White. Constituents. 1:3-497 Soda (Na20) ........... Potash (K20) .......... .55 9.00 Constituents. S-496 S-498 Ru-359X Soda. (Na 0) 2 Potash (K 0) 2 0 0 ..... 0 4 " 0 0 0 .44" 9.04 .08 .54 6.96 10.10 SLA1'E DEPOSITS OF GEORGIA. 153 S-497. Tennessee road, 1 mile north of Cartersville city limits. 1. B. F. Gorman property, lot 202, 5th district, 3d section. Sample sent by J. T. Norris. Hu-372-X. F. E. Matthews property, lot 230, 5th district, 3d section. Sample collected by J. P. D. Hull. Hu-358-X. Mrs. Joe G. Green property, lot 229, 5th district, 3d section. Sample collected by J.P. D. Hull. S-496. From the prominent hill 1 mile southwest of White. S-498. Tennessee Road near overhead crossing of L. & N. Railroad, 1 mile south of White. Hu-359-X. E. W. Hicks property, lot 299, 5th district, 3d section. Sample collected by J. P. D. Hull. The first sample (S-497) was taken from an exposure beside the Tennessee Road at the crossing of a branch a mile north of the Cartersville city limit and probably on lot 194, 4th district, 3d section. The exposure, of which the sample represents an average, shows 25 feet stratigraphically of light gray, partly weathered shale, of which only 1 foot is hard enough to be called slate. The cleavage strikes N. 15 o E. and dips 60SE. Lots 202, 230, and 229, from which the next three samples were taken, are in a hilly area west of the Louisville & Nashville Railroad and 5 miles due north of Cartersville. The Cartersville formation here contains some sandstone lenses which form the back-bones of hills over a hundred feet high, but there are also beds of slaty, high-potash shale. Sample Hu-372-X represents a thickness of 15 or 20 feet of beds of gray slate, alternating with gray or yellowish shale through a thickness of 35 or 40 feet, exposed in a ditch. The strike is N. 45 E., with a steep dip to the southeast. Sample Hu-358-X is from the next land lot to the north, from an exposure north of the public road and east of a branch of Pettit Creek, near the residence of J. C. Carson (colored). The sample represents a 12-inch and an 18-inch layer of purplish shale separated by 20 feet of alternatfng layers of gray and yellowish weathered shale and sandy shale. The strike is N. 65E., dip 55SE. Sample S-496 is from the hill south of the Grassdale road a mile southwest of White, and on lot 262 or 263, 5th district, 3d section. No exposures of rock in place were found on the hill, which is largely covered with fragmental sandstone. The sample was taken from fragments of gray slate float which are found over a considerable area near the summit of the west slope of the hill. 154: GEOLOGICAL SURVEY OF GEORGIA Sample S-ZJ-98 represents 10 feet of beds exposed in the road cut on the Tennessee road just north of the overhead bridge of the Louisville & Nashville Railroad a mile south of White. All. of the material is much weathered and clayey in appe-arance, so the potash content of nearly 7 per cent is remarkably high. The beds strike N. 45E., and dip 50SE. Samp~e Hu-359-:X is from the E. W. Hicks property, lot 299, 5th .- district, 3d section, just south of the American Potash Company quar- ry. 'J..1he shale is exposed in a road cut and in several small pits, from one of which the sample was taken. \ BELT NORTHEAST OF WHIT:B1 . The slate belt from White northeast to the place where it is cut off by the Cartersville fault varies from half a mile to a mile in width. No exploration work has been done, excepting on the Yancey and McMillan properties. Partial analyses of a number of samples rom road cuts and natural exposures are listed below, followed by brief notes on the localities. Partial analyses of samples from fh;e slate belt nor-theast of White. Constituents S-477 1 S-483 S-515 S-484 S-487 S-296 Potash (K 0) ... .51 .46 .. 2 Soda (Na 0) 2 9.44 5.48 " .20 .53 .18 .16 .36 8.02 7.61 8.40 8.35 8.64 S-489 Soda- (Na 0) ...... .15 Potash 2 (K 0) ..... 7.84 2 S-490 I S-495 .52 .54 7.22 7.92 2 S-295 .39 .19 8.38 8.86 S-494 .37 7.34 Complete aJJt(J;lysis of sample S-296. Silica (Si0 ) 2 ..Alumina (A1 0 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 Ferric oxide (Fe 0 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 R Ferrous oxide (F'eO).............................. 55.25 20.60 6.40 2.01 SLATE DE-POSITS OF GEORGIA 155 Magnesia (MgO) ................................. . Lime (CaO) ...................................... . Soda (Na20) ...... . ... Potash (K.,O) .................................... . Ignition . : . ...............................,....... . Moisture ........................................ . Titanium dioxide (Ti0 ) ..... 2 1.98 .00 .36 8.64 4.17 .34 .96 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100. 71 S-477. 1. S-483. S-515. S-484. S-296. S-487. S-489. S-490. S-495. Pinelog. 2. S-295. S-494. Railroad cut Ph miles east of White. Dysart property, lot 217, 22d district, 3d section. Near residence of 0. J. Smith, lot 319, 22d district, 3d section. Road cut 2 miles east-southeast of Pinelog. Junction of Sugar Hill road and Pinelog-Waleska road. Pinelog-Waleska road 2:lh miles east of Pinelog. Pinelog-Waleska road 2:lh miles east of Pinelog. Pinelog-Waleska road 2lh miles east of Pinelog. Pinelog-Waleska road 2:lh miles east of Pinelog. One-fourth mile north of Pinelog-Waleska road 2:lh miles east of Rufus Jones property, lot 294, 23d district, 2d section. Rufus Jones property) lot 294 23d district, 2d section. Mrs. L. J. Bradley property, lot 283, 23d district, 2d section. Sample S-477 iWas taken from a small exposure in a cut on the Iron Belt Railroad 1~ miles east of White. This locality is east of the principal high-potash slate deposits, and may be only an outlier. The hill just west of the exposure is covered by fragments of quartzite, of which some masses appear to be in place. The Dysart property, lot 217, 22d district, lies west of the McMillan property, and is largely underlain by the Conasauga formation, to which the shale (No. I) containing 5.48 per cent of potash may belong. The Louisville & Nashville Railroad cut just southwest of the Cartersville Poor Farm is near the southwest corner of this lot. The slate exposed in the cut is a typical green slate of the Conasauga formation, and an average sample contains 2.75 per cent potash and 1.47 per cent soda. Apparently the whole of the prominent hill just east of the railroad is of similar material. Sample S-483 represents about 6 feet of beds exposed on each side of the public road in front of the residence of 0. J. Smith, just north of the crossing of Little Pinelog Creek. The material is a weathered shale 156 GEOLOGICAL SVRVEYOF GEORGIA of clayey appearance, and the potash content of a little over 8 per cent is remarkably high. .A sample collected by M. W. Hayward from a corn field on the same lot contained 8.30 per cent potash. SampleS-SIS is from an exposure in a road cut a mile east of Rydal, and near the western boundary of the Cartersville formation area. These beds extend through the prominent hill south of the Sugar Hill branch of Pinelog Creek, but t:q.e formation in this hill seems to consist largely of sandy or quartzitic beds. Baker property.-Dr. T...: H. Baker, of Cartersville, owns a great deal of property in the northern part of the Cartersville slate belt, including the following 160-acre lots: . 321, 320, 319, and 318; 23d district, 2d section; 252, 254, 255, 256, 257, 283, and 284, 22d district, 2d section. Exposures along the Pinelog-Waleska road, which is shown on the Bartow County map as crossing lots 293; 294, and 295, 23d district, 2d section, are also said to be on properties belonging to Dr. Baker. Going east on the Pinelog-Waleska road from the Tennessee road there is a considerable area of calcareous shale and impure, magnesian 1imestcme, evidently belong to the Conasauga formation, and yielding a dark~red soil. . ' .At the top olf the hill east of ;tJie Sugar Ni1LEork of Pinelog Creek, the boundary between the Conasauga and Cartersville formations is crossed. The field at the top of the hill is covered wit)l sandstone float, .and in front of the house north of the road and 0.5. mile east of the creek is a well from which both sandstone and gray' slate were taken. (Maplooality 20.) Sample S-487 is an average of the slate fragments on the dump at the well. Starting down the east slope of the hill, 220 yards east of the well is a bed of.:gray slate exposed in the roadside cut. The cleavage strikes N. 47E. and dips 60StE., and the thieknessof the mass o:f practically fresh slate is about 75 feet across the cleavage, that is to say, one of the thickest continuous gray slate beds in the district. Sample S-489 is an average of the entire thickness, while sample S-296 represents only, the hardest beds. .An average sample was also collected by M. W. Hayward, and showed 8.02 per cent potash. This slate would not be suitable for roofing on account of ''false'' and irregular cleavage. It con- SLATE DEPOSITS OF GEORGIA 157 tains a considerable amount of finely crystalline hematite, which gives it a purplish color. This excess of ferric oxide seems to be the principal rea_son for the potash content falling about one per cent lower than that of the gray slates .farther south. For 90 yards eastward and down the slope from this bed of slate is much-weathered, clayey shale. At this point is a 7-foot bed of hard, fresh, blue-gray slate, striking N. 44E. and dipping 38SE. From here on down to the foot of the hill to the east are exposures of much weathered shale with a few thin beds of comparatively fresh shale. Sample S-490 is an average of this entire unit, starting with the 7-foot bed of hard slate and measuring 190 yards eastward along the road. The potash content of over 7 per cent is remarkably high, as most of the material appears to contain no more potash-bearing minerals than any ordinary residual clay. At the end of the section from which the preceding samples were taken a branch road turns north to the Rufus Jones residence. Two hundred yards north of the main road is an area of about an acre thickly covered with gray slate float in a cultivated :field. Sample S- 495 is an average of this float. Half a mile east of these exposures, at the junction of the Pinelog- W aleska road and the Sugar Hill road, is the exposure from which sample S-484 was taken. The sample is from a 3-foot bed of partly weathered gray slate, rwhich forms an open syncline, with the axis striking northwest. The overlying and underlying material is softer and more weathered. A short distance east of this locality is the eastern boundary of the Cartersville formation, but the Beaver limestone and the Weisner quartzite are exposed up the valley of Pinelog Creek as far east as Martins Mill. Jo1~es property (Map locality 2I).-Rufus Jones owns a part of lot 294, 23d district, 2d section, lying north of Dr. Baker's property along the Pinelog-Waleska road, 3 miles east of Pinelog. The property is now (1918) controlled by the Vithumus Company. Sample No.2 in the preceding table was sent in by Jones. S-295 was collected by S. W. McCallie and the writer from an exposure along the road just east of Jones' house. Good beds of high-potash slate strike northeast through the property, with exposures along the north- 158 GEOLOGICAL SURVEY OF GEORGIA south public road and in the hills both east and west of a branch of P.inelog Creek. Bradley property.-Mrs. L. J. Bradley owns- lot 282 and the east half of lot 283, north of the Jones property. The slate beds from the Jones property continue northeast onto these lots, where they are cut off by the Cartersville fault. The prominent hills in the northeast part of the Bradley property are made up of the early Cambrian "mountain rock.'' Farther north the Conasauga formation abuts against the "mountain rocks" along the great fault, the Cartersville formation oeing cut 01:!-t entirely. Hample S-494 is from an exposure in a gully on the Bradley property about half a mlle northeast of Rufus Jones's residence.- The sample represents 10' feet of beds of greeniSh-'gray :slate. This. slate resembles some portions of the Conasauga formation in appearance, but. its high~potash content. indicates that it belongs'. to the Carters- ville for:rilation. DEPOSITS NEAR CASSVILLE Belts of the Carters:cille .formation containing much high-potash material' outcrop' along the' tliree1par:allel, nor-theast:tre:riding. ridges southeast of Ca.Ssville: The three belts are each about 2 miles long, and are united into a single broad area at.tlie north. Thevalley-s Between the ridges are covered with residual soil and transported material whose charact~rindicates'that it is underlain by limestone. Most of the sarriples analyzed have been taken from a group of properties from 1 .to 1Yz miles southeast o.f CassVille. All of these partial analyses are here listed, followed by brief notes on the properties. Partial analyses of slate from the vicinity of OassviUe. Constituents S-491 1 2 3 4 5 6 Soda (Na 0) .. .80 .25 .19 .76 .36 .16 .27 2 Potash (K 0). 9.12 9.00 8.96 9.16 7.56 8.34 7.60 2 SLATE DEPOSITS OF GEORGIA 159 Constituents S-492 S-493 7 8 9 10 11 Soda (Na 0) .. 2 .35 .57 .14 .55 1.57 .37 .87 Potash (K 0). 2 10.08 6.86 10.20 6.98 8.38 9.85 9.29 Constituents 12 13 Hu-372 Hu-373 Hu-374 Hu-375 S-519 Soda (Na 0) .. .34 2 .36 .41 .22 .89 .87 .20 Potash (K 0). 7.99 5.37 5.48 6.14 7.02 5.76 7.08 2 S-491, 1, 2, 3, 4, 5, and 6.-G. H. Headden property, south half of lot 130, 5th district, 3d section. S-492, S-493, 7, 8, and 9-J. H. Walker property, north halves of lots 130, 159, and 166, 5th district, 3d section. 10.-Lot 159, 5th district, 3d section. Sent by J. T. Norris. 11, 12, and 13.-W. W. Daves property, parts of lots 159, 160 and l66, 5th district 3d section. Hu-372, Hu-373, and Hu-374.-M. L. Johnson property, lots 124 and 125, 5th district, 3d section.. Hu-375.-Lot 127, 5th district, 3d section, %, mile east of Cass Station. S-519.-Isolated exposure on public road 2 miles northwest of Cartersville. Headden property (Map locality 22).-The property of G. H. Headden, of Cassville, consists of 60 acres in the southern part of lot 130, 5th district, 3d section. This lot includes a part of the western of the three slate ridges, along the middle public road leading eastward :from the Dixie Highway between Cass Station and Cassville. Sample S-49I was taken at the top of the ridge near the public road. It represents 5 feet of actual outcrop and float slate :for a distance of 100 feet down the east slope. In the outcrop the cleavage strikes N. 43E. and dips 46SE. There are also small outcrops of sandstone and much sandstone float along the top of the ridge. Samples Nos.1 and 2 were sent in by Headden, and Nos. 3, 4, 5, and 6 were collected by S. W. McCallie. All are from natural exposures on the property. No exploration work has been done on the property to show thickness and continuity of the high-potash shale beds, but the natural exposures are rather extensive, and the situation is very favorable for working. 160 GEOLOGICAL SURVEY OF GEORGIA Walker property (Map locality 23) .-The property of J. H. Walker consists of 255 acres in the north portion of lots 130, 150 and 166, 5th district, 3d section. The property lies north of the Headden property. Its maximum length from east to west is 1~ miles aud it extends across both the western and middle slate ridges. Sample S-492 is from an exposure in a gully near the bottom Q.f the east slope of the rwest ridge."' The sample is an aver~ge of all the beds . . . -~ . of greenish and purplish slate which make up about half of an interval o'60 feet across the .cleavage. The other b~ds of the exp~sure are mor~ orlesEf feldspathic sandstone. The cleavage strikes N: 40 to 50E. and dips 3.5 to 60SE. . . . Sample S-493 is an average of a 6-foot and an 8-foot bed of p:Ur- p1ish.:.gray slafte exposecfhigher on the siope, along an abandoned road rwhich crossed asaddle in tb,e ridge. S~:r;nple No, ?'.:was taken by 1V.Ir. walker .from 'a naturai exposure near tlie' foot of tlie west ~lope. of the 'w~st ridge, and' this sample has. a higher pot~sh contetit than any other coilected from the Cartersville formation up to the present time. Sam- ple No. 8 is a feldspathic sandstone from the west ridge, .and No. 9 is from an exposure on the middle ridge. .Although: no explorat1on wo'rk' haslJeen done on this property', the indications are that the rwest ridge, which is between 100 and 150 feet 'high, consists larg6~Y of slate or. shale containing from 7 to more. than 10 per cent potash. The situation is very favorable for steam shovel 'working,. and a spur track cou1d be built up the level valley from Cass Station on the Western & Atlantic Railway, a distance of 2 miles, ~thou~ great trouble or expense. Daves. p~operty (11Iap locality 24).-W. W. Daves, of Cartersville, OW'P-S parts. e-f, lot~ .159, 16Q,. and 166, 5th district, 8d section. This pr~p'erty is oll, 't~e mi~cn~ siate ridge, east of theHeadden and south of the Walker properties. Saniple No.10, -takeriby J. T. Norris, is from lot 159, but may be from either the Walker o'r Da~e.s property. Nos.. 11, 12, and 13, col- -lected by W. W. Daves, are from lots 159, 160, and 166; respectively. johnson property (Map .locality 25) .-M. L. Johnson owns lots 124, 125, 128, and 129, 5th district, 3d section, a total of 640 acres, including SLATE DEPOSITS OF GEORGIA PLATE X I A. LOOKING EAST FROM THE TENNESSEE ROAD NEAR THE CARTERSVILLE POOR FARM, BARTOW COUNTY, SHOWING PINELOG MOUNTAIN WITH FOOTHILLS FORMED BY THE CARTERSVILLE FORMATION. B . SLATE MINE OF THE AMERICAN POTASH COMPANY, NEAR WHITE, BARTOW COUNTY. SEPTEMBER, 1918. SLATE DEPOSITS OF GEORGIA 161 all of the west shale ridge south of the Headden property. Samples were collected by J.P. D. Hull. Samples Hu-372 and Hu-373 are gray slates from exposures on the west and east slopes of the ridge, respectively, on lot 124. Sample Hu-374 is from lot 125. These samples all run considerably lower in potash than those from properties farther north, but they may not represent the best beds on the Johnson property. Other exposures.-Sample Hu-375 is from a small exposure on lot 127, 5th district, 3d section, three quarters of a mile east of Cass Station, and near the south end of the middle slate ridge. Sample S-SI9 is from an exposure on a public road 2 miles northwest of Cartersville, and probably on lot 162, 4th district, 3d section. This exposure is on a shale belt running northeast toward Wyvern, and apparently isolated from both the main Cartersville and Cassville areas, but its high potash content indicates that it also belongs to the Cartersville formation. DE~POSIT'S NEAR GIMSSDALE The following is a list of partial analyses of high-pota~h shale taken near Grassdale, followed by brief notes on the properties. Padia~l aJnaliyses of slate from the vicinity of Grassdale. Constituents S-516 S-517 S-518 1 2 3 S-513 S-514 Soda (Na 0) .. .75 .51 2 .38 .40 .35 .32 .40 .78 Potash (K 0). 2 4.22 8.68 9.39 7.94 9.45 9.17 7.55 6.66 S-516, S-517, S-518, 1, 2, and 3.-W. W. Carpenter property, 1 mile west of Grassdale. S-513.-Public road lf.J mile south of Grassdale. S-514.-Public road ~ mile east of Grassdale. Carpen,ter property (Map locality 26).-The property of W. W_ Carpenter consists of 50 acres in lot 191, 5th district, 3d section, a mile west of Grassdale. This property is approximately at the northern extremity of the Cassville belt of the Cartersville formation. 162 GEOLOGICAL SURVEY OF GEORGIA Samples Nos. 1, 2, and 3 were sent in by Mr, Carpenter; samples S-516, S-5!7, and S-518 were taken by th.e writer from approximately the same locations. S-516 and No.1 are from fragments of feldspathic sandstone from a cultivated :field south of Carpenter's residence~ S517 and No.2 are from a bed of slaty shale crossing the road and :field south of the house. 8,518 and No. 3 are from exposures along the ascent of the hill several hundred yards farther south. The material of tlie Cartersville formation on this property is a hard, rough shale with poor cleavage. In appearance it resembles some of the crucareous shale beds of the Conasauga formation, but the analyses show it to be as high in potash as the more micaceous and slaty phases. No exploTation work has been done to show the extent and thickriess, but the same material evidently extends southwestward alori.g the three parailel ridges to the vicinity of Cassville. Other exposures.-Samples S-513 and S-514 are !rom exposures on the public roads, respectively half a mile south and hal:E a mile east ly come from an isolate belt of Cartersville slate, somewhat mo:t:e than ly come from an isolated belt of Cartersville shale, somewhat more than a mile long and several hundred yards wide, entirely surrounded by limestone. I CASS STATION AND LOCALITIES FARTHER WEST The following is a list of partial analyses of samples of slate or shale with high potash content, taken near and west of Cass Station. Partial analyses of slate from the ticinity of Cass Station. .. ' Constituents S-499 1 2 3 4 5 Soda (Na 0) ...... .53 2 .54 72 .56 Potash (K 0) ..... 2 7.78 4.88 4.64 5.59 .45 .40 4.27 9.58 S-499. From greenish shale float on the northern slope of Walker Mountain Ph miles west of Cass Station. 1. Lot 91, 5th district, 3d section. Sent by J. T. Norris. 2. Lot 126, 5th district, 3d section. Sent by W. T. Gaines. 3. Lot 126, 5th district, 3d section. Sent by C. S. Cox. 4. Lot 126, 5th district, 3d section. Sent by Western & Atlantic Railroad agent, Cass Station. 5. Lot 287, 4th district, 3d section. Sent by C. C. Brown. SLA1'E DEPOSITS OF GEORGIA 163 Lots 91 and 126, 5th district, 3d section, include Cass Station. The shales from these lo~s and from the north slope of Walker Mountain are greenish, and evidently belong to the Conasauga formation. Their potash content averages higher than that of most of the Conasauga green shales, but not quite as high as that of the typical Cartersville shale and slate. The high potash content is not especially remarkaole, because depositional conditions must have been very similar while both formations were being laid down, and some parts of the Conasauga formation may be found considerably above the average in potash. Sample No. 5 has an extremely high potash content, and comes from lot 287, 4th district, 3d section. This lot is 5 miles in an air-line west of Cartersville and 3 miles southwest of Cass Station. This locality is far west of the previously recognized areas of the Cartersville formation, but the high potash content of the sample indicates that it comes from that formation. The area is probably an outlier produced by folding or faulting and there is a possibility that others may be found west of the explored deposits. THE SERICITE SIGRIST DEPOSITS OF PICKENS OOVNTY. 165 APPENDIX THE SERICITE SCHIST DEPOSITS OF PICKENS COUNTY INTRODUCTION Before the discovery of the high-potash slate and shale of the Cartersville district, the sericite schist deposits of Pickens County had attracted attention as a possible source of potash. .A brief description of the deposits was published by Hopkins1 in 1914. Since the publication of that report the deposits have been examined in more detail by members of the State Survey, and the material has been mined on a small scale by several companies. In 1912 four carloads of sericite from lot 121 were shipped to Hewitt, North Carolina, where it was ground and marketed under the trade name '' pyrophyllite. '' During 1915 and 1916 a small quantity was mined from lot 120 by the .American Mica Company and ground at the plant in Canton, Georgia. The .American Mica Company has for several years mined chlorite schist in Cherokee County. This material is finely pulverized and sold under the name of ''ground mica'' for use in foundry facings, elect11ical insulation composition, etc. The sericite was probably put to the same uses. In 1917 the deposits on lots 97 and 99 were opened by the .American Potash Company. These are the largest workings in the district. The material was shipped to Portland, Georgia, and treated by a process which renders the potash available. (See p. 136.) The mines were abandoned when the company started to work the high-potash shale of the Cartersville district. The deposit on lot 118 was :Fgiira'l se:aim_eifts: Ali of the rocks show the effects of at least two periods of ..disturbance, one of w. hich p:r;.6auc~d . ' . ,. t.h:~e .. . $.ch...f. ~t~~e \ ~r ~laty . . texture, " and later. mo~e~ents threw the original cleavage planes into folds, with development of con- spicuous false cleavage. The sericite district is in the Piedmont PlJteau .physiographic division, buti~ within a;few miles o t1;J.e southern end.ofthe Blue Ridge escarpment. This part of the Piedmont has rugged and broken to- pbgraplif. Th_e sericite depositS are at an 8ltitude o about i5oo feet above sea level, ap.d the -relie in the se.ricite district is about 500 feet, but Sharp Mountain; one mile west of the deposits, rises to an altitude of ~ore tha.n 2,400 feet. The two roads to Jasper are both.hilly and unimproved, making the haul of 5 or 6 miles to the railroad expensive and, in 'Wet weather, very difficult. Building a railroad or tramway to 1 Safford, J'. M., Geolog;y of Tennessee, 1869. .... SLATE DEPOSITS OF GEORGIA PLATE Xll A . SERICITE SCHIST, "PIT NO. 7," L OT 1 20, 13TH DISTRIC T, 2D SECTION, PICKENS COUNTY. B . SERICITE SCHIST, "PIT NO. 8," LOT 1 20, 13TH DISTRICT, 2D SECTION, PICKENS COUNTY. THE SERICITE S!CHIST DEPOSITS OF PICKENS COUNTY. 169 connect with the Louisville & Nashville Railroad at Jasper or Tate would be expensive, on account of the broken topography. CHARACTER OF THE MATERIAL PHYISIUAL UHARAUTERISTIUS The sericite schist has a pale apple-green or bluish-green color, with silvery luster and perfect cleavage. It is soft enough to be easily cut with a knife, and thin damp pieces are slightly flexible. When rubbed between the fingers it has a smooth, greasy feel, like flake graphite. The material was for a long time mistaken for talc, which it resembles, but the sericite is slightly harder and has more perfect cleavage than talc. The pure sericite is associated with and grades into sandy sericite schist, schistose quartzite, graywacke, and soft, white, sandy, kaolinic or feldspathic schist. Descriptions of thin sections of these materials examined under the microscope are given below. Specimen S-207.-This is a very pure sericite schist, containing ex- 10.90 per cent K 20, from lot 120. The cleavage is straight and ceptionally good. Under the microscope the section appears to consist almost ent~rely of sericite. The whole mass acts practically like a homogeneous crystal of mica. The section, cut oblique to the cleavage, gives a perfect interference figure with small optic angle. Besides the sericite flakes making up the closely inter~woven texture of the rock, there are a few larger, porphyritic muscovite crystals cutting across the schistosity. One of these measures 0.06 by 0.60 mm. There are a few very :fine grains of quartz, most of which are elongated in the same direction as the mica flakes. Some of these grains show strain effects under crossed nichols. Chlorite occurs in very small greenish scales. This mineral eVId-ently gives the green color to the rock. Small rounded grains of zircon are present. The largest are observed measures 0.03 mm. in diameter. 170 GEOLOGICAL SURVEY OJJ' GEORGIA Extremely fine needles of rutile and dust-like grains of opaque minerals, hematite, ,magnetite, or ilmenite, are just visible under the highest power of the microscope. Feldspar is probably present in the mass; but it could not be identified as distinct mineral grains. Specimen S-2Io.-This is a sericite schist, containing a very little grit: from lot 119. Ithas especially well developed faise cleavage along ,Planes spaced about 10 to the centimete~;- and making an angle of '20' to 45- de~ees: with- thi .schistosity, causing the rock to break into rhombohedral blocks. Under-the microscope the rock is seert"to consist almost entirely of sericite in parallel scales. The scales, ho~ever, are bent into mono~ clinal folds along the planes o-f false cleavage (See Plate XIII., A and B). Quartz is more abundant in this section than in S:.2o7, but still it makes up a very small proportion of the mass. Most of the quartz grains lie along certain bands. The largest grain noted measures 0.09 by 0.15 mm. The section includes a rectangular area measuring 0.64 by 2.60 mm. of kablinie materiaL The area probably represents an original feldspar crystal, and consists partly of sericite; with kao-linized material in irregular areas. The kaolinic materialis-massive o1> cryptocrystalline with abulldant specks of opaque minerals. The sericite flakes are oriented parallel with those of the ground mass. Specimen S-22I:-This is:a soft, cream-colored, feldspathic schist from lot 9.7 ~r .98._ :This material is kaoliriic in appearance, alth?ugh the analysis-shows 'that it contains 4.71 per cent K 20. The mate:dal is powd.ery, so no .section IWa_s cut, but the powder was examined under the microscope. Quartz is the most abundant mineral; and occurs 'in fine grains, both. rou~ded .and a:rigclar. The largest grainsme:asure 0.02 ~~-in diameter, but most grains are much SJ::naller. Feldspar occurs in angular grains, mostly cleavage plates with faces almost at right angles. Th'e surfaces are rough and corroded, due SLATE DEPOSITS OF GEORGIA PLATE XIII A.. SECTIO.N S-210. SERICITE SCHIST FROM LOT 119, SHOWING FOLDING OF THE ORIGINAL CLEAVAGE PRODUCING SEC ONDARY OR F ALSE CLEAVAGE. TRANS MITTED LIGHT. MAGNIFIED ABOUT 13 DIAMETERS. B. SECTION S-210. SAME AREA AS A. CROSSED NICHOLS. MAGNIFIED ABOUT 13 DIAMETERS. C. SECTION H -71. QUARTZITIC SERICITE SCHIST. CROSSED NICHOLS. MAGNIFIED ABOUT 50 DIAMETERS. D. SECTION 71. Q UARTZITIC SERICITE SCHIST, SHOWING RECRYSTALLIZED QUARTZ GRAINS CUT BY PLATES OF SERICITE. CROSSED NICHOLS. MAG NIFIED ABOUT 130 DIAMETERS. THE SERICITE &CHIST DEPOSITS OF PICKENS COUNTY. 171 to partial kaolinization. The maximum size of the feldspar grains is about tbe same as of the quartz, but the average size is smaller. Very small, colorless, crystalline scales are abundant. They have very low birefringence, visible only with the red tint plate. 'l'hese scales may be both kaolin and hydro-mica, but they are too small to be definitely determined by microscopic tests. There is also a little finely granular, white, kaolinic material, in which no crystalline structure is visible. The only other minerals noted were a few grains of green material, probably chlorite, and a few black, opaque grains, proha.b1y magnetite. Specimen H-42.-This is a quartzitic sericite schist from lot 120. Q11artz, recrystallized in interlocking grains, makes up about 75 per cent of the area of the section; sericite, in parallel oriented flakes makes up hardly 25 per cent. Accessory minerals are rounded grains of zircon, elongated needles of apatite, a brown, slightly pleochroic mineral, probably staurolite, and a little chlorite. Specimen H-43.-This is a slightly schistose graywacke from lot 120. The principal minera.ls are feldspar and quartz, with feldspar slightly predominating. The rock is roughly banded, hut contains only enough sericite to produce a very imperfect cleavage. Most of the feldspar is orthoclase (potash feldspar) ; but there is some plag~oclase, probably albite (soda feldspar) ; and many grains of banded feldspar, apparently a perthitic intergrowth of orthoclase and albite. The orthoclase shows beautifully the alteration of feldspar to sericite. Small scales of sericite are developed along the cleavage planes in the feldspar, and all of the flakes are oriented parallel to the mineral cleavages of the feldspar grains. The largest feldspar grains measure 1.0 mm. in diameter. The feldspar grains are much larger than any of the quartz grains. Quartz occurs in interlocking grains, shorwing much more evidence of recrystallization than the feldspars. Some bands of the rock consist of l'il'2 almost pu.re quartz, and are of .med:ium textu:re, whlle the quartz in the feldspar"rich bands is very finely crystalline. Therte are a few flakes of sericite in the mass of the r{i)ck, but most of the sericitr present oeetirs as an alteration product within or sur- rouB.ding the .fuldspa:r cry-Stals. Sp.ecimen H-7I.-This is a quartz-sericite s!Chist from th:e sericite belt (exact locality not known). The rock consists of about 50 per cent qu.artz and 50 pe,r cent sericite. Both minerals have been completely ;rre{}rystaUized. The quartz occurs chiefly in elongated grains filling spaces between bands of sericite (See Plate XIII., 0). In some planes thEHI'Iliarlz grains are eut by thin :fiakes of serieite {See Plate XIII.,.D).. CHEMICAL AND MINERALOGICAL COMPOSITION AU availalill'HaxJa4. both feldspar and mica are present in such material, and the feldspar greatly predominates, hut the exact ratio of the two minerals is not determinable either by chemical or microscopic analysis. MODE OF OCCURRENCE Most of the. o.eeurrences. of the pu:Ee .sericite s.e?st,. eoloratio.n has, been dcme in the' surroTI.Ikding area, no other deposits of lJ!mre sericite have been found.... The depositsrolf. hig:P..grildE; sericite are.in. thin,, le:aticul~ beGls. The thiekest~mg~ p.ed;1kno:wiEbdS.,,l-Q,,Jreati,b.ut ibe.ds,(JVJel:3 :Eee;trthickane:iiiDusua]:;.?;:p.d, the_. a;v.erage_:thiekn:essjs-probably less_. thaa ~~}V~~'!?- .Pits No. 7 and No. 8 are two small openings exposing. serieite beds 60 feet and . + 200 feet, horizontiealiy, f:r0nt the l:red exposed in the long trench. The thiekness of these upper sericite beds eould not be aeeurately measured ' but is not great. However, the exposures show that beds of pure seri- cite may be expeeted in .this vicinity through a thiekness of more than 100 feet of beds, made up principally of feldspathic or micaceous schists softened by weathering, and including some thin beds of quartz- ite and graywacke. PitNo. 9 is dn. the same side of the branch as No.6, 300 feet north- east of No.7, and at a height of 25 feet above the level of the branch. The wbrk consi~ts princip:ally in st:Hppiiig, but a little sericite has been taken out. A trench has been cut across the bedding, showing excel- lent sericite with a thickness o'r l()' eet, 'measured acto'sr{ihe cleavage. This unii includes only one 6-inch bed of impure material, and is the thickest single bed of pure sericite which has been found anywhere in the district. In the, west end of the opening the strike is N. 50E., dip THE SERICITE SCHIST DEPOSITS OF PICKENS COUNTY. 185 35SE. At the east end the line of strl.ke bends to the north, and the beds dip nearly east. Pit No. 10 is in the west central part of lot 120, about 100 yards from the line of lot 119, nearly half a mile west of the principal workings on lot 120. The pit is in a steep hillside sloping south, near the head of a small hollow. The sericite bed is a little over 3 feet thick, but is impure, containing ferruginous laminae and much granular quartz in some beds. The strike is due east, dip 30 to 50S., a little steeper than the slope of the hill. The sericite lead from this pit passes into lot 119. LOT 119 Lot 119, known as the Kuhtman place, lies west of lot 120. The sericite belt enters the lot near the center of the east side, swings to the south, and passes out of the south side nea.r the southwest corner. The deposit at locality No. 11, near the center of the lot, was worked by J. E. Brantly for the Vithumus Company. Enough sericite to make several carloads has been mined and piled up along the road, but only test shipments rwere made. The sericite piled up is selected material, and may be expected to average 10 per cent potash. Work was done in two pits, one above and one below the public road, which runs northeast to southwest. The upper pit is 25 feet northwest of the road. It has a maximum depth of 10 feet and has been worked for 25 feet along the strike, showing a bed of sericite 5 feet thick, measured across the cleavage. The cleavage strikes N. 55 E. and dips 458E., apparently a little steeper than the dip of the true bedding. The associatedmaterial is weathered to a red clay. The lower pit is just below the road, south of the first, and along the same bed, which also outcrops in the road. This pit is worked 30 feet along the strike. The bcttom of the pit was filled rwith water when examined, but there was a thickness of 3 feet of slightly sandy sericite in sight, striking N. 55E. and dipping 35SE. The sericite from these pits is much wrinkled and contorted by folding after the development of the schistosity, and very perfect false 186 GEOLOGICAL SURVEY OF GEORGIA. cleavage is developed in some portions. Most of it contains granular quartz in q~antity too small to decrease the potash content very much, but the grit would prevent its use as a substitute for .talc or ground mica in lubricants. .A.bou~ 300 feet west of the principal workings is a trench showing somesandy sericite schist and several thin beds of good sericite, none more than a .few inch~s thick. Back of Brantly's camp, 400 feet east of the workings, is another trench showing a 2-foot bed of slightly sandy sericite, striking N. 60E., dipping 45S.E. The associated material is the usual light-col- ored feldspathic schist. " The sericite belt has not been explored southwest of these pits, but farther southwest there is a SJ;Uall exposure of fairly pure sericite in the public road on lot 135. The bed is 12'1ncheEtthick; and. strikes N. 60E. _LOTS :f)7 AN:P 98 'r:ae Ki~- Padg,ett.proper>ty; .late>r; purchased -by,Whlliam: Rrichards, includes :!rot 98 amrd a r>art of lot 97: These- lots: aie norlhwest of the main .seJ!i~i'lle-:be-l~jl~"~J!I.(~,,tktl.Mlepxrs;i~s-~mnm~.t:!Jeilio:Q;go;;ifoi,a;:st~ati:gn&phieally lower bed,.mile8s; thei~~pr~s-~nc~ .is-to he e~plain:ed by'a-large fairlt: The most ex.tensie work:ilm;!:!IJhe1 di'S:t:Pict''wlli~vd01Ee::ttb!fot.J9of llyi't1ie :Ain:etican: Potash Company. PitNo.l2, the mine of the American Potash Company was started at an outcrop of a 3-foot bed of pure, solid sericite schist, 150 feet southQf the-house, which ~s situated near the west line o.f lot 97. There. are three large pits, cbvering most of an area 200 by 300 feet in extent; on the west slope of a hilL There are some thin beds of pure sericite schist with over 10 per cent.potash, but most ofthe material is sandy, rough, and iron stained. The material shipped was not selected with great care; and is said to have ave;raged only a.bout 8 per cent potash. The sericite is interbedded ~i.tp. soft felqspathic schist and hard, quar.tzose gray'wacke. The schistosity dips in various directions, and is folded into small open synclines and anticlines, but on the average it dips to the east' at a low angle, following the slope of the hill. THE SERICITE SCHIST DEPOSITS OF PICKENS COUNTY. 187 .At the top of a hill, about a quarter of a mile southwest of the house, is a pit 6 feet deep. It cuts 3 feet of sericite; somewhat less pure than the original exposure near the house, underlain by soft feldspathic schist (See analysis S-22I). This pit is probably on lot 98. The sericite bed strikes N. 70W. and dips 20NE., less steeply than the slope of the hill, so that it forms only a capping on the upper part of the slope. The sericite bed on the hill may be a continuation of that near the house, but it could not be traced between the two exposures. Near the abandoned ridge road, on lot 98, is another pit 7 or 8 feet deep, cutting white feldspathic schist but no pure sericite. .LOT 99 On lot 99, the Burrell property, a pit was opened by Major George Miles, and about a carload of sericite was shipped by the .American Potash Company. Pit No. 13 is on. the west slope near the top of a ridge, just east of the new public road. The pit is worked in 50 feet from west to east, has a maximum depth of 17 feet, and a width of 15 feet from north to south. .A bed of pure sericite forms a syncline in the east face of the pit. The bed is 2 feet thick on the limbs, but is somewhat thicker at the bottom along the axis of the fold. There are several beds of sericite 2 or 3 inches thick interbedded with the soft schist above the principal sericite bed.. The associated material is the usual soft, white or yellow-stained feldspathic schist. The sericite is much crumpled by the later folding, and is more coarsely crystalline than most deposits. It contains some pockets of vein quartz and is somewhat iron-stained, but the potash content is evidently at least 10 per cent. The fold pitches to the east at an angle of approximately 5, so the sericite should come out lower on the other side of the ridge, which trends northwest. 188 GEOLOGICAL SURVEY OF GEORGIA LOT 84 On lot 84, the Pendley place, a short distance south of the old Pettett Post Office, are several small exposures of sericite schist. The schist is blue-gray in color, impure, soft, and slraty, and seems. to occur in very thin beds in soft white schist, The stratigraphic position is evidently lower than that of the pure sericite in lots 97 and 98. .. INDEX PAGE A Adair slate property ...........111-112 Age of slate ...................... 26-27 Allred place, sericite schist on ..180-182 American Metal Company, Analyses of sericite schist......172-175 137-138, 140, 144, 146 American Mica Company ...... 164, 182 American Potash Company, 132, 136-137, 165, 186-187 properties of ...............150-152 Analyses of slate, 17, 21, 68, 70-71, 77-78, 80, 9~ 98 106, 110, 111-112, 113-114, 117 118-119, 134, 142, 144; 148, 151 152, 154-155, 158-159, 161, 162 Apison shale of Georgia. . . . . . . . . . . . 49 Appalachian Valley in Georgia... 43-54 geologic history of ........... 52-54 geology of .............. ; .... 45-52 physiography of ............ 43-44 structure of ................. 44-45 Arkansas slate deposits . . . . . . . . . . 1 B Bagwell, John, slate property. . . . . 104 Bagwell, W. H., slate property, 120-121 Baker, Dr. T. H., slate prop- erty ....................156-157 Bartow County, slate deposits of, 140-163 Bedding of slate ................. 8-11 Bennett, T. A., slate property, 150-152 Black Diamond Slate Company property .................88-92 Blance, Joseph G., slate prop- erty . . . . . . . . . . . . . . . . . . . . . . . 1 Bolivar Station, slate deposits near ...................108-111 Bradley, Mrs. L. J., slate prop- erty ....................... 158 Brantly, J. E. . ................ 138, 185 Bristol, W. A., cited ............. 31, 39 Brown quarries, Rockmart, sketch of slate on . . . . . . . . . . . . . . . . 11 Brown, Robert H., slate miner.... 65 c Cambrian rocks of Georgia....... 47-50 Cambro-Ordovician rocks .of Georgia, 50-51 Carboniferous formations of Georgia . . . . . . . . . . . . . . . . . . . 52 Carpenter, W. W., slate prop- erty ....................161-162 Cartersville district ............128-163 Cartersville fault . . . . . . . . . . . . . . . . . . 44 Cartersville formation ... 48-49, 128-132 areal distribution of . . . . . . . . . . . 128 economic geology of .......131-132 geology of ..................128-132 lithologic characters .......129-130 paleontology of ................ 131 PAGE physiographic expression of. . . 131 potash shales and slates of, 131, 132-163 stratigraphio relations of. .. 128-129 structure and thickness of. . . . . 130 Cartersville Poor Farm slate de- posits ..................... 146 Cartersville slate ........... 3, 7, 22, 26 Cartersville-White slate belt..152-154 Cass Station, slate deposits near, 162-163 Cassville, slate deposits near ... 158-161 Cedartown slate area ............ 95-97 Cement dust, recovery of potash from ..............132, 134-136 Chemical analysis of slate.. . . . . . . . 32 Chemical changes in weathering of slate ..................... 20-22 Chemical composition of sericite schist of Pickens County ......................172-175 slate .........................17-20 Cherokee Slate Company.......... 1 property ...................... 75-81 Chickamauga formation of Georgia 51 Chickamauga limestone of Georgia 51 Clark, W. P. . ..................... 112 Classification of slate ............ 6, 7 Cleavability of slate . . . . . . . . . . . . . . 30 Cleavage, slaty ..................11-13 Columbia Slate Company pros- pects ..................... 92-93 Conasauga formation; Fairmount slate district ............ 99-104 Conasauga formation of Georgia, 49-50 Conasauga green slate ........... 22, 26 Canasauga green slate belt. ..... 22, 26 Coons, A. T., cited .............. 38, 40 Corless, G. B .................. 137, 150 Cornelius, W. 0., slate property .. 97-99 Corrodibility of slate . . . . . . . . . . . . . 32 Cost of production of slate........ 4 Cottrell electric precipitation, 132, 139 Cumberland Plateau, Geology of, 45, 46 D Dale, T. Nelson, quoted, 6, 22-23,27-30, 30-32, 34, 74,106-107 cited ..................... 13, 33, 73 Daves, W. W., slate property ..... 160 Davis, G. W. . . . . . . . . . . . . . . . . . . . . . 112 slate miner . . . . . . . . 3, 104, 140, 146 Davis, Mrs. Ellis, slate property.. 82-83 Definition of schist . . . . . . . . . . . . . . . . . . . . . . . . . 6 slate . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Development of slate deposits .... 34-36 Dever, J. F. slate property.... 1, 83-84 Dever, Mrs. Sarah J., slate prop- erty . . . . . . . . . . . . . . . . . . . . . . . 75 Devonian rocks of Georgia. . . . . . . . 52 Dikes in slate .. .. .. . .. .. .. .. .. .. . 17 Discoloration of slate . . . . . . . . . . . . 31 Disharoon, E. Q., slate property, 126-127 Durham, P. H., slate property .... 112 190 INDEX PAGE Dysart slate property . . . . . . . . . . . . . 155 E PAGE Hopkins, Dr. 0. B., cited, 61, 62, 64, 118, 164 Hull, J. P. D., fossil found by 48 Electric resistance of slate........ 31 Electrical uses of slate .......... 39-40 Ellijay folio, U. S. Geological Sur- . vey ...................... 167 Ellis Davis & Son slate quarry ... 82-83 Engineering & Mining Journal. . . . 132 Everett,- William, slate prospect ... 85 Everhart, Dr. Edgar, analyst . . . . . . . . . . . . . . . . . . . . . . . . 106 cited ..................138, 144, 15p J Joints in slate . . . . . . . . . . . . . . . . . . . . 15 Johnson, M. L., slate property ..160-161 Jones, Colonel Seaborn . . . . . . . . . . 72 slate property .. .. . .. .. . .. .. .. 2 Jones, Rufus, slate property .... 157-158 K Knox dolomite of Georgia........ 50-51 F' Kuhtman sericite property.....185-186 False cleavage ...................13-14 Fairmount .district .............. 99-128 Faults in slate ............... . . . . 16 Fish Creek slate area . . . . . . . . . . . . 94 Fossill found J. P. D. Hull .. ..... 48 G Galpin, S. L. . ..................... 132 Geologic . history of Appalachian Valley ................... 52-54 Geologic,.reiations of. slate ... ~ ..... 26-217 Geologic history of Appalachian ' Geo Alo:gPypVa:o:cl'afa';;l,lc:ehmi:.nVGale.lo:!~r!!g~: iaG1.eotragbilae:-i.45.~.f>:44.6' Cartersville district ........ 128.-132 Fat:imo:unt. district __ ..... , : . ~ . :9:9.:1o4 County P.ickens seriCite . d'e~ .. :i;li!is'its.~';:,c,.,::.;::::: .~--;; :t65',;6.9. Rockmart district ............ 54-59 Georgia, App:Hachian, Valle~ o. .. 43 ...5.4, Georgiai Gi1een Slate. CompanY,..... .,. 3. :Property . , ................. ro"4..:fo7 Georgia Potash & Chemical Cor- . i;iciratiori . .'............. 139, 165 d:eorgia slate .................... 43-54 condition affecting develop- ments of ................. 34-36 tests of . . . . . . . . . . . . . . . . . . . . . . . 33 Georgia slate deposits . . . . . . . . . . . . 43 Gordon County, slate deposits of, 121-128 Grain of slate .................... 14-15 Grassdale, slate deposits near .. 161-162 Green slate belt of the Conasauga formation ............... 99'-104 areal distribution of. . . . . . . . . . . 99 geology of : : ..... : .......... 99-104 lithologic characters of.....100-101 physiographic expression of 102-104 stratigraphic relations of .... 99-100 structure and thickness of.. 101-102 Griffi;n; W. W .................104, 106 H Haden, C. J. . . . . . . . . . . . . . . . . . . . . . . 75 Hardness of slate . . . . . . . . . . . . . . . . 32 Hayes, C. W., cited ...... 47, 48, 49, 54 Hay:Ward, M. W ........... 137, 150, 156 Headden, G. W., slate property ... 159 Hicks, E. W., slate property: ..... 154 History of the slate industry ...... 1-5 Hollan, D., slate property......... 95 L La Forge, Dr. Laurence, cited, 48, 167, 168 Lake, Vincent F., slate splitting machine . . . . . . . . . . . . . . . . . . 38 Leith, C. K., quoted ..........11-12, 13 Lot 84, sericite schist deposH:s on.. 188 Lot 96,. sericite schist deposits on 178-179 Lots 97 and 98, sericite schist de- . posits on ...............186-187 Lot 99, sericite schist deposits on.. 187 Lot 119, sericite schist deposits on, ' '! 185-186 Lot- 120, sericite schist .deposits on, . . . . 182-185 Lot 121, seriCite sch-ist deposits on, . 180-182 Loughlin;. G." F;,: crtea: . . . . . . . . . . . 4, 39 ,.,(i McCallie, s. W ................ 157; 159 McCoy, 'Gus, slate property... :117-120 McDaniel, W. D., slate property... 112 McMillan, J. E~; slate property..146-150 M Mahan and Hickens slate prop- erty ......................... 126 Map of slate-bearing formations in Georgia . . . . . . . . . . . . . . . . .. . 42 Martin, Gabriel, sericite schist property ............... 182-185 Maynard, Dr. T. Poole ........... 139 cited ...... 68, 106, 108-109, 115, 124 Merriman, Mansfield, cited ...... 31, 32 .Merz, A. R., cited ................ 134 Methods of working slate ........ 37-38 Microscopic analysis of slate. . . . . . . 32 Microscopic sections of sericite schist .................. 169-172 Miles, Major George .............. 187 lv.fineralogical composition .of slate, 22-26 N Nee!, Mrs. J. W., slate property, 123-124 .Nelson, W. :A; .................. 137 Norris, John T., agent for slate property ............... 139-140 INDEX 191 PAGE 0 Ordovician .rocks of Georgia....... 51 Origin of slate ................... 27-30 p Padgett, Kim, sericite schist prop- erty .................... 186-187 Pendley sericite property. . . . . . . . . . 188 Phalen, W. C., cited ............. 167 Philpott, Reuben, slate property.. 84 Phinizy, J. W., slate property ... 97-99 Physical characteristics of slate .. 7-17 Physiography of Appalachian Val- ley, Georgia .............. 43-44 Pickens County, sericite schist de- posits of ...............165-188 Polk County, slate deposits of ... 65-99 Porter, J. J., cited ............... 135 Porosity of slate . . . . . . . . . . . . . . . . . 32 Portland Cement Association, arti- cles on potash recovery ......... 135 Portland Slate quarry ............ 93-94 Potash shales and slates, Carters- ville district ....... 131, 132-136 developments in ...........136-140 individual deposits of......140-163 Potash, sources of .... 131, 132-136, 165 Price per square of slate ......... 2, 4 Pritchard & Davis slate mines .. 72, 74 Pritchard & Davis slate quarry, sketch of slate in......... 10 Procter, R. L. . ................... 115 Production of slate in Georgia and United States ............. 3-5 Purdue, A. H., cited .......... 1, 31, 33 Pyron slate property ............. 150 R Research Corporation ............. 139 Rhodes, A. G. . . . . . . . . . . . . . . . . . . . . 75 Ribbons in slate ................. 9-11 Richard, William ............ , . . . . 186 sericite schist property .....178-179 Rockmart district . . . . . . . . . . . . 2, 54-99 Rockmart Shale Brick & Slate Company ................ 65-72 analysis of slate from . . . . . . . . 21 Rockmart slate .............. 51, 54-59 areal distribution of ......... 54-55 geology of ................... 54-59 lithologic characters of ..... 56-57 paleontology of . . . . . . . . . . . . . . . 59 physiographic expression of.. 58-59 stratigraphic relations of. ... 55-56 structure and thickness of. .. 57-58 Rockmart slates . . . . . . . . . . 7, 22, 25, 51 tests of . . . . . . . . . . . . . . . . . . . . . . . 33 typical sections .............. 59-65 Rody and Burkey patents ........ 137 Roofing slate .................... 38-39 Rogers, A. H. . . . . . . . . . . . . . . . . . . . . 137 Rogers, W. B., cited.............. 1 Rome formation of Georgia....... 49 Ross, W. H., cited ................ 134 J. s Seaboard Air Line section, slate exposures ................ 59-63 Schist, definition of . . . . . . . . . . . . . . 6 PAGE Sculping of slates . . . . . . . . . . . . . . . . . 30 Sections of Rockmart slate ...... 59-65 Security Cement & Lime Com- pany ...................132-135 Sericite schist deposits of Pickens County ................ 164-188 chemical composition of ....172-175 mode of occurrence of. .....176-177 origin of . . . . . . . . . . . . . . . . . . . . . . 177 Sericite schists, microscopic sec- tions of ................169-172 Shale quarries of Southern States Portland Cement Company, 87-88 Shear zones in slate . . . . . . . . . . . . . . 16 Sibley, R. P., slate property ..... 85-87 Silurian deposits of Georgia...... 52 Slate, age and geologic relations of. 26-27 analyses of, See Analyses bedding of .................... 8-11 chemical composition of .....17-20 classification of ............... 6, 7 cleavage of .................. 11-14 cost of production of . . . . . . . . . 4 definition of . . . . . . . . . . . . . . . . . . 6 dikes in . . . . . . . . . . . . . . . . . . . . . . 17 electrical uses of ............ 39-40 faults in . . . . . . . . . . . . . . . . . . . . . . 16 grain of ......................14-15 joints in . . . . . . . . . . . . . . . . . . . . . . 15 methods of testing ......,,~ .. 30-32 working .............. .,,,,... 37-38 mineral composition of, ta;,ble. 24 constituents of, classification 23 mineralogical composition;,~f.. 22-26 origin of . . . . . . . . . . . . . . . '''' .. 27-30 physical characteristics ~~ ... 7-17 price per square of ...... ,'.... 2, 4 production in Georgia, to.tal. . 2 United States .........\ .... 3-5 quarries, development of." ... 34-36 ribbons in .................... 9-11 roofing ................... :: .. 38-39 sections of Rockmart ........ 59-65 shear zones and cleavage bands in . . . . . . . . . . . . . . . . . 16 tests of Georgia . . . . . . . . . . . . . . 33 texture of . . . . . . . . . . . . . . . . . . . . 8. uses of ................... .4, 38-40 veins in . . . . . . . . . . . . . . . . . . . . . . 16 waste ........................ 40-41 Slate deposits of, Arkansas . . . .. . . . . . . .. . . . . . . . . 1 G~oq;i?- . . . . . . . . . . . . . . . . . . . . . . . 43 V1rg1n1a . . . . . . . . . . . . . . . . . . . . . . 1 Slate industry, history of ........ 1-5 Smith, Smith, J. 0. R.r.., ..................104, 107 slate property ... 155-156 Sonorousness of slate . . . . . . . . . . . . 30 Southern Green Slate Company property .......... ; .... 115-117 Southern Railway section, slate exposures in ............ 63-65 Southern Slate Company prop- erty ..................... 85-87 Southern States Portland Cement Company ........... 1, 133. 135 shale quarries ............... 87-88 slate property ............... 72-75 Specific gravity of slate . . . . . . . . . . 32 Spencer, J. W., cited . . . . . . . . . . . . . 56 Starkweather, J. W., slate prop- erty ...................121-123 Steele, Heath ..................... 137 Stockett, A. W., quoted ........132-133 192 INDEX P.A.GE Strength of slate . . . . . . . . . . . . . . . . . 31 Structure of Appalachian_ Valley,_ Georgia ..................44-45 u United States Bureau of Standards ........................ 33, 41 Uses of slate . . . . . . . . . . . . . . . . . 4, 38-40 v Van Hise, C. R., cited ............_ 28 Veins in slate .. : . . . . . . . . . . . . . . . . . 16 Virgiiiia slate deposits . . . . . . . . . . . . 1 Vithumus Company ... 138-139, 165, 185 P.A.GE w Wagner, C. R., cited ............. 134 Walker; J. H., slate property ...... 160 Watson, T. L., cited . . . . . . . . . . . . . 1 Watson, W. 0., slate property .... 108 Weisner quartzite d:f' Georgia..... 47 Woody, L. D., slate property..... 121 White-Cartersville slate belt, 152-154 White, N~ A.,. slate property...... 112 White, slate deposits near.....154-158 y Yarbrough, Hiram, slate property 125 Yancey, J. M., slate property.. 140-146