Ic 25 > YEO F FAO(S7/ GEORGIA STATE DIVISION OF CONSERVATION DEPARTMENT OF MINES, MINING AND GEOLOGY GARLAND PEYTON, Director THE GEOLOGICAL SURVEY Information Cireular 25 SUBSURFACE GEOLOGY OF THE GEORGIA COASTAL PLAIN by Stephen M. Herrick and Robert /C. Vorhis United States Geological Survey Prepared cooperatively by the Geological Survey, United States Department of the Interior, Washington, D. C. ATLANTA 1963 MBL/WHO! (NNN WAU | 0 0301 0024233 5 CONTENTS ABSTRACT INTRODUCTION Previous work Oe Mapping methods °e@3e7ee ee © © © © © © © © © eo ew 8 ee 8 ew 8 ew we 8 ee ee ee 8 8 ee ew ee oe 8 ee 8 8 8 ew Cooperation, administration, and acknowledgments e200 eee © © © © © © eo ee eo oe we ee 8 ee STRATIGRAPHY wile! \eiieliie! (elvfell (e) ie! (else) 1e) .0) sei \e\ Je] ie! je] ie) lie) wile \e) ie! (#1 Je), 10|\ wipe; (00s) 0.)/e) 10: je: le! ie w! we) 6) lei, ©) ww) ce) wives iene «ie: 8 Quaternary and Tertiary Systems «0 ee ep eee ec eo © © © © © oO 8 8 eo 8 eo we ew ee ee ee ew oe ew eee 8 Recent to Miocene Series ee Tertiary System Ce ee ee Oligocene Series Ce Eocene Series ee Upper Eocene rocks eo 2 © © © © © © © © © © © we 8 © © © 8 8 ew ew ew © 8 8 © © 8 8 © © 8 8 © © 8 8 ew ew 8 Middle Eocene rocks Lower Eocene rocks Pe a ee Paleocene Series Pr er ee Cretaceous System eee ee © © © © 8 eo © © © 8 8 8 ew ew 8 ew ew eo 8 8 8 8 ee oe 8 8 ee © 8 © 8 © 8 8 8 8 8 8 oe 2 Upper Cretaceous Series homo ooo.o OO DOD OOO ODD OO O00 OO 0 OO Or0)0 00 070 0-080 Oyo OeOeD Post-Tuscaloosa deposits jo) (el /e| 4) 1e)1e: © \e. © 0) 001 .s° #1.0 | 0) (¢\() 6| ©) 0 (0) 0) 0) (8) 0, \@, (03(0' @) (00) 0) 0) 0) 10: (0j'¢ Tuscaloosa Formation ie) Jol otto) elie: ef ef) alle; \e] «| 0) e) © (e) elle) .e) 10 .¢ 70, 4¢) 16 .<) ¢) e/1e) (ene) ee) 6), e118: 0) 91/0) 10; 0) 0 Lower Cretaceous(?) Series GHRUIOMNUIRIS, on nn Gb ooo dae ooo lee be ol Giolo Set dee BU Cen O chig Maid ol ane mec: cO Onc oedeHen coy nacecucen EMEA EroWi stich cule! felilelemieniomiclne/ feito iieiiefiel olen ielied else lodienleiielielen ie iemewememeuleuiei.e! 1e mene wenejne) (0, rejuesLerpeae) 6) /\e)),©, Figure 1. Map of Coastal Plain of Georgia showing location of logged wells and geologic SCCUIONS semen ener ens AUG) Catone Bacio lo cea Oo © eo Hoooo s Peo mime bo crolnte.o : 2. Thickness-distribution map of Recent to Miocene deposits ......-.-.++e+6 POR Oe 3. Structural-contour map of the top of Oligocene deposits........... aa teliel s)'e cell eit el ouerte 4, Thickness-distribution map of Oligocene deposits .. 1... cee eee ee eee cer reeeees 5. Distribution of Oligocene index fossil: Rotalia mexicana var. . 1... e eee eee eee tees 6. Structural-contour map of the top of upper Eocene depositS -- ++ +++ eee eter rece f 7. Thickness-distribution map of upper Eocene depositS ... 1... eee eee teens 5 8. Structural-contour map of the top of the middle Eocene deposits....... Bion ao apo 9. Thickness-distribution map of middle Eocene deposits .....-5--2-+ ++ eee eeee bao0 10. Structural-contour map of the top of lower Eocene deposits and erosion surface...... Il) Thickness-distribution map of lower Eocene: deposits |. 22 2. 2. snes « citer e © 0) «elie tee) lel 12. Structural-contour map of the top of Paleocene deposits ......-.2-seseeessesee 13) ihickness—distribution map or Paleocene depOSits carers cet eer sce stelle oe tele ieliaiaiieite 14, Structural-contour map of the top of Upper Cretaceous post-Tuscaloosa GlSjofelstlesrs Dos ceo f ceoknin peuwalo lo we O45 oo clo. pecee lb Gtepivoec eich emerenonoe sks AER ech once 15. Thickness-distribution map of post-Tuscaloosa Cretaceous depositS .........2200- 16, Structural-contour map of the top of Tuscaloosa Formation.......... ho Oo 8 Oro o 17. Thickness—distribution map of Tuscaloosa Formation. ........+ccccecsccereee 18. Structural-contour map of the top of Lower Cretaceous(?) deposits both (aatolspkeysl ible eKelu ws Glan nen ce eo DO ae eo oe oe neck ata 6 oye . oo 19, Thickness-distribution map of Lower Cretaceous(?) deposits..... Soho atwoodds boy oO 20. Structural-contour map of the pre-Cretaceous surface ......escercceccvecs eee 21. Geologic section, Early County northeastward to Richmond County..........- eee 22. Geologic section, Seminole County northeastward to Richmond County..... Se eo 23. Geologic section, Brooks County northeastward to Beaufort County, S.C. .......... 24. Geologic section,.Early County easterly to McIntosh County.........-+-2+++--ee05% 25. Geologic section, Decatur County eastward to Echols County.......... Sha ceases (eu 26. Geologic section, Clay County southeastward to Echols County.........2-5-+---- 27. Geologic section, Macon County southeastwardto Glynn County..........-..+.2e.. 28. Geologic section, Chattahoochee County southward to Decatur County........ ong ILLUSTRATIONS Il Table 1. 2 3. 12. TABIEES Previous subsurface geologic maps of the Georgia Coastal Plain..... Previous geologic sections through the Coastal Plain of Georgia..........0c000e. IIEME OA Gi Shyrloolls Cin WIS Sh Go db oo Gud 6 6 olo O Ob Ob aba GH Os oe bee OliigneSnS PwieerMimbiscel OF CeOGue oooadoouaaonuodeouobaouuooonesbous MowerniEoceneshoraminiferaoiiG CORP alsrei as <\lol eles) elke) sis) eis, (a) 's) «1 o vele seve euicliene) tel eileie) s paleocene HOLaminiLerasOls GEOL Plait. sel cncl cio) ciretie Ye Mstielist-c/re1 (ei rsiseie; eiletle\\si (el el (op etiepse eucemenss Correlation of surface and subsurface units of post-Tuscaloosa GRICE ALS oo dluaoadoooonpoebdcé6 Goud COU Ube ou Oo DG oo O Oooo uN Foraminifera from the post-Tuscaloosa Cretaceous of Georgia...........-2..e0.6 Foraminifera from the marine facies of the Tuscaloosa Formation ING COGS awa MeaU ne MCM-MoMeiish en -MemeMalemelet olaiei cb eliet elem sielcrionstelfel eieustwelereieielcietaneene Generalized dip of formational contacts in the Coastal Plain of Georgia III eee ee eo eo ow eo ee © © © © © oo 48 56 Pe IV SUBSURFACE GEOLOGY OF THE GEORGIA COASTAL PLAIN Stephen M. Herrick and Robert C. Vorhis ABSTRACT The subsurface geology of the Coastal Plain of Georgia has been restudied using data from 354 litholog- ic-paleontologic logs. Two contrasting areas of deposition are described: an updip area of clastics and a downdip area of limestones. Because faunas ofthe clastics are tound to be different from those of the lime- stones, foraminiferal lists for each type are included as well as for each geologic unit. In the Coastal Plain the sediments are wedge-shaped, being in general thinnest inland and thickest near the present shoreline. This wedge is modified in some of the units by the presence of depocenters where the thickness is greater than in surrounding areas. Locally, overlap is important in the northern part of the Coastal Plain with middle Eocene sediments overlapping those of the Paleocene and lower Eocene and being overlapped in turn by upper Eocene sediments. An outgrowth of the study has been some reinterpretations as well as some reinforcing of the stratigraphy. The Charlton Formation is regarded by the authors as being late Miocene in age and is tentatively corre- lated with the Duplin Marl of the Carolinas and eastern Georgia. The Cooper Marl and the underlying Barnwell Formation of late Eocene age are the updip clastic equivalents of the upper member of the Ocala Limestone. The lower member of the Ocala Limestone is the part of the formation that crops out in Georgia, the upper member not extending far enough updip to crop out. The Lisbon and Tallahatta Forma- tions of middle Eocene age extend through much of the subsurface of Georgia and are the updip equivalents’ of the Avon Park and Lake City Limestones of Florida. The lower Eocene clastic deposits correlate with the Wilcox Group of Alabama and their downdip limestone equivalent is the Oldsmar Limestone of Florida. The Paleocene deposits consist of the Clayton Formation overlying, in southwest Georgia and in Chatham County, fossiliferous marls equivalent in age tothe Tamesi (Velasco) of Mexico. The surface updip post-Tuscaloosa deposits correlate with their downdip marine equivalents of Navarro, Taylor, and Austin age. The geologic structure is outlined on maps showing the top of the Oligocene, upper Eocene, middle Eocene, lower Eocene, Paleocene, Cretaceous, Tuscaloosa Formation, Lower Cretaceous(?), and pre- Cretaceous. Other maps show the thickness and distribution of sediments of the Recent to Miocene, Oligo- cene, upper Eocene, middle Eocene, lower Eocene, Paleocene, post-Tuscaloosa Cretaceous, Tuscaloosa Formation, and Lower Cretaceous(?) sediments. Additional interpretation of the structure is shown on 8 geologic sections. The major structural basins in Georgia are the Atlantic Embayment in the southeast and the Gulf Trough in the southwest. INTRODUCTION The most important mineral resource of the Georgia Coastal Plain is its ground-water supply. In order to ascertain the magnitude and distribution of this supply in the sediments of the Coastal Plain, a good understanding of the geological framework that contains the ground water and directs its flow is needed. The purpose of this paper is to present the interpretation of the subsurface geology so that the ground-water hydrology of the 35,000 square miles that comprise the Coastal Plain of Georgia will be better understood. This report does not deal with ground water directly but is a basis for detailed ground-water studies in the Georgia Coastal Plain counties. This report is based largely upon the records of wells reported by Herrick (1961) in a report frequently ferred to herein as ‘‘the well-log report.’’ In that report the lithology and fauna from numerous samples e described in detail. For more information on individual wells the reader is referred to the well-log port. Cuttings from water wells have been a source of much of the geologic ‘knowledge of the Coastal Plain. However, the vast magnitude of the ground-water resource in Coastal Georgia has caused most wells to be drilled to relatively shallow depths, thereby limiting the data available on the geology of underlying for- mations and aquifers. So far about a hundred wildcat oil-test wells have been drilled in the Coastal Plain of Georgia and these have been the other major source of data. However, many were drilled without adequate sampling and logging and with minimal geologic study so it is not misleading to say that the Georgia Coastal Plain is almost virgin material to the oil-driller’s bit andthat this area currently can be considered a relatively unexplored province. The approximately 100 oil tests give a well density of about 1 for each 350 square miles. Many of these wells are grouped so that the 34 oil tests logged by Herrick (1961) probably give a more repre- sentative figure for use in a ratio--namely, 1 geologically studied oil well for each 1,000 square miles of Coastal Plain. The 354 oil-test and water wells described in the well-log report give a ratio of one well for every 100 square miles of Coastal Plain. Ratios such as these indicate that much more geologic study of well samples will be needed for an adequate interpretation of Coastal Plain geology and that the present report still allows for much additional work. Although this is a preliminary study with great dis- tances separating the wells studied, much new information has been added to the knowledge of the subsur- face geology and areas where additional work is needed have been delineated. This report summarizes paleontologic and stratigraphic work in the Coastal Plain of Georgia by the senior author done intermittently over several years. The maps are based almost solely on the logs pre- pared by him (Herrick, 1961). The maps, geologic sections, tables, and part of the text have been prepared by the junior author after some restudy of the well-log data. Differences to be found between the data as ' mapped herein and as published in the well-log report represent changes in interpretation. The maps and sections (see fig. 1 inside back cover) are based on the published logs of 354 wells in the Coastal Plain of Georgia (Herrick, 1961). Because these logs have all been made by the senior author, they represent a uniform considered treatment, a balance often difficult to achieve when synthesizing data from many different sources. Therefore, with the wealth of new data, a completely fresh interpretation seemed needed. A major exception in this policy is the area along the Georgia~Florida line where the new maps were made to agree with the published literature: The thickness of the Miocene was reconciled with that for Florida by Vernon (1951); the top of the Ocala was reconciled with data given in Black and Brown (1951) and Meyer (1963); and the thickness of the Ocala tied to that given by Puri (1957). Paul L. and Esther R. Applin kindly furnished picks on the top of the Lower Cretaceous(?) Series in the following wells: Colquitt 170, Early 121, and Echols 189; also from discussions with them revisions of the Lower Cretaceous(?) in the well-log report were made in Liberty 363, Mitchell 109, Seminole 187, and Wayne 52. Unpublished lithologic logs by the late Vaux Owen, Jr., furnished formational tops in the following wells: Sumter 281 and Sumter 296. Supplementary data on oil tests in Georgia were taken from Hurst (1960). The foraminiferal names in the faunal lists of this report are mainly those as given in the well-log report. The authors are cognizant that many of the names are not in accordance with recent generic revisions, Examples include Epistomina caracolla which is now Hoglundina caracolla; Rotalia mexicana var. mecatepecensis, which has also been called Neorotalia mecatepecensis (E.R. Applin, 1960, p. B208) and Streblus mexicanus mecatepecensis (Cole and Applin, 1961, p. 127); many of the species of Cibicides that now would be put in Cibicidina; and many of the species of Discorbis that could be regrouped under Rosalina, Neoconorbina, and Rotorbinella. Nomenclatural changes such as these would be desirable mainly for those concerned with taxonomic usage. However, for the many who are concerned with check- ing their finds against the plates and descriptions as contained in paleontological publications, the use of the older established names seems highly desirable. Because the names as given are generally those found with the published plates, comparisons can be made far more readily than if the ‘‘up-to-date’’ names had been used. Previous Work The interpretations in this report represent a fresh look at the stratigraphy, paleontology, and struc- ture of the Coastal Plain in Georgia. Although the previous work has not been used directly, it has been examined. Because the pertinent geologic literature on the area is synthesized by Murray (1961) and is summarized by LeGrand (1961), the authors believe that any extensive review of the literature is un- necessary in this report. The review of the literature on the Coastal Plain of Georgia is condensed into two tables: one listing published subsurface geologic maps; the other listing published geologic sec- tions. Also, in the discussion of the stratigraphy, pertinent paleontologic papers are cited. The subsurface maps in table 1 include those of the entire Georgia Coastal Plain as well as those of individual counties. To facilitate use of the table, the maps generally are listed by geologic age of the top or thickness of the unit mapped. Where titles mentioned base of a unit, this was altered to indicate the top of the next lower unit. The list is restricted to original contributions and does not include maps that are copied from previous publications. The geologic sections pertaining to the Georgia Coastal Plain (see table 2) are listed by author. 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‘PRET ‘“UTTddy pue uttddy adUdIOJOY describe the location of the geologic section, the county name and the Georgia Geological Survey number of the well are given: e.g., Atkinson 107. Under this number are filed in the sample library maintained by the Georgia Department of Mines, Mining and Geology, the cuttings of the wells which are available for further study by geologists and paleontologists. The numbers also are the same as those used in the well-log report by Herrick (1961). One paper which the authors have used extensively is that by Paul and Esther Applin (1944), on the “Regional subsurface stratigraphy and structure of Florida and southern Georgia.’’ Because the Ap- plins’ paper has been so remarkably useful, the authors have chosen to model this present paper more or less along similar lines. Mapping Methods The data presented are separated by horizontal distances measured in miles but the vertical measure- ments are in feet. Furthermore, errors in sampling and in interpretation of the samples can have too much influence in locating contour lines if the data are contoured mechanically. Therefore, the maps were prepared with the contours drawn to show the major structure thereby eliminating many of the minor features that strict mechanical contouring would show. At this stage in the investigation of the subsurface, the major features are not yet fully understood so adding minor ones would tend to obscure rather than aid interpretation. The contoured maps have been superimposed to try and make the maps consistent one with another. Because of the wide spacing of many of the wells and lack of wells elsewhere the maps can be drawn with remarkably differing interpretation. Therefore, these maps are presented as the current interpretation of the authors and with the realization that they will need to be modified considerably as new data become available and as other interpretations are found to be more valid. In order to make the maps more readily comparable, the contour interval on most of the maps is 100 feet, The tops of the lower Eocene down to the Tuscaloosa (of Late Cretaceous age) are contoured at an interval of 200 feet. The top of the Lower Cretaceous(?) and the pre-Cretaceous were contoured at 500-foot intervals. The thickness-distribution map for the Lower Cretaceous(?) was prepared with a contour interval of 400 feet. Because of the many maps included in this study, the symbols used are listed and described in table 3 rather than having essentially the same explanation repeated on each map. Table 3.--Explanation of symbols on maps — — — Structure-contour maps — — — ees Structure contour 10 Altitude of top of unit mapped 1Oe Top of unit above this altitude 10 ie Top of unit below this altitude B Altitudes based on estimated value for land surface @ Altitude based on estimated thickness Datum is mean sea level Contour interval is 100 feet for maps ofthe top of the Oligocene, upper Eocene, and middle Eocene; 200 Feet for top of the lower Eocene, Paleocene, post-Tuscaloosa Cretaceous, and Tuscaloosa Formation; and 500 feet for top of the Lower Cretaceous (?) and pre- Cretaceous: — — — Thickness-disiribution maps — — — Line of equal thickness 100 Logged thickness 1007 Plus sign is used to indicate that the figure is a minimum value and that additional thickness is probable; the location of the plus indicating whether the additional thickness is above or below, or as in the case here, with two plus signs, the unit is likely to have additional thickness both above and belowthe 100 feet that were logged as being part of the geologic unit e Thickness estimated O Absent Contour interval is 100 feet for all maps except the Lower Cretaceous(?); for it the contour interval is 400 feet. Cooperation, Administration, and Acknowledgments The availability of material for a report such as this is evidence of the willing and splendid coopera- tion received from the water well drillers of Georgia, and the oil industry, who made the well cuttings available for study and who furnished the drillers logs and the electric logs. The work was done under a cooperative program for ground-water investigations conducted by the U.S. Geological Survey and the Georgia Department of Mines, Mining, and Geology, Garland Peyton, Director, and under the supervision of J. T. Callahan, former district geologist, and H. B. Counts, current district engineer, U. S. Geological Survey. Paul L. and Esther R. Applin, geologists with the U. S. Geological Survey, have both discussed phases of the work with the authors and the report has benefited from their helpfulness. W. Storrs Cole, Professor of Geology at Cornell University, through his correspondence with the authors, discussed several aspects of the stratigraphy and paleontology thereby making available some of his vast experience on ‘‘larger’’ Foraminifera. The illustrations have been drafted by Willis G. Hester. 8 STRATIGRAPHY At least four structural-depositional features characterize the Coastal Plain of Georgia in its overall aspects. The first obvious feature is that the Coastal Plain is composed of a wedge-shaped block of strati- fied sediments that rests upon a pre-Cretaceous basement complex ranging from Triassic(?) to Paleo- zoic to Precambrian in age. In Mitchell County, Triassic(?) rocks overlying the basement complex were encountered at depth whereas black shale of Paleozoic age was penetrated at depths of 3,782 feet and 6,950 feet in Echols and Early Counties, respectively (Applin, 1951, p. 25). Depth to the underlying crystalline basement varies according to the position on the dip. Crystalline rocks of Precambrian age were encountered in updip areas, such as Richmond and Washington Counties, at 162 and 871 feet; in middip areas such rocks were penetrated at depths of 1,685 and 2,532 feet in Houston and Laurens Counties; and in downdip parts of the Coastal Plain in southeastern and southern Georgia at 4,075, 4,250, 4,674 (Applin, 1951, p. 21), and 4,125 feet (Applin, 1951, p. 27), in Appling, Liberty, Camden, and Echols Counties. In extreme southeastern Seminole County, 7,620 feet of sediments were penetrated in the deepest known embayment area in the Coastal Plain of Georgia, but even so the depth was not great enough to encounter pre-Cretaceous rock. The second outstanding feature is that most of the Coastal-Plain sediments are composed of two con- trasting but stratigraphically equivalent types of sedimentary deposits, a fact first noted by the Applins (1944, p. 1679). In updip parts of the Coastal Plain the deposits are distinctly clastic by nature and, in their overall aspect, resemble those of the western Gulf Coastal Plain. Downdip, the lithology grad- ually grades into limestone. The limestones of downdip areas are lithologically and faunally similar to their stratigraphic equivalents in peninsular Florida. In Glynn County, for example, this limestone facies includes all geologic formations beginning with the early Miocene down to and including the strata of Navarro (Late Cretaceous) age. Beginning with the beds of Taylor age, the remainder of the scedi- ments belonging to the Upper Cretaceous as well as those of the still older Lower Cretaceous(?) are of the clastic type in Georgia. Still farther south, as for example the Everglades area of Florida, these clastics of Cretaceous age grade laterally to limestones. Accompanying the facies change in cowndip parts of the Coastal Plain is a corresponding change in foraminiferal microfaunas. As pointed out by the Applins (1944, p. 1680), the Foraminifera of the clastics are similar to those of the western Gulf Coast whereas those of the limestone facies are similar to those of Cuba, the West Indies, and Mexico. A good example of this is the foraminiferal tauna characterizing the Paleocene in Georgia, a micro= fauna that shows rather close relationship to that of the West Indies and Mexico. The third outstanding feature of the Coastal Plain in Georgia is what Murray has called ‘‘depocenters’’ (1961, p. 5, 89). These are areas of maximum deposition. An example of such a depocenter is the east- west trending belt of greatest thickness of the post-Tuscaloosa in the central part of the Coastal Plain. (See fig. 15.) Murray (1961, p. 281) attributes these depocenters to: (1) major variations in locale or rate of sedimentary accumulations, whatever their cause, and (2) regional warpings related to epeirogenic and isostatic adjustments. The fourth structural-depositional feature of the Coastal Plain in Georgia requiring mention is forma- tional overlap. From Lower Cretaceous(?) through upper Eocene time this was taking place in Coastal- Plain Georgia. The best example of this phenomenon is that of the upper Eocene which overlaps middle Eocene and Upper Cretaceous deposits in east-central Georgia, finally coming to rest directly upon Precambrian rocks in the Piedmont. In this report a brief description of the subsurface stratigraphic section starts with the Miocene and ends with the Lower Cretaceous(?), the stratigraphic units being taken up in descending order. The veneer of post-Miocene strata is thin except for coastal Georgia and other more localized areas and is of such minor importance in the subsurface that it is omitted from this report. Quaternary and Tertiary Systems RECENT TO MIOCENE SERIES Deposits of Recent to Miocene age have been identified throughout about three-fifths of the Coastal Plain of Georgia in more than 300 wells. (See fig. 2.) The uppermost unit is composed mainly of sand and is restricted in general to the coastal counties of southeast Georgia. The sand of post-Miocene age, is not discussed further in this report for it is of little importance in the subsurface, is remarkably barren of microfossils, and is the subject of another paper currently being prepared by the senior author. The Miocene sediments compose the major portion ofthe deposits as mapped in figure 2 and the northern limit as shown is the general boundary of the occurrence of Miocene sediments. This inner limit of the outcrop trends from the southwest corner of Decatur County northeastward through the counties of Grady, Mitchell, Crisp, Bleckley, to Laurens County and thence southeasterly to the Savannah River along the southeast corner of Burke County. Lithologically the upper and middle members of the Miocene in Georgia are composed of clastics, while the lower member consists of a series of limestones. The clastics are continuous throughout the entire area covered by this unit. If they grade downdip into limestones, such rocks have not yet been found anywhere in the subsurface of Georgia. It is possible, however, that such a downdip limestone facies does exist somewhere off the coast of Georgia. In the six coastal counties and eastern Wayne County the upper unit of the Miocene consists of dark-brownish-green, granular, rather loosely consolidated, abund- antly micaceous, locally phosphatic and fossiliferous clays which rest either on beds of dolomitic lime- stone also of Miocene age as in Chatham County, or directly upon the underlying clays of the Hawthorn Formation, as for example in Glynn County. This upper member rapidly pinches out up the dip, coming to the surface as isolated outcrops along the major river valleys. Examples are exposures along the south bank of the Savannah River, particularly at Ebenezer Landing, Effingham County, along the south bank of the Altamaha River at Doctortown, Wayne County, and along the St. Mary’s River south and southwest of Folkston, Charlton County. These strata represent the Charlton Formation (Veatch and Stephenson 1911, p. 392); they are tentatively correlated by the authors with the Duplin Marl of late Miocene age in the Carolinas and eastern Georgia, whereas the U. S. Geological Survey considers them to be of Plio- cene age. The Hawthorn Formation, the middle unit of the Miocene Series, consists of pale to dark-green (mottled at the surface), phosphatic (at depth), very sandy, locally fossiliferous and cherty, micaceous clays that are interbedded with scattered tongues of fine to coarse-grained, arkosic, phosphatic sand; both the clays and sands gradually thicken and become fossiliferous in a downdip direction. Beneath these clastics but to some extent interfingering with them is a series of limestones considered to be Tampa equivalent of early Miocene age. These limestones are whiteto cream, sandy, phosphatic, locally cherty, and sparing- ly fossiliferous. In southwest Georgia, particularly in Mitchell and Colquitt Counties as well as along the Georgia-Florida border from Decatur County eastward through Camden County, these basal Miocene limestones have been locally altered, becoming light to dark-brown, recrystallized, saccharoidal, sandy, phosphatic, dolomitic limestones. In areas where dolomitization has not taken place the lower Miocene limestones are distinguished from the underlying but older limestones of Oligocene age through the pre- sence of quartz grains and phosphatic pebbles, and by the fossils where present. The Recent to Miocene thickens gradually from a few feet in its updip outcrop area to over 600 feet in two depocenters (see fig. 2). One of these depocenters is long and linear extending diagonally across Grady County in a northeasterly direction as far as northeastern Toombs and northwestern Tattnall Coun- ties. The other area of greatest thickening appears to center in Brantley, Pierce, and Glynn Counties. Some of the publications in which Miocene microfossils are described and illustrated include several articles by Cole (1931 and 1941) and Cushman (1918 and 1930). Fossils that are diagnostic of the sub- surface Miocene of Georgia include molluscan shells, occasional vertebrate remains such as fish teeth, vertebrae(?), etc.; ostracods; and the Foraminifera Archaias floridanus (Conrad) and Rotalia beccaril (Linné) var. Small Foraminifera* were noted in two recently drilled test holes in updip Chatham County, Ga., and Beaufort County, S. C. Subsequent analysis of this microfauna by the senior author indicated these Foraminifera to be late Miocene (Duplin) in age. *M. J. McCollum U. S. Geological Survey geologist in Savannah, Ga., first called the authors’ attention to the presence of these fossils in these test holes. This microfauna is being studied and processed for future publication by the senior author. 10 ‘syisodap auad01W 0} yUeDeYy yO DoW UOIINGI4AISIP—SSeUxdIY|—d¢? aunbi4 ov8 oS8 = Cc oot foloromne on LL -—-—-12-—-- 719 ll € 91qo4 aes sjoqwAs jo uoljoud|dxa 404 “syisodap auas0b110 40 doy ay} yo dow snojuod—jounyonaysg —¢ asunbi4 O 0 ot 9 (e) ° 0S 92 k Ov ¢ O 610 Q~- € 8|qD) aas sjoqwks sayjo 40 uoljOUD|dxa soy Buissim auar0b110 12 Tertiary System OLIGOCENE SERIES Beds of Oligocene age have been identified in over 300 wells in the subsurface of the Coastal Plain of Georgia. In subsurface areal extent the Oligocene Series approximates that of the overlying Miocene. (See fig. 3.) These strata occupy a position intermediate between the upper Eocene below and the Miocene Series above. As yet, however, the authors have been unable to correlate these beds of definite Oligocene age with the two outcropping formations of Oligocene age that have been map- ped in Georgia: the Flint River Formation (Cooke, 1943, pl. 1) and the Suwannee Limestone (Mac- Neil, 1947). Until such time as a study of the outcrop and the subsurface is successfully completed it seems preferable to refer to the subsurface deposits as Oligocene Series or Oligocene undifferentiated. The Oligocene Series increase in thickness from a few feet in updip areas to an average of 100 feet over most of the central part of the Coastal Plain of Georgia. (See fig. 4.) The maximum thickness listed by Herrick (1961) is 211 feet for a well in Dodge County. Lithologically the Oligocene in Georgia is representative of the limestone facies, the clastic facies lying much further west in Mississippi where the entire known Oligocene section of the Gulf Coast is developed. The upper part of the limestone facies in Georgia is composed of light-gray to cream to light-brown, dense, nodular and cherty, locally somewhat sandy, fossiliferous limestones. Locally abundant chert inclusions are common particularly in the upper few feet, a characteristic that often causes diffi- culty in drilling. The lower part of the Oligocene consists predominantly of cream, relatively soft, somewhat chalky, fossiliferous limestones. At the base of this unit however, are rather dense, massive, sparingly fossili- ferous limestones which on the electric log, produce a pronounced resistivity ‘‘kick.’’ These limestones contain only molds and casts of molluscan shells but no Foraminifera. In southwest and southern Georgia the Oligocene is dolomitized locally and is composed of light to dark- brown, saccharoidal, recrystallized, unfossiliferous limestones. In Chatham County the limestones of this unit become progressively sandier to the northeast, finally grading into sand in southeastern Beaufort County, S. C. Over most of the southeastern part of the Coastal Plain these strata have been considerably eroded, and, in southern Charlton and southwestern Camden Counties, are absent presumably having been completely eroded subsequent to their deposition. Fossils are abundant in the Oligocene deposits but as yet they have not permitted the stratigraphy to be worked out convincingly. The upper beds of Oligocene age in Georgia generally contain as the dominant form in the smaller foraminiferal assemblages an abundance of Rotalia mexicana var. mecatepecensis. Thus figure 5 which shows the occurrences in Georgia of this form presumably also indicates the areal distribution of the upper limestone of Oligocene age. In many wells in which R. mexicana var. was not reported another Oligocene form was reported: Rotalia byramensis var. Unfortunately, in all the wells in which Oligocene Foraminifera were indentified, only one well, McIntosh 84, has both species reported. In it R. byramensis is reported from the sample interval 445-455 feet; R. mexicana var. is reported from 486-505 feet. If it were not for this the authors would favor considering the large area in southern Georgia where R. mexicana var. is missing to be where the upper beds of Oligocene age were eroded or never deposited, It is interesting to note that the rather large list of Foraminifera identified by Vernon (1942, p. 66) as being from the Suwanee Limestone does not mention R. mexicana var. but does list R. byramensis var?. However, Vernon (p. 56) qualifies the stratigraphic origin by pointing out that the unit from which the fossils came may ‘‘not (be) the precise equivalent of the Suwanee in its type area.’’ He further points out that correlation is rendered difficult by the lack of larger Foraminifera in the type section of the Suwannee Limestone in Florida. The Foraminifera he lists accord closely with those found in the Oligocene beds in wells of Lowndes and Brooks Counties. The difference in fauna could be due to difference in facies with contemporaneous sedimentation or to difference in time of. deposition. Some of the more important publications dealing with the Foraminifera of the Oligocene include papers by Cushman (1922a and b), Cushman and McGlamery (1942), Cole and Ponton (1930), and Todd (1952). The Foraminifera characterizing the Oligocene of Georgia are rather abundant (at least in total numbers of specimens as found in well cuttings), distinctive, and varied. Some of the foraminiferal species that are diagnostic of the Oligocene in Georgia include Quinqueloculina leonensis Applin and Jordan, Camerina dia (Cole and Ponton), Rotalia mexicana Nuttall var., Asterigerina subacuta Cushman var. floridensis 13 ‘Syisodap aues0bl190 yo dow UONNQIA4S!P ssauyoluy —b oainbly 14 ‘IDA DUDIIXAW DI/D{O¢/ :\1SSO} xXapul auaDO0BIIQ 4O UOIyNGI4ysIG—G enbl4 S31IW OF Oz Ol fe} Ol | a / d ( ae ra -—--—.. puno} SOM ISSO} xXapUl a4aYM | [EM e) NOILVNV1dX3 Applin and Jordan, and Lepidocyclina mantelli (Morton). The Foraminifera contained in the Oligocene Series in Georgia include those species that are indigenous to this unit as well as several specijes that represent reworked specimens from the middle Eocene, a phenomenon that has been adequately discussed by several investigators as for example Cole (1941, p. 15, 16) and the Applins (1944, p. 1682-1683). Be- cause these reworked fossils in the Oligocene represent forms that were originally described from and are characteristic of the middle Eocene limestones of peninsular Florida, they have never been found in the middle Eocene clastics of Georgia. Thus, in attempting to find the source beds from which they were re- moved, they could not have come from erosion of middle Eocene clastics. Rather, they must have been weathered out of and transported away from the limestone facies. By this method of reasoning, the rework- ed forms so widespread in the lower Oligocene sediments of Georgia must have been transported north- ward and derived from middle Eocene limestone in the Gulf of Mexico, southwestern Georgia, or penin- sular Florida. The following faunal list summarizes the more important foraminiferal species observed in wells penetrating the subsurface and are regarded as diagnostic of the Oligocene in Georgia. Table 4.--Oligocene Foraminifera of Georgia Textulariidae: Spiroplectammina mississippiensis (Cushman) Textularia adalta Cushman conica D’Orbigny tumidula Cushman Miliolidae: Quinqueloculina leonensis Applin and Jordan Several species of Pyrgo Lagenidae: Robulus arcuato-striatus (HantKen) articulatus (Reuss) cultratus Montfort Polymorphinidae: Globulina sp. Nonionidae: Nonion advena (Cushman) .alabamense Cushman and Todd inexcavatus (Cushman and Applin) Nonionella hantkeni (Cushman and Applin ) var. byramensis Cushman and Todd oligocenica Cushman and McGlamery Elphidium leonensis Applin and Jordan texanum (Cushman and Applin) Camerinidae: Camerina dia (Cole and Ponton) Operculinoides sp. 16 Table 4.--Oligocene Foraminifera of Georgia - Continued Buliminidae: Reussella byramensis Cushman and Todd oligocenica Cushman and Todd Angulogerina byramemsis (Cushman) vicksburgensis Cushman Rotaliidae: Discorbis alabamensis Cushman alveata Cushman assulata Cushman byramensis Cushman hemisphaerica Cushman subaraucana Cushman tentoria Todd Eponides byramensis (Cushman ) Rotalia byramensis Cushman var. mexicana Nuttall var. mecatepecensis Nuttall siphonina advena Cushman Cancris sagra (D’Orbigny) vicksburgensis: Todd Baggina xenoula Hadley Amphisteginidae: Asterigerina subacuta Cushman subacuta Cushman var. floridensis Applin and Jordan Cassidulinidae: Alabamina mississippiensis Todd Chilostomellidae: Pullenia alazanensis Cushman Anomalinidae: Anomalina bilateralis Cushman Cibicides americanus (Cushman) -americanus (Cushman) var. antiquus (Cushman and Applin) hazzardi Ellis lobatulus (Walker and Jacob) mississippiensis (Cushman) pseudoungerianus Cushman cf. C. refulgens Montfort Planorbulinidae: Gypsina globula (Reuss) Orbitoididae: Lepidocyclina mantelli (Morton) sp. 17 Table 4.--Oligocene Foraminifera of Georgia - Continued REWORKED FORAMINIFERA: Valvulina floridana Cole martii Cushman and Bermudez Discorinopsis gunteri Cole Coskinolina floridana Cole* Dictyoconus cookei (Moberg) Lepidocyclina antillea (Cushman) EOCENE SERIES Upper Eocene rocks - - Upper Eocene deposits have been identified in more than 300 wells that are distributed over the Coastal Plain of Georgia. This unit is uncomformably overlain by beds of Oligocene age and unconformably overlies beds of middle Eocene age. The subsurface upper Eocene in Georgia is correlated, in part, with the Barnwell Formation and Cooper Marl of Georgia and the Ocala Lim=stone and Inglis Limestone of Florida. The subsurface areal extent of upper Eocene sediments covers a much larger part of the Coastal Plainthan either of the two previously discussed stratigraphic units. (See figs. 6 and 7.) ‘ The upper Eocene beds are composed of an updip, clastic facies, which interfingers with its middip limestone equivalent, the Tivola Tongue of the Ocala Limestone (Cooke and Shearer, 1918, p. 51), along a line trending northeastward through roughly the center of Houston, Bleckley, Washington, Jefferson, and Burke Counties and then southeastward to the Savannah River to northeastern Screven County. More- over, the Barnwell Formation progressively overlaps geologically older formations in a northeasterly direction across east-central Georgia. Thus the Barnwell Formation, beginning in eastern Twiggs County, successively overlies middle Eocene and Upper Cretaceous strata, finally resting directly upon crystalline (basement) rocks as erosional remnants, or outliers, insouthern Hancock, Warren, McDuffie, and Columbia Counties. As a result of this overlap and subsequent erosion of the overlying Barnwell Formation, particu- larly along the major streams, sediments of middle Eocene and Late Cretaceous age have been exposed as erosional ‘‘windows’’ in the northeastern part of the Coastal Plain. The updip clastic facies of the upper Eocene deposits in Georgia is composed of the Barnwell Formation and the Cooper Marl. Lithologically the Barnwell Formation consists of fine to coarse-grained, gray to yellow to pink to red (at the surface), arkosic sands interbedded with cream to bluish-gray to pale-green, blocky, glauconitic, locally fuller’s earth (type), fossiliferous clay or marl, and some thin beds of rather dense light-gray, somewhat sandy, sparsely glauconitic, locally fossiliferous limestone. In this report the clays or marls of the Barnwell Formation are collectively called the Twiggs Clay Member, after Cooke and Shearer (1918, p. 41-81). Overlying these clastics and also included in the Barnwell Formation are flat white to gray, somewhat chalky, sandy, cherty, sparsely glauconitic, sparingly fossiliferous limestones which Cooke (1943, p. 65) calls the Sandersville Limestone Member. This limestone occupies a small area in the subsurface of south- ern Washington, Jefferson, and Burke Counties, northern Emanuel, eastern Bleckley, and probably most of Johnson County. On the basis of one echinoid, Periarchus quinquefarius (Say), Cooke regards this limey facies as representative of the youngest upper Eocene occurring in the Coastal Plain of Georgia. However, the authors feel that this limestone may belong to the late upper Eocene, or Cooper Marl, or even to the still younger Oligocene deposits, At any rate, muchmore subsurface data are needed in order to establish firm- ly the true geologic age of the Sandersville Limestone Member of the Barnwell Formation. The remainder of the updip, clastic facies of the upper Eocene sediments in Georgia belongs to the geologically younger Cooper Marl which overlies the Barnwell and Ocala Formations and was named by Cooke (1935, p. 73-75; 82-89) from exposures in the Coastal Plain of South Carolina. In the subsurface of central-east Georgia the Cooper Marl underlies a rather extensive area that includes parts of Dooly, *Considered by Douglass (1960, p. 258) as synonymous with Dictyoconus floridanus (Cole) 18 Pulaski, Houston, Bleckley, Laurens, Johnson, Emanuel, Bulloch, and Screven Counties as well as most of Jenkins and Candler Counties. Lithologically, the Cooper Marl is a cream to light-gray, somewhat sandy, rather loosely consolidated, glauconitic, rather abundantly fossiliferous marl. ‘lhe downdip lime- stone facies of the upper Eocene in Georgia is the Ocala Limestone, which is composed of two kinds of limestone. The upper division is composed of flat white, highly calcitized and somewhat saccharoidal, porous, abundantly fossiliferous limestone. It occurs as a wedge that pinches out inland somewhere in the second tier of counties, as for example in eastern Effingham and Bulloch Counties. The lower part is found throughout the subsurface of the Coastal Plain wherever the Ocala Limestone is present and consists of cream, somewhat granular, much calcitized, sparsely glauconitic, sandy (at depth), fossili- ferous limestone. On the basis of lithology as well as paleontology, the outcropping Ocala Limestone in Georgia is representative of the lower division, the upper division not extending this far updip, as noted above. Like the Oligocene limestones the limestone facies of the upper Eocene is composed, through secondary alteration, of light to dark-brown, recrystallized, saccharoidal,dolomitic limestones in south- western and extreme southern Georgia. In eastern Mitchell and Decatur Counties, and in Grady and Thomas Counties, the top of this stratigraphic unit has been arbitrarily picked in wells on the first appearance of dark-brown dolomitic limestones. These upper Eocene dolomitic limestones are only partially dolomitized in Brooks, Lowndes, Echols, and Clinch Counties, where the top of this unit may usually be picked on the basis of appropriate Foraminifera. Thicknesses of the upper Eocene vary from a few feet in the area of outcrop to over 700 feet. A few of the more important publications on the upper Eocene Foraminifera include articles by Cush- man and Applin (1926), Cushman (1935 and 1945), Gravell and Hanna (1938), Howe and Wallace (1932), Cole (1944 and 1945), and Puri (1957). The Foraminifera of the upper Eocene are the most abundant and distinctive of any Tertiary unit in the Coastal Plain of Georgia. Moreover, both the Twiggs Clay member of the Barnwell Formation and the Cooper Marl contain excellent assemblages of the smaller Foramini- fera. The Ocala Limestone contains the most abundant foraminiferal faunas of any formation in the Coastal Plain. In downdip areas, where the upper division is present, this limestone is composed almost entirely of fossil remains such as molluscan shells, small brachipods, echinoid spines, bryozoan remains, ostracods, and Foraminifera. The lower division of the Ocala Limestone is not as abundantly fossiliferous as is the upper part but it contains many more of the larger foraminiferal species. Of the outstanding guide fossils of the upper Eocene in Georgia, those from the Twiggs Clay Member of the Barnwell For- mation include Textularia hockleyensis Cushman and Applin, Valvulineria jacksonensis Cushman, Nonionella hantkeni (Cushman and Applin) var. spissa Cushman, and Hantkenina alabamensis Cushman. Those from the Cooper Marl include Gaudryina jacksonensis Cushman, Marginul Marginulina cocoaensis Cushman, Bulimina jacksonensis Cushman, and Eponides carolinensis Cushman. Those from the upper division of the Ocala Limestone include Textularia dibollensis Cushman and Applin var., Pianularia truncana (Gumbel), Lin- gulina ocalana Puri, Operculinoides floridensis (Heilprin), Mississippiana monsouri Howe, Asteroc clina nassauensis Cole, and Pseudophragmina flintensis (Cushman). In addition to these diagnostic Foramini- fera at least one species of a small brachiopod, Argyrotheca wegemanni Cole,often occurs in the upper division of the Ocala Limestone. Species from the lower division of the Ocala Limestone include Textularia dibollensis Cushman and Applin var. humblei Cushman and Applin, Eponides cocoaensis Cushman, Siphonina jacksonensis Cushman and Applin, Cibicides mississippiensis (Cushman) var. ocalanus Cushman, Camerina striatoreticulata (L. Rutten), Operculina mariannensis Vaughan, Amphistegina pinarensis Cushman and Bermudez var. cosdeni Applin and Jordan, Lepidocyclina Ocalana Cushman, and Asterocyclina georgiana (Cushman). The detailed faunal list in table 5 contains the more prominent foraminiferal species that have been observed both in surface and subsurface occurrences of the upper Eocene deposits in Georgia. 19 ‘syisodap aua00y seddn jo do} ays jo dow snoju0d—jDanjyonsjg—9 aunbiy peo eae 262-082— OOS + re- Ni “0 \c-¥Gan) \ - 9be- 390¢€ O enaN 6$2- ‘syisodep gua00q ueddn jo dow uodlsnqiajsip—sseuyoiu;—z eunbiy asueiodedeys x -= a ae Pn -— [hs a a a oe SS a oS 2 oS Ueulysno) EUsApealomon seepluOTUON Ve —t— | os ao TTT TT TS SS SS Sm — eMeZO pue URWIYSND SeTOUNNT ET[SpFOUISTS Y-- Se | ere myers a ee ee a eee TRANS STO) EJOSITUIOS ee | eee wee Pape (emezO pue ueWYysnd) e19ajTIS09 ‘reA (UeUYSND) STSUSUOSyOEr x TO SS SS SS SS SS > > = (aE) EEE Sa BUTYCIOWOWSTS fe eee Ee eS |e ne OM at ae TO SS SS S&S = SU oa WEIN) eS Se SS SS FS a SS = SS = =e) RRRED CERO Eryn eE el eee — = = Xena Shes = TTS STS SS SS = = (raysuan] UA) BSOGOTS ‘zea AuStqGI0,q eqqTs Se See So eS S| Oa SSS oS SS SS Alsasola cage eurmqors X me f—-- xX mo] -- HH le | eH HH roman) OSE xX egroleer x crcl oor xy ee Om KOO ll Re eK eH eH KH er eH ee er re er rr rr (Ang 10,0) StaremBeray BUTTS soeprutydsowAod xX —— mene nm em Pe aK Xr Je ee ee He ee He ee ee ee ee ee = say eysonqinoe CURSE] Y=-- ae ee mee meen | ae TOT rr gg Buee D0 eUTINBUTT] F aa FG eae |e aes ae oe Sa tae Gag aes) pene gee eee ee ey ae oe 7 a a ~ adRTIEM PUP SMOH eURTSAIOUI ETIBUaDeIeS yee lee Se ea a Le a me ie se a ee ee eens ee Se | ee inh ae | ag er mcr) ak oars rad ed ome 77 7 7 = (Tequind) ereisootssiy X xX x TT a = — = = = —ueuysno STsusuypores ‘rea Tequiny eqesnloiey eIIESOPON x-- m= y melo m-xK-- ST eT Te AY DW Elo) EERO x --|lJ----- TTT TT Se ee wm ee ee ee eS eS = —(UeWYSND) sTsuav0s09 Xioaiie aA || een Xp oo aa an a ie a oe ee reunions) s[suerscooonenr EIuSG ae eis ees TTT TPT SPT Re 77 Pe 2 2S > Sie) San = Ste 22 aes aoe ee aed ae et ee Type uewysnD) sfsuesexal ‘rea (Tequind) efieseay “a i ae Gy is RS Se ae Gee oe ST SS Se = = —UPLIYSND STSUdeOD0D eUT NUTSIE x = CT ye | oe id Se SS ES) SS SS Se aiiiits)) eee | SS SS SS SS SS SS SS SOLAS] PUL UPLUYSND EUeper0es EIaENULTa De oes ia eoieieceat |S) aig oma, sages | ae tes a TOTS SS = = = (urrddy pue uewysno) stsueAe;yooy ‘rea (ssney) Snsoquilt X -—--]| ----- a a a a a ee eddy pue uewysnd) snuexe] “rea (ssney) sniepnopize se | CS en, el A -—-— — — sueWYsny snuel[ored "rea (UdyIWeH) SNyel4Is-o]end1e KT en xe stm ern nr nm Per nr nna ar a a a = = = = (RQUEND) ENIEqUIT[-oIe]e SHINqoY toepruese] X Ttprr err ee Je ee me He Ke Ke ne er er er er er nr er rrr reysng sfsusuosyoe! euyAapney SoePIUTTINSsuIsA YS S TTX TT fem exter epee eer re rr ae a 8 res Taoneugns KT a a aa a oe 5 = & = eye SETH X 7 TS Pe ana a a a a a a eae a = yddy pue uewysnod stsueAe|yo04 ens —-—- xX TT yr rr mom oe eH eH He eH Kl ee ee ee er ee ee en a a a a A a = = ste Petey SGI rare | meena mae WGC Sc cae me ee cea oe - Serr rT Toto muddy pue ueunsno terquiny ‘zea uytddy pue uewysno stsueTfoqip ea sO XK erm dr nr XY wm eK Perr rrr rrr rewysno Byepe BfaenixeL i == — = — Ge a eee a ae oe Rem TELUS @) ST SUS UMEC EI Eis aA (uewysnd) sTsueTdd{sstssTw eupywiWiededostds ToepITIe[NIXd L Tre AelO SUOISSUITT BTEIO aedooa S33IML BTBA0N) JO EAosfUMeaO. 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JAN SYOLAUS TIOUE Ss) SCSae es || a a eS uljddy pue uewysno sTsueuosyoel --- a a a a a a RTE PUL BMOH STSUSTITAUEP euTUOYdTS a a a Oo MONE nosuOUMeUlOdTSoToSTIN ==s=y --] ~- ee ee ee eer 7-777 7 7 7 7 = (urddy pue uewysno) sfstetosyoer SoSHon a ae ee ee ee a a a a a aa ae ae ae ee ne er er — — —uewysnd STSUSEOS0D —--—-—-— | HK HK HK Ke eK er ee er rr rr rr Tt uewysny stsuautjores Ssapfuody —j--—-—--—--—- leer er Ke ee em rrr rrr rrr rrr = = meg Stu pyaTySutads KX mS) RS SP SST SS HST euuey ‘Gd ‘5 pue uemysnD ejeteuiEd0I00 “zeA AusTqI0,qiiueplos Sooo ooo SS a So SoS a SS ee Ss SO ----—— — — —900 STsuanesseu Socsnceeanet| “aoe ee —- ee ee rr ee = =) ing STSUOTOATIT CIS —--y-- |] ee eK AH A RM A a a A A A = = = seg deaeupse3 3 BuTproaA5 j= — eK KR eK eK eK KH KH KH KH HH COST pue uewysnD euexs} a I DC i NO CELI] OV UOT TIO) STSUSUOSHIEL ees 9 meee ee me) oe <= SNe wusns sTsueuosyort BLIOUT[NATeA —----- - --—--—-—— uewysn eueoneseqns SSS oS OSS — — — — — — — — uewysno esourds-ojngoTs —- a} ee ere er er Ke Ke ee oe oe oe ed oe OTe SU PULSUELUY Sl iS TS uo cO000 SS oS SSS oo SoS SSS a el TIPU SNS) ACIS SE, —--| —--------- SOR OPS SSS OSS SS SS STE) HEE SCE OE al ‘SEPITTEION eee ee ee ee — — — — — = PESO CUSAPE “IEA UEUlYsnO jAperg EUTIEsT AL, xXx-- —- eee er ere er Ke Kee -~ Serr rr rer er ere sovlerysna eueyeso eupzes0[neuy aaa | Soosecoe 5 a= aaa aa = «END StsusTidos SS os SS ee Oo —--— - - K- KH HK Ke Ke KH KH KH KH KH HH 3ewyYsn9 stsustosyset mH~o—-] H- HH - HK KK KH ee ee ee ee ee = = = = —resnn steaqe 23 EY DS SS all (oD WD) (ECTS so —- ee Ke er em er nr a a aa ae eae eer eee er ere uewysnD SsTsueeos0d eUTIESTA‘) —— — — — — (uewysnd) st[tdinos — — — (uewlysnd) euasoe e[fessney 11 V1 11 | I | | | | I | l | | l 11 1! 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BUTATTO ee Kf) er rr rr rrr rrr rrr rrr rH reysng Stsusuosyoel eutmting Ko a (A0819I0,C) PUTSSTIUEZETS eTTSUTWTING soepIUTWITING — ee eH ee ee Rm eo a ee ee ee a = SS > rE IEND BULTEDO eUTZEIS0O1919}H — eR He A a a a a a = = = = = = — envy Sotouuepaems BUTTNOISdO 2 I OD (Cel gE)) GSEC COE: Ses OUIHIMOREEO) I es a EHTS 9) CRI BEECH SAS CSET) soepTUTIEWeD X= — Ja ae ee eo Se = Se eS = — — ESN SHUGOTAOWe SepropIycTa xo - |---- - A @ A A A ee a a a = resp es yma tanTpTydTa ee =e ee ee eR ee reysna esstds ‘re (uttddy pue uewysnd) tuexquey e[[ouoTUON x-- aH a Re a = = = = = = = = = = semouy, pure uewYysngD Sshiyeuela TOTION (penutquoD) septuoTucCN jae AelO aedoop S23IM L PanutqwoD - efs10S5 jo eAosluTuieAO, Sooo TodaT]--"S aTqeL UOISTAIP IOMOT Jo doj ie UT SeWIOD~ Ys lah are Vet ieee eae el boii Sage pein |W aed nape ae ae ge es as ee ao Fees ete — (uewysn) stsuaquTg euruTsesydopnes | — = a a a oe a a a aS ae a a ae a Seas a ae a GOOD STsUonessen xo ote re moe om mm mofo ccc cle ccc ccc Km ooo —-— -— me — — — — — —(ueunsng) Fiepss0e8 suppoko0aS1sy saeprutToAo0osTq X uewysnd PueTeoo agi | reas ae ge (eae eee amet ee a on tieg pee a aiitanoq “y pue aujoula] Jredeyo eutfoAooptde] *SePIPTOIGIO _ a a a en ee ee ee es ee ee ee eee eee (SOLO (DUE oye cl) She Inolsos: a gM a Re ph ee ane hc a meee ee ee eS oa (Bey) CINIO[S eUTSCAD) saepTUT[nq1oueTd Xi see same | aaa ame a 1mm came Sum Get pk |e a a re ae a a oe (Ue ULISN) Snuelzecunopnes Se Fe ed --- 7 7 7 TO MoDRTTeEM pue amoy STSUdeITYSeNo apa Dig om aes al Dae | RPT! pecans on a IE ee SOL —-—-— — — > m uewysng snueteso ‘rea (UeWIYsND) STSUeT oe el is ae we X oS = Sa oa ke ee ee et eo ee = ae ee? be (ESTO) Sts uRy TSST > [= 6), ge as aa CR eat ee eae prs rere aa — ~ ~ “(qooef pue JaxTeA\) sntnreqoT 7 timein .) hint oa Sila ao oe | SS = SS SS SOeIEM DUS OMOL] SISUSTITAUED 7-7 TT ST 7 > =(uddy pue uewysno) Snnbrue ‘zea (uewysno) Snuestrewe oe Mi Ge aa a oe ee ae a a led — — (uewysnd) snuectieaue seproiqIig Decne via gare), Gerri cai oman | Heme rare ee anes | tee oe i ae es So —----—- — — ~ = vewysng stsuaredood *1eA ueWIYSND sTsuae0d05 x a a a a ot a aa a as aa ae ae ae a UELUIYSn@ stetoeooosuenr nucle SSePIUL[PWOUY xo co cl--- ee Hp o ex co cf oc oo cf ee nnrr = = = = cewysng SFSTSEOSOS UTTEIOIOGOT LdePITTeIOIOGOTN Xoo ale ox oo l------ - - HH HH HH HH resng REE ENA soeprulueyquey Da aaa a i a ea la ala a 7-7 TT TT a = = FOeTTEM PUe SMOH STSUST[IAUeP SS | a a nd ae ceed eal eine uma D IIUSM a) OE STIUL IIE RUUT LEG iyi sos tt me rm rm em em me er er oe er er er rr rrr rewysna eues33tMi ee es ee a Sa ETT x-c- TS xT tr mr rr re er a a a a a a a a a a a query PSOGOTS VUTTNPTSSED ‘sepIuI[NpIsseD SC cals sp ies || air aman aan ae: | = kk a am a a baa eee Bet cee | pe ae ea ao oe uepsof 8 ultddy Tuapsoo *1eA zepnulzeg pue uewysno sTsuereuld eutseistydury ‘oeprurseistydwy Jamo fi | seddn [Ie ARTO SUOISSUITT eTe9O aadoog s33IML penutquoD - ®fsa0e5 Jo edosjuyWeao,| Stlcoog Teddy--"s atqeL Middle Eocene rocks--Sediments of middle Eocene* age have been observed from over 100 wells in 44 counties of the Coastal Plain of Georgia. This stage uncomformably overlies the lower Eocene, is overlain unconformably by the upper Eocene, and is composed of the Lisbon and Tallahatta Formations. The Lisbon Formation is the subsurface equivalent of the McBean Formation (Veatch and Stephenson, 1911, p. 237) which crops out at McBean and on McBean Creek in Richmond County in eastern Georgia. The Lisbon Formation includes the rocks in the subsurface between the underlying Tallahatta Formation and the overlying Gosport Sand. Both the Lisbon and McBean as now used by the Federal Geological Sur- vey include only the equivalent of the Cook Mountain Formation or the Ostrea sellaeformis zone. As originally defined the McBean included some beds of late Eocene (Jackson) age and as used by Cooke (1943) it included beds of the Tallahatta west of the Flint River. In order to eliminate such inconsistencies in stratigraphic terminology when applied to the subsurface, Counts and Donsky (in press) and Herrick (1961) have extended the use of the formational names Lisbon and Tallahatta throughout eastern Georgia. Based on known occurrences as given in the well-log report, the Lisbon Formation has been found east of the Flint River in the subsurface of the following Georgia counties: Appling, Atkinson, Bleckley, Burke, Chatham, Coffee, Crisp, Dooly, Emanuel, Jenkins, Liberty, Montgomery, Pulaski, Screven, Toombs, and Turner. The Tallahatta Formation as reported by Herrick (1961) is found in the following Georgia counties east of the Flint River: Appling, Atkinson, Chatham , Coffee, Crisp, Dooly, Emanuel, Liberty, Pulaski and Toombs. The Lisbon and Tallahatta Formations compose the updip, clastic facies of the middle Eocene in Georgia and are correlated with the same formations in Alabama. They also correlate with their downdip limestone equivalents, the Avon Park and Lake City Limestones of peninsular Florida. In the subsurface the areal extent of the middle Eocene (see figure 8) is somewhat less than that of the upper Eocene, although solution of the Ocala Limestone of southwestern Georgia tends to cause the maps to fail to show this. In southeastern Twiggs County the middle Eocene is overlapped by beds of late Eocene age (Barnwell Foramtion), the middle Eocene appearing along the major stream valleys as erosional “‘windows’’. Furthermore, the Tallahatta Formation of early middle Eocene age is overlapped by the geologi- cally younger Lisbon Formation of late middle Eocene age--such overlap taking place in eastern Sumter County. From this point the line of overlap continues in a northeasterly direction across the Coastal Plain through southern Houston County and through the middle of Bleckley, Laurens, Emanuel, and Screven Counties. The updip, clastic facies of the Lisbon Formation consists of interbedded, fine to coarse, subangular, sparsely phosphatic, locally fossiliferous sand; cream to gray to pale-bluish-green to dark green, sandy, finely glauconitic, cherty, fossiliferous clay or marl; and white to light-gray, rather dense, massive, sandy, coarsely but sparsely glauconitic, fossiliferous limestone. These sediments interfinger with their downdip limestone equivalents along a line that runs approximately through northern Seminole County east northeastward through the centers of Mitchell, Tift, Telfair, Treutlen, and Emanuel Counties, thence easterly through northeastern Effingham County to the Savannah River. White to gray, coarsely glauconitic limestone is prominent in deep wells in Toombs and Emanuel Counties, thus proving the existence of this facies of the Lisbon Formation this far north in the Coastal Plain. In updip areas the base of the Lisbon Formation is often composed of white to cream, rather massive, sparsely glauconitic, shelly, coquina- like limestones, which show up on an electric log as prominent resistivity ‘‘kicks’’. Downdip from Mont- gomery and Toombs Counties these white to gray, coarsely glauconitic, rather massive limestones are replaced by cream, somewhat chalky, much calcitized, granular, gypsiferous, sparingly fossiliferous, locally dolomitized limestones. In Echols, Clinch, Camden, and Glynn Counties the Lisbon con- sists entirely of alternating beds of cream, chalky, and brown, dolomitic limestones, a type of lithology that is similar to that of the Avon Park Limestone of northeastern Florida. Where present, the bulk of the limestone facies of the Lisbon is composed of these cream, chalky, granular lim=stones. The chalky limestones are for the most part lacking in microfossils, except for certain horizons where such fossils occur abundantly. The updip or clastic facies of the Tallahatta Formation consists of interbedded, fine to coarse, sparsely phosphatic, fossiliferous sand; thin, dark-green to dark-brownish-gray, silty, micaceous, glauconitic, *Owing to a lack of fossils the Gosport Sand is not always differentiated from the underlying and geologi- cally older Lisbon Formation. For this reason it has been thought best to include this formation as part of the Lisbon in the discussion that follows. 25 "SyISOdap euad0j a|ppiw ay} 4yO do} ays 4O dow ANOJUOI—jO4NJoNAWS—g eu4nbi4 9c8 9&8 ov8 oS8 SSW OF € 9190) aas sjoqwhs sayjo 40 uol;DUD|dxa soy + Buissiw auas0z app; i \S i pk NN CWE °nsys : NOILVNV1dxX3 » a eck o&8 ove oS8 Qo? ase ole lock "syisodap 9u9904 ajppilw yo dow \—o- ee ys +8¢1 7 OFE UOlINI4JSIP—SSeUyIIY|]—6 a4nbi 4 008 9S8 t —— — HAE) S3IW OF 02 EN cea (ea \ € a]qo, eas sjoqwAs jo uolyDUD\dxa 404 ov8 oS8 lock Di locally cherty clay or marl; and occasional beds of light-gray, sandy, coarsely glauconitic limestone. The top of the sand section, which generally is also the top of the Tallahatta Formation in updip areas, usually contains abundant molluscan shells, giving a coquina-like appearance. Examples of this type of lithology are found in wells situated in southwest Georgia, particularly in Terrell, Lee, and Dougherty Counties. At the base of the Tallahatta in updip areas, prominent chert beds are often found, a feature that is so particularly characteristic of this formation is southwest Georgia that the bed was formerly called ‘‘buhr- stone.’’ Interfingering with these clastics, the downdip Tallahatta consists of light to dark-brown, saccha= roidal, coarsely glauconitic, locally fossiliferous limestone that is interbedded with occasional beds of fine to coarse-grained, granular limestone. The downdip limestone facies of the Tallahatta Formation is similar to that of the overlying Lisbon but is much more dolomitized and considerably more glauconitic. The middle Eocene gradually increases in thickness from a few feet in its outcrop area to over 1,300 feet in southeastern Georgia (see fig. 9). An area of greatest thickness, or depocenter may occur in south- west Georgia. Some of the published articles in which many of the middle Eocene Foraminifera are described and illus- trated include those by Howe (1939), Cushman and Todd (1945), Cushman and Herrick (1945), Cole (1929), Applin and Jordan (1945), and Bandy (1949). A few of the more commonly occurring guide Foraminifera of the Lisbon Formation in Georgia include: Buliminella robertsi (Howe and Ellis), Discorbis inornatus Cole, Asterigerina lisbonensis Cushman and Todd, Cibicides westi Howe, Cibicides pseudoungerianus (Cushman) var. lisbonensis Bandy, and Lepidocyclina antillea Cushman. Some of the fossils indicative of the Tallahatta Formation include Valvulineria danvillensis (Howe and Wallace) var. gyroidinoides Bandy, Cibicides blanpiedi Toulmin, Cibicides pippeni Cushman and Garrett var. stavensis Bandy, Cibicides. tallahattensis Bandy, and Asterocyclina monticellensis Cole and Ponton. The faunal lists in table 6, though by no means exhaustive, reflect the Foraminifera found in the two types of facies-environment that existed in early and late middle Eocene time in Georgia. 28 BIZIOSH UaIseaYyINOS Jo susd0q STPpIwWl ATA UT OJ payooT aq pynoys Inq ssouINe ay; Aq PeAtasqoO ION x Xm rpm rm rr rr rar saa (Uy pure wewysnd) winuexei wintprudTg X — =-|— -— — = A R= = = R= = = = = reysna essids *1ea (utjddy pue uewysno) Tueyuey e][ouOTUON X emf --—--—-—- ee eH KH HH KH HH — — seo, pure uewysno Siieueyd SA SS Sa SS SS SSS SES) Simei pes Ka a a rer ee er ee eH — - —(ddy pue uewysno) siyeAeSxouy X ~ ele eo oe or nr na a A ee ee ee = > & & (ues) euaape U0TUON sOePTUOTUON KX tree er er er er eH HH KS Seqoy pue emoyY epnu ‘zea ueUYsND euUeApe eUuTYydIoWATOg X -cle- ee ope oe er rr rrr rrr rr meZO pure URWYSND SEIOWLINIA E[[OeplOWSIS X--l-- occ ecco oc occ CC — — — — — —(uewysnd) stsuauosyoel eUTYdIOWOUISTS x —--|---------------- & - = = = = = = = — = (s2n0y) Spuopeeoyds | a a aca a eee ee ee er ee ean (AUS IO L@ GINS TLE code TAeUT [Naan Ss) soeprurydszouisjog XY — fe — = — RA A Re Re He A ee a a a a a a snoy 2ISOOTINGG CUSBET Re | ee eee a ee am Be cee ae ele —(utjddy pue uewysn9) Stsueudsyoel euTTelueq X —~ ooo ne Re A A ee = ee ee ee ee = = = = (2b) STSUSTTIABIEA _ Xe ocl-- - ee ee em rr rr rr rr rrr resp stsuseos0d euT[NUIZIeN X moh erm em em mr rt rr OP IIOY pul ueWYsND eueTsI003 eTAe[NUeTd X emt ttt tr aaa a a aa = = = = = (A019 0,) SHTETIONT SS ea | ee oa ee (TCLUN SS) ESTP OL EAST NG OM ‘oepluozsey] DD eS a a SE BES GaN SOBPTLOTTITIN Xoo) mem rm rm er er nr rar aaa aa ee > (rerrysnd) SnuBdTIEUIe SNUODOAIDIG Kem emp mm rr a rr rrr an Or crc er rr rrr rrr 48102 ULPTIOTZ VUT[OUTFYSOD MoS | Sea sf Sooo oe oe SS -Sttrr e rm em eH epsof pue urjddy juewysnd eupwrtnqosqri9 IK eas bee Fe eae Sama | GaN cae mee ine wy we cee nar at ns rm - See Oe Oe OK epsof pue uyfddy puewysno eurtpnaTeA SOePTUT[NATEA, Pe os | (eae Sree ees —---—--—-—— — — —wyddy pue uewysno stsuaTfoqrp X Te] ort ee er rrr HH HH er er eR Re eR Re eH = = = = neg roid 2 SS SS i > SAE) Cho LSC GENeHL X ~-—|--—--——-— — — — -- — —(uewysnd) stsusmeqeye ‘rea (ueuysnd) s{suetddiss{sstw eurwuejoetdordg SOBPITIe[NIXaL, SoloRry SoD} sotoerj setoey Suo{sowTT oT3seTD SudIsoWTT o1aselD uoTIeWIIOY eNeYe]IeL uoTleWI04 uogsTy BTBIOSD JO eLOJIUTWIeIO eUeco”y S[PPIIN--'9 STGe.L 29 Ye SS xX _ — —— — xX -- Sf es ee X -- SOTOP] SOTORJ auo1sowrT OTIS eTO uOTIeUIIO eEYETIEL SoToRy aUuoISOUITT Se I I I I I ! I 1 I I | | 11 | I | SOTOR} onselo uOoTIeWIIO4 UOqSTT penutjUod - PTSIOSD JO eXosIUiMIeIO, oudoOy S[DPr mot ep rr rr rr rr = soured *y 1c ToBIZSdo BaFSrstyduTy X-—--]--—----- ee ee me er KH Kr KH KH KK ~ppOL pue uewysno stsuseuogsT] euliestieisV ‘aepturseistyduy a |e are ee etree oe ree ae —Fddy Due UsWUSn ai SisuoloOsyoEL oa cal | cae drama cae a ae ae a ae ae 7S tT SSH mK — —ueUsna stsueuZOgrepo euruoydrs == — — (UeWySsn®) snuvorxoul — — — — —uewysng s{suee0s00 Saptuodg KmmMerrr ere -— — — —euUeH ‘Gd ‘5 pue uewYsND elerewied0190 “eA AuZIqIiO,C TIueptos es eee ee |e ee ef me ee 09) | SUSTESS EL GUID [ONAS) Xm) errr rr erm rm rm rm or re rm rm er rm er rr rrr SCOTTY pue uewysny euexsi Cae) ee a ed eee ie CEST TMT SASd eAPAUIIE LIU SN@ SISUSUOSNOEL - StF T rT TTT TO oT om Apueg SdprourprosAB -zea (a0eTTeM Pue OMO}{) STSUST[TAUSP ETIOUTTNATeA, eee atlas a lanier ee tT ple | Ta T Zul STSUSEN Goh 7 0 Gels 2S 823 2S eas oS Se SS eS SO del SEC Sin ir memes a ed an a ar a melee eee ee eel OTS) ST IVIELOLT CX ecmiad | teem eet eee eee ee i eae ote eee aed ed OT TO] Te DUPE USNS) aeUPTS100 EXGiet remem | seni mei es re” ne etme md eg ee eet) eel ne nee eee EE ITT ST EIU NSSU Ss TCqaOOST GL x7 ole - eee ee eH HHH HH HH HH = = = = ewsno Seape STG Dar ana [he ar arsd ent ee Sr ee ee oe me STOO] VALEOTATA “G1 JO 2d ae aa Nae = = SS = = = = IP Luysn sistiedangsyorA euriaraS *SEPIT[PION Se a or lige erie pea -—-S- - te OH HH HH — (UOWog pue uPWYSsSNdD) STSUSXOSTIM SULIEIIIL Se ees |e es es SSS aoe — ee er rr rr ee = = — = sng stsuasainqsyora X --/|/—-—-—-—-—- 2S S65 SS 5 Ses —— — — — — — vewsnd stsuaredoos eutsesotnsuy NO Se —- ee ee Ke Ke Ke Ke —-——-— (sewoyy pue uewuysnd) elepunioigns elTessney X 7~orr-- eH er ee K —_------ —-—-----— -— — — ~—uTddy pue uewysno Stores ee — — — — — — — — SLIBGOY pure SMO Iplessnosq eUlAT[og Xeel-—--—------- + SO ee eS ia) cee Xe ee fe eee ee eee ee —_— — — — — — — SHISGOY pue aMop] WaInsoul Oe SS Se See —-------+- — — —urljddy pue uewiysnd stsuaT[oqIp eul[nZI1A (sTITa pue oMoH) [Sireqor eTjeutwting seeprUyWTINg 2 I SE IT SE | OKC X- - = PSOE PDS | eee a Os oe SN ee Xeon Kem em ele iar cr crc cc eer er ee Keoe X-- y- - oD NT I | a oem se eS ee a See ee eS x Wilecoxensiss GUShmanvanG 2 Ort Or see ye eee ee ee ee ee X Verneuilinidae: Gaudryina pyramidata Cushman — —~ —- —-—- —~—-—~ ~~ ~~ ~~ ~~ ~ ~~ — — — X Glavulliinoidesimidwayensis! Cushman) — ya) eS SSS Se xX Lagenidae: Robulus midwayensis (Plummer) — — — ——— ——~— — — — _ — xX Pscudoemamuulicenus (UMM e) ee ee ee es ay eed oe xX EMS EMAL USN (UMA) mel ee Sa aed a rs ty a xX pseudo-costatus (Plummer) —-—- —~——~———-—-—-—-—--—-—-— Bis wilcoxensis Cushman and Ponton— —-——-————-—-—--—-—-—-—- x alabamensis Cushman — — = = — —-—- —-——-—-—~—-—- —— Xi degolyeri (Plummer)— — —-—- —-—-—-—-—-—-—-----—--—-- xX cf. R. rosettus (Gumbel)— ——— —~—~—-—~~—~—~——-—-——-—- xX Dentalinalcandnenaer(Plumme:) east) = ee eee Xx ColeimCushmantandsD uSenlowtyypen ety) ent et reen ey ee ee eae MoSsesccoos x wileorenicens Cusitiingin— Ass es ee oe eee ee XK Nodosaria latejugata Gimmie eee mete ee, eC Sat eae, oR pel Sie X affinis Reuss ~ —~ — — — — — — = — — — — =| — x Sea ooe cs X Pseudoglandulina manifesta (Reuss) — — — — — — — se ply aes aed enol irtee, V ei iak x Vaginulina midwayana Fox and Ross —— — — = — — — — — — ~— — x lontiticrna (Pliner) SE 5 ey 5 Ee Ee ey ee ea eS Se xX Polymorphinidae: Guttulina problema D’Orbigny —~ —- ~~ — —- —~ —~ —~ — — eS a I Sd aN Gloawiling algo. DY Oyeoikemy; 5 ee ee eae ee x Sigmomorphina soldadoensis Cushman and Renz — — —~ —~ — — —~ — — xX Polymorphina cushmani Plummer-- —~— —-—————-——— — — X Camerinidae: Operculinoides catenula (Cushman and Jarvis) ~$ — —~ — — _ _ __ ~ Xx Alveolineilidae: Bomelisweunberiy © oles te jem ae eee Nee ney ens As, angen DL ee x Heterohelicidae: GuembelinaljmmidwayenSas (Gus hare and ooo yee Meme es ee es ie ees ee xX Buliminidae: BuliminaycacumenatayCushmeaniand) Parker, jee le | eee lee tee ee eel eee x jauvestlerent) Cues owaagetiay feavel Sra, Sst ee X (eSinobulinainayiquadizatayke bummer, es ey eu ee I ee eu Te ee eae ale a aa eee x exo) into phone syetolsats (Cbelnene a a Oe a ee al Ne 37 Table 8.--Paleocene Foraminifera of Georgia - continued Clayton Tamesi” Rotaliidae: Formation Equivalent Discorbis midwayensis Cushman var. soidadoensis Cushman and Renz — —X midwayensis Cushman var. trinitatensis Cushman and Renz — —— — X Valvulineria wilcoxensis Cushman and Ponton—- — ——-—-=—-—-——-— axe cf. V. umbilicatula(?) (D’Orbigny)—- - —-—-—--—-—-—--—-—--—--—-—--—------—--—-—-+— x Gyroidina aequilateralis (Plummer) — — —- —-—- —-—-—--—-----— x subangulata (Plummer)— — -~ —-—-—-—-—-—-—-—-—-—-—-——-— es es ee xX Eponiclesi lotus: (Schwager) jaca ee me jollbynanaavenst=4a (Gitte) eVeu¥evol ©) X Parrella expansa Toulmin— — — — —- —-—-—-~—~—-------- X Rotalia havenensis Cushman and BermudeZ —_ — — — = mm mee ee x Siphonina prima Plummer — — — —~ = = —- -> - Omer ee x Cassidulinidae: Alabamina wilcoxensis Toulmin— — —~ — —~—~—-—-———=—-—-——— x Chilostomellidae: Allomorphina paleocenica Cushman — — —~ — — —- —~ ~~ ~~ —-—--—--—--—-----=— X subtrianguiaris (Kline) velascoensis Cushman Xx Chilostomella ovoidea Reus§s ~ ~ ~~ mM mmm OP OP Om Om Om Om Om em er er er ee er X Chilostomelloides 20ocenica Cushman = ————_——-—-—--—-—-—-—-—- eee ee xX Globorotaliidae: Globorotalia cf. G. membranacea (Ehrenberg)— = — — = ——=—-—-—-—--- = —-—=—— xX velascoensis (Cushman) ~~ —-—-—-—-—-—-—--—--—-—--—--—--—--—--------7--- Xx crassata (Cushman) var. aequa Cushman and Renz .. — ~~ — — — — ee Ee re ee % Anomalinidae: Anomalina midwayensis (Plummer)— — — —- —- ——-—-—-—----—-— ue jaACUtawPIUMMe ra ee a a SNE, ea he pe Dine umbonifera (Schwager) — — —- —- —- —~—-—-—--—-------- x Boldia madrugaensis Cushman and Bermudez — — — — ~ — — — — — x Cibicides alleni (Plummer) — — —- —- —-—-—--—-7- 7-77 TTT x ROWELL TOULMIN —\<— 25 oe Ge ee x Tewmanae (Plummer) —~ — — — —- —- ~~ —-—-—--—-—--—--—--—-— xX Discocyclinidae: Pseudophragmina (Athecocyclina) stephensoni (Vaughn) —~ — —~ — — — — xX 38 “syisodep sued098/Dq 40 do} ays yo doW ANOJUOD—|D4ANJONIJG—g| osunbi4 of 8B oS8 t eens SAW O 02 Ol olf € 91q04 4 aas sjoqwhs sayjo 40 uolpUD|dxa 404 —l¢¢ off ° Buissiw) auad0a/Dy pud auas07g 1aM07 SS NOILVNV 1d X93 ov8 ° 8 ‘stisodap auas0a|Dq jo dow UO!INGI4JSIP—SSeUuydIY |] —¢| ~a4nbi4 0/8 oc8 of8 ov8 oS8 Cc . SS IW OF 02 Ol (Sia at ase eae € a1qoy + gas sjoquks sayyo 40 uolpDUD}dxa 404 lof Buissiw auad0a|0g pud auaz0”" 1aMo7 NN SSS NOILVNV1dX3 ov8 oS8 Cretaceous System UPPER CRETACEOUS SERIES Post-Tuscaloosa_deposits .-- Cretaceous sediments of post-Tuscaloosa age have been identified in 90 wells in 33 counties of the Georgia Coastal Plain. Post-Tuscaloosa deposits have been found throughout the Georgia Coastal Plain except inthe northeastern part where the lithology of the post-Tuscaloosa is iden- tical with that of the underlying Tuscaloosa Formation. As pointed out by Eargle (1955, p. 5-6) the ‘‘Tus= caloosa’’ as found in this northeastern part has been identified on the basis of lithology rather than by stratigraphy. However, because foraminiferal evidence is nonexistent to support this opinion, the Tus- caloosa-type sediments in the northeastern part have all been logged as Tuscaloosa Formation (Herrick, 1961). In preparing maps however the data in the northeast were considered to indicate only the top of the post-Tuscaloosa (see fig. 14). On the map showing thickness and distribution of the post-Tuscaloosa de- posits (fig. 15) as well as the maps showing the Tuscaloosa top (fig. 16), and its thickness distribution (fig. 17), the northeastern part was left uncontoured because of this uncertainty. From study of outcrops in western Georgia, the post-Tuscaloosa has been divided from top downward into Providence Sand, Ripley Formation, Cusseta Sand, Blufftown Formation, and Eutaw Formation, all of which are extensions of the same formations as found in eastern Alabama (Eargle, 1955). These forma- tions when traced downdip in the subsurface gradually merge into three units that are faunally distinctive and which for lack of formational names are considered to be equivalents of beds of Navarro, Taylor, and Austin age. The updip formations correlate with the downdip beds as shown in Table 9. It has been Table 9.-- Correlation of surface and subsurface units of post-Tuscaloosa Cretaceous age P F Subsurface units Geologic formations at surface Providence Sand Beds of Navarro age (= Lawson Limestone of Florida) Ripley Formation, upper part Ripley Formation, lower part Cusseta Sand Beds of Taylor age Blufftown Formation, upper part Blufftown Formation, lower part , Beds of Austin age Eutaw Formation 41 olf} off ‘syisodap 0/8 psooj09sn|—jsod snoesdn1e419 «4addm jo do} au} jo dow a ——— i -- LL } 4ANOJUOD —|D4ANJONAIS —p] o4nbi4 ¢ a1qD, aas sjoquAs jo uoljoUDIdxa 404 ov8 oS8 42 ‘Ss yisodep snoednja49 DSOO|DISN] 4sod jo dow UOIINGIUISIP—SseUuydIYy | —“"G| e4nbly SS TIW OF 02 Ol Tite € 9|qD}’ eas sjoquiAs a --—-. yO udljouD|dxe 404 43 thought best to include all these formations under the term post-Tuscaloosa for the following reasons: 1, Originally these formations were named for surface deposits that were mappable units in updip areas of the Coastal Plain. Subsequently, as a result of a search for oil and fresh-water aquifers, it was learned that the majority of these formations, owing to downdip facies changes, tended to lose their identi- ties in the subsurface. Similarly, east of Ocmulgee River, even the updip surface outcrops of these forma- tions have undergone facies changes in an easterly (along the strike) direction, causing the entire Upper Cretaceous Series to grade laterally to a lithology identical with that of the Tuscaloosa Formation. 2. In addition to facies changes, faunal changes have also taken place in a downdip direction. Certain foraminiferal species have been found to persist over more and more of the vertical subsurface strati- graphic section thus increasing their vertical ranges and at the same time lessening, to some extent, their value as guide fossils. A good example of this is Anomalina pseudopapillosa Carsey, a foraminifer that is a reliable index fossil for the Ripley Formation in some updip areas. Down the dip, however, this foraminifer has been found higher in the section, appearing (in wells) in the lower, or marine, part of the geologically younger Providence Sand for which it has become one of its guide fossils. Thus, these formational names, particularly as regards the Providence and Ripley Formations, cannot be used over the greater part of the subsurface ofthe Coastal Plain of Georgia. An exception to this is the Eutaw Forma- tion, which extends from outcrops to downdip areas, overlying the Tuscaloosa Formation as a fine to medium, phosphatic, glauconitic, shelly, somewhat indurated sand. The subsurface areal extent of the post-Tuscaloosa is next to the largest of all the stratigraphic units making up the Coastal Plain of Georgia, being second only in size to the underlying and geologically older Tuscaloosa Formation (see fig. 14.) Thus, this unit, except for a narrow strip immediately south of the Fall Line, underlies the entire Coastal Plain. The greatest surface exposures of the post-Tuscaloosa are found just east of the Chattahoochee River Valley, in Stewart and Chattahoochee Counties. Northeast of this area, however, this unit is progressively overlapped as far as the Ocmulgee River, east of which the post- Tuscaloosa is completely covered by geologically younger sediments. Except for southeastern Georgia the post-Tuscaloosa consists of clastics throughout its subsurface areal extent in Georgia. In the updip parts of the Coastal Plain this unit is composed of light-gray to dark-bluish-gray to dark-brown (mottled in surface exposures), blocky to laminated, sandy, abundantly, micaceous, locally lignitic and kaolinitic, pyritiferous, glauconitic, fossiliferous clay and marl. These clays are interbedded with numerous tongues of fine to coarse-grained, subangular to subrounded, pyritiferous, lignitic, micaceous, arkosic, locally glauconitic and fossiliferous sand, and some relatively thin beds of gray, dense, sandy, coarsely glauconitic micaceous, somewhat phosphatic, fossiliferous limestone. In downdip areas these clastics gradually change to light-bluish-gray, chalky, micaceous, pyritiferous, fossiliferous marls which are interbedded with beds of sand or limestone, the latter similar tothose of updip areas. In extreme southeastern Georgia, the upper part of the post-Tuscaloosa, of Navarro age, is composed of somewhat chalky, much calcitized, granular, locally gypsiferous, fossiliferous limestones, the latter representing the limestone facies of this unit in Georgia. The greatest thickness of the post-Tuscaloosa, or depocenter, occurs in central and coastal areas of the Coastal Plain (see fig. 15), attaining a total thickness of more than 1,400 feet. South of the cen- tral part of the Coastal Plain the post-Tuscaloosa in extreme south Georgia thins to 800 feet or less. A few of the more important contributions to the paleontology of the Upper Cretaceous include articles by Carsey (1926), Plummer (1931), Cushman (1940), and Cole (1944), The post-Tuscaloosa represents the lowest stratigraphic unit in Georgia with abundant and characteristic Foraminifera. Some of the diagnostic fossils occurring in the upper division of Navarro age are Gaudryina rudita Sandidge, Robulus spisso- costatus Cushman, Vaginulina webbervillensis Carsey, Guembelina globulosa (Ehrenberg), ‘Loxostoma plaitum (Carsey), Epistomina caracolla (Roemer), Anomalina pseudopapillosa Carsey, and Cibicides harperi (Sandidge). In the middle division, or Taylor, one should mention such species as Robulus stephensoni Cushman, Robulus muensteri (Roemer), Bolivinoides decorata (Jones), Globotrun- cana arca (Cushman), Planulina texana Cushman, and Planulina “taylorensis (Carsey). Likewise Kyphopyxa christneri (Carsey) and Vaginulina texana Cushman are considered diagnostic of the lower division of Austin age of this stratigraphic unit. The faunal lists in table 10 show in greater detail the more important smaller Foraminifera that have been observed in the post-Tuscaloosa of Georgia. 44 Table 10.--Foraminifera from the post-Tuscaloosa Cretaceous of Georgia FORAMINIFERA OF NAVARRO AGE: Lituolidae; Haplophragmoides sp. Textulariidae: Spiroplectammina semicomplanata (Carsey) Textularia ripleyensis W. Berry Verneuilinidae: Gaudryina rudita Sandidge Pseudoclavulina amorpha (Cushman) clavata (Cushman) Lagenidae: Robulus navarroensis (Plummer) pondi Cushman spisso-costatus Cushman Marginulina texasensis Cushman Dentalina alternata (Jones) basiplanata Cushman gracilis D’Orbigny legumen Reuss Nodosaria affinis Reuss Vaginulina webbervillensis Carsey suturalis Cushman Palmula reticulata (Reuss) Frondicularia inversa Reuss Polymorphinidae: Guttulina adhaerens (Olszewski) Globulina lacrima Reuss Heterohelicidae: Guembelina globulosa (Ehrenberg) striata (Ehrenberg) Buliminidae: Bulimenella carseyae Plummer var. Bulimina aspera Cushman and Parker Loxostoma plaitum (Carsey) Rotaliidae: Valvulineria cf. V. umbilicatula (D’Orbigny) Gyroidina depressa (Alth) Eponides haidingerii (D’Orbigny) Epistomina caracolla (Roemer) Siphonina prima Plummer Cassidulinidae: Ceratobulimina cretacea Cushman and Harris Chilostomellidae: Pullenia americana Cushman coryelli White Globigerinidae: Globigerina cretacea D’Orbigny Globorotaliidae: Globotruncana cretacea Cushman Anomalinidae: Anomalina clementiana (D’Orbigny) henbesti Plummer inguis Jennings. seudopapillosa Carsey Planulina correcta (Carsey) Cibicides harperi (Sandidge) 45 Table 10.--Foraminifera from the post-Tuscaloosa Cretaceous of Georgia - continued FORAMINIFERA OF TAYLOR-AUSTIN AGE; Verneuilinidae: Gaudryina rudita Sandidge Clavulinoides trilatera Cushman trilatera Cushman var. concava (Cushman) Valvulinidae: Dorothia bulletta (Carsey) Lagenidae: Robulus muensteri (Roemer) stephensoni Cushman Marginulina austinana Cushman cretacea Cushman dorsata Cushman silicula (Plummer) sp- Dentalina alternata (Jones) gracilis D’Orbigny lorneiana D’Orbigny Nodosaria affinis Reuss obscura Reuss sp. Vaginulina cretacea Plummer taylorana Cushman texana Cushman Frondicularia cf. F. inversa Reuss Kyphopyxa christneri (Carsey) Lagena hispida Reuss Polymorphinidae: Globulina lacrima Reuss Bullopora sp. Nonionidae: Nonionella austinana Cushman cretacea Cushman Heterohelicidae: Guembelina striata (Ehrenberg) Bolivinoides decorata (Jones) Buliminidae: Virgulina tegulata Reuss Rotaliidae: Valvulineria allomorphinoides (Reuss) infrequens Morrow Stensioina americana Cushman and Dorsey Gyroidina depressa (Alth) Globigerinidae: Globigerina cretacea D’Orbigny Globorotaliidae: Globotruncana arca (Cushman) fornicata Plummer Globorotalia micheliniana (D’Orbigny) Anomalinidae: Anomalina sp. Planulina austinana Cushman taylorensis (Carsey) texana Cushman 46 Tuscaloosa Formation .-- The Tuscaloosa Formation* has been identified in the subsurface in about 70 wells, the majority of which are situated along the northern limit of the Coastal Plain. Sediments of Tuscaloosa age underlie the post-Tuscaloosa and overlie the Lower Cretaceous(?) and are correlated with the Tuscaloosa Group of Alabama and, in part, with the Eagle Ford and Woodbine Formations of Texas. In subsurface areal extent the Tuscaloosa underlies the entire Coastal Plain of Georgia, hence is the largest of the stratigraphic units discussed. (See fig. 16.) Geographically, this unit is bounded on the north by the crystalline rocks of the Piedmont. To the south these strata merge with equivalent subsurface sediments in northern Florida. The Tuscaloosa Formation consists entirely of clastics, which may be broken down. into three readily recognizable lithologic divisions. The upper part is composed on nonmarine, fine to coarse, subangular, micaceous, arkosic, pyritiferous, locally lignitic sands that are interbedded with nonmarine, gray to green (mottled in outcrop), blocky to laminated, locally iron-stained, kaolinitic and lignitic, micaceous, sandy clays. The middle division is composed of interbedded sands and clays, which, in updip areas, resemble those of the upper part. Downdip these deposits change to marine, dark-gray to dark-brown to black, laminated, somewhat fissile, abundantly micaceous, speckled**, glauconitic, car- bonaceous, fossiliferous clay and shale, that are interbedded with thin beds of fine to medium~grained, micaceous sand. The lower division of the Tuscaloosa is usually composed, in its uppermost part, of a fine-grained, somewhat micaceous, glauconitic, locally indurated, marine sand. Below this sand the remainder of the lower division consists of interbedded nonmarine, coarsely-grained, subrounded, highly arkosic, micaceous sands and red to purple, blocky, sandy, sideritic, micaceous clays. Prominent and extensive inclusions of kaolin, originally derived from the weathering of crystalline rocks to the north of the Coastal Plain, occur in the upper part of the Tuscaloosa Formation. These deposits are found only a few miles south of the Fall Line in a belt extending from Taylor County eastward into southern McDuffie and Columbia Counties in east-central Georgia. Thickness of the Tuscaloosa Formation approximates that of the post-Tuscaloosa Cretaceous unit (see fig. 17) with the area of greatest thickness, or depo- center, lying in an east-west, linear belt in the central part of the Coastal Plain. Southeast of this belt the Tuscaloosa tends to thin to less than 300 feet in southeastern Georgia. The maximum thickness in this depocenter is somewhat in excess of 900 feet. Literature dealing with the microfossils of the Tuscaloosa Formation and equivalent deposits is limited compared with that of the previously discussed unit. This is doubtless due in part to a failure until com- paratively recent times to recognize the marine character of the Tuscaloosa in downdip areas of the Coastal Plain. Munyan (1943) was the first to note the marine Tuscaloosa in the subsurface of Georgia and Cushman and Applin (1946) were the first to demonstrate the presence of smaller Foraminifera in the marine portions of the Tuscaloosa in Georgia. A summary of the important literature dealing with the Foraminifera of the Tuscaloosa Formation and equivalent deposits elsewhere in the Gulf Coast in- cludes articles by Lozo (1944), Loeblich (1946), Cushman and Applin (1946 and 1947), Frizzell (1954), and Applin (1955). Foraminifera have been observed by the senior author in several wells penetrating marine portions of the Tuscaloosa Formation in downdip areas of Georgia. These fossils, however, are not identified as to species though they clearly belonged to at least two genera, Ammobaculites and Hap- lophragmoides, which make up an appreciable part of the foraminiferal faunas identified by various in- Vestigators from the Tuscaloosa of Georgia. For the sake of completeness in this report the following faunal list has been prepared from the above noted articles. *In this report the formational name Tuscaloosa isused in preference to Atkinson. The name Tuscaloosa is considered by the authors to be more applicable to the continental deposits whereas the name Atkinson is more applicable to the marine equivalents as found in extreme south Georgia and Florida. **Finely disseminated mica flakes impart a speckled appearance to these shales. 47 Table 11.--Foraminifera from the marine facies of the [Tuscaloosa Formation in Georgia Lituolidae: Haplophragmoides langsdalensis Applin advenus (Cushman and Applin) Ammobaculites bergquisti Cushman and Applin Textulariidae: Ammobaculoides plummerae Loeblich Verneuilinidae: Gaudryina barlowensis Applin Placopsilinidae: Acruliammina longa (Tappan) Placopsilina langsdalensis Applin Lagenidae: Frondicularia barlowensis Citharina recta (Reuss) Rotaliidae: Valvulineria infrequens Morrow var. Globigerinidae: Globigerina cretacea D’Orbigny 48 ‘uolyDW4O4J oOSOO|DISNL 4o do; ayy }O dow sNnoyyod—fOANJONA}S —9I aunbi4 € 91q0} 89S sjoqwAs 40 uoljyODUD|dxa 404 ‘uoOl}OWIOY oOSOO|DISN, jo dow uodljnqiajsip—ssauyoiy); —7]| e4nbi4 ov8 c SSW OF olf olf oe oz off lof € 81q0} aes sjoqwdhs jo uolouD\dxa 4104 ol8 oc8 o£8 ov8 oS8 50 LOWER CRETACEOUS(?) SERIES Strata of Lower Cretaceous(?) age, have been identified in 18 wells that are distributed over 16 counties in the Coastal Plain of Georgia. These sediments underlie the Tuscaloosa Formation and overlie older rocks ranging in age from Triassic(?), to Paleozoic, to Precambrian. From available data the subsurface areal extent of this stratigraphic unit is considerably less than that of the overlying Tuscaloosa Formation. The northern limit of recognizable Lower Cretaceous(?) begins in Georgia at the Chattahoochee River in southern Chattahoochee County, trends eastward approximately to central Houston County, thence southeastward to the coast of Georgia, in eastern Bryan County (see fig. 18). If this interpretation is true then this unit is absent from the entire northeastern part of the Coastal Plain as well as from a somewhat restricted, linear area situated immediately south of the Fall Line. However, in the latter area this may or may not represent the true subsurface picutre. In this part of the Coastal Plain both the Tuscaloosa and Lower Cretaceous(?) units are nonmarine in origin, hence are lithologically so similar as to be practically impossible to differentiate. It is possible, therefore, that beds of Early Cretaceous(?) age may have been included with the Tuscaloosa in wells situated in this part of the Coastal Plain. Although these deposits were mapped by Eargle (1955, pl. l)as belonging to the lower part of the Tuscaloosa Formation, some inconclusive shreds of evidence support a possible Lower Cretaceous(?) age for these sediments: 1) these strata underlie conventional sediments of Tuscaloosa age, 2) they overlie crystalline rocks of Precambrian age in western Muscogee County and 3) they appear to be lithologically somewhat different from the usual, updip Tuscaloosa of this part of the Coastal Plain. In much of the northeastern part of the Coastal Plain, wells are not deep enough to reach the Lower Cre- taceous(?) hence the presence (or absence) of this unit here is not known. Many more additional data are needed before this problem can be solved. The Lower Cretaceous(?) in Georgia is composed entirely of clastics which consist of interbedded nonmarine, varicolored, coarse, subrounded, very arkosic, mi- caceous sand and brick-red to pale-yellowish-green, blocky, abundantly micaceous, locally sideritic, sandy clay. Owing to their brilliant red color these clays are often referred to by drillers as ‘‘red beds,” when encountered in wells. The Lower Cretaceous(?) thickens greatly in southwestern Georgia (see fig. 19) where more than 2,600 feet have been logged as belonging to this stratigraphic unit. Using the map of the pre-Cretaceous surface (see fig. 20) as a base, the maximum thickness in Georgia of lower Cretaceous(?) may be on the order of 3,5000 feet. Such a thick series of sediments would indicate the exis- tence of a possible depocenter in this part of Georgia during Lower Cretaceous(?) time. Due to the nonmarine nature of all the Lower Cretaceous(?) deposits found in Georgia, no microfossils have been observed in the series. Further downdip in Florida, where this unit becomes marine in character, these strata have been identified as being of Early Cretaceous age -- the reason for assigning an Early Cretaceous(?) age to this unit in Georgia. Sl "adDJANS UOISOJa pun sy}isodap (¢) snoadpja19Q 4OMO7 JO do} Oy} 4O doOW ANOJUOI—|DANJONAYGS—g| a4nbi4 aif L an ON NOILVNV1d X93 ‘syisodap (¢) snoadDJa19 4OMOT 40 dow uUOljNgi4jsip—sseuydIy;—‘6] asnbi4 olf ock 0/8 "aoDyANS snosd0jaij —a4d =auj jo dow snojyuoo—joanyonsjg—oOg aenbiy o£8 ov8 oS8 € a|qo} aas sjoquwis 40 uolsOUD\|dxe 404 ov8 oS8 ock 54 sTRUCTURE The geologic structure in the Coastal Plain of Georgia is shown on nine structure-contour maps and eight geologic sections (figs. 21-28). Geologic data are unavailable for large areas of the Coastal Plain making the problem of structural interpretation more uncertain. Even for the Oligocene, the data of which are reasonably well distributed, the thickness-distribution map (fig. 4) has been one of the most difficult to contour satisfactorily. Knowing that as more data become available, the contours will need revision, it was believed desirable to give on each map the data used. The elevations and thicknesses so given can thus be used by future workers who may wish to modify the interpretations as made for this report. It is probable that additional drilling may indicate greater dips, structures, and faults than have been interpreted from data now avail- able. The name ‘‘Gulf Trough of Georgia’’ is herein proposed for a major structural feature of the subsurface in southwest Georgia. This feature was recognized by P. L. and E. R. Applin (1944, p. 1727) as ‘‘extend- ing southwestward across Georgia through the Tallahassee area of Florida to the Gulf of Mexico.’’ This trough is a linear feature extending northeastward from Grady County through northwestern Thomas and Colquitt Counties (See figs. 3 and 6). The thickness of Recent to Miocene deposits (see fig. 12) suggests that the trough may also continue through Tift, Irwin, and northern Coffee Counties. The fauna found in the rocks of this trough is similar to that from the Gulf of Mexico. Furthermore, the presence of a tro- pical Oligocene sea in central Georgia as found by Esther R. Applin (1960) suggests a connection of that sea with the Gulf of Mexico which presumably could have involved this trough. The trough appears quite prominently on the maps showing the top of the Oligocene (fig. 3) and the top of the upper Eocene (fig. 6). The top of the middle Eocene (fig. 8) indicates that the axis of the trough parallels that of upper Eocene and Miocene deposits but displaced a few milesto the southeast. Below the top of the middle Eocene nothing is known regarding this feature, but the deep paralles trough in the pre-Cretaceous surface (see fig. 20) suggests that it may persist in the intervening sediments. A major structural feature in southeastern Georgia is herein proposed to be called the ‘‘Atlantic Em= bayment of Georgia’ (see figs. 3, 6, 8, and 27). The deposits in the embayment contain fossils that are similar to forms living in the Atlantic Ocean for which reason the name has been chosen. Although the lack of data hinders an understanding of the deeper buried units, the embayment appears to have originated in middle Eocene time and continued as a depositional basin intermittently through Miocene time. Overlap has been mentioned previously in connection with the discussions of stratigraphy. Examples appear on the east-west trending geologic sections. A Cretaceous high in Wilkinson 441 (fig. 21) is over- lain by upper Eocene with middle Eocene deposited down the flanks of the high. Similarly a Cretaceous high is found in Pulaski 472 (fig. 27) with Paleocene and lower Eocene deposited northwest of it and Paleo- cene deposited to the southeast of it but the Cretaceous high and the younger sediments on its flanks are all overlain by middle Eocene. The sedimentary units in the northwestern half of the Georgia Coastal Plain all have a gentle dip to the southeast. The tops of the Oligocene and upper Eocene both dip about 9.5 feet per mile. The dips on tops of successively lower units increase to about 24 feet per mile on the Cretaceous (see table 12.) The dips of sedimentary units in the southeastern half of the Coastal Plain are slightly less than those in the northwestern half but they are more variable in direction. The dips range from 4.0 to 23 feet per mile from southward to eastward. The direction of dip can be determined from figures 3, 6, 8; 10, 12, and 14, 55 Table 12.--Generalized dip of formational contacts in the Coastal Plain of Georgia Dip in feet per mile Upper or northwest half Lower or southeast half 4.0 to 8.5 Surface measured Top of Oligocene 5.0 to 8.3 Top of upper Eocene Top of middle Eocene Top of lower Eocene Top of Paleocene Top of Cretaceous 56 The dip of 24 ft/mi (feet per mile) is equal to an angle of dip of 0°16'. The steepest mapped dips, found in Colquitt County, amount to 48 ft/mi or only 0°31’. Thus nowhere in the area discussed can dips be found that would be apparent even if outcrops were available and exposures ideal. The great extent of the area however permits considerable vertical change to occur due to these exceedingly gentle dips. An unconformity as indicated by paleontologic evidence occurs in the northeastern part of the Coastal Plain where middle Eocene deposits lie on Cretaceous. The approximate areal extent of the unconformity is shown on figures 10 and 12 and it is also shown on the sections in figures 21, 22, and 27. A block uplift or tilting at the end of Cretaceous time may have raised the area above sea level and prevented deposition of Paleocene and lower Eocene sediments. The areal extent of the unconformity in the sub- surface agrees with the few available surface data. A geologic map by MacNeil (1947) shows that the Pa- leocene is found at the surface only as far east as Houston County and that no exposures are found east of the Ocmulgee River. This has generally been inferred to be caused by overlap. The subsurface data now indicate that overlap occurs only in the downdip area and that a major unconformity separates the Cretaceous from the overlying middle Eocene sediments. Unconformities are known in the Coastal Plain but except for the major one discussed above they are usually difficult or impossible to recognize solely from study of well samples. Marine and continental conditions are known to have alternated but such alternation is represented by sands for the continental deposits and fossiliferous, glauconitic, phosphatic clastics and limestones for the marine deposits. Weathered zones indicating a hiatus in sedimentation are not generally recognized in the study of well cuttings but have to be inferred from other data. Unconformities at the tops of all the units that have been mapped in this report are thus either known or inferred. These are in every case disconformities rather than angular unconformities. From comparison of logs in the well-log report by Herrick, faults seemingly occur in Crisp County between wells 155 and 390 (see fig. 22) and in Clay County between wells 402 and 435 (see fig. 26.) The fault in Crisp County has a vertical displacement of about 40 feet in the Tertiary beds. Figure 22 suggests that in Crisp County a vertical displacement of about 99 feet may have occurred and that in early Tertiary or pre-Tertiary time displacement may have been about 400 feet. Other faults may occur in the Coastal Plain but the distance between the logged wells is so great that differences in elevation of formational tops are more easily explained by gentle dips rather than by faults. Later work may possibly reveal structure that is impossible to determine with available data. 57 “Ajunod =puowysiy of psomyspeyjsou Ayunog Ajsng ‘uoljoas s1bojoag9—)Z2 asnbi4 1 oose [ S31IW be nosoojau9, seddn 92 6d! OQNOWHOIY 261 NNOHIV9 — 00» (e661 NOLSNOH €€! 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L) Js / 61 JOY ald Ajunoy) syooig ‘uoljoas o1bojoag9-—¢g enbi4 201 S3TIW v2 >snoaonjaig saddn NOSNIWLV ~ ii 8S2! oui ieee 00S 4,000¢ 4,0002 7400S psi SHOOY¥s o. 60 6c LA:) HSOLNIOW /d 96S HSOLNIOW 96 2S INAVM 6i1 39u3ld “Ajyunoy ysojujow of Ajsaysoe ee aaa] beeen let ioe | S3TIW be 8 (o} (¢) snoaonyjas S2v 201 NOSNIWLV Ajuno9 = Ajs03 49M07 ze f 111N0109 313 HOLIW *u0149eS 9160}089 —pg aunbi4 —,0009 J ONIW3S — oor 61 300' 500’ 1000 4 E BE GRADY THOMAS 205 | sie BROOKS LOWNDES ECHOLS 189 BROOKS 469 173 | Recent — ro to. | x9. Miocene DECATUR 228 Upper Eocene 16 MILES Figure 25—Geologic section, Decatur County eastward to Echols County. 62 le yeu CLAY 4028435 CALHOUN Se re COLQUITT 192 GALHOUN ore) 170 22 LOWNDES 33 BROOKS 173 189 oc — = fos INN us 400' “y \CHATTAHOOCHEE SEA LEVEL 500' 1000' 1500) 1784' 2000° 24" 2279' 2500' 2629" Upper Cretaceous 3000' 3229' mils 3579' 3934° 4000° 4500 5000' 24 MILES J 5500' 6000' Figure 26——Geologic section, Clay County southeastward to Echols County. 63 G G’ MACON 229 APPLING 148 TELFAIR TELFAIR R 507 375 wueELE WAYNE 454 WAYNE 52 GLYNN 1000’ 1500' 24 MILES 4000 4500 Figure 27—Geologic section, Macon County southeastward to Glynn County. 64 362 980° H / CHAT TAHOOCHEE f7 341 STEWART = 451 RANDOLPH 500'+ 552 CALHOUN 192 SEMINOLE 187 DECATUR 168 SEA LEVEL ira ir nu -500' Upper Cretaceous 1o96' 1416 -1000'}- oe ° @ ° < a) -1500' ‘ -2000'}- 193)" -2500'}- 2816 -3000' ' 3466 -3500 24MILES —4000' -—4500' -5000' -5500' -6000' Figure 28-—Geologic section, Chattahoochee County southward to Decatur County. 65 UNSOLVED PROBLEMS The interpretations as given in the text, on the maps, and in the geologic sections must be considered preliminary rather than final. The authors realize that much interpretation is based on meager data and that more detail will be added as additional data are obtained. As yet it is only conjectural as to whether anomalies found in the study of the data for the Coastal Plain are indicative of local variations in thick- ness of sedimentation or possible presence of two or more sets of faults. Also, some of the anomalies could be due to errors in determining land surface elevations of wells or errors in collecting and labelling well samples. The indications are enough to make tantalizing the desire for answers but inadequate to permit much more than guesses. However, it is possible that finding the answers may have considerable economic significance to Georgia. The surficial deposits of Oligocene age in Georgia have been mapped as the Flint River Formation by Cooke (1943) and as the Suwanee Limestone by MacNeil (1947). Additional work is needed to establish whether two different formations of Oligocene age occur in Georgia or whether these two are the same formation with the Flint River Formation representing the weathered and eroded remnants of the Suwanee Limestone. This problem needs to be solved before a really valid correlation can be established between surface outcrops and the subsurface. The age of the phosphate-bearing, sandy limestone at the base of the Miocene in southeastern Georgia and adjacent parts of South Carolina is uncertain. Owing to a lack of fossils the age of this limestone is regarded in this report as basal Miocene though it could be late Oligocene. If the Cooper Marl in Georgia is found to be Oligocene in age (now considered to be late Eocene(?)) then this phosphatic limestone lying at the base of the Miocene could be equivalent to the uppermost Cooper Marl in this part of Georgia and South Carolina. The age and areal extent of the Cooper Marl in Georgia also needs further study. As noted previously, the fauna of the Cooper Marl in Georgia suggests that the formation is the updip equivalent of the upper unit of the Ocala Limestone. From this correlation, both would seem to be late Eocene in age. However, the Cooper Marl of South Carolina is now considered to be Oligocene in age (Malde, 1959, p. 19). Until positive correlation can be established between the Cooper Marl of both Georgia and South Carolina, the reader is urged to consider that all mention of the Cooper Marl in this report applies only to the de- posits of that name as found in Georgia. In a report on a tropical Oligocene sea in central Georgia, Esther R. Applin (1960) published a log of a well in Coffee County showing 640 feet of Oligocene sediments. This thickness is so unusual in Georgia that the senior author examined another cut of the samples and found himself in substantial agreement with Mrs. Applin. In none of the other wells does the Oligocene exceed much over 200 feet. The reason for this local thickening is as yet an enigma. The fossils found indicate an orderly sequence throughout rather than a repetition of strata such as could result from faulting. Further study is needed to explain this anomaly and to determine its areal extent and structural significance. Because the data were so anomalous they were not entered on the maps in this report. The upper Eocene and Oligocene Foraminifera found in the Dougherty Plain of southwest Georgia suffice to indicate that rocks of those ages once covered part or all of the Plain. More work is needed to know why this large area should have been so uniformly leached of its limestone cover and when it occurred. In Georgia the upper division of the Ocala Limestone contains Asterocyclina nassauensis, Operculinoides floridensis, and Pseudophragmina flintensis. The presence of these three larger Foraminifera indicates definite upper Eocene age of this unit. However, the remainder of the fauna appears to be closely re- lated to that of the Cooper Marl suggesting that the Cooper Marl in Georgia is late Eocene in age rather than Oligocene as in South Carolina. The upper division of the Ocala in Chatham County appears to be the downdip limestone equivalent of the Cooper Marl as exposed in Jenkins and Houston Counties. As yet, the age of the Sandersville Limestone Member of the Barnwell Formation is subject to question. It may be a limestone of Oligocene rather than late Eocene age. Further study of its occurrence in the subsurface of east-central Georgia is needed to solve this problem. A sand is found between the Ocala Limestone of late Eocene age and the Lisbon Formation of middle Eocene age. In the logs of the well-log report (Herrick, 1961) this sand was either called Gosport Sand or included in the Lisbon Formation. Further study is needed to ascertain whether this is actually Gosport or whether it may be entirely or in part equivalent to the Moodys Marl Member of the Jackson For- mation of late Eocene age. 66 The Gulf Trough is southwestern Georgia is known to affect the dips and thickness of units down through the upper Eocene. It would be interesting to know more about this structure at depth and what caused it. The surface formations may have been downwarped affecting the deeper formations or local differential compaction may have caused the trough with no structure reflected in the deeper sedimentary units. In the northeastern part of the Georgia Coastal Plain, the Cretaceous deposits have been lumped to- gether as Tuscaloosa Formation (Herrick, 1961) and as ‘‘rocks of Tuscaloosa to Providence age undif- ferentiated’’ (Eargle, 1955). To correlate those rocks with their equivalents to the west, the study of spores should be undertaken. This seems to be the only method currently available that can permit such a cor- relation to be made. 67 REFERENCES Applin, E. R., 1955, A biofacies of Woodbine age in the southeastern Gulf Coast region: U. S. Geol. Survey Prof. Paper 264-I, p. 187-197, pls. 48-59. 1960, A tropical sea in central Georgia in late Oligocene time: U. S. Geol. Survey Prof. Paper 400-B, p. B207-B209. Applin, E. R., and Jordan, Louise, 1945, Diagnostic Foraminifera from subsurface formations in Florida: Jour. Paleontology, v. 19, no. 2, p. 129-148, pls. 18-21. Applin, P. L., 1951, Preliminary report on buried pre-Mesozoic rocks in Florida and adjacent States: U. S. Geol. Survey Circ. 91, 28 p. 1952, Volume of Mesozoic sediments in Florida and Georgia: Geol. Soc. America Bull., v. 63, no. 12, p. 1159-1164. 1961, Atlantic Coastal Plain on Tectonic map ofthe United States: U. S. Geol. Survey and Am. Assoc. Petroleum Geologists. Applin, P. L., and Applin, E. R., 1944, Regional subsurface stratigraphy and structure of Florida and southern Georgia: Am. Assoc. Petroleum Geologists Bull., v. 28, no. 12, p. 1673-1753. 1947, Regional subsurface stratigraphy, structure, and correlation of Middle and early Upper Cretaceous rocks in Alabama, Georgia, and North Florida: U. S. Geol. Survey Oil and Gas Inv. Prelim. Chart 26, in 3 sheets. Bandy, O. L., 1949, Eocene and Oligocene Foraminifera from Little Stave Creek, Clarke County, Alabama: Bull. Am. Paleontology, v. 32, no. 131, 210 p., 27 pls. Black, A. P., and Brown, Eugene, 1951, Chemical character of Florida’s waters, 1951: Florida Water Survey & Res. Paper 6, fig. 3. Bonini, W. E. , and Woollard, G. P., 1960, Subsurface geology of North Carolina-South Carolina Coastal Plain from seismic data: Am. Assoc. Petroleum Geologists Bull., v. 44, no. 3, p. 298-315. Braunstein, Jules, 1959, Eastern Gulf Coast oil and gas geology: Georgia Geol. Survey Mineral News- letter, v. 12, no. 1, p. 12-16. Carsey, D. 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N., 1950, Foraminifera of the type Kiowa Shale, Lower Cretaceous of Kansas: Kansas Univ. Paleont. Contr. no. 6. Protozoa, art. 3, p. 1-15, 2 pls. 1957, Planktonic Foraminifera of Paleocene and early Eocene age from the Gulf and At- lantic Coastal Plains: U. S. Natl. Museum Bull, 215, p. 173-198, pls. 40-64. Lozo, F. E., 1944, Biostratigraphic relations of some north Texas Trinity and Fredericksburg (Coman- chean) Foraminifera: Am. Midland Naturalist, v. 31, no. 3, p. 513-582, 5 pls. MacNeil, F. S., 1944, Southwestern Georgia Field Trip: Southeastern Geol. Soc. (Guidebook) 2d Field Trip, 63 p. MacNeil, F. S., 1947, Geologic map of the Tertiary and Quaternary Formations of Georgia: U. S. Geol. Survey Oil and Gas Inv. (Prelim.) Map 72. Date let ae 1959, Geology of the Charleston phosphate area, South Carolina: U. S. Geol. Survey Bull. 1079, 105 p. McLean, J. D., Jr., 1953, Four new species of Foraminifera from the lower Tertiary of New Jersey: Cushman Lab. Foram. 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Assoc, Petroleum Geologists Bull., v. 29, no. 7, 885-955. 1947, The Atlantic Coastal Plain, its geology and oil possibilities: World Oil, v. 127, no. 3, p. 44-50, 58. 1948, Studies on the subsurface geology and paleontology of the Atlantic Coastal Plain: Acad. Nat. Sci. Phila. Proc., v. 100, p. 39-76, Shifflet, F. E., 1948, Eocene stratigraphy and Foraminifera of the Aquia Formation: Maryland Dept. Geology, Mines and Water Resources Bull. 3, p. 43-80, pls. 1-5. Sloss, L. L., Dapples, E. C., and Krumbein, W. C., 1960, Lithofacies maps, an atlas of the United States and southern Canada: New York, John Wiley & Sons. Southeastern Geological Society, Mesozoic Committee, 1949, Mesozoic cross section B-B’, Beaufort County, South Carolina to Highlands County, Florida and Mesozoic cross section C-C’, Toombs County, Georgia to Volusia County, Florida: one sheet, scale 1 inch to 10 mi. Todd, Ruth, 1952, Vicksburg (Oligocene) smaller Foraminifera from Mississippi: U. S. Geol. Survey Prof. Paper 241, 53 p., 6 pls. Toulmin, L. D., 1941, Eocene smaller Foraminifera from the Salt Mountain Limestone of Alabama: Jour. Paleontology, v. 15, no. 6, p. 567-611, pls 78-82. 72 Toulmin, L. D., 1952, Volume of Cenozoic sediments in Florida and Georgia: Geol. Soc. America Bull,. v. 63, no. 12, p. 1165-1176. 1955, Cenozoic geology of southeastern Alabama, Florida, and Georgia: Am. Assoc. Petroleum Geologists Bull., v. 39, no. 2, p. 207-235. Veatch, J. O., and Stephenson, L. W., 1911, Preliminary report on the geology of the Coastal Plain of Georga: Georgia Geol. Survey Bull. 26, 466 p. Vernon, R. O., 1942, Geology of Holmes and Washington Counties, Florida; Florida Geol. Survey Bull. 21, 161 p. 1951, Geology of Citrus and Levy Counties, Florida: Florida Geol. Survey Bull. 33, 256 p. Wait, R. L., 1958, Sources of ground water for irrigation in Dougherty County, Georgia: Georgia Geol. 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Survey Mineral Newsletter, v. 8, no. 2, p. 69-77. 73 A Acruliammina longa 48 Alabamina atlantisae 24, 31 danvillensis 24, 31 mississippiensis 17 obtusa 24 wilcoxensis 33, 38 Allomorphina paleocenica 38 subtriangularis 38 velascoensis 38 Alveolinellidae 37 Ammobaculites bergquisti 48 Ammobaculoides plummerae 48 Amphistegina lopeztrigoi 30 pinarensis cosdeni i9, 24 Amphisteginidae Ws Ps 0 she Angulogerina byramensis Wf cooperensis 30 ocalana 23 vicksburgensis 17530) Anomalina acuta 33, 38 bilateralis 17/5, Shi clementiana 45 henbesti 45 midwayensis 36, 38 pinguis 45 pseudopapillosa 44, 45 umbonifera SiS}, pete: Anomalinidae 17, 24, 31, 33, 38, 45, 46 Applin, P. L. and E. R. 2,8 Appling County 9, 25 Archaias floridanus 10 Argyrotheca wegemanni 19 Asterigerina lisbonensis 28, 30 subacuta 17 subacuta floridensis ME ayy texana - see A. lisbonensis Asterocyclina georgiana 19, 24 monticellensis 28, 31 nassauensis 19, 24 Atkinson County 20 Atkinson Formation 47 Atlantic Embayment of Georgia 59 Austin age, beds of 41, 44, 46 Avon Park Limestone 25 B Baggina xenoula 17 Barnwell Formation 18, 25 Bashi Marl Member 32 Beaufort County (S. C.) 10, 13 Bleckley County LOTS 9s 25 Blufftown Formation 4] Boldia madrugaensis 38 Bolivina broussardi 30 gracilis 30 jacksonensis 23 jacksonensis striatella 23 midwayensis 37 INDEX Bolivinoides decorata 44, 46 Borelis gunteri 37 Brantley County 10, 32 Brooks County 13, 19 Bryan County 32, 36, 51 Buhrstone 28 Bulimina aspera 45 cacumenata 37 jacksonensis 19, 23 kugleri 37 quadrata 37 Buliminella carseyae var. 45 elegantissima 23 robertsi 28, 30 Buliminidae 17, 23, 30, 37, 45, 46 Bulloch County 19 Burke County 10, 18, 25 Cc Camden County Camerina dia striatoreticulata Camerinidae Cancris sagra vicksburgensis Candler County Cassidulina globosa subglobosa twiggsana winniana Cassidulinidae Cedar Keys Limestone Ceratobulimina cretacea Charlton County Charlton Formation Chatham County Chattahoochee County Chilostomella ovoidea Chilostomellidae Chilostomelloides eocenica Cibicides Cibicides alleni americanus americanus antiquus blanpiedi danvillensis harperi hazzardi howelli lobatulus mauricensis mississippiensis mississippiensis ocalanus newmanae ouachataensis pippeni stavensis praecursorius pseudoungerianus Wi 24 ols 9, 10; 13; 25, 32, 36 16523337 33, 38, 45 36 45 TOMAS 32 10 10; 135-25;,32 44, 51 38 17, 38, 45 175724, 31 19, 24 38 17, 24 pseudoungerianus lisbonensis 28, 31 pseudowuellerstorfi 31 cf. C. refulgens i7/ tallahattensis 28, 31 westi 28, 31 Cibicidina - See Cibicides Citharina recta 48 Clavulinoides midwayensis 37 trilatera 46 trilatera concava 46 Clay County 327 Clayton Formation 36 Clinch County 19, 25, 32, 36 Coffee County 29,105 Cole, W. S. 8 Colquitt County 10, 55 Columbia County 18, 47 Cook Mountain Formation 25 Cooper Marl 18, 19, 66 Coskinolina floridana 18, 29 Cribrobulimina cushmani 29 Crisp County MOE AS Sy Cusseta Sand Al 1D} Decatur County 10, 19 Dentalina alternata 45, 46 basiplanata 45 cocoaensis 22 colei 37 cooperensis 22 gardnerae 37 gracilis 45, 46 jacksonensis 22029) legumen 45 lorneiana 46 wilcoxensis 37 Dictyoconus americanus 29 cookei 18 floridanus 18 Discocyclina - See Asterocyclina Discocyclinidae 24, 31, 33, 28 Discorbis 2 Discorbis alabamensis 17 alveata 172523 assulata 7 23413.0 byramensis 17 cocoaensis 23 georgiana 30 globulo-spinosa 23 hemisphaerica 17 inornatus 28, 30 midwayensis soldadoensis 38 midwayensis trinitatensis 36, 38 subaraucana 7/5, 2S tallahattensis 30 tentoria 17 yeguaensis 30 Discorinopsis gunteri 18 Dodge County 13 75 Dooly County Dorothia bulletta Dougherty County Duplin Marl E Eagle Ford Formation Early County Echols County OL 255132 150 Effingham County 10, 25 Elphidium leonensis 16 texanum 16, 29 twiggsanum 23 Elphidoides americanus 23 Emanuel County 18, 19, 25 Epistomina caracolla 2, 44, 45 Eponides byramensis 17 carolinensis 19, 23 cocoaensis 19, 23, 30 dorfi 32, 33 haidingerii 45 jacksonensis 23 lotus 36, 38 mexicanus 30 plummerae 38 Eutaw Formation Al F Faults Clay County 55 Crisp County 55 Flint River Formation 13, 66 Frondicularia barlowensis 48 inversa 45, 46 G Gaudryina barlowensis 48 jacksonensis 19, 22 pyramidata 37 rudita 44, 45, 46 Globigerina cretacea 45, 46, 48 Globigerinidae A5, 46, 48 Globorotalia cocoaensis 24, 31 crassata aequa 38 cf. G. membranacea 38 micheliniana 46 velascoensis 38 wilcoxensis 327 33) Globorotaliidae 24, 31, 33, 38, 45, 46 Globotruncana arca 44, 46 cretacea 45 fornicata 46 Globulina gibba 22, 37 gibba globosa 22, lacrima 45, 46 Glynn County 9, 10, 25, 32, 36 Gosport Sand 25, 66 Grady County LOOMS 5) Guembelina globosa 44, 45 midwayensis 3y/ striata 45, 46 Gulf Trough of Georgia 55 Guttulina adhaerens 45 irregularis 2229 problema 37 spicaeformis 22729 Gypsina globula 17, 24 vesicularis 24 Gyroidina aequilateralis 38 crystalriverensis 23 depressa 45, 46 nassauensis 23, 30 soldanii octocamerata 23, 30 springfieldensis 23 subangulata 38 H Hancock County 18 Hantkenina alabamensis 19, 24 longispina 31 Hantkeninidae 24, 31 Haplophragmoides advenus 48 langsdalensis 48 Hatchetigbee Formation 32 Hawthorn Formation 10 Helicostegina gyralis 32, 33 Heterohelicidae 37, 45, 46 Heterostegina ocalana 23 Hoglundina caracolla -See Epistomina caracolla Houston County Wh tite}, dS), AAS), a I Inglis Limestone 18 Irwin County 55 J Jefferson County 18 Jenkins County 19, 25 Johnson County 18, 19 K Kyphopyxa christneri 44, 46 1 Lagena acuticosta 22, 29 hispida 46 Lagenidae 16, 22, 29, 32, 37, 45, 46, 48 Lake City Limestone 25 Laurens County OF 105.195 25 Lawson Limestone 4l Lee County 28 Lepidocyclina antillea 18, 28, 31 chaperi 24 mantelli 16, 17 ocalana 19, 24 Liberty County 9, 25, 36 Lingulina ocalana 19, 22 Lisbon Formation 25, 66 Lituolidae 45, 48 Lowndes County 13, 19 Loxostoma plaitum 44, 45 M Macon County 32 Marginulina austiniana 46 cocoaensis 19, 22, 29 cretacea 46 dorsata 46 fragaria texasensis 22 silicula 46 sublituus 22 texasensis 45 vacavillensis 29 McBean Formation 25 McDuffie County 18, 47 McIntosh County 32 Miliolidae 16, 29 Mississippina monsouri 1LOm23 Mitchell County 10; 19525 Montgomery County 25 Moodys Marl Member 66 N Nanafalia Formation 32 Navarro age, beds of 41, 44, 45 Neoconorbina - See Discorbis Neorotalia mecatepecensis - See Rotalia mexicana var. Nodosaria affinis 37, 45, 46 fissicostata 22 latejugata 37 latejugata carolinensis 22 latejugata var. 29 obscura 46 Nonion advena T65.225°29 alabamense 16 chapapotense 22 inexcavatus 16, 22, 29 micrus 22, 29 planatus 23, 29 Nonionella austiniana 46 cretacea 46 hantkeni byramensis 16 hantkeni spissa I Peis OAS) oligocenica 16 Nonionidae 16, 22, 29, 46 O Ocala Limestone 18, 19, 25, 66 Oldsmar Limestone 32 Operculina mariannensis 19, 23 Operculinoides catenula 36, 37 floridensis 19, 23 Orbitoididae 17, 24, 31 Osangularia - See Parrella Ostrea sellaeformis zone 25 Owen, Vaux, Jr., 2 12 Palmula reticulata 45 Parella expansa 36, 38 Patellina advena 30 Pierce County 10 Placopsilina langsdalensis 48 Placopsilinidae 48 Planorbulinidae M75 PHA Planularia georgiana 225929 truncana NG), BP Planulina austiniana 46 cocoaensis 24 cocoaensis cooperensis 24 correcta 45 taylorensis 44, 46 texana 44, 46 Polymorphina advena nuda 29 cushmani 37 Polymorphinidae 16, 22, 29, 37, 45, 46 Providence Sand 4l Pseudoclavulina amorpha 45 clavata 45 Pseudoglandulina manifesta 37 Pseudophragmina cedarkeysensis 33 flintensis 19, 24 stephensoni 36, 38 Pseudopolymorphina decora 22 dumblei 22 Pulaski County 19, 25 Pullenia alazanensis 17 americana 45 coryelli 45 Pulvinulinella - See Alabamina Pyrgo 16 Q Quinqueloculina leonensis 13, 16 R Reussella byramensis 17 eocena 23 oligocenica 17 sculptilis 23 subrotundata 30 Richmond County 9, 25 Ripley Formation 4] Robulus alabamensis 37 alato-limbatus 22, 29 arcuato-striatus 16 arcuato-striatus carolinianus 22 articulatus 16 articulatus texanus 22 cultratus 16 degolyeri 37 inornatus DA}, BY) 77 limbosus hockleyensis 22 midwayensis 36, 37 muensteri 44, 46 navarroensis 45 pondi 45 pseudo-costatus 37 pseudo-mamilligerus 37 cf. R. rosettus 37 spisso-costatus 44, 45 stephensoni 44, 46 turbinatus 37 wilcoxensis SYS By/ Rosalina - See Discorbis Rotalia beccarii var. 10 bryamensis var. 13, 17 havenensis 38 mexicana mecatepecensis 2, 13, 15, 17 Rotaliidae 17, 23, 30, 33, 38, 45, 46, 48 Rotorbinella - See Discorbis S Sandersville Limestone Member 18, 66 Saracenaria moresiana 22 Schley County 32 Screven County 18, 19, 25 Seminole County on25 Sigmoidella plummerae 22, 29 Sigmomorphina jacksonensis 22, 29 jacksonensis costifera 22 semitecta var. 22 soldadoensis 37 Siphonina advena 17 claibornensis 30 danvillensis 23 jacksonensis 197523;,30 prima 33, 38, 45 wilcoxensis 33 Spirillina vicksburgensis 30 cf. S. vivipara 30 Spiroplectammina laevis cretosa 37 mississippiensis 16 mississippiensis alabamensis 22,729 plummerae 37 semicomplanata 37, 45 wilcoxensis 32, 37 Stensioina americana 46 Stewart County 44 Streblus mexicanus mecatepecensis - See Rotalia mexicana var. Sumter County 25, 32 Suwannee Limestone 13, 66 ab Tallahatta Formation 25, 28 Tamesiequivalent 36 Tampa equivalent 10 Tattnall County 10 Taylor age, beds of 41, 44, 46 Taylor County AT7 Telfair County 25 Terrell County 28 Textularia adalta 16, 22, conica cuyleri dibollensis dibollensis humblei 19, hannai hockleyensis 19, plummerae ripleyensis subhauerii tumidula Textulariidae 163227 29; 335,375 45, Thomas County 195 Tift County 25, Tivola Tongue Toombs County 10, Treutlen County oy Trifarina bradyi advena wilcoxensis Turner County Tuscahoma Formation 32, Tuscaloosa Formation Tuscaloosa Group Twiggs Clay Member Twiggs County 18, U Uvigerina cocoaensis dumblei gardnerae glabrans jacksonensis topilensis_ Vv Vaginulina cretacea longiforma midwayana suturalis taylorana texana 44, webbervillensis 44, Valvulina cushmani floridana martii Valvulineria allomorphinoides danvillensis gyroidinoides 28, infrequens 46, jacksonensis 19% jacksonensis dentata jacksonensis persimilis scrobiculata 32, texana 235 cf. V. umbilicatula 38, wilcoxensis S210 Valvulinidae 29, Verneuilinidae 22S AO AOS Virgulina dibollensis mcguirti tegulata zetina 29 16 78 Warren County 18 Washington County 9, 18 Wayne County 10, 32 Webster County 32 Wilcox Group of Alabama 32 Woodbine Formation 47 85° B1° EXPLANATION 133 ° I Well ! A A’ el Alinement of geologic section, tee figures 21-28 ‘ a) _-—-— “\ a = | oe / a 3 “Os ata . JENKINS; 4 3 Eeraisone A OHNSON > ae SN / noe ko D IL \ { SCREVEN6 Sem ee ey ee ae oe ‘ Se ee 1 - E MOANUEL > = MUSCOGEE /— J 1 es ZT RSS nt : — ‘sez LN & ont \ kh pf 422 ey Vleck ues \ LC AUREN S- Sy % / 5 le tS yt ‘ cao i ft = ro H USTON 106 , Ar } 7 N ° i 3 A SIMARIOIN) 1 Sh. ra mK, a S TREUTLEN ag BULLOCH tirtancocter Nao ula eH eC Sey \ ee / “CANOLER / see v a e a are 600 7 ~ 242 eS % FE] Na “ fa ase i 1 ee Boneh 408 aca 3390 s Polar / Noe Se Ie 432 : ad if We! § y- - > 7 A y TN ‘ = if. 1 ye te IL 0. 258 i eee ° \ Va 1 aoe i =o y . - a a s0sf—-—> - 42 _,|342 ° 222. —=_ oom ‘ \ Bia ete Maree ere Me Saeae \ ' 488 S U Me ER 143 (em ¢ ogy |STEWART | ‘ m4 ] eWHEELER 4 be 1 TOOMBS) evans \ “ee Vara 507 K ~ y = =f wil gio : ae: Maina bap . ; o AN Yn 180 = 7 22 He eae SW iG I= AR Paar |} FE “460 =) a-ak | 0/42 = , ° Se S ee A ° , BEN HI oe atu DAVIS | TURNER 1 **eo | : -. -——— =. ! . ig 168 5 # pee — 274 = | R wei Nn [qe L ie FISNICHOIRIRMENE celia acrown © 292 anaes 24s r- : ‘io ees Nee ase a ee aa erie te Xv ° X = 425 =f ! = K Ss i (ems a BERRI EN HES ONT SMITHERS. Foren we a8 j ie ee 4 ‘ e J ee % Figur UIT T fo os (, ule f- | 3° ahs — 24 eaea 1 \ 87 — ; ‘ sIe SEMINOLE} i OTE. ally i \ 1 on by) 9, | “ ) ommiee a | COL TINNNG as ara eS | THOMAS UN eee iy \ Sf as GRA D Y bo, “re hea 00K s tH 173 26 m ee N Sod H' as | web 25 wy ee ema a oe < lo ! | « 1 ee as NY oto | Bo heh ios FP fl S00l itn | O| R | Da a i a 10 i") ° 20 30 MILES iL AHHH = E =| 35° ae 83° al” Figure I—Map of Goastal Plain of Georgia showing location of logged wells and geologic sections. 24a : i; mawrie-he