IC 34 GEORGIA
STATE DIVISION OF CONSERVATION
DEPARTMENT OF MINES, MINING AND GEOLOGY A. S. FURCRON, Director
THE GEOLOGICAL SURVEY Information Circular 34
RECONNAISSANCE OF THE GROUND WATER AND GEOLOGY OF
THOMAS COUNTY, GEORGIA
By C. W. Sever U.S. Geological Survey
Prepared in cooperation with the U.S. Geological Survey
ATLANTA
1966

CONTENTS

Page

Abstract --------------------------------------------------------------------------------------------------------------------------- - - - - - - - - - - - 2

Introduction -------- --------------------------------- - - - - - - - - ---- -- - 2 Geologic formations and their water-bearing properties___________________ ----------------------------------------------------------- 2

Geologic structure -------------------------------------- - - - - - - - - - - - - - 7 Quality of ground water-------------------------------------------------------------------------------------------------------------------------------------- ~ Recharge and the piezometric surface____________ _------------------------------------------------------------------------------------------------ 12

Thomasville well field ------------- ----------

--- -- 12

References _____________---------------------------------------------------------------------------------------------------------------

14

ILLUSTRATIONS

Page Figure 1. Hydrologic map showing wells and the piezometric
surface of the Suwannee Limestone - - ------ - -- ---- - ---------- - -- 3

2. Map showing configuration of the top of the Suwannee Limestone - - - - - -

6

3. Map showing configuration of the top of the Tampa Limestone___________

7

4. Geologic section A-A' ______________________ --------------------------------------------------------------------------------------------- 8

5. Photograph showing folding of beds in the Alum Bluff Group ---------------------------------------------- 9

6. Map showing regional geologic structures in Southwestern Georgia and adjacent areas ______________ ----------------------------------------------------------------------------------- 10

7. Graph showing annual pumpage from the Thomasville well

field 1923-1963 -------------------

- - -- --------

12

8. Graph showing response of water level to rainfall and pumpage in the Thomasville well field 1961 to 1964 --------------------------------- -------------------------- 13

9. Graph showing response of water level to pumping in the Thomasville well field ------ ------------- --

- - - -- 14

TABLES

Table

Page 1. Generalized section of geologic units underlying Thomas
County, Ga., and their water-bearing properties ----- - - - -- -- --------- 4

2. Chemical analyses of water from municipal and industrial wells, Thomas County, Ga. ----- - --- ---- -- - --

------------ - - - 11

3. Chemical quality of water from aquifers, Thomas County, Ga....------------------------------------------ 11

1

RECONNAISSANCE OF THE GROUND WATER AND GEOLOGY OF
THOMAS COUNTY, GEORGIA

C. W. Sever

ABSTRACT
This report briefly describes the geology and the availability and chemical quality of ground water in the upper Eocene to Recent aquifex of Thoma County, Ga. The Tallahatta Formation and the lower part of the Lisbon Formation, of middle Eocene age, contain saline water, the overlying formations all contain fresh water.
The Ocala Limestone of late Eocene age and the Suwannee Lime tone of Oligocene age are the principal aquifers tapped by dome tic, municipal, and industrial wells. The maximum yield of these two aquifers varies greatly within Thomas County. They yield only about 60 (gpm) gallons per minute near Meigs in northwestern Thoma County, but will yield more than 3,000 gpm near Thomasville in the central part of the county.
Contours drawn on the top of the Suwannee Limestone show a northeastward-trending fault with a displacement of as much as 190 feet. The rocks are upthrown on the southeast side of the fault. Changes in lithology and thickness of lower and middle Miocene sediments indicate that movement occurred during early and middle Miocene time. General absence of the Citronelle Formation of Pliocene age southeast of the fault indicates that faulting may have occurred again during post-Miocene time.
INTRODUCTION
This report presents the results of a reconnaissance investigation made of the ground-water resources in Thomas County, Georgia, by the U.S. Geological Survey iu cooperation with the Georgia Department of Mine , MinJng and Geology. It briefly de cribes the geology and the availability and chemical quality of ground water in t he upper Eocene to Recent aquifer of Thomas County, an area of about 540 square miles along the Georgia-Florida state line in central south Georgia.
A well-numbering system based on geographic oordinate is t1sed in this report. Each well is assigned two numbers separated by a letter. The first number and the letter refer to a coordinate system used to identify the individual 71f2-minute quadrangles. Beginning at the southwest corner of Thomas County, the number 13 through 16 de ignate from west to east each 71f2-minute interval of longitude and similarly, the lette1s D through G designate from south to north each 71/2minute interval of .latitude. These quadrangle

coordinates are shown on figure 1. The final number represents the well numbered serially within a quadrangle. Accordingly, well 14F12 was the 12th well to be located within the 7%-minute quadrangle represented by coordinates 14 and F.
Wells for which drill cuttings are available have also been given a Georgia Geological Survey (GGS) number. These numbers are shown unde1 "Rema1ks" in tables. Drill cuttings from these well are on file in the sample library of the Georgia Department of Mines, Mining and Geology in Atlanta.
GEOLOGIC FORMATIONS AND THEIR
WATER-BEARING PROPERTIES
Thomas County i underlain by more than 7,000 feet of eclimental'Y rock ranging in age from Cretaceous or older to Recent. However, data are not available concerning rocks underlying the Tallahatta. Fo1mation of middle Eocene age, tbu the eli cus ion of geology and water-bearing properties is limited to the Tallahatta and overlying formations. These are summarized in table 1.
The Tallahatta Formation i thought to underlie all of Thoma County but only well 14E16, the deepest well in the county, has penetrated thi formation. Accotcling to Herrick (1961, p . 398400) the bottom 23 feet of this well penetrated fine-to coarse-grained glaucmritic and belonging to the Tallahatta Formation at a depth of 1,612 to 1,635 feet. Water fl:om this interval i hjgbly mineralized a11d i under greater hydro tati pre sure tha11 water in the overlying limestones. When well 14E16 wa completed, the highly mineralized water from t he Tallahatta Formation flowed up the well bore, then entered the Ocala Limestone and contaminated the city of Thomasville's well field. The well was subsequently plugged with cement and abandoned.
About 200 to 600 feet of glauconitic limestone of the Lisbon Formation of middle Eocene age overlies the Tallahatta Formation in Thomas County. The Lisbon consists of glauconitic white limestone interbedded with glauconitic marl. Gypsum and pyrite are common in the lower part of the formation. Water-bearing properties of the Lisbon are relatively unknown. Layne-Atlantic Company reported that at Meigs the upper part of the formation contained slightly mineralized water and the lower part contained saline water.

2

MITCHELL
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COLQUITT

COUNTV

17
......,...,._0
EXPLANATION

--65--
PU:tl~ l ri, C0t'I IOU, Shows ollirude of piezometric surface,
COI'IIour interval 5 feet; datum is mean sea level
_______..
General direclion of ground-water tlow
A---A' Line of geologic sec lion S.CUGn JhOwn on F'oure 4
o1
Well and identification number

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Figure 1.-Hydrologic map showing wells, and the piezometric surface of the Suwannee Limestone, March 16, 1964.

3

Series Recent to
late Pleistocene Pleistocene Pliocene
Miocene
oj::.
Oligocene
Eocene

Table 1.-Generalized section of geologic units underlying Thomas County, Ga., and their water-bearing properties.

Group

Stratigraphic Unit

Lithologic Composition

Thickness (feet)

Water-bearing properties

-Undifferentiated Loose sand and gravel along major streams

0-25 Contains appreciable water. Not developed because rnaterial occurs only in low areas subject to flooding.

~

Undifferentiat ed Loose sand

Terrestrial dep osit s of cr oss-bedded yellow t o Citronelle Formation red gravel, sa nd, and clay

Upper Zone

Marine deposits of fuller 's earth clay; gray clayey sand; and white calcareous-cemented sandstone

Alum Bluff

Middle Zone

White phosphatic sandy limestone

Lower Zone

Phosphatic fine-grained sand interbedded with

(Chipola Formation marl and thin white sandy limestone.

equivalent)

Tampa Limestone

....

Q)

p. p.

Yellowish-gray very phosphatic sandy lime-

;:J stone

....

a.> ~ 0

Phosphatic sandy marl containing gravel interbedded with sandy limestone. Pyrite is

...::l sparse to common near the base.

Suwannee Limestone

Dense pure white limestone with a porous secondary chert layer developed near the top of
the formation east of the Ochlockonee fault. The formation is dolomitic and contains gyp-
sum northwest of the fault.

Jackson

Ocala Limestone

Dense brown dolomitic limestone containing gypsum.

Claiborne

Lisbon Formation
Tallahatta Formation

Loose granular white glauconitic limestone interbedded with light-gray glauconitic marl. Gypsum and pyrite are common in the lower part of the formation.
Glauconitic sand and marl interbedded with light-gray sandy glauconitic limestone and dark-brown glauconitic dolomitic limestone.

0-10 0-80 0-80 0-50 0-110 0-70
0-85 75-210
175-700
200-600 200-400

Not developed in low areas because of flooding ; generally dry in high al'eas because of drainage.
Yields 1 to 5 gpm to dug wells. Cased out of all drilled wells. At places water is polluted. Generally missing southeast of the Ochlockonee fault.
Act s a s confining layer f or Miocene aquifer system.
Yields about 6 gpm. Specific capacity is about 0.3 gpm /ft. Limestone missing southeast of Ochlockonee fault.
Yield unknown. Will cave into well unless cased out. Screens needed for development. Not utilized in Thomas County.
Yields 5 to 50 gpm. Tapped by many domestic wells northwest of the Ochlockonee fault. Either absent or drained dry southeast of the Ochlockonee fault except along the southern edge of the county. Screens and gravel-packed well construction generally are neeessary to prevent fine-grained sand from entering the well.
Yields practically no water to wells. Acts as confining layer for principal artesian aquifer northwest of the Ochlockonee fault. Generally absent southeast of the Ochlockonee fault.
Good aquifer where unconformably overlain by Tampa Limestone. East of the Ochlockonee fault it yields as much as 1,000 gpm. Specific capacity is more than 50 gpm per foot of drawdown. Yield to wells decreases northwestward from the Ochlockonee fault. Yields are reported to be less than 20 gpm to wells near Meigs.
Good aquifer where unconformably o v e r I a in by Suwannee Limestone. Capable of yielding more than 3,000 gpm to wells located east of the Ochlockonee fault. Yield to wells decreases northwestward from the fault. Yields are reported to be less than 30 gpm to wells near Meigs.
Yield unknown. Upper part contains slightly mineralized water. At Meigs water in lower part is saline.
Contains highly mineralized water.

Lower Eocene to Cretaceous

No data available

more than 5,000

Probably contains highly mineralized water.

The Ocala Limestone of late Eocene age overlies the Lisbon Formation; it is a dense, brown dolomitic, gypsiferou lime t one that contaills Jig_ht ly mineralized water. The Ocala underlie the ent ire count y and i tapped by mo t of he industrial a nd muni cipal wells. I yield i variable. A Meigs, Layne-A tlantic Company reported t hat the Ocala yielded le t han 30 gpm to their te t well (13G6). In contrast, at Thoma ville the Ocala yields a much as 3,000 gpro wit h about 14 feet of drawdown. The permeabiDty of the Ocala in the Thomas ville area has probably been increased because of fracturing of the rocks by post-Eocene folding and faulting.
The most extensively developed aquifer in the county, the Suwannee Limestone of Oligocene age, overlies the Ocala Limestone. It generally is a white, non- andy, oolitic, fossiliferous limestone that at places i , almo t a microcoquina; it becomes somewhat dolomitic northwest of the Ochlockonee fault (fig. 2). The Foraminifera Para1otalia mexicana m eoatepecensis (Rotalia mexicana var. of former usage) generally can be found in cuttings from the upper 10 feet of Suwannee Limestone in Thomas County. This foraminiferal species is considered by Herr ick and Vorhi ( 963, p. 13) to be diagnost ic of the Oligocene in Georgia. Other diagno tic species list ed by t hem inclnde Qztinq-ueloculinct leonensi.s Applin and Jordan N u1nrnulit es (ex-Ca1ne1ina) dia (Cole and P011t on), and A ste?-ige?'ina subacuta Cu hman var. [lO?'iderMis Applin and Jorda n. The Suwam1ee Lime tone i easily di t inguished f1om overlying Miocene limestones by the absence of sand and from the underlying Ocala Limestone by the diagnostic Foraminifera.
The Suwannee Limestone is the principal source of water for domestic wells over much of Thomas County, however, the maximum yield and the qual-
ity of its wat er varie within the county. It
maximum yield decreases northwestward from the Ochlockonee fault, and t he water become very bard and contains abundant di olved sulfates. At Meigs, Layne-Atlantic Company reported that it yielded les t han 30 gpm t o theiT test well (13G6). However, southeast of the fault it generally will yield everal hundred gallons per minute of moderately hard water of good quality. An exception is along the crest of the Barwick arch (fig. 2) where the upper part of the
uwannee .Lime tone generally either is drained dry or contains water that is corrosive.
Overlying the Suwannee Limestone is the Tampa Limestone of early Miocene age which can be divided into two members in Thomas County. The lower member of the Tampa is predominately a sandy marl with interbedded thin white sandy limestones. It is as much as 100 feet thick in the northwestern part of Thomas County, but yields little or no water to wells and acts as a confining layer to water in the underlying limestone aquifer system. The lower member of the Tampa Limestone is absent southeast of the Ochlockonee fault.
The upper member of the Tampa Limestone is an easily recognized, gray to brown, dense, sandy

limestone containing abundant chert and phosphate. It is about 20 feet thick in the outbea tern part of Thomas County and t hickens to about 70 feet in the northwest ern part, but it maintain a similar lithology across the entire county. This member (the Chattahoochee Formation of previous usage) is easily distinguished from other Miocene limestones by its color and sand content; its denseness which causes a prominent high anomaly on electric logs; its phosphate content that contains traces of uranium which causes a distinctively high radiation anomaly on gamma radiation logs; and its microfauna which includes specimens of Archaias sp., Sorites sp. and numerous fragments of larger shells. Northwest of the Ochlockonee fault this upper member is a source of as much as 300 gpm of moderately hard water of good quality to many domestic and a few municipal and industrial wells. Screens and gravelpacked well construction are necessary in some
places to prevent fine-grained sand from entering
the well . Southeast of the Ochlockonee fault this member either is drained dry or has been eroded and is missing and is not a source of water.
Overlying the Tampa Limest one is the Alum Bluff Group of middle Miocene age. Northwest of the Ochlockonee fault this group i divisible into three mappable units or zones: A sandy marl lower zone; a phosphatic sandy limestone middle zone that causes a high anomaly on gamma radiation logs; and a fuller's earth clay upper zone. Southeast of the Ochlockonee fault the middle zone is missing and the group becomes a sandy clay with interbedded sandy marl which could not be differentiated.
Only one drilled well (13F20) taps the Alum Bluff Group in Thomas County. It taps the middle zone in northwestern Thomas County. There this zone will yield a maximum of 6 gpm of moderately hard water of good quality. Numerous dug wells tap sand beds within the Alum Bluff Group in the county. The water from these sand beds reportedly is corrosive and some places contain excessive dissolved iron.
About 90 feet of gravel and coarse sand of terrestrial origin overlies the Alum Bluff Group within the Meigs basin. This unit is known as the Citronelle Formation and is considered by the U. S. Geological Survey to be of Pliocene age. On the Barwick arch this unit generally is absent but occasionally is represented by as much as 20 feet of and and gravel in what appears to be old river channels. Southeast of the Barwick arch the lower part of the Citronelle appears to interfinger with shallow water marine beds in which the author and several others have found numerous fossil mammal teeth and a ray plate. The teeth were identified as M erychippus sp. and Dicerathe1'ium sp. by Olsen (1963) who considers them to be of late Miocene age. Numerous dug wells tap this formation in Thomas County. The maximum yield to these wells is not known but the yield is adequate for domestic supplies. The water, however, is corrosive and contains excessive iron.
Beds of sand and gravel of Pleistocene to Recent age have been deposited along the flood plains

5

of streams within the county. They generally are thin and contain water that is probably corrosive. These sands are generally subject to flooding, so no wells have been developed in them.
Many remnants of terraced surfaces, believed to have been continuous at one time, are found in Thomas County (fig. 4). Cooke (1945) named the terraces and concluded that they were of

Pleistocene age. In Thomas County, two of these terraces, the Wicomico (90 feet) and the lower Sunderland (120 feet), generally occur as flat swampy areas whose shapes and distribution resemble embayments, lagoons, and other features found along the present-day coastal areas. In contrast, the remnants of the Sunderland (150 feet), Coharie (200 feet), and Brandywine (260 feet) terraces occur as a series of flat-topped hills.

1 -116
0
I
N TY 114
0

ao

- 11 7 0
EXPLANATION
- -60- -
Con lour Shows ollilude of lop of Suwannee
Limestone Contour 1nlervol 20 feeli do1um is mean sea level
90 0 We ll
120 X Outcrop
L E0N

0 "'
0 0

60

F

L

0

R

D

A

Figure 2.- Map showing configuration of the top of the Suwannee L imestone.
6

MacNeil (1950, p. 99) concluded that the terraces below 150 feet were Pleistocene terraces of marine origin and those above 150 feet were older fluvial terraces of subaerial origin possibly modified by
later seas. MacNeil's interpretation is one possible explanation of the difference between the two types of terraces in Thomas County, but this difference could be related to structural uplift along the Barwick arch described elsewhere in this paper. The loose sands that at places occur on these terraces either are drained or contain water that is corrosive and high in dissolved iron

content. Wells on the lower terraces would be subject to flooding.
GEOLOGIC STRUCTURE
Contours drawn on the top of the Suwannee Limestone of Oligocene age and the Tampa Limestone of early Miocene age (fig. 2 and 3) show that these rocks in northwestern Thomas County are downfolded along a northeast-plunging structure called the Meigs basin (Sever, in review). In central Thomas County the rocks have been up-

IO 0

.......

53 0

E X PLANATION

--60--

Contour

...

:;"ows allitude of top of Tampa Limestone

0

Contour interval 20 feet; datum is

nreon n o l .~o~l

0

85 0

Well
ID 180 X

Out crop
Number br well s. ond o ulc.rops is
ollilude ol lop ol Suonnee w ~ oo" - -
Lme<;Jtone, in leet obo ve or be low meon seo le Ye I ,
1

L E0N

F

L

0

R

0

A

I

0

rE F !

I

2

l

<I

~ -~- ,

5 .. 1LS
,

Figure 3.-Map showing configuration of the top of the Tampa Limestone.
7

0

0

0

'b

.---~r--.--__2,_-r-----'ir----.--r--- 0 ~~ ~

I
<J.

o
8

~
-a

0 .s"'

_.J

0

Figure 4.-Geologic section A-A'

folded along a northeast trending arch named the Barwick arch. These folds are separated by the Ochlockonee fault which has a displacement of about 100 feet in central Thomas County (fig. 4) and about 200 feet in northern Thomas County (fig. 2). Rocks on the southeast side of the fault are upthrown with the amount of displacement increasing to the northeast.
Thickening and displacement of Miocene formations show that folding and faulting occurred periodically during early and middle Miocene times and may have continued into post-Miocene time. Structural contours drawn on the top of the Suwannee Limestone (fig. 2) show that the Oligocene rocks have been displaced along the Ochlockonee fault by later (post-Suwannee) faulting. Data are not available to determine if movement began during Oligocene or earlier time. However, contours drawn on the top of the Tampa Limestone (fig. 3) show that it, too, has been displaced along the Ochlockonee fault, but the amount of displacement is about 20 to 100 feet less than the displacement in the top of the Suwannee Limestone. This difference in displacement indicates that some movement occurred along the Ochlockonee fault after deposition of the Suwannee Limestone and prior to cessation of deposition of the upper member of the Tampa Limestone. Absence of the lower marl member of the Tampa Limestone (fig. 4) east of the fault suggests that some movement occurred during early Miocene time prior to or contemporaneous with deposition of this lower member.
The upper member of the Tampa Limestone generally has about the same maximum thickness and the same lithology across the entire county suggesting that it was deposited during an interval of relative stability. However, displacement of this limestone across the Ochlockonee fault shows that faulting again occurred after its deposition.
Southeast of the Ochlockonee fault the Tampa Limestone was uplifted at the end of early Miocene time, and, at a few places (fig. 4), deep channels were incised through the Tampa and into the upper part of the Suwannee. Sands and clays of the Alum Bluff Group of middle Miocene, which were deposited over this irregular surface, filled the channels.
Northwest of the Ochlockonee fault the Alum
Bluff Group is divisible into three mappable zones:
A sandy marl lower zone; a sandy limestone mid-
dle zone; and a fuller's earth clay upper zone.
Thickening of the middle zone in the Meigs basin
(fig. 4) suggests that some movement occurred
contemporaneously with its deposition. Within the
Meigs basin commercial deposits of attapulgite
and fuller's earth clay occur in the upper part of
the upper zone. These clay beds are absent east
of the Ochlockonee fault. Data are inadequate to
determine if they were never deposited or if they
were deposited, uplifted by later folding and fault-
ing, and then eroded. However, beds of the Alum
8

Bluff Group have been folded since their deposition (fig. 5) and at places faulted. Many of these
Figure 5.-Folding of beds in the Alum Bluff Group.
folds and faults were probably caused by differential compaction within the Alum Bluff Group, and some probably are cau eel by continuing solution and collap e of the L11lderlying lime tones, but many of these st mcture could have been cau ed by continued movement along the Ochlockonee fault during middle Miocene to post-Miocene time.
General absence of the Citronelle Formation southeast of the Ochlockonee fault and downwarping within the Meigs basin of the top of the Alum Bluff Group indicate that folding and possibly faulting occurred again during post-Miocene time.
'rhe Ochlockonee fault, Meigs basin, and Barwick arch trend parrallel to the Chattahoochee anticline (fig. 6) as it was .redefined by Sever (1964b). All these structures are oriented parallel to structural trends in the Appalachian Tectonic Province

and may have been caused by structural movement within the Province during Miocene time. The Brevard fault zone on figure 6 shows the structural trend of the Appalachian Tectonic Province in Georgia.
These structural trends are almost normal to the general northwesterly structural trend in Florida which is shown by the Ocala uplift on figure 6. The close spacing of contour line north of Thomasville in figure 3 uggests that there may be minor northwest-trending structures intersecting the major northeast-trending structures within the area.
QUALITY OF GROUND WATER
The quality of ground water is generally controlled by the lithology of the aquifer, or rock in which the water is contained. Water obtained from a limestone aquifer will contain dissolved calcium and bicarbonate because limestone is composed of the mineral calcium carbonate. If the rock is dolomite, a magnesium carbonate, its water will contain dissolved mag11e hun and bicarbonate. If the limestone is sandy its water may contain dissolved silica. Additional minerals known to affect the quality of water in aquifers in Thomas County are common salt, a sodium chloride; gypsum, a calcium sulfate; pyrite, an iron sulfide; and glauconite, a potassium iron silicate.
The water from municipal and industrial wells in Thomas County contains dissolved mineral concentrations that are well below the recommended limits for drinking water as listed in the U. S. Public Health Service Drinking Water Standards, 1962 (table 2). The concentrations of dissolved minerals in ground water from municipal and industrial wells in Thomas County are summarized in table 2. The concentrations of dissolved minerals in ground water from each aquifer are summarized in table 3. Chemical analyses of water f om municipal wells how the water to be moderately hard to very hard with the hardest water coming from well at Thoma ville and Coolidge, the citie. located nearest the Ochlockonee fault.

9

, ------ --------,7

I

I

I

\

\

\

EXPLANATION
Area where Oligocene
ro~~r
Area where upper Eocene rocks ~rop out

*MONTGOMERY
ALA.

Savannah

*L
TALLAHASSEE

OCHLOCKONEE FAULT

('- THOMAS COUNTY

: --- - ----- ~

0 .:

:_) 0

Jacksonville

GULF OF

25

0

I II I I I

25

50

75 IOOMILE

I

I

I

I

Figure 6.-Regional geologic structures in southwestern Georgia and adjacent areas.

10

Table 2.-Chemical analyses of water from Municipal and Industrial Wells, Thomas County, Ga.

(Analysed by U. S. Geological Survey)

Owner City of Barwick City of Boston City of Coolidge City of Ochlocknee
City of Pavo City of Thomasville City of Meigs
Thomasville-Thomas County Airport
Waverly Petroleum Products Company
..............

Well number
16F10 15E5 15G7 13F22
16F4 14E12 13G6
14F12
13G3

Aquifer
Suwannee Limestone
do
do
Tampa and Suwannee Limestone
Suwannee Limestone
Ocala Limestone
Tampa, Suwannee, and Ocala Limestone and upper part of Lisbon Formation
Ocala and Suwannee Limestone
do

Parts !Jer million

Date of
collec-
tion

.. Depth Ternof pera- -;;

well ture (feet) (OF)

~o-So o!o~

...="=~
.. r;.. ~

1-7-64 308 70 20 O.D3

do

235 70 21

.10

1-6-64 383 74 25

.09

do

450 64 36 .C6

El

El
=~'2
~".'1..~.1~

.....:=;,;
=~
:":':!:!!!~

=El
=oo=oz~ =

-~
r:l
.o5;:c~
=-~

~
.~
-f:o ~.,~
=~~=

=. o~~ ~
=oo
oo~

-;"=:
u .-E=~~ =.~-

40

9.7 3.1 0.5 158

7.1 3.8

41 11

3.2

.6 168

6.8 4.0

65 31 22

3.5 148 185 15

32 16 20

3.8 162 42 10

~;:

..~~ ~

0

.!:::0

.E![i;
r..~

Z~~z

0.3 0.3

.2

.3

.7

.I

.9

.0

do

305 69 39

.03 33 13

2.9

.6 165

.2 2.7

.3

.0

5-8-58 400 76 22

.00 47 20

7.8 1.0 158

8.2 9.0

.4

.0

4-21-64 832 77 38

.08 16

6.8 32

9.7 152

4.8 5.0

.8

.2

1-6-64 300 70 21

.08 34 13

2.9

.6 154

6.2 3.5

.2

.3

1-24-64 905 75 29

.05 22 13 12

3.6 152

3.6 4.0

.3

.0

Table 3.-Chemical quality of water from aquifers, Thomas County, Ga.

Hardness as Sped-

(CaCO,) fie con-

1!;~-c;cr~:.,:!.

i~:SE~~~;0

~ ~
c:!:E

~

duct-
gj m:?s = ance (micro .. ~
z ~ .. 250 C)

pH

168 140

10 260 7.7

176 147

10 275 7.7

438 288 166 615 8.0

242 146

13 360 7.8

182 136

288 130

207

68

245 7.6 70 418 7.8
0 271 8.5

162 137 162 107

11 250 7.6 0 245 7.9

Color
s s s
5

Remarks

5 2
GGS No. 59

5 GGS No. 19 GGS No. 495

Aquifer System Pliocene
Miocene
Do
Principal Artesian Do
Do Do Early Tertiary Do

Formation
Citronelle Formation
Middle Zone of Alum Bluff Group
Upper member of Tampa Limestone (NW of fault)
Suwannee Limestone (SE of fault)
Suwannee Limestone (NW of fault)
Ocala Limestone
Upper part of Lisbon Formation
Lower part of Lisbon Formation
Tallahatta Formation

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lure (OF)

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Parts per million

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Hardness as fie con-

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ductanee (micro-
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pH

60

0.0 43

184 32 26 295 5.6

2.0

.5

.1

129 66

0 120 7.3

Color

Remarks

5 Nitrate, sodium, and chloride contents of this water suggest that it may be polluted.
s

8.3 2.1 192

3.8

5.7

.4

.0

203 152

0 302 7.7

5 Average of 3 analyses

39

11

58

28

45 18

3.1

.6 162

6.8

3.6

.2

.3

167 140 10 260 7.6

22

3.8 144 162

14

.7

.1

385 258 140 570 8.2

7.8 1.0 156

80

8.5

.4

.1

270 260 130

70 8.4

244

68 5,320

254

310

48 29

276 1,871 7,300

.0

.0 24,218 788

7.5

5 Average of 4 analyses
5 Average of 2 analyses
5 Average of 3 analyses No analysis available. Water probably is slightly mineralized but usable.

RECHARGE AND THE PIEZOMETRIC SURFACE
The piezometric surface shown in figur es 1 and 4 is an imaginary surface representing the static water levels (in feet above mean sea level datum) in wells tapping the Suwannee Limestone as measured in March 1964. It is useful in showing areas of recharge and discharge. Ground water flows from areas of high piezometric elevations toward areas of low piezometric elevat ions in a direction generally normal to each contour. The general directions of ground-water flow in the Suwannee Limestone in Thomas County are shown by arrows on figure 1.
Rainfall recharges the Suwannee Limestone in Thomas County southeast of the Ochlockonee fault where the limestone is at or very near the land surface by direct inflow through sinkholes or by percolation through the overlying sands and clays. High piezometric elevations near Barwick suggest that appreciable recharge takes place in that area. Little or none of the water recharging the Suwannee in Thomas County moves laterally across the Ochlockonee fault. Instead, it discharges down the fault into the underlying Ocala Limestone. Most of the water in the Suwannee Limestone northwest of the Ochlockonee fault entered the aquifer north of Thomas County.
Data are inadequate to construct a piezometric map of any aquifer other than the Suwannee Limestone. However, water levels in the Tampa generally are from 30 to 60 feet higher than water levels in the Suwannee, and water levels in the
1000

Ocala are about 10 to 20 feet lower than those in the Suwannee.
THOMASVILLE WELL FIELD
As the city of Thomasville has grown, the amount of water used has increased (fig. 7). The water is pumped from 5 wells spaced from 70 to 700 feet apart that tap the Ocala and Suwannee Limestones. A continuous record of the water level in a sixt h well (14E15), located within the well field, was obtained using a water-level recorder. Figure 8 shows how the water level changed between October 1961 and September 1964 in response to recharge from local rainfall and discharge by pumpage. The water level generally declined in response to the pumpage, but rose in response to recharge from heavy rainfall during the periods June to September, 1962 and January to September, 1964.
Figure 9, a copy of the recorder graph of well 14E15 for December 26 to 30, 1963, shows how the water level changed in response to pumping from three of the wells at Thomasville. The water level generally oscillated with diminishing amplitude for about 2 minutes after a pump was either started or stopped. The amount and direction of change in the water level depended upon whether a pump was started or stopped, the pumping rate, and the distance from the observation well to the pumped well. Well14E12 is located about 310 feet west of the observation well and was pumped at a r ate of 1,170 gpm. Well 14E10 is located about 310 feet to the southwest and was pumped at a

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Figure 7.-Annual pumpage from the Thomasville well field 1923-1.963.

12

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1964

Figme B.-Response of the wateT level at the Thomasville well field to minfall and pumpage 1961 to 1964.

rate of 1,000 gpm. Well 14E14 is located about 95 feet to the southwest and was pumped at a rate of 500 gpm.
The lack of development of a drawdown cone around the Thomasville well field, and the quick response of the water level at Thomasville to local

rainfall, indicate that the Ocala and Suwannee Limestones in the Thomasville area are extremely permeable. This permeability probably results from ground-water solution of the limestone along numerous joints created during folding and faulting of the rocks.

13

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26

27

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29

30

DECEMBER 1963

Figure 9.-Response of the water level in well 14E15 to periodic pumping of wells 14E10, 12, and 14, Thomasville well field.

REFERENCES
Cooke, C. W., 1945, Geology of Florida: Florida Geol. Survey Bull. 29.
Herrick, S. M., 1961, Well logs of the coastal plain of Georgia: Georgia Geol. Survey Bull. 70, 461 p.
Herrick, S.M., and Vorhis, R. C., 1963, Subsurface geology of the Georgia Coastal Plain: Georgia Geol. Survey Inf. Circ. 25, 67 p., 28 fig.
MacNeil, F. S., 1950, Pleistocene shore lines in Florida and Georgia: U. S. Geol. Survey Prof. Paper 221-F, p. 95-106.
McCallie, S.W., 1896, A preliminary report on a part of the phosphates and marls of Georgia: Georgia Geo!. Survey Bull. 5A, 98 p.

Olsen, S. J., 1963, An upper Miocene fossil locality in north Florida: Florida Acad. Sci. Jour., v. 26, no. 4, p, 308314.
Sever, C. W., 1964a, Relation of economic deposits of attapulgite and fuller's earth to geologic structure in southwestern Georgia: U. S. Geol. Survey Prof. Paper 501-B, p. B116-118.
______________ _______________ , 1964b, The Chattahoochee Anticline in Georgia: Georgia Geol. Survey Min. Newsletter, V . 17.
----- ---- (in press) Miocene structural movements in Thomas County, Ga., in Geological Survey Research 1966: U. S. Geol. Survey Prof. Paper 550-C.
U. S. Public Health Service, 1962, Drinking water standards: Public Health Se>rvice Publication no. 956.

14