Tertiary sea-level fluctuation in South Carolina

Palaeo,geography, Palaeoclimatology, Palaeoecology Elsevier Publishing C o m p a n y , A m s t e r d a m - Printed in The Netherlands

TERTIARY SEA-LEVEL FLUCTUATION IN SOUTH CAROLINA D. J. COLQUHOUN AND H. S. JOHNSON JR.

Department of Geology, University o["South Carolina, Columbia, S.C. ( U.S.A. ) Division o['Geology, South Carolina State Development Board, Columbia, S.C. (U.S.A.) (Received April 8, 19671

SUMMARY

Recognition of physical, chemical, and biotic parameters associated with cyclic formations allows determination of former marine fluctuation. It is possible to observe major sea-level changes from at least the Late Miocene to the Recent with respect to the Atlantic coastal plain and to infer relative changes of sea level in earlier Tertiary time. The following major fluctuations are indicated: (1) sea-level rise in Cretaceous and relative stability through Early Eocene (Black Mingo) time; (2) sea-level fall in pre-Claiborne; (3) sea-level rise in Claiborne (Congaree, McBean, and Santee) and relative stability through Late Eocene (Barnwell), Oligocene (Cooper), and Early and possibly Median Miocene (Hawthorne) time; evidence of a change from warm pre-Oligocene seas to cooler waters during Oligocene and through Early and possibly Median Miocene; tectonic warping during this Oligocene-Median Miocene interval; (4) sea-level fall; (5) sea-level rise to at least 190 ft. in warm climate in Late Miocene (Duplin) time; (6) slow sea-level fall with prograding alluvial fans-deltas? to possibly less than 140 ft. in Late Miocene?-Pliocene?: (7) pause or rise to 140 ft. and formation of Parler Scarp during Late Miocene?Pliocene?; (8) sea-level fall; (9) pause at 100 ft. or possible lower fall and rise to 100 (circa) ft.; formation of Surry Scarp (Pleistocene); (lO) sea-level fall to less than 0 ft. with pause at 70 ft.; and (11) sea-level rise to 45 ft. (Sangamon). The Pliocene-Pleistocene boundary must lie between the cutting of the Parler Scarp and the formation of the Wicomico terrace (100+ ft. or less) and may be represented by the regression to 100 ft. or to a stand below 100 ft. and return.

INTRODUCTION

The South Carolina coastal plain lies in the central portion of the Atlantic coastal states, between North Carolina to the north and Georgia to the south. Palaeogeography, Palaeoclimatol., Palaeoecol., 5 (1968) 105-126

106

D. J. COLQUHOUNAND H. S. JOHNSONJR.

NORTH CAROLINA lip Sportonburg

Rocklnghom

Anderson

~

,

. t" "" e,-" O x 0-~\~.,

• v. c ,,.

::.:.,.

,:

-

Myrtle

~x'~x"--~t

; . ~ ~'- ... ~,~,,, ",'~J

'

"

•

." " : . - . " :

,... ~

Aiken,J~.'~. ~.\~

GEORGIA

Wilmington

\~,¢3

,'" '~.:-;..v~,,v? Jll,~¢ ~ :.V ..... ,p~.-/-," ~,o ,j,,',," ~

mh i ,

.'" ~

J

Georgetown

... c, .,...,.F .r. Ghorle|ton .

y

.~

~

I1

0 10203040

SCALE[_.~MI LES LOWER COASTAL PLAIN OF

SOUTH CAROLINA A

T L A N T I g

OGEAN

Fig.1. Major physiograohiccoastal plain subprovinces. The coastal plain is expressed physiographically in three regional belts roughly parallel to the Atlantic Ocean: the upper coastal plain, which is underlain by sediments varying in age from Cretaceous to Early or Median Miocene; the Middle coastal plain, which in addition is underlain by Late Miocene, Pliocene?, and Pleistocene?; and the lower coastal plain, which in addition is underlain predominantly by Pleistocene sediments (Fig.l). Geomorphically these regions are characterized by differing interplays between primary topography, regional tectonism, and erosion. In general the upper coastal plain expresses a surface of fluvial and more rarely eolian erosion. Relief varies from locally very strong differences in elevation (on the order of 90-100 m) to areas of generally flat terrain with changes in local elevation amounting to a meter or a few meters. The upper coastal plain lies between approximately 150180 m maximum elevation where it overlies the Piedmont at the Fall Line and approximately 75 m minimum elevation seaward at the Orangeburg Scarp where it lies in contact with the middle coastal plain. The middle coastal plain surface is one in which fluvial erosion has proceeded to the point that primary topography is confusing. Relict surfaces which regionally depict alluvial fan or deltaic shaped landforms can be visualized in examining the topography; but minor landforms such as bars, barrier islands, meander scars, etc., cannot be seen with certainty. At least four terraces lying in belts roughly paralleling the Atlantic coast can be noted, one lying with its landward surface Palaeogeography, Palaeoclimatol., Palaeoecol., 5 (1968) 105-126

107

TERTIARY SEA-LEVEL FLUCTUATION 1N SOUTH CAROLINA

near 75 m (Hazelhurst), a second lying at 65 m (Coharie), a third lying at approximately 52 m (Sunderland), and a fourth lying at 43 m (Okefenokee). The lower coastal plain expresses a surface that is dominantly one of primary topography. Effects of fluvial and eolian erosion after landform emplacement are most apparent landward, where larger landforms such as barrier island chains and marsh surfaces can be noted, and least apparent seaward, where individual storm beach ridges can be seen on aerial photographs, topographic maps and soil maps. Six terraces have been recognized on the lower coastal plain, their landward surfaces rising to approximately 33, 21, 12, 8, 5 and 3 m. They have been named the Wicomico, Penholoway, Talbot, Pamlico, Princess Anne, and Silver Bluff, respectively.

TECTONIC FRAMEWORK OF DEPOSITION

Tectonically the Tertiary and Quaternary sediments of the coastal plain

NORTH

CAROLINA

GREAT CARO_

9.\OG c'--

sv'°s

NA

ARCH

SOUTH CAROLINA

Wrlmrng ton

PIEDMONT @ N

CAPE

I

FEAR

GEORGIA Georgetown

( ...-..,..

M A R ON

Charleston

."

SHELF GEORG

50

20 I

40 I

50

60 I

70

M ILES

"~ "

EAST

IO

i"

ATLANTIC OCEAN

.."

~

BASPN

.'"

R[DGELAND

@~..... *'

Arch

'"'

-'Savannah

TROUG u BEAUFO

~T

Trough

ARCH

SAPELO

~'

or

basin

SL~NE

She I f

'J B r u n s w i c k

Fig.2. Major structural features of the coastal plain of South Carolina•

Palaeogeography, Palaeoclimatol., Palaeoecol., 5

(1968) 105-126

108

D. J, COLQUHOUN AND H. S. JOHNSON JR.

occur as a wedge thickening seaward on the Marion shelf (named after Lake Marion, S.C.) from their landward erosional edge at the Fall Line to a maximum thickness of nearly 1,068 m in the southeasternmost area of the state, lying upon the Precambrian?, Paleozoic and Early Tertiary rocks of the Piedmont-like basement. In addition to southeastern thickening, two major tectonic features influence portions of the geologic column--the Great Carolina Arch (Cape Fear Arch) which lies to the north, and the East Georgia Basin which lies to the southeast, marginal to the Atlantic coast (Fig.2). To the north, Cretaceous strata occur near the ground surface overlying the basement arch and are planed off seaward by Late Miocene, Pliocene, and Pleistocene marine erosion. Southerly from the arch, Eocene, Oligocene and Early Miocene strata occur successively in belt-like subcrop areas extending from the sea inland and southwesterly to parallel the present coast (Fig.4-6). These rocks as well are planed off by Late Miocene, Pliocene? and Pleistocene marine scour seaward. In addition to the major tectonic features, local minor structures such as the Burton Arch (Beaufort) and the Ridgeland Basin have been noted (SIPLE 1956, 1965; HERONand JOHNSON, 1966). Relief associated with these structures is of low magnitude surficially, being of the order of a few meters. Apparently these features affect only pre-Late Miocene sediments.

STRATIGRAPHY

Stratigraphically the Tertiary and Quaternary sediments of the coastal plain express general terrestrial or near shore characteristics landward, and marine shelf characteristics seaward. The terrestrial nature of several of the units in the vicinity of the Fall Line, such as the Middendorf Formation of Late Cretaceous age, the Black Mingo Formation of Early Eocene age, the Claiborne age sediments and the Miocene, present complicated and difficult relationships (even where detailed field work is conducted) because of similarity in lithic appearance. Seaward almost the entire section becomes of marine origin with quartzose or carbonate sediments dominant. The spatial positions of the terrestrial and marine sequences within the various time-stratigraphic units provides interesting data on relative stand in sea level, with respect to the coastal plain, during the Late Cretaceous, Tertiary and Quaternary (Fig.3). Recognition of former sea-level fluctuations with respect to coastal plains rests in physical, chemical and biotic parameters preserved in cyclic formations. Physical parameters include volumetric shape, textures and structures of the landward base and top of the formation as well as the formation's physical facies. For example, unconformities may be divided into two major types; a landward type consisting of a former land surface of valleys and divides, and a seaward type consisting of a marine-scoured plain inclined seaward with decreasing gradient. The two types are transitional within former river valleys where Palaeogeography, Palaeoclimatol., Palaeoecol., 5 (1968) 105-126

i

ooo.

PLAIN

\%'~/

~x

"-~r ~

-

}

"

L

20

Beaufort

I

I~

/ !

/ I

/

I

/_

. t

~

~

?~"

~

t~

/

\

-.

L-

--

/

~

30

i

LATE

/

/

...... ?

?

"

/

"-

es

Hiatus

Major

%P

.

""

~ ..

~

/ ~

/ ~

"

transition

<<" "

" 'Co

"

/

/

"" . -z~--~

/-


.... --

"

g

"

"

""

"

-

-.

--

"

""

"

"

o

2"

F

w/P,i-

"%,

144

"~

Z

(~)

¢,...)

q

~m

" ~o,~,~,~_f l 0t:7M47." OIv

,Dive

L I M E S TON E

~L-

"C'h

~''~o

~Y

'

HAy-

OCALA

o~><..

-

, ~LAc~.

S

~ '~

CASTLE

I I P~.

-

'// -1 /

"" /

.

-

'~

~J..dO.Z'.~O/(/"

==

-- -- _C-.~//z~ ~

," .

"

/i

|

OC.,.AZA ///#.4,.c-~,7-.OiV~c-

..... -.

/

SCARP

/

OLIGOCENE-E A R L Y AND MED}AL MIOCENE PLEISTOCENE / /

~

BETHERA 1=

PLEISTOCENE / / /

LOWER COASTAL PLAIN

2`<,"% - .

facies

Physiogropny

unconformit

""

"

- " -

'.

- - ~ ._

~

SCARP

" "" z.,/'/'4,.~ -

"

/

%"%-

,~.

<-',p,,,0 4"<5-

~-

"0:-

"~x-

"%u

~-----_L~L2~

PLIOCENE

~

~ /SURRY

I I

SCARP

PARLER

"~'_-~

~

-- _

-- ~- .~ - - \- . ~

? ~

-

~

SCARP

ORANGEBURG

I~ Io

f (" ~

Mile,

#o/~.-*

. ~ ~ _-

ao.oo.

_ --

~ . ' ~ i ' - ~b

LIj~J

/~ ,~7-LJ- .o..I

RY~

,.~.

¢

/

)

~

I0

j

....

^ s--s-J ~ ' ~

~-~

COASTAL

\,

Columbio

o@°

i

O

".

~l

~

iO

COSaLE

"~W.

c('4 ~- \

TO

GOCENE-- E ARLY MEDIAL MIOCENE

SA N D H I L L S ~ ~

OLI

M I D D L ECOASTAL P L A I N

Fig.3. Generalized cross-section f r o m the t a l l line to Atlantic O c e a n o n the coastal plain of S o u t h C a r o l i n a .

t

t).\

<-<~

KAOLIN

t'~v

1600 L

I

-,~oo!

- 400

I

~-..~--.-_.~-'~'--:.--'~,__

~'~.-~N

~

'!

[

~<

S A N D H I L L S' - R E D

fCOBBLY FOSSIL t HORIZON

_.L

i

E ~--

of

WHITE

UPPER COASTAL P L A I N

110

D. J. COLQUHOUNAND H. S. JOHNSONJR.

estuarine scour has modified the surface, but along former strands the seaward type transects the landward, and serves to mark maximum marine transgression. Chemical parameters include dominant and trace mineralogical and elemental parameters of the formation's facies. For example, fluviatile sediments deposited by Piedmont draining streams as determined by physical and biotic relationships are mineralogically immature in the coarse sand sizes. Feldspar, pyroxene, and other unstable species are common. Kaolin-type clay minerals are dominant landward in fluvial facies. Montmorillonitic and illitic type clay minerals increase seaward with respect to kaolin (HERON et al., 1965, p.31). Biotic criteria for differentiation of sedimentary environments include isolation of terrestrial, shoreline and marine communities as reflected in assemblages. Water depth, temperature, nature of the substrate and salinity are indicated by assemblages. These physical, chemical and biotic criteria, uniquely or in concert, allow determination of former marine fluctuation with respect to coastal plains within a given cyclic formation. True sea level itself in time, however, is distorted by tectonic flexing or warping of the coastal plain, for example through crustal unloading, tectonic downwarping, or marine transgressive depression. Increase in area of observation over which an ancient stand of the sea with respect to the coastal plain remains constant allows progressive rejection of the distorting factors and adds confidence to a true elevation. Intercontinental correlation at many points on relatively stable plains would refute them as major factors in distortion of ancient levels. There is a general shape, lithic and biotic succession that results from sealevel fluctuation from a low stand through a higher stand and a subsequent lowering of sea level on coastal plains. It is a "cyclic formation" in the sense of STEPHENSON (1928). It consists of environmental progressions initiated by sealevel change which tends to lead forward toward re-establishment of dynamic equilibrium. The environmental progressions are both terrestrial and marine in origin and may be defined in terms of continental emergence or submergence. Four major environmental progressions result. Each is characterized by lithic and biotic successions or facies which may be studied in the Recent in incipient form, or in the Pleistocene where they are more completely developed through longer time periods: (1) continental emergent or emerging cycle, (2) continental submergent or submerging cycle, (3) marine submergent or submerging cycle, and (4) marine emergent or emerging cycle. Recognition of physical, chemical and biotic parameters associated with these cycles allows determination of former marine fluctuation with respect to coastal plains. Thus it is possible along the Atlantic coastal plain to observe the major sea-level changes from at least the Late Miocene to the Recent with respect to that coastal plain, and to infer relative changes of sea level in earlier Tertiary time. Palaeogeography, Palaeoclimatol., Palaeoecol., 5 (1968) 105-126

1I 1

TERTIARY SEA-LEVEL FLUCTUATION IN SOUTH CAROLINA

CRETACEOUS PERIOD

The oldest known coastal plain sedimentary rocks in South Carolina are Late Cretaceous in age (CooKE, 1936). Present thinking is that they represent an interfingering and essentially transgressive relationship between fluvial, marginal marine, and marine deposits (Fig.4) (HERON et al., 1!)65). The Middendorf Formation (i.e., Tuscaloosa Formation of Cooke) is generally present in the upper coastal plain subprovince and is composed principally of light colored cross-bedded kaolinitic sands and lenses of white massive kaolin. It represents deposition in a predominantly fluvial environment under oxidizing conditions. Seaward, in the general vicinity of the boundary between the upper and middle coastal plain subprovinces, the Middendorf Formation grades to and interfingers with gray to black montmorillonitic kaolinite clays and thin beds of gray to white slightly glauconitic sand of the Black Creek Formation. The Black Creek Formation was deposited in palustrine, estuarine, beach, and very shallow neritic environments along a low, flat, shifting littoral zone. Carbonized wood fragments and pyrite are common in the characteristically gray to black sediments. The clays are commonly non-calcareous.

Ngc°~~c,

M~IDDENDORF

,.p ,

.

I

BLACK

/ .

CREEK

SHOREL[NE

°,

LATE

CRETACEOUS

FACIES ..... PEE

/ " 20 MILES

DEE

SHELF

FACIES

I

Fig.4. Late Cretaceous facies o f the South Carolina coastal plain (Late Miocene Pliocene and Pleistocene terrain not shown).

Palaeogeography, Palaeoclimatol,, Palaeoecol., 5 (1968) 105 - 126

112

D. J. COLQUHOUNAND H. S. JOHNSON JR.

Farther seaward the Black Creek Formation is overlain by and possibly merges with the Peedee Formation; most of the eastern coastal plain is underlain by Peedee. The Peedee consists of gray to greenish black calcareous glauconitic clayey silts and fine grained sands with thin beds of gray calcareous sand or hard sandy limestone. The Peedee was deposited under shallow to moderately deep marine shelf conditions. Locally the contact between the Peedee and Black Creek formations appears unconformable (SWIFT, 1966), but the essential relationship seems to be one of continuous deposition across a facies boundary. In the subsurface the Peedee Formation overlaps the Black Creek Formation from southeast to northwest, and the Black Creek apparently tends to overlap the Middendorf in similar fashion. The overall picture in South Carolina in Late Cretaceous time is then one of essentially continuous deposition across facies boundaries in a generally rising sea. HERON and WHEELER (1964) have described these formations in some detail in a traverse following the Cape Fear River in North Carolina. Black Creek Formation marginal marine deposits are now found in outcrops as high as 30-38 m above present sea level. How much higher the Peedee sea may have reached is speculative, as a clear shoreline facies is not known.

PALEOCENE-EARLYEOCENE(WILCOX) Paleontologists have, on fossil evidence, traditionally called for a significant hiatus between Late Cretaceous and earliest Tertiary deposits in the Carolinas. The basal Tertiary Black Mingo Formation of South Carolina, however, is made up of beds that are more similar than dissimilar to the Late Cretaceous Middendorf-Black Creek-Peedee sequence in lithology and environment of deposition (Fig. 5). In the uppermost coastal plain Black Mingo beds are predominantly coarse grained cross-bedded sands suggestive of deposition in littoral and possibly fluvial environments. They appear to lie unconformably on the Cretaceous Middendorf Formation, and a recent study by POOSER (1965, p.1 I) indicates a relief of 9-13 m on the Black Mingo-Middendorf contact in western Calhoun County, South Carolina. At many places in the updip area the topmost Middendorf beds have a marked purple and white mottling thought to represent a paleosol. This could have formed essentially contemporaneously within the oxidizing fluvial Middendorf environment. Neither the paleosol nor the relief on the pre-Black Mingo surface can be taken as conclusive proof of a major hiatus between earliest Tertiary and Late Cretaceous deposits. Seaward, in the middle and lower coastal plain, the Black Mingo Formation is made up of greenish gray glauconitic sands and beds of opal claystone (HERON et al., 1965) "fullers earth" as much as 10 m thick. The environment of deposition Palaeogeography, Palaeoclimatol., Palaeoecol., 5 (1968) 105-126

TERTIARY SEA-LEVEL FLUCTUATION

113

IN SOUTH CAROLINA

"

;:::.:.:"."5

..... ~

"

.,<:..:..-..) (--.::_.~,...:

I"%"

fi,

, -,

~

',;

/

CLAIBORNEJACKSON

~q

,i

/

FACIES CLAIBORNE- JACKSON C A R B O N A T E SHELF FACIES ,

#. &

ATLANTIC

~,

TER# ,ij

(- .~)

OCEAN

" -~

~

120 MILESI ,,

. . . . .

I

(

Fig.5. Paleocene and Eocene facies in the South Carolina coastal plain,

was a large bay or shallow restricted sea in which amorphous silica was quite abundant. Pyrite and finely divided carbonaceous material are also common, and the environment must have been rather like that of the Late Cretaceous Black Creek Formation. Farther to the east, in the lower coastal plain, glauconitic sands and gray fossiliferous limestones become more abundant and the environment of deposition apparently changed to a more normal shallow shelf. Lithologically and mineralogically the opal claystone of the Black Mingo Formation closely resembles the Paleocene Porters Creek Formation of the Gulf Coast and Mississippi Embayment. Fossils in the Black Mingo are generally considered Paleocene (Midway) or Lower Eocene (Wilcox) in age, and the faunal evidence strongly suggests that the Black Mingo is time transgressive across these epochs (POOSER, 1965, pp.11-13). In the middle and lower coastal plain the Black Mingo Formation is difficult to separate from the underlying Late Cretaceous Black Creek-Peedee sequence and there is no clear evidence of a significant break in deposition between the Cretaceous and Tertiary deposits. Black Mingo environments being so like those of the Late Cretaceous, and there being no clear break in the depositional record in downdip areas, it therefore is likely that Black Mingo deposits were laid down in an Early Tertiary continuation

Palaeo#eography, Palaeoclimatol., Palaeoecol., 5

( 1 9 6 8 ) 105 126

114

D. J. COLQUHOUN AND H. S. JOHNSON JR.

of the Late Cretaceous sea, essentially during a stillstand"or slow regression from the high of Late Cretaceous Peedee time. Marginal marine Black Mingo deposits are found in the upper coastal plain as high as about 120 m above present sea level.

MIDDLE AND UPPER EOCENE

Middle and Upper Eocene deposits of South Carolina include the Congaree, Warley Hill, Santee Limestone, McBean, and Barnwell (?) formations. Recent work by POOSER (1965, pp.13-20) has shown these units to represent lithofacies laid down in an essentially transgressing sea; the following discussion is largely a summary of his findings. Fig.6 shows the essential relationships in Orangeburg and Calhoun Counties, South Carolina, in the upper and middle coastal plain. The Congaree Formation consists of poorly sorted quartzose sands and interbedded silty sandy light green montmorillonitic clays and thin hard siltstone and sandstone beds. The lithologies strongly resemble those of the Tallahatta Formation (Middle Eocene) of Mississippi and Alabama. The Congaree intertongues downdip to the southeast with glauconitic sand of the Warley Hill Formation, and is absent farther downdip where the Warley Hill lies directly on the Black Mingo Formation (Paleocene-Lower Eocene). The Congaree is therefore interpreted as the shoreward facies of a transgressive sea, deposition having been largely in estuaries and wide shallow bays. In updip areas the basal meter of the Congaree Formation contains coarsegrained quartzose sand, rounded quartz pebbles, and cobbles and boulders of pisolitic bauxitic kaolin. These pisolitic kaolin cobbles are common at the base of the Middle Eocene in Georgia and in South Carolina as far northeast as the center of the state. They are derived from weathered, somewhat bauxitized, out-

NW

Wagener

BARNWELL FM.

Orangeburg

--------~

x x

x x x x x

x x

x

k ~°0°0000°°000o

fossit

SE

JACKSON

................ ~.~#L-....... , .... : .................... ---/-~ .....

(silicified

Hill

SA

..... ? .... ? . . . ~

~-qPx

Holly

Z -"?

--9--

xz/

•

.j

lag g r a v e l )

Fig.6. Schematic section showing facies relationships in Median and Late Eocene of the South Carolina coastal plain.

Palaeogeography, Palaeoclimatol.. Palaeoecol., 5 (1968) 105-126

TERTIARY SEA-LEVEL FLUCTUATION IN SOUTH CAROLINA

l 15

crops of kaolin in the Middendorf Formation (Late Cretaceous). The bauxitization must have occurred during a period of weathering and erosion in late or postBlack Mingo time and prior to the Middle Eocene transgression. The Warley Hill Formation, up to 15 m thick, is made of non-calcareous to calcareous glauconitic sand. It represents the basal unit of the transgressive Middle Eocene sea in downdip areas, and grades upward into the Santee Limestone. In updip areas it intertongues with the Congaree Formation as indicated above. In the middle and lower coastal plain the creamy yellow to white fossiliferous highly calcareous Santee Limestone makes up the entire Middle and Upper Eocene section except for the basal Warley Hill facies. Updip the Santee intertongues with and grades into the yellowish sands, thin sandstones, and olive green montmorillonitic clays of the McBean Formation (Fig.6). The McBean represents essentially a recurrence of the Congaree environment and is separated from the Congaree by an unconformity mappable in the upper coastal plain but not distinguishable in the Santee Limestone downdip. This unconformity is therefore thought to be due to a relatively minor regression of the Santee sea, after which transgression continued. COOKE and MACNEIL (1952) applied the name Castle Hayne Limestone to the upper part of the exposed Santee Limestone section at the Carolina Giant Cement Company quarry near Harleyville, Dorchesler County, South Carolina, because they found fossil evidence that this part of the limestone section was late Middle Eocene (gate Claiborne) and equivalent to the Castle Hayne Limestone of North Carolina. This extension of the name Castle Hayne is rejected by COt~QtJHOUN ( 1962), HERON (1962) and POOSER(1965, p. 18) and by the present authors because the entire limestone section fits the typical Santee Limestone lithology and there is no clear evidence of a significant break in deposition. The name Barnwell Formation has been applied to red massive clayey sands of probable Middle and Upper Eocene age in the upper coastal plain. These deposits overlap McBean, Congaree, and Black Mingo deposits and are the weathered residuum of glauconitic sand and soft glauconitic limestone that probably represent the continued transgression of the Middle Eocene sea through Late Eocene (Jackson) time. Differentiation between McBean and Barnwell deposits is difficult in extreme updip areas, but their identification is considerably easier downdip where a pebble zone, faunal zonation and more definite lithic differences are apparent and suggest an hiatus. Farther downdip the upper part of the Santee Limestone may be equivalent to the Barnwell Formation (i.e., of Late Eocene age). The pisolitic kaolin cobbles at the base of the Middle Eocene in South Carolina suggest an interval of exposure and weathering between Black Mingo (Paleocene-Early Eocene) and Congaree (Middle Eocene) time (Fig.6). The change from the gray pyritic carbonaceous sediments of Late Cretaceous (excepting the Peedee) through Lower Eocene time to the more open aerated conditions of the Palaeo,Teo,oaphy, Palaeoclimatol., Palaeoecol., 5 (1968) 105 126

116

D. J. COLQUHOUN AND H. S. JOHNSON JR.

Middle and Late Eocene also substantiates the view that there is a significant break in the rock record at the end of the Lower Eocene. This hiatus probably represents a major regression of the sea. Renewed transgression marked the beginning of the Middle Eocene. The sea continued to rise through Middle and Late Eocene time with occasional minor regressions. Latest Eocene marine deposits in South Carolina overlap all older coastal plain sedimentary units and in places along the innermost coastal plain occur now at elevations as high as 200 m above present sea level.

OLIGOCENE, LOWER AND MIDDLE MIOCENE

The Oligocene and Lower Miocene rocks of South Carolina form a uniform unit in the sense that they are affected by similar tectonic movements and possess similarities in lithology when contrasted to the Middle Eocene units and subsequent Upper Miocene, Pliocene and Pleistocene rocks. The time period is represented by the Cooper Marl and Hawthorn Formations. Various portions of the section have been studied in part generally and in part intensively by COOKE (1936), COOKE and MACNEIL (1952), SIPLE (1957), MALDE (1959), POOSER (1965), HERON and JOHNSON (1965), COLQUHOUN and DUNCAN (1964) and COLQUHOUN (1965). Cooper and Hawthorn rocks occur in two major areas of the coastal plain in South Carolina, a coastal area within the lower and middle coastal plain, and a landward area within the upper coastal plain. The areas are separated from one another by subsequent Late Miocene and younger marine scour. Both rock-stratigraphic units were first recognized in the coastward subcrop area where they underlie Late Miocene, Pliocene and Pleistocene sediments. The subcrop of the Cooper Marl, a term used first by SLOAN(1908) although previous workers had used other forms of the name, lies south and in the vicinity of Lake Moultrie, gradually bending to a southwesterly direction and lying roughly parallel to the coast, to intersect the Savannah River in the vicinity of Allendale (Fig.7). The northern edge of the Cooper Marl subcrop is erosional, having been planed off by subsequent scour. Little evidence for continental or shoreline deposition has been recognized in this area. There is little evidence of a basal transgressive sand between the Cooper and the underlying Santee Limestone, and, although there is much evidence for abrupt change in sedimentation through the introduction of fine clastics and subsequent change from a light grey skeletal microgranular limestone of the Santee to fine-grained, clayey, calcareous, olive to brown, occasionally phosphatic marl of the Cooper, it is believed that the contact is transitional. The clastics probably have resulted from upwarp of the Great Carolina Arch. The Cooper Marl has been assigned to Late Eocene (COOKE, 1936); Early Oligocene (COOKE and MACNEIL, 1952); Early to Late Oligocene (MALDE, 1959), and with qualification, Oligocene (POOSER, 1965). Palaeogeography, Palaeoclimat ol., PalaeoecoL, 5 (1968) 105-126

TERTIARY SEA-LEVEL FLUCTUATION IN SOUTH CAROLINA

1 17

P I EDMON T

d %

/, •

"0"

COOPER

MARL-

HAWTHORNE FORMAT ION

FACIES 20 M I LES

I

ATLANTIc

I

OCEAN

Fig.7. Cooper M a r l - H a w t h o r n Formation facies in the South Carolina coastal plain.

The Hawthorn Formation of Early Miocene age (CooKE and MACNBL 1952), overlies the Cooper Marl and has been mapped generally seaward of the latter (CooKE, 1936, pl.2). Drilling on close-spaced centers within its area of subcrop north of Charleston has not revealed lithic differentiation between the Cooper and Hawthorn Formations generally although in other areas their correlatives are distinguishable. In southeastern South Carolina the Hawthorne lies directly on the Santee Limestone in sharp contact, and commonly exhibits a basal phosphatic pebble zone and indurated sediments. In eastern central South Carolina the Cooper Marl lies directly on the Santee and is overlain by Hawthorne strata. Within the upper coastal plain in northeastern Georgia and southwestern South Carolina (Fig#), littoral sands of the Hawthorn Formation, as indicated by coarse-grained, well-sorted slightly feldsp~:thic sand containing Halymenites sp., have been noted overlying typical Cooper Marl lithology. The shoreline environments grade landward into a "'characteristic mottling of deep purple, pink and grey in the sandy clays and gravels" (SwLE, 1957) of continental environments. Farther landward the Hawthorne sediments overlie marine clastic Barnwell (Jackson) strata. A high stand in sea level between the Late Eocene and Oligocene, and a Palaeogeography, Palaeoclimatol., Palaeoecol., 5 (1968) 105-126

118

D. J. COLQUHOUN AND H. S. JOHNSON JR.

drop in sea level from Oligocene to Median 'Miocene, is indicated. A possible regression may be present in Oligocene or Early Miocene time to account for southeastern phosphatic and quartz (SLoAN, 1908, pp.287-289) pebble occurrences. The introduction of clastics into the seas commencing with the development of the Cooper Marl lithology, and the coincident appearance of relatively immature gravels within the landward Hawthorn Formation together with the arcuate subcrop pattern of all post-Cretaceous subcrop beds to and including the Hawthorn, attests to the upwarping of the Great Carolina Arch. The appearance of deep water hystrichosphaerids (Leopold, in MALDE, 1959), deep water Foraminifera, and deep water Ostracoda (PoOSER, 1965) within the Cooper Marl lithology, may indicate deep water, but it may also indicate a cooling of water temperatures from the warm water, teeming with life, of the Santee Limestone. It may also, if the latter is true, indicate glaciation which would account for the Early to Median Miocene regression.

LATE MIOCENE, PLIOCENE, AND EARLY PLEISTOCENE

The Late Miocene, Pliocene, and Pleistocene rocks of South Carolina are sediments characterized in their emplacement by major eustatic fluctuation in sea level. Thus, in varying degrees, they possess similar lithologies, similar volumetric shapes in lithofacies development, similar topographic expression, and to a certain extent similar development of soil types. This similarity in common characteristics has resulted in a proliferation of terms applied to the units. The time interval is represented by the Duplin Marl, Waccamaw, Wicomico, Talbot, Princess Anne, and Silver Bluff Formations, as well as several others, depending on whether formations be defined on the basis of unique lithology, physiography, or on the basis of major erosional unconformities in updip areas. The time intervalis represented physiographically by the Hazelhurst, Coharie, Sunderland, Okefenokee, Wicomico, Penholoway, Talbot, Pamlico, Princess Anne and Silver Bluff Terraces. Most of the associated units have been named on the basis of similarity in topography and underlying sediments, or on the basis of faunal assemblages. Both criteria lead to confusion. More than one terrace can be developed on the surface of a single submergent-emergent sequence. Thus the Coharie and Sunderland in central South Carolina are underlain by a single cyclic unit. Terraces are not necessarily underlain by coincident lithologies. Thus the higher terraces of the middle coastal plain have sediments of continental origin generally at their surfaces, whereas the Wicomico and Penholoway Terraces (which are part of the same cyclic unit) exhibit both continental and marine surface sediments. Similarly confinement of terms to a major lithofacies within a cyclic unit leads to confusion. The Duplin Marl is generally not a marl as currently mapped in South Carolina, Palaeogeography, PalaeoclimatoL, Palaeoecol., 5 (1968) 105-126

] 19

TERTIARY SEA-LEVEL FLUCTUATION IN SOUTH CAROLINA

PIEDMONT

\o

HIGHLAND

HIGHLAND HIGHLAN •

\\

LUV/ AL ORANGEBURG

SCARP I

SHELF

L A T E MIOCENE (DUPLIN)PLIOCENE ? FACIES

FACIES 0

L_.-# ~

~

.~

20

40

60

80

I

I

t

MILES

'

Fig.8. Late Miocene (Duplin)--Pliocene? facies on the South Carolina coastal plain.

partially because it was leached through subsequent weathering, but also because it was never a marl in the first place. The middle coastal plain topography originated in the Late Miocene during a marine transgression and resulting scour of Cretaceous and Tertiary strata from a low stand in sea level after the emplacement of the Hawthorn Formation. The Duplin Marl was then deposited, and during slow regression the continental "terrace" sediments emplaced. The precise age of the terminal surface of the Coharie and Sunderland Terraces is unknown, but it was formed prior to the formation of the Wicomico Terrace which lies seaward, in the Pleistocene• The division between the upper and middle coastal plains (Fig.l) and the landward extent of the Duplin Formation, is the Orangeburg Scarp (Fig.8). It is a regional feature marking the boundary between the upper coastal plain and the middle coastal plain. The Orangeburg Scarp traverses the coastal plain of South Carolina without major regard for larger tectonic features. It has been traced north through North Carolina into Virginia (WHITE, 1965), and occurs to the south at least as far as the northern Florida panhandle• Similar changes in topography at similar altitudes have been noted elsewhere. Palaeogeography, Palaeoclimatol., Palaeoecol.,

5 (1968) 105 126

120

O. J. COLQUHOUN AND H. S. JOHNSON JR.

Eustatism The base of the Duplin Marl is locally irregular and of high relief. Drill holes have penetrated to sea level, at least, in several areas of the middle coastal plain without encountering its lower beds. In other areas, the Duplin Marl is only about 15 m in thickness and lies on a relatively level plain which inclines seawald in a manner similar to the marine-scoured surfaces of COLQUHOUN (1965) or subsurface terraces of COLQUHOUN(1962). The surface is overlain by quartzose sands containing exogenic and endogenic shell debris, a characteristic of basal transgressive environments. At a few locations red clays resembling "terra rossa" have been found at the surface of the Santee Limestone where that unit forms part of the subcrop. In other areas bleached Cooper Marl, grading with depth to normal Cooper lithology, has been noted. It is concluded that a significant regression occurred prior to continental submergence in the Late Miocene, and inasmuch as these indications of former land surfaces are developed on the Hawthorn Formation to the south in Georgia, the regression must have occurred after Early Miocene time. True eustatic fluctuation rather than major tectonic warping is indicated by the widespread nature of the physiographic observations as well as by the similar attitude of the basal marine unconformity to younger unconformities. If the observances are tectonic, then we must accept the idea that the Atlantic, and portions of the eastern Gulf, coastal plains were involved, and that these areas dropped as a block with only minor tilting.

Age of the Coharie and Sunderland The nature of the sedimentation during a fluctuation in sea level indicates that the ultimate surface presented during a still-stand in the level of the ocean on the lower Atlantic coastal plain is that of coalescence of deltas and alluvial fan-like sediments over previously marine environments (COLQUHOUN, 1965; in press). The condition is rarely met within the Pleistocene cyclic formations of the lower coastal plain, but is the general rule in the case of the middle coastal plain. Inasmuch as the fully developed cyclic sedimentary unit is primarily dependent on time, it is assumed that insufficient time existed for the Wicomico (including the Penholoway) or the Talbot (including the Pamlico), to allow the condition to develop. Sufficient evidence to be presented elsewhere has accumulated to indicate that the Talbot and Pamlico Terraces represent a single interglacial period. It is apparent that the Coharie and Sunderland terraces were constructed during a much longer time interval. In addition to attainment of a full development of cyclic stages as indicated by surficial continental facies, the Coharie and Sunderland Terraces possess much thicker soil profiles than their seaward equivalents. Simple averages of thickness to the base of the B horizon in flat divide areas are of the

Palaeogeography, Palaeoclimatol., PalaeoecoL, 5 (1968) 105-126

TERTIARY SEA-LEVEL FLUCTUATION IN SOUTH CAROLINA

121

order of 6 m for the Coharie and Sunderland surfaces, 2-3 m for the Wicomico, and 1-2 m for the Talbot. The soils are of a different nature as well. Middle coastal plain soils are more frequently of the tropical ferruginous type than the more common jetlozem and crasnozem types of the lower coastal plain. Fossil evidence as well indicates a relatively long time interval. The Coharie and Sunderland surfaces are underlain by Late Miocene assemblages at depth, as POOSER (1965) has shown. Within the soil profile of marine units, including a leached C zone and the continental units, no fossils occur, so that a positive statement to the effect that all sediments are of Late Miocene age is impossible. Nevertheless, on the above evidence it is suggested that the time interval involved for the formation of the Coharie and Sunderland Terraces includes at least the Late Miocene, based on invertebrate assemblages. It is also suggested that the decreasing elevation of the terminal surfaces of the terraces (though not in degree the subsurface planar unconformity) reflects a decrease in elevation of the sea itself, with a pause in regression at 52 m to form the ubiquitous Branchville Scarp which separates the Coharie and Sunderland surfaces.

The Parler Scarp and the Okefenokee Terrace The Parler Scarp forms the physiographic division between the Sunderland and Okefenokee Terraces in South Carolina. It can be traced from the vicinity of the Okefenokee Swamp in Georgia to the north intermittently to the vicinity of Florence, S.C., where it has been obliterated by landward erosion associated with the emplacement of the Wicomico Formation. In central South Carolina the Parler Scarp marks a major change in the elewttion of basal marine scoured unconformities. To the northwest the base of the Duplin Marl lies near 37 m. Toward the southeast the base of the Duplin? Formation lies near 32 m. Deltaic or alluvial sediments overlie shallow clastic continental shelf facies in each area, and COLQUHOUN and DUNCAN (1964, 1966) have termed the latter the Okefenokee Formation. POOSER (1965) has assigned a Late Miocene age to the marine sediments lying landward and seaward of the Parler Scarp. It is suggested that a Pliocene age may be applicable as well (COLQUHOllY et al., 1967). Unique former land surfaces associated with post-Sunderland pre-Okefenokee time have not been noted with certainty in all areas studied; hence the Parler Scarp may represent a pause in regression, or a primary shoreline resulting from subsequent transgression. The Okefenokee surface in central South Carolina is a climax or fully developed cyclic formation, depicting a deltaic former land surface overlying a marine sequence of the same cyclic unit. Inasmuch as that surface decreases in altitude from 41 m landward, slow continental emergence is indicated during the Pliocene? Palaeogeography, Palaeoclimatol., Palaeoecol., 5 (1968) 105 126

122

D. J. COLQUHOUN AND H. S. JOHNSON JR.

The Surry Scarp and the Wicomico Terrace The Surry Scarp has been traced southward from Virginia to near Trail Ridge in southern Georgia by FLINT (1940). The Wicomico Terrace lies seaward, according to COOKE(1936). In South Carolina the Surry Scarp is actually a melange of several scarp types (Fig.9). It is a primary shoreline, secondary barrier island, marine scarp, estuarine valley wall or mature river valley wall, depending on its geographic area of development. It is not continuous. The Wicomico Terrace is actually a surface varying in elevation from at least 37 m to 21 m above mean sea level. Variations in elevation are caused by the elevation of the ocean during emplacement of the various landforms that comprise the surface of the terrace, as well as the agency that formed or shaped these geographic bodies. Inasmuch as sea level fluctuated at least as high as 34 m above its present surface to 21 m where it paused, it should be apparent that plains reflecting marsh surfaces, for example, will show this variation. Following the pause at 21 m, sea level dropped at least 17 m below its present surface before readvancing to 12 m to form the Talbot Terrace, in Sangamon time. The age of the Wicomico Formation, which is expressed physiographically by the Wicomico and Penholoway Terraces, is Early Pleistocene

PIEDMONT

I ( ~ A R P

/

LIMIT

/

~

-SHOR-EL-,E

MIOCENE-PL/OCENE ? ,,IIPLEISTOCENE CONTINENTAL

(

~

O

N

/~-..',

~

L AND MARINE SEDIMENTSIP' I

OKEFENOKEE(LATE

( ~ ' - ' P [ . [ O C E ~

~

~

~

~

,

NE)

FAGIES

I

A~_~

Fig,9. Okefenokee (Late Miocene-Pliocene) facies development area in the South Carolina coastal plain.

Palaeogeography, Palaeoclimatol.,PalaeoecoL, 5 (1968) 105-126

TERTIARY SEA-LEVELFLUCTUATIONIN SOUTHCAROLINA

123

as determined by mega and microfossils (CoLQUHOUN et al,, 1967). It may be assigned to the Yarmouthian, although an Aftonian age is not precluded.

CONCLUSION

An interpretation of sea level fluctuation is depicted in Fig.10. The left portion of the graph shows only relative changes in sea level as indicated by spatial changes in shoreline and shelf environments from the Late Cretaceous through Median Miocene. Tectonic distortion through warping associated with the Great Carolina Arch and East Georgia Basin, as well as general thickening on the Marion Shelf, probably because of crustal unloading in the Piedmont and crustal loading seaward, has distorted all pre-Late Miocene contacts and boundaries. The chart depicts continental submergence in the Late Cretaceous followed by slow submergence through Paleocene time. This is in agreement with the facies relationships discussed and illustrated in Fig.3 and 4. It should be noted that the slow submergence as indicated by lithologic change, may be brought about by decrease in sediment supply from the landward source area as well, which would allow encroachment of the sea. It may occur as well by downward flexure of the coastal plain and Piedmont itself. Such downwarping, however, must account for the normal northeast-southwest trends of facies boundaries and must be regional in nature. Decrease in sea level, or general upwarping of the continent, is indicated in the Early Eocene (Wilcox) Black Mingo Formation. Subsequent transgression or downwarping is indicated at the beginning of Claiborne sedimentation when the pisolitic kaolin cobbles were emplaced on a former land surface. The Claiborne advance continued through Jackson time with a minor fluctuation represented by the "Cobbly fossil horizon". The shoreline lay beyond the Fall Line boundary and has been eroded subsequently. The clastic-carbonate shelf transitional boundary remained parallel to general coastal plain trends. General sea-level drop or upwarping of the continent is indicated from later Oligocene through Median Miocene. Shoreline environments were warped from normal coastal plain trends to a more easterly direction, probably as a result of warping associated with the flexure of the Great Carolina Arch. The right portion of the graph shows relative change in sea level as indicated by deltaic and marsh surfaces in the vicinity of shorelines from the Late Miocene to the Recent. It is thought that the changes are relatively true for sea level itself. The changes parallel the regional coastal plain trends. The marine scoured plains express approximately the same attitude under each of the submerged-emerged marine sequences. General fall in sea level is indicated following the Late Miocene transgression to about 75 m above mean sea level. Pauses during this regression are indicated at 65 and 52 m. Emergences are indicated just prior to Late Miocene time; possibly in Pliocene? time prior to the formation of the Parler Scarp; prior Palaeogeography, Palaeoclimatol., Palaeoecol., 5 (1968) 105-126

9EI-50I (896I) g "l°aa°a°lVd "l°WtUlla°aVlVd"fvdva#°a~°avPd SEA

LEVEL

FALL

SEA

LEVEL

HISE

>

1 ~

TUSGALOOSA ( morine Grid ~o~--~o~ine ) = MIDDENDORF BLACK GREEK • PEE DEE FORMATIONS

m

m

/

,~•

C~

0

o

Z

< ¢D 0

C C

c0X>

rm

CLAIBORNE

t

:~ ~

m

BLACK

rrl C~

0

MINGO

FORMATION WILCOX

0

1.

PRE-CLAIBORNEREGRESSION

WARLEY,ILL.SANTEE

;

McBEAN , GONGAREE ,

'~

. . . . . . . . . . . .

CASTLE BARNWELL

"~

-- . . . . .

J

.-I 0

........

- ....

I

FORMAT,ONS

r~ FORMATION ~

--I

O--

HAYNE FORMATION

o(::)::0~

~m

) ./

JACKSON

MARL , FLINT

COOPER

C

o

RIVER

FORMATION

----

o EARLY

_¢

o;

8

MEDIAL

FORMAT ION

HAWTHORNE

~ ~

. . . . . . . . . .

m .~, POE-LATE MIOCENE REGRESSION . . . . . LATE

=.. P

~ mr~

- - ' ' 7 -

"~--- _/~='-'7

"~ . . . . . . . . .

__~ .

Y_~'~(~

~

MARL

N

~ ~ //

I

~

~-

o

m

/

:z c

:o

r~

OKEFENOKEE

~:z u) I:,

~

~ o o

m r~Z

~

:~

,,.-

=

"~

FORMATI ON

"11 m rrl -4

~

~

DUPLIN

NEBRASKAN -o •

AFTONIAN ~ KANSAN

?

o

u)

z

•

FORMATION

ILLIN01SAN?r~ "n~

/" - 5- - - _- ~ _ ~

~i

"-"'---

~o

" "~" :3

"

TALBOT

~:

FORMATION

-.-

,L-._-__-

o

~

1"t

WISGONSIN

* ~.~.._.

I

WISCONSIN

o

~'(

RECENT

"~If NOSNHOf "S "H (INV ND_OHJ-10~IOD "f "(I

'~[

TERTIARY SEA-LEVEL FLUCTUATION IN SOUTH CAROLINA

125

to the formation of the Wicomico Terrace or formation; prior to the emplacement of the Talbot Formation; and others to be discussed elsewhere. Thus, prior to Pleistocene glacio-eustatism three major transgressive-regressive or submergent-emergent sequences are noted: Late Cretaceous to Wilcox Eocene; Claiborne Eocene to Median Miocene; and Late Miocene to Early Pleistocene. Culmination of these sequences occurred in the Late Cretaceous; Jackson or Early Oligocene; and Late Miocene, respectively. Superimposed on these fluctuations is evidence for a major drop in sea level itself. Maximum submergence of the Atlantic coastal plain in this area probably occurred in Late Eocene (Jackson) or Early Oligocene time. Since that time, in spite of sea-level fluctuation or coastal plain warping, sea level has been dropping, relative to that surface. Because of Oligocene and Early Miocene warping of the major structural features actual altitudinal changes cannot be assigned to sea level prior to Late Miocene time. Since Late Miocene time, sea level has descended over 75 m to its present surface. This has been a regional drop that encompasses the entire Atlantic coastal plain from southern Virginia to at least northern Florida and southern Georgia, and, if fluctuations of similar nature quoted by WARD (1965) be taken as equivalent in time (contrary to his Pleistocene assignments), they involve Australia as well. The reasons for this drop are speculative. It may result from: collapse of the quasi-cratonic basins (FAIRBRIDGE, 1965); expansion in the volume of the ocean basins; expansion of the earth; loss of world volume of water; or formation of the ice caps. Warping of the coastal plains does not seem to be the answer, unless the widespread nature of these observances can be accepted. The Plio-Pleistocene boundary remains uncertain. Based on megafossils, it is as yet unknown in this area. The Okefenokee has been assigned to the Late Miocene or Pliocene?; the Wicomico, which lies immediately seaward, to the Early Pleistocene. Based on Foraminifera, the Pleistocene boundary is dubious. The Okefenokee may be Late Miocene or Recent. No important differences in fauna have been noted. Based on Ostracoda, the Okefenokee is Late Miocene. Based on major sea-level fluctuation, glaciation commenced in the Late Miocene when the first major change in sea level (of the Neogene) occurred. In summary, what is apparent is a regional drop in sea level commencing in Late Eocene or Early Oligocene with relatively major fluctuations in sea level commencing in Late Miocene.

ACKNOWLEDGEMENT

The author gratefully acknowledges support of the National Science Foundation. Palaeogeography, Palaeoclirnatol., Palaeoecol., 5 (1968) 105- [ 26

126

D. J. COLQUHOUN AND H. S. JOHNSON JR.

REFERENCES

COOKE, C. W., 1936. Geology of the coastal plain of South Carolina. U.S., Geol. SurE., Bull., 867:196 pp. COOKE, W. W. and MACNEIL, F. S., 1952. Tertiary stratigraphy of South Carolina. U.S., Geol. SurE., Profess. Papers, 243-B. COLQUHOUN, D. J., 1962. On Surficial sediments in central South Carolina, a progress report. S. Carolina, State Develop. Board, DiE. Geol., Geol. Notes, C: 63-80. COLQUHOUN,D. J., 1965. Terrace Sediment Complexes in Central South Carolina--Atl. Coastal Plain Geol. Assoc. Field Conf. 1965, Guidebook, 62 pp. COLQUHOUN, D. J. 1967. Coastal Plain Terraces in the Carolinas and Georgia. H. E. WRtGHT (Editor), Proc. Intern. Assoc. Quat. Res., VII, 16 (in press). COLQUHOUN, D. J. and DUNCAN, D., 1964. Rock-stratigraphic distribution of sediments lying northwest of the Surry Scarp, S.C. Southeastern Geol., 5:119-142. COLQUHOUN, D. J. and DUNCAN, D., 1966. Geology of the Eutawville Quadrangle. S. Carolina, State Develop. Board, DiE. Geol., 12: map. COLQUHOUN, D. J., HERRICK, S. and RICHARDS, H., 1967. A fossil assemblage underlying the Penholoway Terrace in Berkeley County, S.C., Bull. GeoL Soc. Am., in press. DALE, W. H., 1892. Contributions to the Tertiary fauna of Florida. Trans. Wagner Free Inst. Sci. 3(2): 200-473. FA1RBRIDGE, R. W., 1965. Collapse of the quasi-cratonic basins. Progr. Geol. Soc. Am., Northeastern Sect., Philadelphia, Penn. FLINT, R. F., 1940. Pleistocene features of the Atlantic Coastal Plain. Am. J. Sci., 238: 757-787. HERON JR., S. D., 1962. Limestone Resources of the Coastal Plain of South Carolina. S. Carolina, State Develop. Board., DiE. Geol., Bull., 28: 128. HERON JR., S.D. and WHEELER,W. n., 1964. The Cretaceous Formations along the Cape Fear River, N.C.--Guidebook 5th. Ann. Field Exe. Atl. Coastal Plain Geol. Assoc., 55 pp. HERON JR., S. D., ROBINSON, G. C. and JOHNSON JR., H. S., 1965. Clays and Opal bearing claystones of the South Carolina Coastal Plain. S. Carolina, State Develop. Board, DiE. Geol. Bull., 31: 66. HERON JR., S. D. and JOHNSON Jr., H. S., 1966. Clay mineralogy, stratigraphy, and structural setting of the Hawthorn Fro, Coosawhatchie District. Southeastern Geol., 7: 51-63. MALDE, H. E., 1959. Geology of the Charleston Phosphate Area, S.C.U.S., Geol. SurE., Bull., 1079: 1-105. MCLEAN, J. D. Jr., 1960. Stratigraphy of the Parris Island Area, South Carolina. Rept. McLean Paleontol. Lab., 4 : 7 2 pp. POOSER, W. K., 1965. Biostratigraphy of Cenozoic Ostracoda from South Carolina. Anthropoda, Publ. Univ. Kansas, 8 : 8 0 pp. StPLE, G., 1946. Progress Report on Ground Water Investigations in South Carolina, S. Carolina Res., Planning Develop. Board, Bull., 15:116 pp. SIPLE, G., 1956. Memorandum on the geology and ground-water resources of the Parris Island area, South Carolina. U.S., Geol. SurE. Rept. SIPLE, G., 1957. Guidebook for the S. Carolina Coastal Plain Field Trip--Geol. Soc. Carolina (unpublished). SrPLE, G., 1965. Salt-water encrouchment of Tertiary limestones along coastal South Carolina. Proc. Symp. on Hydrology of Fractured Rocks, Dubrovnik, Yugoslavia, Oct. 7-14, 1965. SLOAN, E., 1908. Catalogue of mineral localities of South Carolina. S. Carolina Geol. SurE., 4th Ser., Bull., 2: 287-289. STEPHENSON, L. W., 1928. Major marine transgressions and regressions and structural features of the Gulf Coastal Plain. Am. J. Sci., 5th. Ser., 16: 281-298. SWIFT, J. P., 1966. The Black Creek-Peedt,e contact in South Carolina. S. Carolina, State Develop. Board, DiE. Geol., Geol. Notes, 10:36 pp. WARt), W. T., 1965. Eustatic and Climatic History of the Adelaide area, South Australia. J. Geol., 73: 592-602. WHITE, W. A., 1966. Drainage asymmetry and the Carolina Capes. Bull. GeoL Soc. Am., 77: 223-240.

Palaeogeography, Palaeoclimat ol., Palaeoecol., 5 (1968) 105-126