CORRELATION OF THE BASAL CRETACEOUS BEDS OF THE SOUTHEASTERN STATES 

By WYTHE CooKE 

SUMMARY 

The basal Cretaceous deposits that fringe the inner 

margin of the Coastal Plain from eastern Alabama to 

central North Carolina, where they are overlapped by 

11iocene sands, have been commonly classified as of 

Lower Cretaceous age and correlated roughlywith the 

Patuxent formati,on of the Potomac group of Maryland 

and Virginia. In this paper thl evidence on which 

this early correlation was based is reviewed, later evidence is considered, and the conclusion is reached that 

all the basal Cretaceous deposits in the area under consideration are of Upper Cretaceous age. 

Acknowledgments are gratefully made of the helpful 

criticism of the manuscript by L. W. Stephenson and of 

his generous assistance in the preparation of the correlation table. 

CURRENT CLASSIFICATION WITH THE LOWER 

CRETACEOUS 

In 1907 Stephenson ·

1 applied the name " Cape Fear 

formation'' to more or less ~rkosic and micaceous sands 

and clays in North Carolina which rest upon the irregularly eroded surface of the crystalline rocks and are 

separated from the next younger di" ision, now called 

Black Creek formation, by a marked erosional unconformity. With regard to their correlation, he says: 

No fossils have been found in these deposits. Upon lithologic 

and stratigraphic grounds the formation is believed to be 

approximately synchronous with the Patuxent division of the 

Potomac series of Maryland and Virginia, although it may 

inClude a portion of that series younger than the Patuxent 

proper. 

A paper read by William Bullock Clark before the 

Geological Society of America in December, 1908, contains the following statement: 2 

Farther southward in North Carolina is the Cape Fear formation (arkosic sands, clays), so called by Stephenson, which is 

evidently continuous with the Patuxent formation, although the 

basal beds of the Coastal Plain are transgressed by later formations· in southern Virginia and northern North Carolina. No 

fossils have been found in the Cape Fear formation, but the 

strata are similar lithologically to the Patuxent farther north 

and unlike the Arundel and Patapsco. 

In later papers Stephenson was induced to abando~ 

the use of the name" Cape Fear" in favor of Patuxent, 

although there is abundant internal evidence that he 

was not convinced of the synchroneity of the "Cape 

Fear" and the Patuxent formations. 

1 Stephenson, L. W., Some facts relating to the Mesozoic deposits of the Coastal 

Plain of North Carolina: Johns Hopkins Univ. Cir., new ser., No.7, pp. 93-99,1907. 

2 Geol. Soc. America Bull., vol. 20, p. 647, 1910. 

85658°-26t--15 

In December, 1910, Stephenson wrote the following 

statement 3 for the "Index to the stratigraphy of 

North America'' : 

The basal portion of the Cretaceous deposits in the region 

included between the Roanoke Valley in North Carolina and 

the Alabama Valley in Alabama is composed of highly crossbedded arkosic sands, in general of coarse texture, with subordinate interbedded layers. and lenses of light-colored clays of 

greater or less purity, reaching an estimated maximum thickness 

of 500 or 600 feet. These have been designated the ."Cape 

Fear" formation in North Carolina by the writer and the 

"Hamburg beds" in South Carolina by Earle Sloan and have 

been regarded as the eastward continuation of the Tuscaloosa 

(Upper Cretaceous) by the Georgia and Alabama geologists. 

In the Carolinas these beds are separated from the overlying 

Black Creek formation by an unconformity. Likewise an 

unconformity separates them from the overlying Eutaw formation in the Chattahoochee and Alabama river regions in 

Georgia and Alabama. Geographically the belt in which the · 

deposits occur is separated from the Cretaceous occurrences to 

the northward in Virginia by an overlap of Miocene beds. 

However, in all their physical characters they bear a close 

resemblance to the Patuxent formation, which forms the basal 

division of the Potomac group in Virginia and Maryland. · 

On account of this physical . similarity and because of their 

supposed buried connection with the Virginia Patuxent, the 

application of the name Patuxent has been extended to include 

these North Carolina arkosic beds. The apparent continuity 

of the North Carolina beds with the similar deposits to the 

south would, in the absence of known unconformities, seem to 

necessitate the adoption of the name Patuxent for all the beds 

in .question in South Carolina, Georgia, and Alabama, unless 

biologic evidence indicating the incorrectness of this interpretation is forthcoming. With one exception no organic 

remains have been found in these arkosic beds south cif the 

Virginia line. A few poorly preserved plant remains have 

been collected recently from an exposure in a bluff of TaHapoosa 

Rive.r at Old Fort Decatur, in Macon County, Ala. These 

were submitted to E. W. Berry, who expressed the opinion 

that the beds containing them are of Low'er Cretaceous age. 

The meager paleontologic evidence thus afforded te,nds to 

confirm conclusions which Mr. Berry and the writer had 

previously reached, based on physical criteria alone. Unfortunately the poorly preserved condition of the leaves renders 

it difficult to determine 13atisfactorily the relation of the formation to the Patuxent formation of Virginia and Maryland. 

However, in Mr. Berry's opinion, the presence of large numbers 

of leaves, apparently dicotyledons, most of which are too 

poorly preserved to permit their specific or even generic determination, seems to justify doubt as to their being as old as the 

Patuxent formation, in which similar questionably identified 

dicotyledons are very sparingly represented. 

In 1914 Stephenson added: 4 

Should future discoveries confirm tlie doubt expressed by 

Berry as to the Patuxent age of the Lower Cretaceous beds 

aU. S. Geol. Survey Prof. Paper 71, pp. 605-606, 1912. 

4 Stephenson, L. W ., Cretaceous deposits of the eastern Gulf region: U. S. Geol. 

Survey Prof. Paper 81, p. 11, 1914. 

137 
138 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1925 

of Alabr.ma and Georgia, and should it be found that the 

Alabama-Georgia Lower Cretaceous deposits are synchronous 

with the "Cape Fear" formation, it would at once become 

apparent that the name Patuxent was not appropriate for 

Lower Cretaceous deposits anywh~re south of Virginia. 

EVIDENCE OF UPPER CRETACEOUS AGE · 

My own field work in South Carolina during 1917 

and 1922, part of which was done in company with 

Mr. Stephenson, led me to the opinion that the 

supposed Lower Cretaceous deposits of South Carolina are really of Upper Cretaceous age. With this 

in mind, Mr. Stephenson, in 1923, revisited Old Fort 

Decatur, Ala., and obtained additional collections of 

fossil plants which, when studied by P~ofessor Berry, 

proved to be of Upper Cretaceous age, probably of 

about the age of the Tuscaloosa formation of westerncentral Alabama. 5 This removes the only paleontologic barrier to the correlation of the b~sal Cretaceous deposits of the States south of Virginia with 

the Upper Cretaceous and restores the original 

correlation made by the Alabama Geological Survey. 

My reason for thinking that the basal Cretaceous 

deposits of South Carolina ·are · of Upper Cretaceous 

age is this: There seems to be no valid distinction 

between the so-called Lower Cretaceous or "Hamburg 

beds" of Sloan and the typical Middendorf beds, 

which contain a large flora of Upper Cretaceous age. 6 

Middendorf lies in the midst of uniform sand hills that 

extend from the North Carolina line along the southern 

border of the Piedmont upland to the valley of Congaree River at Columbia. No one has succeeded in 

separating the "Hamburg" from the Middendorf in 

this area. The type area of the "Hamburg" is on 

the east side of Savannah River opposite Augusta 

and is obviously the continuation of the so-called 

Lower Cretaceous of Georgia. The lithology in the 

two areas is very similar. 

The Middendo~f beds, named by Sloan in 1904,7 

were described ten years later by Berry 8 under the 

name "Middendorf arkose member of the Black 

Creek formation." Berry considered the Middendorf 

a member of the Black Creek because a good many 

species of plants are common to the two, but in my 

opinion the differences in the floras are more significant than the, resemblances. Of the 65 species from 

the Middendorf listed by Berry, 39 have not been 

found in the Black Creek formation in the Carolinas. 

Stronger evidence that the Middendorf should · be 

considered an independent formation is afforded by 

the stratigraphy and areal distribution. The Middendorf consists chiefly of light-gray, white, or buff crossbedded arkosic sand and lenses of white or light-9ol5 Berry, E. W., The age of the supposed Lower Cretaceous of Alabama: Washington Acad. Sci. Jour., vol. 13, pp. 433-435, 1923. 

6 Berry, E. W., Upper Cretaceous and · Eocene floras of South Carolina and 

Georgia: U. S. Geol. Survey Prof. Paper 84, 1914. 

7 Sloan, Earle, A preliminary report on the clays of South Carolina: South Carolina Geol. Survey, ser. 4, Bull. 1, p. 75, 1904. 

s Berry, E. W., op. cit. (Prof. Paper 84), p. 1. 

ored clay or kaolin that contrast sharply with the overlying black or very dark clay and sand of the typical 

Black Creek, from which they are separated by a pro~ 

nounced unconformity. · The area occupied by the 

Middendorf is much greater than that of the Black 

Creek in South Carolina, and the type locality of the 

Middendorf, ·which lies near the center of its belt of 

outcrop, is 20 miles from the nearest exposure of the 

Black Creek formation. It seems fitting, therefore, to 

restore the Middendorf to the rank of formation. 

The name Middendorf formation · ca:q also be applied 

to the "Hamburg beds" and to the equivalent "undifferentiated Upper Cretaceous n deposits ~ (formerly 

called Lower Cretaceous) east of Flint River in 

Georgia. However, some of the beds in Georgia 

having the aspect of the Middendorf may be considerably younger than the typical Middendorf of South 

Carolina. The basal Cretaceous deposits of South 

Carolina and Georgi~, as well as those of Alabama', 

are therefore of Upper Cretaceous age. 

Concerning the basal Cretaceous of North Carolina 

Stephenson 10 says: 

Although the "Cape Fear beds" appear to be continuous 

with the Lower Cretaceous arkosic beds of ·South Carolina 

[Middendorf formation], Georgia, and Alabama, it is po~sible 

that. they are not actually continuous; for the irregular character of the bedding, the presence of numerous local unconformities within the beds, and the lack of extensive exposures 

render the detection of an important unconformity difficultand such an unconformity may exist. 

The discovery that the Middendorf lies uncon..: 

formably below the Black Creek formation, like the 

"Cape Fear" formation, is additional evidence that the 

"Cape Fear" and the Middendorf are of the same 

age. However, there are cert~in rather obvious 

differences in lithology between the beds in North 

Carolina and those in South Carolina. The beds of 

the " Cape Fear" formation in their best exposures 

along Cape Fear River are persistent and generally 

compact and uniform, but those of the Middendorf 

formation are ' variable, lenticular, and usually softer.-

Yet beds resembling the "Cape Fear" occur at several places in South Carolina, notably at Eureka Mill 

Pond, 5 miles southwest of Cheraw, and near the Cheraw-Camden road 2 miles west by south of Patrick. 

At the type locality of the Middendo:d formation the 

plant-bearing clay bed merges_ into tough argillaceous 

gray sand resembling the typical "bape Fear." It 

seems certain that the'' Cape Fear" and the Middendorf 

.are at least in part equivalent. 

The following hitherto unpublished note on the 

u Cape Fear" formation is contributed by Mr. Stephenson: 

On Little River, near old Manchester, on the northern edge 

of Camp Bragg, Cumberland County, N. C., there are exposures 

g Prettyman, T. M., and Cave, H. S., Petroleum and natural gas possibilities in 

Georgia: Georgia Geol. Survey Bull. 40, pp. 75-76, 1923. 

10 Stephenson, L. W., op. cit. (Prof. Paper 81), p . 11. 
CORRELATION OF BASAL CRETACEOUS BEDS OF SOUTHEASTERN STATES 139 

of compact greenish-gray more or less sandy clay interbedded 

with compact argillaceous arkosic micaceous sand, hard enough, 

in fact, to be classed as a soft sandstone. These beds are harder 

and appear more ancient than the more typical it Cape Fear" 

sediments above them. It is possible that these harder beds 

may belong to a Cretaceous formation older than the overlying 

more typical unconsolidated beds of the it Cape Fear," with 

which they have heretofore been included. 

In view of the fact that _ the" Cape Fear" formation 

may include more than the Middendorf of South 

Carolina, it seems best to retain for the present the 

name "Cape Feat" rather than to extend the use of 

the name Middendorf, which has priority, to all of the 

" Cape Fear" of North Carolina. However, the name 

Middendorf doubtless eventually will be applied to 

the corresponding deposits in North Carolina. In the 

light of the present known facts, the name Patuxent 

obviously can not appropriately be used in North 

Carolina. 

PREFERRED CORRELATION 

The precise correlation of the Middendorf with 

formations west of Flint River can not yet be stated 

with assurance. Florally, the Middendorf in South 

Carolina is most closely related to the Tuscaloosa 

forma:tion, 21 of its 65 species of fossil plants being 

present also in the Tuscaloosa, whereas only 9 are 

common to the · Eutaw; but as some of the common 

species have a long range and wide distribution, the 

number of significant species is less than the figures 

given. It seems probable that in Georgia the beds 

having a Middendorf aspect represent a period of time 

somewhat longer than that of the Tuscaloosa and 

including part, perhaps all, of Eutaw time. These 

relations are indicated in the subjoined correlation 

table, which is based -Qhiefty upon the work of 

Stephenson. 

Correlation of the Upper Cretaceous formations of the Southeastern States 

Western Alabama 

Eocene. 

Eastern Alabama and Georgia west of Flint River 

Eocene. 

Georgia east of Flint River and 

South Carolina west of Congaree Valley 

Eocene. 

Eastern South Carolina 

Eocene. 

Peedee formation. 

North Carolina 

Eocene. 

b ~~ ~-~~~~~~ Peedee formation. 1 

Wanting. 

c ~~~ --------~-----------1 

Selma chalk. Ripley formation. 

Wanting. 

Snow Hill marl 

member. 

Snow Hill marl I 

member. 

dl------,-------------1------~--~---------1 

Eutaw 

formation mat ion 

Tombigbee 

· sand member 

. ········ ·························? 

Black 

Creek 

formation 

Black 

Creek 

formation 

· ~~~ ~~~~~ ~~~~~ ~~-~ ? 

Tuscaloosa formation Tuscaloosa formation. Middendorf formation. Middendorf formation. "Cape Fear" formation. 

~~~~~~W~~~ w~~~~~~~w~·~ ~~~~~~~~~~ ~~~w~~~~~w~ ~~~~~~~~~ ~~? 

Paleozoic. 

I 

Crystalline rocks. Triassic and crystalline rocks. 

'-----------"-- -----..J..___--~-__!__----- ----' 

Crystalline rocks. Crystalline rocks. 

a. Top of Exogyra costata zone . b. Top of Exogyra cancellata subzone. c. Base of Exogyrl! costata zone and Exogy_ra cancellat~ subzone and top of Exogyra ponderosa zone. d. Top of Morton_1cer~s subzone; ~he base 1s not defimtely established but appears to be restricted within the Tom big bee sand member of the Eutaw formation. e. Exogyra upat01ens1s zone, Th1s zone ~as not been found in outcrop in the Carolinas but has been recognized near the bottom of a 2,000-foot well at Charleston.