SOME DEEP WELLS NEAR THE ATLANTIC COAST IN VIRGINIA AND THE CAROLINAS 

By w. c. MANSFIELD 

ABSTRACT I INTRODUCTION 

Study of cuttings from deep wells along the Atlantic seaboard 

corroborates the fact, inferred several years agofrom the surface The purpose of this paper is to describe briefly and 

distribution of the geologic formations, that the region of the to illustrate (fig. ~) the major stratigraphic divisions 

Wilmington Summervi lie N,.c. 5

:r,c. Fori" : Near Charleston Caswell : Havelock S.C. N,.c. i NiC. i I ~: ------!50J1/LES---------+f---~ --65fr.1~ES--~;----------150 niLES 

Fort 

Monroe Va. New Goveim:nent Well, 1902 

Seo levei----',..,_ __ _J 

454-":To 750' 

reported / 

Eocene or ?. / 

CretoceoC/S 700 -:.: 

2,0071 ' . 

Stepllensot? 

/.914 

CRETACEOUS 

Mansfi'ela; Step!?enson 

and Henbest 

..... 

INDEX MAP 

I 

i6 ~---------------------------.~---.Sealevel 

· .. 1,630' 

TERTIARY 

AND 

QUATERNARY 

-----..,._.._ ___ __ -._, 

---~----­ --

CRETACEOUS 

TOP OF CONTINENTAl.. DEPOSIT 

Monsfl'eld_, 1.927 

--.. · 8Lt-0' 

·.··· 

... 

·.· 

··. 

... ·:. 

::: 

Oarfon; 1.902 

FIGURE B.-Correlation of logs of deep wells near the Atlantic coast in Virginia and the Carolinas. Depths shown are measured from mouth of each well. 

Cape Fear River in North Carolina is up-warped. Depths to 

crystalline bedrock in five wells are as follows: Fort Monroe, 

Va., 2,246 feet; near Havelock, N. C., 2,318 feet; Wilmington, 

N. C., 1,109 feet; Fort Caswell, N. C., 1,540 feet; Summerville, 

S. C., 2,450 feet. At Havelock and at Summerville the Upper 

Cretaceous-Eocene contact lies about 700 feet below the surface1 

but at Wilmington it is a few feet above sea level. 

t Mansfield, W. C., Washington Acad. Sci. Jour., vol. 19, no. 13, p. 287, 1929. 

75987 - 37 

now recognized in six deep borings along the Atlantic 

Coastal Plain in Virginia and the Carolinas and to 

show the relations of these major divisions to each.· 

other. 

Much of the information concerning these deep bor~ · 

ings has already been published, but it seems desirable 

to give a diagrammatic summa:ry of all of them. A · 

159 
160 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1936 

co~plete log of the boring at Summerville, S. C., has Cretaceous deposits was placed at a depth of 254 feet. 

not been published, but certain features concerning it The basement rock was reached at 1,540 feet.' The 

'have been briefly mentioned. fact that this well is nearer the coas~ than the well at 

The Coastal Plain sedimentary deposits iU: Virginia Wilmington accounts. for the greater depth to the 

and the Carolinas rest upon a basement composed basement rock. The Cretaceous sediments comprise 

mainly of crystalline rocks probably of pre-Cambrian about 80 percent of the deposits penetrated by the 

age. These basement rocks are at the surface in the well. 

Piedmont Plateau, which borders the Coastal Plain _ Well a-t Summerville, S. C.-No complete log of the 

on the west, but near the inner edge of the Coastal oil-prospecting well drilled at Summerville, S. C., has 

_Plain, as at Halifax, Rocky Mount, and elsewhere, the been published, but Cooke 6 . has given a brief log of 

upper surface of the basement dips beneath the topo- this well. He assigns the .strata penetrated between 

graphic surface, and at the coast it lies deeply buried 37~ and 313 feet to the Eocene; between 313 and 1,580 

beneath sediments ranging in age from Cretaceous to feet to the Upper Cretaceous; and below this depth 

Recent. The thickness of the sediments has been questionably to the Upper Triassic. 

determined by the. well borings. _ A study of the mollusks in the upper part of the well 

gave no positive evidence of the exact depth of the 

DETAILS OF THE WELLS contact between the Eocene and youngeJ,' deposits or 

· The indiv:idual wells are briefly described below, the depth of the contact between · the ·Eocene and 

beginning with the northernmost· one. Cretaceous. However, around the depth of 700 feet 

Government well at Fort Monroe, Va.-A detailed Stephenson recognized Cretaceous fossils belonging 

section of the Government well at Fort Monroe has chiefly to the genera Belemnitella and Inoceramus, and 

been given by Darton.2 The contact of the Eocene L. G. Henbest identified a Cretaceous foraminifer at a 

Pamullkey group with the underlying marine Creta- depth of 640 feet. Henbest examined the Foraminifceous sed~ents is placed at a depth of 840 feet below era to a depth of 708 feet, especially to determine the 

the surface.: The basement rock was reached at a position of the Eocene-Cretaceous contact. He idendepth of 2,_246 feet. tified the followillg forms, which he states may be of 

Well near Havelock, N. C.-A complete record of an either Cretaceous or Eocene age: Lenticularia cf. L. 

oil-prospectl~g well, the Great Lake well 2, drilled jonesi Sandidge (depth, 503-515 feet); Robulus cf. R. 

near Havelock, N. C., has been published -in a paper cultratus Montfort (depth 515-527 feet); Gyroidina 

by Mansfield.3 In this well the strata down to a depth sp. (depth 600-618 feet), close to G. alabamensis 

of 684 feet · were referred to the Tertiary and Quater- Sandidge of the Ripley formation of Alabama. At a 

miry. At that depth a stratigraphic break or uncon- depth of 640 feet and below he recognized Robulus 

formity marks the dividing line between the Eocene navarroensis (Plummer), which he regards as definitely 

deposits above and the Cretaceous deposits below. a Cretaceous species (range Taylor and Navarro, both 

The Cretaceous sediments are about 1,634 feet thick Upper Cretaceous). 

and comprise about 70 percent of the thickness of the In the section given in figure _ 8 the Cretaceoussediments penetrated by the well. ·The nature of the Tertiary contact is tentatively placed at a depth of 

sediments between approximate depths of 1,630 'and 600 feet. . 

1, 785 feet indicates a continental deposit: Granite, The materials penetrated in the Summerville well 

probably of pre-Cambrian age, was reache<l at a between depths of 600(?) and 2,450 feet are similar 

depth of 2,318 feet: to those in the Havelock well, in which no Triassic 

Well at Wilmington, N. C.-A complete record of a sediments were recognized, and are here referred in· 

well drilled at the plant of the Clarendon Waterworks their entirety to the Cretaceous. 

Co., Hilton Park, Wilmington, N. C., has been given Beginning at a depth of 1,675 feet, the materials, 

by Stephenson.4 The fossils were· determined . by consisting of reddish sandy clay with inclusions of 

T. W. Stanton. The Cretaceous sediments range from coarse quartz grains, suggest, ~ccording to Stephenson, 

the surface down to a depth of 1,109 feet, where the a delta or aterrestrial deposit and may represent the 

basement rock was reached. Tuscaloosa formation of the Upper Cretac~ous. 

Well'at Fort ·Caswell,N. C.-A record of a well drilled A crystalline basement rock of a somewhat doubtful 

at F9rt _Caswell, N. C., near the mouth of tho Cape ·age was reached at a depth of 2,450 feet. 

F~ar Riyer, has been given by ·stephenson.5 The Well at Charleston, S. C.-A record of a well drilled 

cqntact . qf the Tertiary and Quaternary with the at Charleston, S. C., has been published in a report by 

2 Darton, N.H., u.s. Geol. Survey Geol. Atlas, Norfolk folio (no. 80), columnar- Stephenson.7 The strata between depths of 454 and 

section,sheet, 1902. 750 ·feet yielded no determinable fossils but are referred a Mansfield, ·w·. C., Oil-prospecting well near Havelock, N.C.: North Carolina 

Det>t: Go'ns-. ~nd Devel. Econ; Paper 58, 1927. · 

~Stephenson, L. W., The Cretaceous formations of North Carolina: North Carolina Geoi. arid Econ. Survey, vol. 3; pp. 163-166, 1912. 

I Idem, Plh ~69-171 

e Cooke, C. W., Geology of the Coastal Plain of South Carolina: U.S. Geol. Sur· 

yey Bull. 867, p. 177, 1936. . , 

. 7 Stephenson, L. W., A deep well at Charleston, S.C.: U.·S. Geol. Survey Prof. 

Paper 90-H, 1914. 
SOME DEEP WELLS NEAR THE ATLANTIC COAST 161 

to the Upper Cretaceous or Eocene. At a depth of 7 50 

feet Foraminefera were found which were regarded by 

.· J. A. Cushman as characteristic Cretaceous species. · 

The basement rock was not reached at 2,007 feet, 

the bottom of the well. 

GENERAL FEATURES 

Three of the wells-those near Havelock, at Wilmington, and at Summerville-lie about in a straight 

line trending N. 56° E., and this line is approximately 

parallel both to the coast and to the line marking the 

inner edge of the Coastal Plain. Wilmington is about 

150 miles from Summerville and about 65 miles from 

the Great Lake well 2, near Havelock. The records 

of these wells show that the surface of the basement 

rock at Wilmington lies about 1,200 feet higher than 

it normally would be expected to lie on the assumption 

of a uniform dip of this surface, and this fact together 

with the surface distribution of the geologic formations 

seems to verify the opinion of Stephenson 8 that the 

lower course of the Cape Fear River approximately 

marks the axis of a broad structural uplift, dating from 

the interval marked by the unconformity between the 

Cretaceous and Tertiary sediments, and that the 

uplifted position has been maintained without marked 

subsidence until the present time. It follows also that 

the Great Lake well 2, near Havelock, N. C., is 

8 Stephenson, L. W ., Major features in the geology of the Atlantic and Gulf Coastal 

Pains: Washington Acad. Sci. Jour., vol. 16, no. 17, pl. 1, facing p. 466, 1926. 

located in a down-warped area, for the CretaceousEocene contact, which at Wilmington is a few feet · 

above sea level, was reached in the well near Havelock 

at a depth of 684 feet, showing a relative sinking of 

the old Cretaceous-Eocene erosion surface amounting 

to nearly 700 feet. Summerville is also in a downwarped area, for there the Cretaceous-Eocene contact 

lies at a depth of about 600 feet. It is also interesting 

to note that the upper l~it of the sediments referred 

to a continental deposit in the well near Havelock is 

1,630 feet and in the well at Summerville 1,675 feet. 

Stephenson 9 shows a synclinal axis trending nearly 

northwest and crossing the Virginia. and North Carolina 

line near the. coast. This axis is south of the location 

of the Fort Monroe well. The basement ·rock lies 

about 30 feet deeper in the well near Havelock than 

at Fort Monroe. The fact that Fort Monroe is a 

little nearer the inner edge of the Coastal Plain and 

farther from the edge of the Continental Shelf than 

the well near Havelock may account for this slight 

difference in the depths at which the basement rock 

was reached. 

Evidence supporting the existence of a northwestsoutheast structural uplift near ·Wilmington has been 

recorded by MacCarthy .

10 

9 Stephenson, L. W., Major marine transgressions and regressions and structural 

features of the Gulf Coastal Plain: Am. Jour. Sci., 5th ser., vol.16, p. 294, fig.12, 1928; 

Structural features of the Atlantic and Gulf Coastal Plain: Geol. Soc. America Bull., 

vol. 39, p. 839, fig. 1, 1928. 

to MacCarthy, G. R., Magnetic anomalies and geologic structures of the Carolina 

Coastal Plain: Jour. Geology, vol. 44, no; 3, pp. 396-406, 1936. 

0