As to the geological age of the Pamlico formation, the geologists who have contributed to the report of 1912, the volume cited, hold that it belongs to late Pleistocene. The writer believes that the formation was laid down at a much earlier time. The mastodon jaw and the tooth of Elephas primigenius found in the Inland Waterway Canal may have been buried there during the prevalence of the Wisconsin ice epoch; but, on the other hand, this may have happened during an older Pleistocene stage.
It will be observed that the Pamlico becomes very narrow along the southern third of the coast of North Carolina. In South Carolina it may be represented by one of the older Pleistocene deposits recorded by Sloan; in part possibly by the Wando clays or the Sea island sands. In the author’s view, it is pretty certain that the Pleistocene molluscan fauna which had been found in the Clubfoot and Harlow Canal and at the locality below Newbern corresponds to the Wadmalaw in the vicinity of Charleston. It seems to appear at the southeastern corner of the State, at Southport, and again in the northeastern corner in Dismal Swamp. According to Shaler (10th Ann. Rep. U. S. Geol. Surv., pt. I, 1890, p. 315), a collection of mollusks made near the northern border of the swamp was submitted to Dr. W. H. Dall. There were 29 forms, of which 24 are yet existing, 5 extinct. There were, therefore, 17 per cent of extinct forms. Dall regarded the deposits as belonging to the Pliocene; the writer believes that they may be referred to the Nebraskan stage of the Pleistocene.
From a study of mollusks collected later in the Dismal Swamp Canal, Woolman (Proc. Acad. Nat. Sci. Phila., 1898, pp. 414–428) concluded that they belonged to a time not earlier than late Pliocene and possibly as late as the Pleistocene. Darton (U. S. Geol. Surv., Folio 80) referred the deposits to the Pliocene. Stephenson (op. cit., p. 290) states that recent investigations have led to the conclusion that the beds should be referred to the Pleistocene. The parties in such a dispute may compromise by referring the beds to the Nebraskan stage. It seems probable that the Chowan formation belongs to a stage a little later than these mollusk-bearing beds and represents a strip of old coast marsh, inhabited by elephants, mastodons, horses, and various other animals.
In discussing the causes which led to the production of Cape Hatteras, Professor Shaler (Proc. Bost. Soc. Nat. Hist., vol XIV, 1872, p. 117) remarked that the hard shelly limestone which comes to the surface just above high-tide level along the shore of the mainland from Newbern to the mouth of the Roanoke River looks much like the shell-bed found near Charleston, South Carolina.
SOUTH CAROLINA.
To the reader who wishes to know what work has been done on the Pleistocene geology of South Carolina, two papers may be recommended. The first of these, historical in nature, was published in 1890 by Professor Joseph A. Holmes (Jour. Elisha Mitchell Sci. Soc., vol. VII, pp. 89–117), the second in 1905 by Dr. Griffith T. Pugh (Thesis, Vanderbilt Univ., pp. 1–74). Those who have contributed most to a knowledge of the palæontology of this formation are Tuomey, F. S. Holmes, Leidy, Dall, Dall and Harris, Earle Sloan, and G. T. Pugh. J. A. Holmes, Tuomey, F. S. Holmes, and Dall have made important contributions to the knowledge of the invertebrate animals. For our knowledge of the vertebrates we are indebted principally to F. S. Holmes and Joseph Leidy. The author who has dealt most recently and in considerable detail with the stratigraphy of the Pleistocene deposits is Earle Sloan, State geologist (Bull. No. 2, ser. IV, South Carolina Geol. Surv., 1908, 479 pages). From these authorities we learn that, while the larger part of the Coastal Plain may be to a greater or less extent overlain by deposits referable to McGee’s Columbian, the deposits which bear fossils are confined almost wholly to a narrow strip along the coast. In this strip have been found the numerous mollusks listed and described by Tuomey, F. S. Holmes, and W. H. Dall, as well as most of the species of vertebrate fossils. The fossiliferous deposits do not usually extend back from the coast more than about 10 miles.
Undoubtedly fossil-bearing Pleistocene deposits are to be found here and there along all the rivers, perhaps to the western border of the Coastal Plain. This is indicated by the discovery of remains of horses and mastodons in Darlington and Richland counties. The thickness of the Pleistocene deposits along the coast is said to amount to as much as 60 feet, but it is usually much less. Only a part of this is fossiliferous, a bed that appears to vary in thickness from about 3 to 8 feet. This is found as much as 8 feet above mean-tide level, sometimes below it. The materials of this fossiliferous bed vary greatly. Sometimes they consist almost entirely of shells of mollusks, in other cases of a blue mud or sand, and with these may be mingled peaty materials, gravel, and again rolled masses derived from the underlying deposits. The fossils contained in the bed mentioned consist of mollusks, and in some places bones and teeth of vertebrates occur in more or less abundance. The bed is underlain often by deposits of Tertiary age. Bones and teeth of the vertebrates, as fishes and cetaceans, that lived when those Tertiary rocks were being deposited may occasionally have been washed into the Pleistocene bed. Again, where the older and the newer beds are exposed along the shores, fossils may be washed out of both and commingled on the beach; then again, a great part of the fossils collected along this coast of South Carolina have been rescued from the phosphate rock gathered for commercial purposes. This has been to a great extent dredged from the rivers; and thus remains of Pleistocene and of Tertiary animals have been mixed indiscriminately together. It is often impossible to determine to what formation a fossil may belong. To add to the difficulty of the palæontologist, the vertebrate remains are sometimes found washed out and mingled with bones or teeth of what appear to have been domestic animals.
Beginning at the northern end of the South Carolina coast-line, the first locality furnishing Pleistocene fossils is, or rather was (Pugh, op. cit. p. 33), White (or Price’s) Creek, in Horry County. Here at a height of about 5 feet above tide was found a bed approximately 6 feet thick apparently thrown up on the shore by storms (Tuomey, Geol. Rep., 1848, p. 187). No vertebrates have been reported from the locality. At Laurel Hill, in the extreme northeastern corner of Georgetown County, Tuomey (op. cit., pp. 187, 188) found a perpendicular bluff 30 feet high, at the base of which was a bed 8 feet thick made up of sand and broken shells. The top of the bed was 8 feet above tide, the highest elevation reached by the bed along the South Carolina coast. Tuomey mentions other localities around Georgetown where the fossiliferous bed was discovered. One was on Santee River. No vertebrates appear to have been met with in this region. In Christ Church parish, in Charleston County, Tuomey discovered several exposures of the bed in question, and this was sometimes so superficial as to be within reach of the plow.
Pugh (Pleistocene Deposits, etc., p. 34) quotes from F. S. Holmes a section which was found at Goose Creek, north of Charleston, as follows:
| Yellow sand | 12 | feet |
| Blue mud | 29 | feet |
| Ferruginous sand, containing bones, etc. | 3 | inches |
| Yellow sand | 3 | feet |
| Pliocene marl resting on Eocene white marl | 12 | feet |