204 TRANSACTIONS OF THE WAGNER FREE 



" Another fact bearing directly on this question is the lesser Pliocene and 

 Post-Pliocene change cf level in South Carolina. The level of the Columbian 

 (Quaternary) perezone above the sea is here less elevated than it is either 

 north or south of South Carolina. The offshore deep-sea soundings show 

 that the sea-bottom rises, in an east-west general direction, off that State, so 

 that the Gulf Stream flows up and over a hill or ridge^ transverse to its course. 

 This indicates a relatively stationary axis or wide fold here over which the 

 Miocene btds are thin, because it was not greatly depressed, and the following 

 Pliocene beds may be supposed to also have been extremely thin — a state of 

 affairs, considering the incoherence of the beds, which would greatly have 

 facilitated subsequent confusion of the fossils, and mixture of the material of 

 the beds. 



" These fossiliferous deposits are mainly confined to the northeastern 

 part of the State. In Horry District, slight exposures were noted by Tuomey ^ 

 on Little River ; better ones were seen along the Waccamaw, for some dis- 

 tance from Conway borough. At Porter's Landing and at Harper's the strata 

 appear as follows : 



Yellow sand. 



b'-l2' I Yellow fossiliferous marl 



8' 1 Cretaceous beds 



" On the right bank of the river, not far from Nixonville, the beds as ex- 

 posed stand thus : 



Loose sand and clay. 



Cretaceous, Exogyra cosfata. 



" From these and other less important exposures on the Waccamaw, 

 Tuomey enumerates 49 species of moUusca, of which he regards 28 as extinct." 



These views having been communicated to Mr. Joseph Willcox, of 

 Philadelphia, that gentleman, with the assistance of Mr. Charles W. Johnson, 

 assistant curator of the museum of the Wagner Free Institute of Science, 

 undertook to contribute to the solution of this interesting problem. In the 

 autumn of 1891 Mr. Johnson, under the direction of Mr. Willcox, after con- 

 ferring with the writer, undertook the search for genuine Pliocene beds in 

 South Carolina. It was thought that the search would be most likely to be 

 successful on the Waccamaw River and vicinity, a majority of Tuomey's really 

 Pliocene species having come from that region, while the seaward position of it 

 relative to the known Miocene of the State enhanced this probability. 



The following is a summary of Mr. Johnson's report, on his investiga- 

 tions : 



The banks of the Waccamaw River are, for the most part low, and in the 

 thirty-six miles examined there were only three places where specimens could 

 be obtained. About four miles above Conway is Grissett's Landing, but the 

 supply of fossils being represented as small, Mr. Johnson did not delay here. 

 An approximate section at the landing gave : 



Soil, 4 to 5 feet. 



Shell marl, 2 to 3 feet. 



Blue (Cretaceous) marl, 4 feet to the water. 



' To this rise or fold in the sea-bottom the writer has applied the name of the Great Caro- 

 linian Ridge. 



' M. Tuomey, Geol. South Carolina, p. 173, 1818. 



