518 PROCEEDINGS OF PHILADELPHIA MEETING. 



eral liundred feet of overl^'ing m iris, and the biihrstone appears to lose its char- 

 acteristics in the extreme eastern part of tlie state. In the northern portion of the 

 state the Eocene formations thin rapidly as the marine Cretaceous beds rise to the 

 surface, and tliey are finally represented by thin outliers, often lying quite widely 

 scattered over the irregular surface of the Cretaceous marls. The western edge of 

 the buhrstone passes from Aiken to within 10 miles of Columbia, and thence to the 

 eastward to below the confluence of the Congaree and Wateree rivers. In the wells 

 at Charleston the Eocene members have a thickness of about 370 feet, and are sup- 

 posed to lie at about 60 feet below the surface. They there consist of marls of vari- 

 ous kinds, which are mainly argillaceous above and more calcareous below. The 

 buhrstone is a very hard silicious rock, often 15 to 20 feet thick, and usually tilled 

 with shells. The overlying marls and marlstones are known as the Santee beds, 

 which consist mainly of light colored marls, with some beds of marlstone of con- 

 siderable extent, and the Ashley and Cooper marls, which are of darker color. 



Miocene Formations 



The Miocene deposits consist of sands and marls, which occair in scattered areas 

 mainly in the northern and eastern counties. Lately Dr iJall has found evidence 

 that the phosphate deposits are also of this age. Tlie thickness of the sands and 

 marls is usually not over 30 feet, and they he on an irregular surface of the Eocene 

 or marine Cretaceous formations. 



Lafayette Formation * 



This is a superficial mantle of orange sands and loams which covers the higher 

 plateau regions. The elevation of this })lateau is about <)")0 feet along the western 

 border of the coastal plain. There it has a thickness of from 30 to SO feet, ami its 

 more loamy jjortions give rise to the greater part of the " Red Hills.'' Its eastern 

 extension has not been traced, but it is thought to be the same as some of the 

 younger Pliocene marls. 



• CoLU.MiJiA Formation 



This is a thin cai)ping, mainly of sands and loams, whic^h covers the lower lands 

 and appears to extend as high as 400 feet or more in the higher region, giving rise 

 to some portions of the "Sand hills." 



RESUME OF GENERAL STRATIGRAPIIIC RELATIONS IN THE ATLANTIC COASTAL 

 PLAIN FROM NEW JERSEY TO SOUTH CAROLINA 



BY N. II. DARTON 



Remarks were made by D. W. Langdon, Jr. An abstract of the latter 

 paper is published in the American Geologist, volume xvii, page 108. 



* Described at several localities by McGee. Twelfth Annual Report of the Director of the U. S. 

 Geol. Survey, I89i/, pp. 347-521. 



