>fAi{vi..\M» (;i:oLO(ii(AL sriiVKY 49 



ill tlio (liircrciit |i<iili()iis of the rcj^Moii. |-'i-.iiii ii> ty|)i(;il <lcvc|(»|)iiiciH 

 in the District of C'oliinil.i.i all the IMfistocene deposits (.f the Middle 

 Atlantic Slope received the name of ('(.lumhia foniiatinn l»y McCjcc who 

 described three distinct phases, viz., tiic lluvial, the iiitcrlliivial, and the 

 low-level. Later J)arton recognized hi^di-icvcj and low-level phases 

 which he called earlier and later Coluiiiliia. .Mure recently Shattuek, 

 of the State Geological Survey, has shown that greater complexity ex- 

 ists in tlie Maryland Pleistocene deposits than had been before recog- 

 nized, and that the later Columbia will have to be further divided, at 

 least loeally. The Pleistocene deposits consist of gravel, sand, clay and 

 loam, the materials in general liecoming finer and more fully stratified 

 with distance from the old shore-line and river-channels. In the latter 

 instance they at times contain large numbers of marine molluscan shells, 

 forming a characteristic calcareous marl. In general, however, the or- 

 ganic remains consist largely of the branches and leaves of terrestrial 

 plants, many of which are exquisitely preserved. 



DlSTRIBUTIOX OF THE STRATA. 



The Eocene strata of the Middle Atlantic Slope form a belt of varying 

 width, extending from northeast to southwest, somewhat to the west of 

 the center of the Coastal Plain. This belt has been traced almost con- 

 tinuously from the southern portion of Xewcastle county, Delaware, to 

 the valley of the ^STottow'ay river, in southern Virginia. Although at 

 times buried beneath later deposits, the Eocene presents fine exposures 

 along all the leading stream-channels, while not infrequently broad 

 outcrops of the formation appear at the surface in the intervening 

 country. 



DELAWARE. 



In Delaware the Eocene is found apparently only near the Maryland 

 line and slightly to the south of the central portion of Xewcastle county, 

 where it occupies a restricted portion of the country between Appoquini- 

 mink Creek on the north and Old Duck Creek on the south. Toward 

 Delaware Bay the formation entirely disappears, the Xeocene resting 

 directly upon the Cretaceous. Even in the limited area where found 

 4 



