208 PHYSIOGRAPHY AND GEOLOGY OP THE COASTAL PLAIX PROVINCE. 



terrace often with a pronounced escarpment throughout the central and 

 northern Coastal Plain and has been traced continuously from the valley 

 of the Deleware Eiver across Delaware, Maryland, and Virginia into ISTorth 

 Carolina. The surface of the Wicomico terrace is less dissected than that 

 of the Sunderland and in general the materials are less decayed. 



The few plant fossils found in the Wicomico formation belong essen- 

 tially to living species although in a few instances they seem to be ancestral 

 types that have since become differentiated into those living in the sand 

 barrens and in the upland country. The differences, however, are so slight 

 that there is no question but that the flora as a whole must be referred to 

 the Pleistocene. The presence of ice-borne boulders furnishes evidence for 

 its probable contemporaneity with the ice-invasion although the particular 

 drift sheet with which the formation should be correlated has not yet been 

 determined. 



The Wicomico represents the upper portion of the Later Columbia for- 

 mation of McGee and Darton and a part of the Pensauken formation of 

 Salisbury. 



The Talbot Formation. 



The Talbot terrace as already described is found at a lower level than 

 the Wicomico and enwraps the same extending up the valleys until it 

 merges into the fluviatile deposits of the Coastal Plain streams as in the 

 case of the preceding Pleistocene terraces. It can be traced all the way from 

 the Delaware valley across Delaware, Maryland, and Virginia to the North 

 Carolina line. 



The Pleistocene age of the formation is proved by the molluscan fossils 

 found along the Dismal Swamp canal and at Cornfield Harbor on the Poto- 

 mac River, most of which belong to species still living in the adjacent sea. 

 Its Pleistocene age is further shown by its evident contemporaneity with 

 a part of the ice-invasion of the northern part of the country, as evidenced 

 by the numerous ice-borne boulders found in its deposits. The formation 

 represents the lower part of the Later Columbia described by McGee and 

 Darton and corresponds to the Cape May and part of the Pensauken for- 

 mations of Salisbury. 



In North Carolina two mappable terrace deposits have been found 

 below the Wicomico level. To these, the names, Pamlico and Chowan, have 

 been applied. Together they seem to be the equivalent of the Talbot and 

 the explanation seems to be found in a halting during the uplift following 

 the deposition of the main portion of the Talbot which permitted the ocean 

 waves to cut a cliff that still persists over extensive areas south of the 



