86 THE PLIOCENE AND PLEISTOCENE DEPOSITS OF MARYLAND 



which the Sunderland is equivalent, but parts of Salisbury's Cape May, 

 Pensauken, and Bridgeton find a place within it. 



Areal Distribution. — The Sunderland formation extends from 

 South Amboy across southern New Jersey, Pennsylvania, Delaware, and 

 Maryland into Virginia and is doubtless continued throughout the South 

 Atlantic and Gulf States. In Maryland it is developed almost exclusively 

 on the Western Shore and lies in an intermediate position between the 

 Lafayette and the Wicomico (Plate I). 



It was developed as a continuous deposit over the margin of the West- 

 ern Shore and the entire Eastern Shore, but erosion has now removed it 

 from the latter and its distribution in the former region resembles in 

 many respects that of the Lafayette. It finds its greatest development in 

 southern Maryland where it forms the divide of Calvert county and of 

 Charles and St. Mary's counties west and south of the Lafayette 

 area. It also veneers the floor of ancient valleys in the Lafayette 

 formation. North of this region it is developed, like the Lafayette, as 

 outliers. A few of these are found within the body of the Coastal Plain 

 region while many others occur either on the Piedmont Plateau or on the 

 margin between it and the Coastal Plain. At the head of the Bay on 

 Elk Neck, it is developed as a fringe about and a little lower than the 

 Lafayette, while just east of Elkton about the margin of Grays Hill, there 

 is a small outlier, the only certain representative of the formation on the 

 Eastern Shore. 



Structure and Thickness. — What was said in regard to the structure 

 of the Lafayette is equally true of that of the Sunderland. Its basal 

 portions are frequently obscured and it was at times deposited on an 

 irregular surface so that a better idea of the formation as a whole may be 

 secured by studying its surface elevations than by making a comparison 

 of isolated basal exposures. 



Along the eastern border of the Piedmont Plateau and the western 

 margin of the Coastal Plain, the Sunderland formation is distributed in 

 outliers in much the same manner as the Lafayette but at a lower level. 

 Some of the most important of these are located at Elk Neck, near Perry- 

 ville, at Upper Falls, at Shipley, and in the District of Columbia (Plate 



