68 THE PLIOCENE AND PLEISTOCENE DEPOSITS OF MARYLAND 



The Sunderland Terrace. — Beneath the Lafayette terrace, wrapping 

 around it like a border, extending np into its body in reentrants, and 

 separated from it by a scarp-line is the next oldest terrace designated 

 above as the Sunderland terrace (Plate 1). This surface has its greatest 

 development in southern Maryland on the Calvert and St. Mary's penin- 

 sulas. It covers the high divides of Calvert county and occupies a similar 

 position in Charles and St. Mary's counties south of the Lafayette terrace. 

 Beyond this region it is represented by outliers many of which are several 

 square miles in extent. They are principally found in the District of 

 Columbia and in the region between the Patuxent and Patapsco rivers. 

 There are also a number of smaller outlying areas which are distributed 

 along the western border of the Coastal Plain between Baltimore and 

 Elkton. South of the Potomac the Sunderland terrace continues on into 

 Virginia, but as it has not been mapped in regions beyond Fredericksburg, 

 it is not known how far it extends in this direction. Northward, beyond 

 Maryland, this terrace has been found in Delaware and Pennsylvania and 

 is extensively developed in southern New Jersey. 



The same may be said of the surface of this terrace as was said in 

 reference to that of the Lafayette, viz., that, in the interior where it has 

 not been modified by erosion, it still retains its original plain, featureless 

 character, but along the borders where it has been attacked by the head 

 waters of streams, it has been transformed into a rolling country (Plate 

 IV, Fig. 1, and Plate X). The relation between the surfaces of the 

 Sunderland and Lafayette terraces becomes manifest whenever the two 

 occur in juxtaposition. Then it is seen that they occupy different levels, 

 that of the Lafayette always being higher than that of the Sunderland. 

 This difference in altitude is sometimes slight, at other times it forms 

 a prominent feature in the topography. Usually the descent from one to 

 the other is gentle, but occasionally it is accomplished by means of an 

 abrupt drop resembling in appearance a sea-cliff which has been modified 

 by subaerial erosion. 



Throughout the region as a whole there are distinguishable two types 

 of descent between the Lafayette and Sunderland terraces. The one type 

 is confined to the Piedmont Plateau, the other to the Coastal Plain, or, 



