MARYLAND GEOLOGICAL SURVEY 81 



channels of the larger streams, although probably in some places 

 entirely filled, were in the main left lower than the surrounding 

 regions. Thus in the uplift following Sunderland deposition the 

 larger streams reoccupied practically the same channels they had 

 carved out in the preceding erosion period. They at once began 

 to clear their channels and to widen their valleys, so that when the 

 next submergence occurred the streams were eroding, as before, in 

 Tertiary and Cretaceous materials. On the divides also the Sunder- 

 land was gradually undermined and worn back. 



The Wicomico Stage.- — When the Coastal Plain had been above 

 water for a considerable time after the close of Sunderland deposi- 

 tion a gradual submergence again occurred, so that the ocean waters 

 once more encroached on the land. This submergence seems to have 

 been about equal in amount throughout a large portion of the dis- 

 trict, showing that the downward movement was without deforma- 

 tion. The sea did not advance upon the land as far as it did during 

 the previous submergence. At many places along the shore the 

 waves cut clift's into the deposits that had been laid down during 

 the preceding epoch of deposition. Throughout many portions of 

 the Coastal Plain at the present time these old sea cliffs are still 

 preserved as escarpments, ranging from 10 to 15 feet in height. 

 Where the waves were not sufficiently strong to enable them to cut 

 cliffs it is somewhat difficult to locate the old shore line. During 

 this time a large portion of Prince George's County was submerged. 

 The Sunderland deposits were largely destroyed by the advancing 

 waves and redeposited over the floor of the Wicomico sea, although 

 those portions which lay above 90 to 100 feet were for the most part 

 preserved. 



Although the Wicomico submergence permitted the silting up of 

 the submerged stream channels, yet the deposits were not thick 

 enough to fill them entirely. Accordingly, in the uplift following 

 Wicomico deposition the large streams reoccupied their former 

 channels, with perhaps only slight changes. ]^ew streams were also 

 developed and the Wicomico plain was more or less dissected along 

 the water courses, the divides being at the same time gradually nar- 

 rowed. This erosion period was interrupted by the Talbot sub- 



