64: THE PLIOCENE AND PLEISTOCENE DEPOSITS OE MARYLAND 



The Coastal Plain, therefore, falls naturally into two divisions, an 

 emerged or sub aerial division and a submerged or submarine division. 

 The seashore is the boundary line which separates them. This line of 

 demarcation, although apparently fixed, is in reality very changeable, for 

 during the geologic ages which are past it has migrated back and forth 

 across the Coastal Plain, at one time occupying a position well over on the 

 Piedmont Plateau, and at another far out to sea. At the present time 

 there is reason to believe that the shore line is encroaching on the land 

 by the slow subsidence of the latter, but a few generations of men is too 

 short a period in which to measure this change. 



The subaerial division is itself separable in Maryland into the Eastern 

 Shore and the Western Shore. These terms, although first introduced to 

 designate the land masses on either side of Chesapeake Bay, are in reality 

 expressive of a fundamental contrast in the topography of the Coastal 

 Plain. This difference gives rise to an Eastern Shore and a Western 

 Shore type of topography. Chesapeake Bay and Elk river separate the 

 two. But fragments of the Eastern Shore type are found along the 

 margin of the Western Shore at intervals as far south as Herring Bay, 

 and again from Point Lookout northwestward along the margin of the 

 Potomac river. On the other hand an outlier of the Western Shore type 

 of topography is found at Grays Hill in Cecil county at the northern 

 margin of the Eastern Shore. The Eastern Shore type of topography 

 consists of a flat, low and almost featureless plain, while the Western 

 Shore is a rolling upland, attaining four times the elevation of the 

 former and resembling the topography of the Piedmont Plateau much 

 more than that of the typical Eastern Shore. It will be seen later that 

 these two topographic types, which at once strike the eye of the pl^siog- 

 rapher as being distinctive features, are in reality not as simple as they 

 first appear, but are built up of a complex system of terraces dissected by 

 drainage lines. 



The Coastal Plain of Maryland, with which most of the State of Dela- 

 ware is naturally included, is separated from that of New Jersey by the 

 Delaware river and Delaware Bay, and from that of Virginia by the 

 Potomac river, but these drainage ways afford no barriers to the Coastal 



