26 The Upper Cretaceous Deposits of Maryland 



long line of barrier beaches which have been thrown up by the waves 

 and enclose behind them lagoons flushed by streams which drain the 

 seaward slope of the Eastern Shore. 



It was stated in the early part of this chapter that the topography of 

 the Coastal Plain is in reality more complex than at first appears, and 

 that this complexity is due to a system of terraces out of which the 

 region is constructed. The subaerial division of the Coastal Plain con- 

 tains four distinct terraces and part of another, while the submarine 

 as far as known, contains one only. This makes for the Coastal Plain, as 

 a whole, a group of five terraces. These terraces, beginning with the 

 highest, are known by the names of Brandywine, Sunderland, Wicomico, 

 Talbot, and Eecent. All five of the subaerial terraces are found on the 

 Western Shore, while only three of them occur on the Eastern Shore. 

 These terraces wrap about each other in concentric arrangement, and are 

 developed one above another in order of their age, the oldest standing 

 topographically highest. 



The Geology 



The area of low land and shallow sea floor which borders the Piedmont 

 Plateau on the east and passes with constantly decreasing elevation east- 

 ward to the margin of the continental shelf has been described under 

 the name of the Coastal Plain. It is made up of geological formations 

 of late Mesozoic and Cenozoic age. These later formations stand in 

 marked contrast to the older strata to the westward, in that they have 

 been but slightly changed since they were deposited. Laid down one 

 above another upon the eastern flank of the Piedmont Plateau, when 

 the sea occupied the present area of the Coastal Plain, these later beds 

 form a series of thin sheets that are inclined at low angles seaward, so 

 that successively later formations are encountered in passing from the- 

 inland border of the region toward the coast. Oscillation of the sea 

 floor, with some variation both in the angle and direction of tilting, 

 went on, however, during the period of Coastal Plain deposition. As a 

 result the stratigraphic relations of these formations, which have gen- 



