68 THE PHYSIOGRAPHY OF CECIL COUNTY 



higher land; flow with shorter and more direct conrses to the Bay, 

 and have cut deeper and narrower valleys. 



All over the Atlantic Coastal Plain region the creeks are constantly 

 bearing great loads of sediment from their easily eroded basins to 

 Chesapeake Bay. As by far the larger number of these creeks have 

 been converted to estuaries at their mouths, the tendency is to deposit 

 their loads of debris as soon as the quieter waters of their lower 

 courses are reached. The result is that their mouths are rapidly 

 filling up, and as a. direct result of this, the little estuaries are being 

 constantly narrowed and shortened, and streams which a few years 

 ago were navigable to a considerable distance from their mouths are 

 now converted into shallow swamps and marshes. "What has just been 

 said regarding the creeks is also true regarding the larger estuaries. 

 These are all fed by numerous creeks throughout their courses and 

 are constantly receiving through them large supplies of debris from 

 the surrounding country. As a result of this tribute, the upper 

 courses of the estuaries have been converted into impenetrable 

 marshes, and the deltas thus forming are rapidly advancing down the 

 stream. The most conspicuous instance of this stream-filling is 

 found at the head of Elk River estuary, where the upper part of the 

 estuary has been converted into a delta some two miles or more in 

 extent; leaving the town of Elkton far inland and connected with the 

 waters of the estuary by only a narrow meandering stream, navigable 

 with great difficulty. 



The Structure of the Atlantic Coastal Plain Region. — The materials 

 of which this region is built up are composed of clay, loam, sands, 

 gravel and boulders. These deposits are loose and unconsolidated, 

 with the exception of crusts of ironstone, which are locally developed, 

 and thin beds of conglomerates which cap certain high hills on Elk 

 Neck and the mainland. Although the materials which have built 

 up the Atlantic Coastal Plain have been deposited at various times, 

 and belong to a large number of different geological horizons, still 

 they all lie either horizontal, or nearly so. Those which have been 

 tilted most, seldom exceed a dip of 40 feet to the mile. The structure 

 of the region, therefore, has not seriously influenced the drainage, 



