31S GEOGRAPHIC DEVELOPMENT OF 



and its surface lias been carved into hill and vale, broad divide 

 and narrow valley, by the action of running water. During the 

 ages past it was a high plateau or mountain range, which was 

 first can3 7 oned and afterward carried away by the Potomac and 

 neighboring rivers of eastern United States. 



The Coastal province is a broad lowland made up of sedi- 

 mentary formations. It extends from the capital to the coast, 

 and thence as shallow sea-bottom for over a hundred miles into 

 the Atlantic, ending in a steep slope toward the ocean-depths; 

 and it stretches northward to New York and southward to the 

 limits of the continent. Thus the Coastal plain is about half 

 land and half sea-bottom. Through the land portion broad 

 estuaries pass, bearing the waters of Potomac and other rivers to 

 the sea ; and in the bottoms of the estuaries and in the sea-bot- 

 toms beyond, certain channels have been revealed by soundings. 



The history of the development of the region may be read from 

 the land-forms of the two provinces, and from the sedimentary 

 formations or deposits of the Coastal plain. 



DEFINITIONS 



The student of geographic development takes note of (1) pro- 

 cesses or agencies, and (2) products. The chief agency concerned 

 in making this region is water, and the chief processes are (a) 

 erosion, and {b) transportation by running water, together with 

 (c) deposition of the transported material in slack water ; or, in 

 more general terms, degradation and subsequent aggradation. 



When a considerable area of earth-crust rises in such manner 

 as to transform smooth sea-bottom to dry land, certain changes 

 are wrought on the surJ'ace : When the rains fall, a part of the 

 water lies long on the level surface and forms marshes, but here 

 and there rivulets form and flow down the gentle slopes toward 

 the sea ; the rivulets cut rills and, as the waters gather strength 

 with increased volume, dig gullies ; eventually the rills unite in 

 streamlets and brooks, and the gullies expand into ravines and 

 valleys ; and in time streams and rivers are formed, each flowing 

 in a gorge or valley of its own making. In this way the surface 

 of the uplifted sea-bottom is carved into valley-systems, and the 

 forms of the valleys determine the forms of the hills and divides 

 by which they are bounded. It is in this way that the lands of 

 the earth are •sculptured ; and the sculpture of running water 

 produces a characteristic topography. 



