1904.] HATCHER — MARINE AND XON-MARINE FORMATIONS. 343 



marshes, such as the Dismal Swamp in Virginia and North Caro- 

 lina and others bordering the lower courses of the James, Roanoke, 

 Cape Fear, Pedee, Neuse and Savannah rivers, and to a less extent 

 the Potomac, Susquehanna and Delaware rivers farther north. 



If we trace the courses of the larger rivers of this region, those 

 rising in the Appalachians, from their sources to their mouths, the 

 course of each will be found to be divisible into three sections, 

 when considered according to the eroding and transporting power 

 of the stream. The first of these three sections, commencing 

 above, extends from the source of the stream to the point where it 

 leaves the foothills of the mountains and emerges upon the coastal 

 plain. Throughout this portion cf its course the stream is both an 

 eroding and a transporting agent, displaying about equal efficiency 

 in either capacity. Below this point, which has been called the 

 "Piedmont escarpment," the stream ceases to be to any great 

 extent an eroding agent, and between the foothills and the 

 swampy region bordering the coast it is chiefly a transporting agent, 

 the current being too sluggish to accomplish any appreciable 

 amount of erosion, and at times becoming so slow as to permit of 

 considerable deposition. Between that point where it enters the 

 marsh lands and its mouth the stream drops all that remains of its 

 load of sediment, save that which is carried seaward by the action 

 of the tides, aided to some slight extent perhaps by the feeble 

 current of the stream, which has now become almost entirely an 

 agent of deposition. 



Now if we turn our attention to the changes that are taking place 

 in the region traversed by these rivers, it will be seen that the first 

 section, or that between their sources and the Piedmont escarpment, 

 is one almost exclusively of degradation, there being little or no 

 deposition going on in this region, while throughout the second 

 section, that lying between the escarpment and the swamps along 

 the coast, the eroding and depositing agencies are unimportant, 

 though about equally effective, resulting on the whole in compara- 

 tively little change in the topography, while in the third region, or 

 that lying between the swamps and the coast, deposition is taking 

 place with considerable rapidity. The inland swamps are being 

 filled in, while along the coast of Virginia and North Carolina the 

 estuaries and sounds located at the mouths of the various rivers or 

 enclosed between the mainland and the low sand spits, thrown up 

 by the waves and extending almost continuously along the coast, 



