332 BOTANICAL SURVEY OF DISMAL SWAMP REGION. 



lating plain, varying in elevation from moan tide level to 6.6 meters 

 (22.2 feet) above that level, except at some points along the outer 

 coast, where the drifting sands form dunes that rise to a considerably 

 greater height. The elevation of by far the greater part of the area 

 is from 3 to <> meters (10 to 20 feet). The maximum altitude, leaving 

 out of consideration the sea dunes, is reached in the heart of the 

 Dismal Swamp, from which point there is a gentle terrace-like slope 

 toward sea level on the north, east, and south. Along the western 

 margin of the great swamp occurs a more or less sharply defined 

 ancient, sea beach, the Nansemond escarpment, which varies in height 

 from U to 15 meters (5 to 50 feet) 1 ami constitutes the natural western 

 boundary of the Dismal Swamp region, j 



Numerous waterways traverse this flat* plain, most of which have 

 their source in or near the Dismal Swamp, and (low northward into 

 the James River and Chesapeake Bay and southward and southeast- 

 ward info Currituck and Albemarle sounds. These are the Nanse- 

 mond and its tributaries, Elizabeth River and its branches, and 

 Lynnhaven River with its numerous ramifications on the northwest, 

 north, and northeast, and North Landing, Northwest, North, Pas- 

 quotank, Little, and Perquimans rivers on the east, southeast, and 

 south. Near their sources most of these water courses arc small fresh 

 streams of sluggish, dark-brown water, rich in finely divided organic 

 matter, but they soon widen out into estuarine channels in which 

 tidal action is distinctly perceptible, and whose waters, in the streams 

 flowing into the .lames and Chesapeake Bay, become first brackish 

 and then salt. The brooks which are tributary to these rivers are in 

 most cases more or less overgrown with palustrine vegetation and 

 their current is usually almost imperceptible. 



PROMINENT PHYSIOGRAPHIC FEATURES. 



The principal physiographic features of the nonaqueous surface of 

 the region are more or less intimately connected with and dependent 

 upon the character of the plant format ions which cover 1 hem, although 

 this, in turn, is of course primarily due to conditions of soil and of 

 drainage. The several areas which may be described in some detail, 

 proceeding from the coast line toward the interior, are: (1) The beach 

 and the dunes, (2) the salt marsh, (:$) the plain, (4) the swamps. 



THE REACH AND THE DUNES. 



This area follows the shore from the mouth of the Nansemond 

 River around Cape Henry and down the outer Atlantic coast, as well 

 as part way around the deep, irregular indentations of the shore 

 line which are formed by Elizabeth and Lynnhaven rivers and their 



1 Shaler, 10th Ann. Hep. Beol. Snrv., pp. 25!) to 3:;i> ( 1890). 



