THE HYDROGRAPHY OF THE SOUTHERN APPALACHIANS. 



PHYSIOGRAPHIC FEATURES OF THE REGION. 



The Southern Appalachian Mountains, located in the 

 States of Virginia, North Carolina, South Carolina, Ten- 

 nessee, Georgia, and Alabama, stand out from and above 

 the surrounding country as an elevated physiographic 

 unit. They rise above the Piedmont Plateau, which boi"ders 

 them on the east and south, and above the valley of East 

 Tennessee, which lies on their western flanks, to a height 

 of from 2,000 to nearl}^ 6,000 feet above sea level. 



This is preeminently a T-eg-ion of mountains. (See PI. IV.) A weii watered 



I J o \ ' region. 



The slopes are mostly covered with deep soil, which is kept 

 in an open, porous condition by the humus that enters 

 into its composition and is spread over the surface, and 

 which is held in place by the myriads of roots of trees and 

 shrubs and grasses growing upon it. (See PI. LXIX a.) 

 In this region the raindrops are battered to pieces by 

 the twigs and leaves and the water is caught by the grasses, 

 shrubs, and ferns below and soaks through the covering 

 humus into the soil and rock fissures underneath. (See PI. 

 LXIX h.) The portion that is neither used b}' the vegeta- 

 tion nor evaporated from the surface emerges about the 

 mountain slopes weeks or months after its fall in countless 

 springs that feed with striking regularity the many brooks, 

 creeks, and i-ivers which thus have their sources here. 

 These conditions combine to make this one of the best 

 watered regions on the continent. 



This region embraces an irregular, mountainous table- 

 land, lying between the steep and well-defined escarpment 

 of the Blue Ridge on the southeast and the less rugged, 

 but higher and more massive Unaka chain on the north- 

 west. Numerous cross ridges separated by narrow valleys 

 and river gorges connect these two ranges or extend out 

 between them. The region, taken as a whole, has an average 

 elevation of more than 2,500 feet, but there are many 

 peaks that rise to about 5,000 feet, and a considerable 



