4 BUREAU OF AMERICAN ETHNOLOGY [bull. 118 



great valley is a part of the Appalachian Valley, which extends from 

 Virginia into Alabama. 



The region west of Walden Ridge and northwest of Cumberland 

 Mountain lies in the Cumberland Plateau province. This area is 

 sharply demarcated from the valley by the eastward facing Walden 

 Ridge and Cumberland Mountain, designated the Alleghany front. 

 The Appalachian Valley shows a uniform increase in altitude from 

 500 feet or less in Alabama to 900 feet in the vicinity of Chatta- 

 nooga, to 2,000 feet at the Tennessee- Virginia line, and 2,600-2,700 

 feet at its culminating point on the divide between the New and 

 Tennessee Rivers. 



The drainage of the valley region is quite diverse. The Powell 

 and Clinch Rivers, flowing into the Tennessee River, form the major 

 streams of the area. The streams fall from an elevation of 900-1,100 

 feet at the valley border to 780 feet at Blacks Ford on the Clinch. 

 All the larger streams are sunk in sharp, narrow troughs 100-500 

 feet beloAv the adjacent country. Most of the surface of the smaller 

 valleys stands at an altitude of 900-1,100 feet. Above this various 

 ridges project from 100 to 500 feet. 



The formations exposed in the valley region are all Paleozoic in 

 age. They have all been disturbed from the horizontal position in 

 which they were deposited. Close folding and faulting due to tan- 

 gential pressure from the southeast has produced the long straight 

 folds, which are almost universally overturned with faults occurring 

 on the northwest side of the anticline. Some faults are continuous 

 for over 300 miles, while the folds are even longer. 



The long, narrow ridges and valleys of the Tennessee Valley were 

 brought into their present attitude by a series of diastrophic and 

 erosional events. During the Paleozoic the region was intermit- 

 tently submerged by marine waters, and with the change of the 

 various kinds of sediments the formations were laid down. 



At the end of the Paleozoic in the Appalachian revolution the 

 strata were folded and faulted, forming an ancestorial Appalachian 

 Mountain system. During the Mesozoic era these mountains were 

 base-leveled and the present drainage system established. A series 

 of uplifts aggregating several thousand feet rejuvenated the area. 

 Differential erosion has produced the present long ridges and val- 

 leys, the ridges being maintained by the more resistant strata, while 

 the valleys are developed on the weaker shales and limestones. 



Of geologic as well as historical interest is Cumberland Gap, in 

 the vicinity of Middlesboro, Ky., a cleft in Cumberland Mountain 

 standing about 1,000 feet below the ridge tops. This gap offered a 

 convenient pass for pioneers into the region of the west. The gap 



