WITH ANTICLINAL AXES AND FAULTS. 335 



first seen at the group of thermals on Snake Run, (Table I, Nos. 

 21, 22,) continue, wilh some fluctuations, to near the southwest 

 end of the valley, the amount of dislocation gradually but irregu- 

 larly augmenting as we trace the Little Mountain in that direc- 

 tion. Beyond this point the fault rapidly increases, so that in 

 the distance of a few miles not only the rocks of the Little Moun- 

 tain, but all the strata intervening between For. II, and For. XI, 

 (carboniferous limestone) have been swallowed up. In this con- 

 dition, occasionally varied by the intrusion of in-wedged knobs 

 or masses of the ingulfed strata, we may trace this extraordinary 

 dislocation along the northwest base of the Peters's and East River 

 mountains for more than fifty miles, after which it is still further 

 continued with a new topography. 



The Sweet Springs flow out from the steep-dipping and in- 

 verted limestone near the centi'e of the valley ; the Red Springs 

 and Snake Run group from points nearer the junction of this 

 rock with For. Ill, of the Little Mountain. The streams fed by 

 these copious fountains, flowing towards the northwest by nar- 

 row transverse valleys through the Little and Snake Run moun- 

 tains, have accumulated a great thickness of tufaceous deposit, 

 forming in the neighborhood of the Red Springs a succession of 

 picturesque cascades. 



Gas, consisting of nitrogen with a considerable amount of car- 

 bonic acid, escapes freely from all these springs, rising from the 

 Sweet Springs in copious streams. Much dissolved carbonic acid 

 is also present, rendering most of these waters decidedly acidu- 

 lous, and enabling them to retain in solution a marked proportion 

 of carbonate of iron, as well as the more usual ingredients, car- 

 bonates of lime and magnesia.* 



Section VI. Through the White Sulphur Springs. 



The axis in which the White Sulphur Springs arise, and that 

 of the thermal of Brown's Mountain, (Table II, No. 43,) are 

 nearly though not exactly in the same line. They are further 



* These are tlie only decidedly acidulous springs in Virginia, and I believe the only 

 ones in the United States, excepting a few which, like Saratoga, contain also a large 

 amount of chloride of sodium. 



