256 GEOLOGY OF TONOPAH MINING DISTRICT, NEVADA. 



Vadose or surface-derived descending water must meet and mingle with these 

 escaping magmatic waters, must change their composition and mitigate their heat, 

 and the mingled waters must in many cases emerge on the surface as warm 

 springs. 



CHARACTERISTICS OF THE NEVADA SPRINGS. 



The conception that the hot springs of the volcanic region of Nevada were 

 largely supplied by magmatic or primitive water from the cooling subterranean 

 lava was formed by the writer in the field in 1902, before reading Professor Suess's 

 paper, above referred to. 



On account of the exceeding aridity of the Great Basin, there are, as a rule, 

 no flowing surface waters, the whole supply emerging from the ground as springs. 

 These springs are hot, warm, or cold. The cold springs usually emerge from 

 depressions, fault or fracture lines, and are especially found near the base of the 

 desert mountain ranges. They usually show two characteristics which indicate that 

 they are of vadose origin: (1) They fluctuate with the season, being abundant in 

 the spring and often becoming scanty or dry at the close of the summer, and (2) 

 they become more numerous and copious in the regions of greater precipitation 

 and very rare in the more arid portions. Near the Sierra Nevada and in the 

 region just east, which receives the overdrift from the Sierra precipitation in the 

 shape of relatively abundant snows and more frequent rains, the cold springs 

 emerging from the base of the mountains are numerous and so large as to 

 frequently form short streams, sufficing often for agriculture, and producing a 

 fringe of ranches along the mountain base, such as that which borders the eastern 

 base of the White Mountains in Fish Lake Valley. The hot springs, on the 

 other hand, so far as the writer's experience and information go, do not show 

 these characteristics of vadose origin; they show no change with the season and 

 are not noticeably associated with regions of greater precipitation. They are 

 noticeably associated with areas of volcanic rocks and are scattered all over these 

 areas, being often very vigorous in the heart of an arid region and sometimes 

 sufficiently copious to form short streams. 



COUPLING OF HOT AND COLD SPRINGS. 



It is a matter of frequent remark in this dry Nevada region that hot springs 

 and cold springs are frequently coupled together and emerge within a short 

 distance of each other. The writer has observed an instance of this at the village 

 of Silver Peak, 25 miles southwest of Tonopah, where a spring of nearly scalding 

 temperature and one at most lukewarm or tepid emerge from the edge of the 

 desert plain at the east base of the Silver Peak Range within a score of feet of 

 each other. These are evidently waters from diflerent sources, and their coupling 



