CENTRAL AND EASTERN NEVADA. 323 



taining from 50 to 60 per cent, of chloride of sodium) are collected for use in 

 the reduction works in the vicinity. It is probable that saline springs exist 

 under this portion of the flat, as the salts which have been removed are con- 

 stantly replaced by fresh incrustations. 



The hot springs in the southern portion of the valley do not differ 

 essentially from others in the State, which are of frequent occurrence in the 

 vicinity of large masses of volcanic rocks. They are a group of circular- 

 shaped pools, from one to thirty feet in diameter, in a slight elevation, 

 formed by the deposit from their waters, on the edge of the wash from the 

 hills; they vary in temperatm^e from that of the air to the boiling point; 

 their supply of water but little more than compensates for the evaporation of 

 the air, and streams run from them but for a short distance. The most 

 interesting of the group is one shaped like a bowl, about three feet in diam- 

 eter and as many deep, from the center of which the steam issues wdth such 

 force as to throw up the water in a Httle jet, a foot or more above the surface 

 of the pool. These springs are used both for bathing and cooking purposes ; 

 their mineral character has not yet been determined. 



Rocks. — The rocks of this range may be divided into three general 

 classes: the sedimentary formations, the ancient eruptive rocks or granites, 

 and the recent eruptive or volcanic rocks. These three classes represent in 

 age the three geological periods — Paleozoic, Secondary, and Tertiary. 



Sedimentary rocks. — On the accompanying map the colors of the car- 

 boniferous formation have been provisorily assigned to all the sedimentary 

 rocks of this range, inasmuch as the only fossil remains as yet discovered 

 here belong to that period. 



Limestone. — The limestone bodies consist of a compact, dark-blue rock, 

 in general, probably somewhat metamorphosed, fine-grained to granular, and 

 frequently intersected by smaU seams of white crystalline calcspar. The 

 only characteristic and well-defined fossil found by the writer in the some- 

 what hmited time of his researches is the Fusilina cylindrica^ which is gen- 

 erally assigned to the lower carboniferous limestone; besides this were a float 

 fragment of siliceous limestone, containing Syringopora, and some molds of 

 shells too much metamorphosed to be recognized. These limestones are 

 found ou. the flanks of the range, resting conformably on the slates. 



