SHOSHONE EANGE. 633 



can be no doubt but that it belongs to the same horizon as the larger body, 

 although, so far as examined, it carries less quartzitic schists, and the rock 

 has a reddish-brown color and vitreous lustre. It dips to the eastward, the 

 planes of bedding being distinctly marked. Under the microscope, all the 

 quartzite bodies of this region, including those from Carico Peak, Dome 

 Mountain in the Toyabe Range, and localities in the Shoshone Eange, pre- 

 sent the same detailed structure and appearance, so much so that they can 

 scarcely be told the one from the other. 



Rhyolites score the ridge on three sides. They extend in low irregu- 

 lar hills to the Heese River Canon, and toward the southeast connect the 

 Shoshone with the Toyabe Range. These low hills hem in Carico Valley 

 to the southwest. 



Along the base of the Shoshone Range, in Reese River Valley, and 

 nearly opposite the rhyolite spur from the Fish Creek Mountains, occur a 

 number of hot and warm springs of considerable interest. They are scat- 

 tered over an area of several acres, and are mostly surrounded by fine light- 

 colored soil derived from the rhyolitic detritus, which near the edges of the 

 pools, where it can obtain moisture, is frequently covered by a somewhat 

 luxuriant growth of alkaline grasses. Each spring forms a basin of clear 

 transparent water, varying in temperature, in the open pool, from 85° to 

 117°. When cool, the water is quite palatable, with only a slight taste of 

 saline ingredients, and appears to deposit but a small quantity of mineral 

 matter. 



To the southward, about one-half mile from the main group, occurs an 

 isolated spring of clear waterj which comes to the surface at the base of a 

 low mound, or dome, of rhyolite. At the time of our visit, the water, which 

 was in a slight state of ebullition from the escape of gases, indicated a tem- 

 perature of 90°. Coating the rocky walls of the spring 6 inches below the 

 surface of the water was a soft, pasty, light-gray mass, apparently formed by 

 the decomposition of the rock by the carbonated thermal waters. A stick 

 forced into this pasty mass penetrated it with ease to a depth of 18 to 20 

 inches before striking the hard rock. A large quantity of the material, was 

 collected for chemical examination. 



