GRANITE MOUNTAIN. 689 



tion of 7,766 feet, while the high basaltic mass north of Granite Mountain 

 measures 6,804 feet. 



Water is very scarce in the range, and is found only in springs, or else 

 confined to small streams in the larger canons, which in most cases become 

 dry early in the autumn. Only over limited areas on the higher spurs and 

 ridges is there any arborescent growth, and even here it is mainly made up 

 of scattered and dwarfed pines. 



In the main features of geological structure, the Pah-Ute resembles the 

 Havallah and West Humboldt Eanges, exposing a nucleus of granite and 

 granitoid rocks, probably of Archaean age, upon which rest unconformably 

 longitudinal beds of quartzites, and overlying limestones and shales, of 

 Triassic age, associated with large masses of coarsely crystalline diorites. 

 Still later, in Tertiary times, the range has been subjected to great volcanic 

 eruptions, represented by elevated masses and broad tables of trachyte, 

 rhyolite, and basalt. 



Granite Mountain. — Granite and highly crystalline Archaean masses 

 form but a small portion of the exposed rocks of the Pah-Ute Range ; and, 

 of these areas, Granite Mountain is, both topographically and geologically, 

 by far the most prominent. It rises above the plains over 3,500 feet, and 

 presents a somewhat isolated appearance, stretching across the entire width 

 of the range, and measuring 10 or 12 miles from the base of the long slopes 

 that on both sides rise out of the recent valley deposit. In width, it varies 

 from 4 to 5 miles, falling away to the north and south in steep spurs toward 

 low passes, the southernmost of which, McKinney's Pass, is the most favor- 

 able place for crossing the range. On the lower slopes, wrapping around 

 the greater part of the base of the mountain, but resting unconformably 

 upon the upturned edges of the rock, occur the Triassic beds already men- 

 tioned. 



One of the most interesting features structurally of Granite Mountain 

 is that the crystalline rocks strike nearly east and west, while the uplifts of 

 the later beds, where removed from the immediate influence of the mount- 

 ain, possess a strike approximately north and south, varying only a few 

 degrees either to the east or west. This is all the more noticeable, as where 

 the strike of the larger masses of Archaean rock has been observed east of 



44 D G 



