506 DESCRIPTIVE GEOLOGY. 



Geologically, the uplift embraces granites and Archaean schists, with 

 the southern portion of the range consisting of Carboniferous limestones 

 referred to the Wahsatch beds, and the northern portion of the range made up 

 of quartzites and overlying limestones, regarded as equivalent to the Weber 

 Quartzite and the Upper Coal-Measure limestones. In the region of Spruce 

 Mountain, subordinate intrusions of diorites and porphyries appear through 

 the limestones, crumpling and displacing the strata and complicating its 

 structure. 



In this range, granite is only known in one locality, at Holland Pass, 

 and, like the similar occurrences in the Gosi-Ute and Ombe Mountains, occu- 

 pies a low position or depression across the main trend of the uplift. At 

 Holland Pass, the range reaches its narrowest dimensions, the granite appa- 

 rently serving as a connecting link between two broader and more elevated 

 masses of Palaeozoic strata. It is barely two miles across the range from 

 Gosi-Ute to Antelope Valley, with an elevation of not more than 500 feet 

 above the Quaternary deposits. In its lithological character, as well as in 

 its position, it closely resembles the granite bodies already mentioned in the 

 Ombe Mountains and Gosi-Ute Range, which is all the more interesting, as it 

 differs so widely from the granite mass of the Wachoe Mountains. 



In a narrow ravine, on the east side of Spruce Mountain, occur out- 

 crops of mica schists and slates, which probably belong to the older crys- 

 talline series. Their geological relations are quite obscure, and it would 

 seem impossible, at least from present observations, to connect them with 

 any series of beds in this region, as they are so isolated from other rocks 

 of like character, and their outcrops cover such a limited area, but their 

 physical and mineralogical habit is such as to suggest their Archaean age. 

 At the same time, it may be stated, that they seem to be more closely related 

 to the crystalline schist series of the Humboldt Range, from which they are 

 only separated by a broad open valley without any intervening uplift than 

 to those of any other large body of crystalline rocks in Western Nevada. 

 These schists and slates are all very distinctly bedded and finely laminated. 

 A characteristic specimen in the collection of this slate represents a rock of 

 a silvery-white color, and consisting of fine grains of white quartz and 



