542 DESCRIPTIVE GEOLOGY. 



White Pine Mountains. — This somewhat isolated group, lying about 

 60 miles to the southward of the limit of the map, may be regarded as a 

 southern prolongation of the East Humboldt Range. In volume III,^ of this 

 series will be found a geological sketch of that well-known mining region, 

 accompanied by a geological map. Since its preparation, however, the 

 district has again been visited, and a hasty examination made of the here- 

 tofore unvisited portion on the west side of Pogonip Mountain, with the 

 expectation, which was realized, of finding still lower formations than had 

 previously been recognized. During this second visit, a large number of 

 fossils were obtained from the different geological horizons represented, 

 including several new species, as well as forms new to the locality. 



In the narrow longitudinal uplifts, lying between the Sierra Nevada 

 and the Wahsatch Ranges, the greater number of which, in general terms, 

 consist of single anticlinal or monoclinal folds, made up of quartzite and 

 limestone formations of great thickness, it is exceptional to find exposed in 

 any one region a wide geological horizon. But here, at White Pine, the 

 mountains, which have an average width of 12 miles from valley to valley, 

 are formed of three distinct north and south ridges, two of which are mono- 

 clinal folds, with a sharp anticlinal lying between them, exposing, from the 

 base of Pogonip Mountain on the western side, to the top of Mokomoke 

 Ridge on the eastern side, strata from the Primordial shales to the Coal- 

 Measure limestones. 



Granite crops out in several small bodies along the base of Pogonip 

 Ridge, but in only one locality was it observed in any large mass, where 

 it occurs in a somewhat isolated hill as a coarse-grained hornblendic rock 

 with a friable texture. At the northern end of the ridge, apparently uncon- 

 formable with the granite, are obscure outcrops of mica slates and black 

 arenaceous and argillaceous slates and shales, in turn overlaid by an unde- 

 termined thickness of a compact vitreous steel-gray quartzite, closely resem- 

 bling the Cambrian Quartzites of other Nevada localities. Above this 

 quartzite, and forming the lower beds along the greater part of the ridge, 

 occurs the Pogonip limestone, which extends to the top of Pogonip Moun- 

 tain, with a thickr.ess of from 3,000 to 4,000 feet of strata. They dip with 



^ Mining Industry, vol. iii, 409. 



