216 GEOLOGY OF THE EUEEKA DISTRICT. 



quartzite in abrupt escarpments. Between Lamoureux Canyon fault and 

 Pinnacle Peak fault the mountain mass presents another broad anticlinal 

 mass, of which Grays Peak forms the summit. The beds on the peak lie 

 nearly horizontal, falling away on both sides at relatively high angles. 

 Toward Pinnacle Peak the Nevada limestones come in, resting unconform- 

 ably against the uplifted block between Pinnacle Peak and Lookout Moun- 

 tain faults. Between these two latter faults, measuring on the surface but 

 scarcely more than 2,000 feet, the only beds exposed are the Eureka 

 quartzites, dipping eastward and capping Pinnacle Peak. East of the 

 Lookout Mountain fault there is a block of Pogonip limestone, beyond 

 which comes the Prospect Mountain Ridge uplift. The only Cambrian 

 rocks found on the surface are the Prospect Mountain limestones, the over- 

 lying horizons, together with the Pogonip limestone and Eureka quartzite 

 of the Silurian, being either buried beneath flows of rhyolite or Quaternary 

 accumulations. About a quarter of a mile to the north of the line of this 

 section the entire Cambrian series is exposed, and the beds are introduced 

 here very much as they are found beyond the line of the rhyolites and 

 pumices. Between the Hoosac and Pinto faults the section again crosses 

 the Carboniferous block, which here includes nearly all of the Weber con- 

 glomerate, as well as the Lower Coal-measure limestones, both members 

 lying at angles inclined from 60 to 70 to the east. Along the Pinto fault 

 the line of contact is obscured by tuff's and pumices. Along the southern 

 extremity of the Silverado Mountains no structural evidences were obtained, 

 as the underlying rocks are for the most part concealed by tuff's and puma- 

 ceous material, but in the section the lavas are represented as overlying 

 Lone Mountain beds, as the latter are found higher up in the foothills above 

 the line of igneous rocks. At the entrance of Rescue Canyon the rhyolites, 

 which break through the Nevada limestone along the line of the Rescue 

 fault, are represented with a width of nearly 3,000 feet. The section 

 crosses the summit of Century Peak and brings out clearly the anticlinal 

 structure of the limestone ridge on the east side of Rescue Canyon. On 

 the east side of the peak the beds gradually fall away toward Newark 

 Valley and are lost beneath the Quaternary deposits. 



