UPPER COAL-MEASURES. 93 



Upper Coal-measures. Beds of this epoch are found conformably overlying 

 the Weber conglomerate, their true geological position being admirably 

 shown at the head of Hunters Creek (atlas sheet vm) in a belt of lime- 

 stone about one mile in length, west of the Weber conglomerate horizon. 

 Both series of rocks dip to the west at high angles, the limestones, 

 however, being cut off by a body of basalt which forms the mass of Basalt 

 Peak and the Strahlenberg. A much larger body of this limestone is found 

 forming the long uniform slope of Diamond Peak, although there its true 

 position is obscured by longitudinal faults, which in places bring it in direct 

 contact with the Lower Coal-measures and in others it abuts unconforma- 

 bly against the Weber conglomerate. 



The thickness attained by the rocks of this epoch is nowhere exposed 

 in the district, the overlying beds having either suffered removal by 

 denudation or else been concealed beneath flows of igneous rocks. West of 

 Diamond Peak a number of narrow valleys cross the limestone, but, as the 

 inclination of the ridge coincides closely with the dip of the beds, they 

 nowhere reveal any considerable thickness. The beds are estimated at 500 

 feet. In the northern and central portions of the state of Nevada the Upper 

 Coal-measure limestones attain a development of nearly 2,000 feet. At 

 Moleen Peak, 'just south of the Humboldt River, they are estimated at 1,800 

 feet in thickness where they conformably overlie a heavy deposit of con- 

 glomerates in their essential features quite like the Weber conglomerate of 

 Eureka. In the field the Upper Coal-measures may be distinguished readily 

 from the Lower Coal-measures by their lighter color and greater preva- 

 lence of fine grained beds. These colors are light bluish gray and drab, 

 the latter possessing a conchoidal fracture and compact texture. These 

 compact limestones frequently present forms of erosion quite different from 

 the coarse grained and granular limestones of the Lower Coal-measures. 

 Throughout the horizon the limestones are interstratitied with belts of grit 



O . 



and siliceous pebbles, held together by a calcareous cement, in which are 

 intercalated thin beds of purer limestone. One or two prominent beds are 

 apparently made up of quartz pebbles and fragments (if an older limestone. 

 carrying such fossils as Fiisilina riilindriru and Pi-<ln<-tnx 



>U. S. Geological Exploration of the Fortieth Parullol, vol. 2. Desrriptive ecology, p. (500. 



