NEWAEK MOUNTAIN. 155 



composition; in mineral composition they are identical. These resemblances 

 are borne out by microscopical investigation, the differences in structure in 

 Richmond Mountain finding their counterpart in Cliff Hills. 



Cropping out beneath the andesites at the north end of the hills are three 

 small exposures of gray limestones, only one of which is represented on the 

 map. It dips westerly at an angle of 15 and strikes nearly north and 

 south. No evidence of the age of these limestones could be obtained, but 

 from their proximity to the White Pine shale and their general resemblance 

 to the Devonian rocks of the Silverado region, they have been referred to 

 the Nevada limestone. In the White Pine shale a few fragmentary plant 

 remains were procured, none of which were sufficiently well preserved to 

 admit of identification, although they bear the closest resemblance to the 

 plants found elsewhere at this horizon. 



DIAMOND RANGE. 



Few of the narrow longitudinal ridges in central Nevada form so prom- 

 inent a physical feature as the Diamond Range. Only the southern end, 

 however, comes within the limits of the Eureka District, but here it is so 

 intimately connected with the County Peak and Silverado uplift as to form 

 a part of the same geological region. 



Diamond Peak, the highest elevation in the range, is situated just 

 within the limits of the survey, although the north and east slopes lie 

 beyond the boundaries of the map. In a study of the sedimentary rocks of 

 the Eureka district, this peak is of the highest interest, showing the rela- 

 tionship between the Devonian and Carboniferous beds in a manner unsur- 

 passed elsewhere in the Great Basin, and at the same time carrying the 

 Paleozoic section nearly, if not quite, to the top of the Upper Coal-meas- 

 ure limestone. 



Newark Mountain, As seen from the east, Newark Mountain present* a 



bold front of blue limestone rising nearly 2,000 feet above Newark Valley, 

 the upper 1,000 feet an abrupt cliff, followed by a highly inclined slope 

 to the plain. Along the summit it is a narrow ridge 3 miles in length, fall- 

 ing off gradually toward the west in strong contrast with the opposite side. 

 In structure, Newark Mountain is an anticlinal fold whose axis may be 

 traced all along the base of the cliff, the eastern side of the arch having 



