12 MINING mDUSTET. 



Rising from a base of 4,500 feet above sea-level, its line of summit peaks 



reaches an average of 7,500 and a culmination here and there of nearly 9,000. 



Although, generally, rising near the middle of the range, these summits, 



from geological accidents, deviate to one or the other side, and overhang the 



valley plains in lofty precipitous peaks. The range may be considered as 



based on an inclined plain, for there is a gradual slope from the foot-hills of 



the Sierra to the bottom of the depressed basin, lying east of the mountains. 



The valleys to the west are never continuous for any great distance, but are 



divided by spurs of the Sierra w^hich invade them from the one side, and by 



low volcanic groups which push out from the other. Receiving the drainage 



of both mountains a considerable fertility is developed ; not enough, it is true, 



to banish the monotone of olive-gray desert vegetation, but sufficient to 



produce fine grass fields and valuable grain farms. Eastward, the Virginia 



Range overhangs the most depressed and dreary part of Nevada. From its 



summit may be seen the sinks and alkaline lakes, the vast stretches of blank, 



naked desert, varied by beds of dazzling saline efflorescence whence, in 



the blazing heat, columns of parched air whirl upward, laden with acrid dust 



and drifting sand, It is almost impossible to conceive a scene of more stern, 



desolate grandeur than may be viewed from the Virginia crest. The Sierra 



Nevada rises high against the west, its summit snow-capped, and its flank 



shaded by a forest of dark-green pines which grow thinner in descending 



toward the plain, and at the foot-hills perish of drought. In the east, beyond 



the chain of sinking lakes, rise rank beyond rank of parallel ranges, strange in 



form and unusually strong and bright in color. Threads of green skirt the 



water-courses, but the general tone is red-brown of rocky mountain-slopes and 



olive-gray of desert vegetation, startlingly relieved by caps of snow and fields 



of snow-like alkali. 



GrENERAL Geology. — A very general sketch of the larger relations of all 

 Great Basin ranges to the Cordillera System has been given in a previous 

 chapter. It is only necessary for the comprehension of Washoe geology to 

 indicate the outlines of closely contiguous hills. 



Both the Sierra and Desert ranges are composed, first, of crumpled and 

 uplifted strata, from the late Jurassic down to the Azoic period ; secondly, of 

 ancient eruptive rocks, which accompany the Jurassic upheaval; and, thirdly, 



