190 GEOLOGY OF THE COMSTOCK LODE. 



Granite. — Gi'aiiite is exteiisivfily developed to the west of the Virginia 

 Range, but reaches the surface in the Washoe District only in a single 

 small area near the Bed Jacket mine, C. D. 6. It occupies a considerable 

 space beneath the surface,' however, for it has been met in th^ Baltimore oxidi 

 the Bock Island, and by a tunnel, just beyond the limits of the map, to the 

 northwest of the Florida. 



The granite must fall away very rapidly to the north and east, or it 

 would be encountered in the Gold Hill mines. Whether this is the conse- 

 quence of a fault or of a steep slope, there is no opportunity for deciding. 

 Near the Bed Jacket the granite here and there shows partings which might 

 be remains of a former stratification ; but a similar S3^stem of parallel cleav- 

 ages is not uncommon over small areas in rocks of an unquestionably 

 eruptive character, and I met with nothing which could be cited as definite 

 proof of a sedimentary origin. 



In the Wales Consolidated, granite is directly overlain by metamorphic 

 diorite, at the Bock Island by schists and limestones, and at the Baltimore 

 apparently by eruptive diorite, metamorphics, quartz-porphyry, and augite- 

 andesite. It must, therefore, have been denuded to a considerable ex- 

 tent before each of several eruptions. It is nevertheless far fresher than 

 most of the rocks in the District, and no considerable quantity of ore 

 has been found associated with it, though some metalliferous quartz has 

 been met with at its contact with younger rocks; but ti'aces of ore are very 

 likely to occur at any contact in a district like Washoe, where every 

 point has been racked by dynamical action and the whole subterranean area 

 has been flooded with mineral solutions. It is possible that ore similar to 

 the Justice body may be found on the contact between metamorphic diorite 

 and granite south of that mine, but there is nothing to indicate that the 

 granite is likely to act otherwise than mechanically in the deposition of ore. 



Metamorphics. — Thcrc is a Small area of distinctly stratified rocks to the 

 south of American Flat, near the Florida. They are limestones and mica- 

 ceous schists, badly broken and contorted, and much metamorphosed. I 

 did not succeed in detecting anything like a fossil in them, in spite of an earn- 

 est search. They are colored as Mesozoic from the general analogy of this 



