754 DESCRIPTIVE GEOLOGY. 



granites. Four or five miles northwest from Oreana, in the foot-hills of the 

 range, occur small outcrops of granite, surrounded by rhyolite. It is of 

 some interest, as it forms the country-rock in which the "Montezuma Mine" 

 is situated, a full description of which may be found in Mining Industry, 

 Volume III of this series. That this granite belongs to the central mass, 

 and is characterized by the same physical habit and mineralogical compo- 

 sition, there would seem to be no doubt. 



On both sides of the anticlinal axis, the crystalline schists are well 

 developed, and, as already mentioned, rest unconformably on the granite. 

 They lie inclined at a very high angle; an observed dip in Trinity Canon 

 indicated C0° to the eastward, while on the west side recorded strikes gave 

 north 45° east and a dip of 50° to 60° to the westward. It is evident that 

 there are exposed here several thousand feet of conformable strata, of nearly 

 uniform lithological character. In color, they vary from steel-gray to black, 

 with considerable lustre. The groundmass is so exceedingly fine that it is 

 almost impossible to recognize, by the unaided eye, any mineral constituent; 

 but thin sections under the microscope develop an admixture of quartz and 

 mica, with some grains of magnetite. Both biotite and muscovite are found. 

 It is somewhat singular that no trace of feldspar is visible. In the region 

 of Trinity Caiion, the slates are traversed by numbers of granitic veins 

 cimilar in mineralogical character to the main body of granite. 



South of the line of the great outbursts of Tertiary volcanic rocks, 

 granites only appear along the Montezuma Range in one or two small out- 

 crops, which derive their chief interest from the indications they offer that 

 the granite probably underlies, at no great depth, a very considerable area 

 of country. One of these localities. Lovelock's Knob, forms an isolated 

 hill east of Lovelock's Station, which rises several hundred feet out of the 

 Quaternary deposits of the Humboldt Valley, only the base of which, how- 

 ever, is of granite. Still farther to the southward, granites again come to 

 the surface, projecting out eastward into the valley at Granite Point. 



North of Indian Pass, along the east side of the range, and directly 

 east of Antelope Peak, occurs the second large body of granite. It extends 

 from Indian Pass to' the mouth of French Cafion, measuring between 8 and 

 d miles in length by 4 or 5 in width, and rising from 1,('00 to 1,500 feet above 



