806 DESCRIPTIVE GEOLOGY. 



with the quartz-grains crushed and elongated in such a manner as to have 

 their longer axes arranged in layers parallel to the plane of stratification. 

 The rock contains a small amount of carbonate of lime. Dark and light- 

 colored bands give the beds a peculiarly striped appearance. 



Directly east of Winnemucca Lake, the range is made up largely of gran- 

 ite, and was only cursorily examined ; no areas of crystalline schists, however, 

 were noticed, and indeed none were observed south of Luxor Peak. Two or 

 three miles northwest from Luxor Peak, and at the base of the range, occurs 

 a low rounded hill of altered slates referred to the Archaean, the exposures 

 of which are mostly concealed beneath a thin layer of soil. It is surrounded 

 by basaltic outflows and Tertiary sedimentary beds, completely preventing 

 the formation from being traced for any distance. The beds lie inclined at 

 a high angle, are thinly laminated, fine-grained, and of a dark iron-gray 

 color. Nearly 1 miles still farther to the northward, and opposite the lower 

 end of the Granite Range, occurs a second area of altered metamorphic 

 beds, which have also been referred to the Archaean series. They are best 

 shown in the deep caiions, but their geological relations, like the other 

 locality, are much obscured by the heavy outburst of basalt that skirts the 

 flanks of the Truckee Range, 



Neither of these isolated outcrops have any special interest in them- 

 selves, but derive their chief value from the indications which they ofifer of 

 the widespread occurrence of Archaean metamorphic rocks, along the Truckee 

 Range. It seems highly probable that a more careful search in the range 

 would discover numerous other outcrops of these same beds, which would 

 tend to fill up the wide gaps and to show more clearly their connection 

 with each other. 



So far as observed, they reach the surface in only a few favored locali- 

 ties, lying for the most part concealed beneath enormous accumulations of 

 later gi-anites, which form the higher central masses, and numerous outflows 

 of the Tertiary volcanic rocks, which break out along the foot-hills. 



The later eruptive granites form the greater part of the Truckee Range, 

 and, as already mentioned, probably extend in an unbroken line for over 

 50 miles. While it cannot be definitely stated that this great rock-mass 

 belongs entirely to the later granitic formation, it may be said that wher- 



