CENTEAL AND EASTERN NEVADA. 341 



goes south, and a few canons beyond forms the sharp aiguille-shaped spurs 

 called the Needles, which are conspicuously seen from almost any point in the 

 valley. Here the width of the granite body is from the very foot-hills to the 

 crest of the ridge about five miles, and it continues with great thickness, so as 

 to form the mass of the range east of the crest for six or eight miles further 

 south. The main crest itself is generally formed of the upturned edges of the 

 white quartzite strata, which rest on the granite, inclined to the west, and seem 

 to increase in thickness to the south, attaining their greatest body in Summit 

 Canon. On the east of the main body of granite south of the Needles are 

 brown quartzose rocks, forming at one point high jagged peaks, representing 

 a considerable thickness. The nature and relations of these rocks have not 

 been accurately determined. A later dynamical action is here rendered proba- 

 ble by the disturbed state of the granite body, which is thrown up in isolated 

 broken masses, forming in one instance two flat lenticular-shaped bodies which 

 rise a thousand feet from the slopes, their sides smooth and perpendicular, 

 leaving an opening scarce a hundred feet wide between them. 



At Indian Pass the granite body is found to be considerably thinner, as 

 are also the quartzites; the granite forms steep craggy slopes at the mouth of 

 the canon, on which rest the quartzites, inclosing a huge quartz vein similar 

 to that at Ophir Canon, about 40 feet thick, striking conformably with the strat- 

 ification, and with it dipping west ; a smaller quartz vein, about six feet wide, 

 with the same dip and strike, occurs higher up. The quartzites expose a com- 

 paratively small thickness, and as the slates form the upper part of the ridge, 

 their debris may cover these to some extent. 



On the western side of the divide, which is crossed by an old Indian 

 trail, the interior basin at the head of Cross's Canon is in the slates and lime- 

 stones, which are still dipping west, but on the lower edge of the basin seem 

 to dip slightly to the eastward, resting on the low rhyolite ridge which forms 

 the lower foot-hills, and forming a commencement of the synclinal fold that 

 is more distinctly seen further south. 



The granite body has about the same thickness in Park Canon, where 

 a brown quartzose rock occurs to the east of it, forming the entrance to the 

 canon below the forks. The granite here has a brownish hue, and seems to 

 contain little or no mica, but in its place a green mineral, probably hornblende. 



