710 DESCKIPTIVE GEOLOGY. 



sliales, and marls, with a litliolog-ical habit like the beds to the westward 

 that have been referred to the Jurassic age. No fossils were found in them, 

 but, from their overlying the Star Peak horizons, and from their resem- 

 blance to the highly metamorphosed Jurassic strata of California, they have 

 been referred to the same age. 



In the lower portions of Willow Canon, to the northward, the same beds 

 are observed striking across the hills as seen in Inskip Canon, with, how- 

 ever, a more easterly trend, owing to the tendency to follow the outlines 

 of the rigid granite. The beds on the north side of the canon are much 

 contorted and twisted, showing considerable movement and fracture. In 

 strike, they vary from north 20° east to north 45° east, and in places stand 

 nearly vertical ; the quartzites being so highly metamorphosed as to present 

 a schistose structure, with blue, black, and purple bands. 



To the northward, beyond the granite, there is a marked recess on the 

 western side of the range, the uplift for nearly four miles becoming quite 

 narrow and proportionately low, and then widening out again to its former 

 dimensions. Quaternary deposits now occupy the recess, concealing the 

 Jurassic strata, which are again well exposed in the Dun Glen Hills. As 

 soon as the strata pass beyond the influence of the granite, the anticlinal 

 structure of the uplift is developed, which it retains till the beds fall away 

 beneath the Humboldt Valley. The axis of this fold lies upon the eastern 

 side of the range, probably in the lower members of the Star Peak Triassic, 

 so that the Jurassic strata do not appear among the easterly- dipping beds, 

 but only along the western foot-hills. On the eastern side, the structure is 

 quite simple, the beds inclining regularly toward the valley, with a strike 

 approximately north 10° east. They consist mainly of limestone, with some 

 interstratified quartzites, mostly narrow belts, but with a lithological habit 

 similar in compactness, texture, and color to the lower quartzites of the 

 Star Peak series. Just east of the summit of the ridge, in the region of the 

 Dun Glen Pass road, the beds are cut by narrow dikes of fine-grained 

 diorites, with a strike approximately the same as the trend of the strata. 

 They are of but little interest except as showing conclusively that they are 

 later than the Triassic bed, through which they penetrate and in some 

 measure accounting for the greatly disturbed condition of the strata on the 



