MONTEZUMA EANGE. 753 



interstratified Star Peak limestones and quartzites, in turn capped in places 

 by Jurassic shales. But in the Montezuma Range, the Jurassic shales rest 

 directly upon the granite, attaining a development of between 3,000 and 

 4,000 feet in thickness. 



The granites and metamorphic crystalline schists of the Montezuma 

 Range are, with the exception of a few small and inconsiderable outlying 

 bodies, comprised within an area of 40 miles in a north and south direction, 

 lying mostly between the parallels of 40° 15' and 40° 45'. Within this 

 limit, they occur in three large irregular- shaped masses, the trend of each 

 body being northwest and southeast. They form nearly all the higher 

 summits, falling away in low rugged hills until concealed beneath the 

 inclined Jurassic slates, or the horizontal beds of the Quaternary. The 

 largest mass of granite in the range is associated with a very heavy body 

 of dark schists and slates, both of which have been referred with but little 

 hesitation to the Archsean age. This Archaean group rises above the 

 Truckee Miocene beds at Indian Pass, extending southward for nearl}^ 25 

 miles in an unbroken line, where it terminates abruptly in an approximately 

 east and west line, being covered by immense outflows of rhyolite and 

 basalt. It occupies in the region of Trinity and Black Canons, the entire 

 width of the range, measuring over 10 miles across, with a general strike 

 of north 40° east and south 40° west. The granite forms the axis of an 

 anticlinal ridge, with the schists and slates resting unconformably upon it, 

 all the higher points consisting of granitic peaks, which present a broken 

 serrated ridge with great diversity of outline, while the overlying beds are 

 exceedingly monotonous in form, with smooth rounded slopes and dome- 

 shaped summits, contrasting in a very marked manner with the granite and 

 sharply defining the line of contact. 



Where the granite was crossed, it appeared to be characterized, in 

 general, by a uniform texture and habit. The specimens collected from 

 the eastern foot-hills west of Rye Patch are a medium-grained rock, of a 

 gray color and a somewhat altered appearance. All the mineral constitu- 

 ents of granite are present, but in small crystals or grains. Both hornblende 

 and mica are well developed, the former in short, green, fibrous crj^stals, 

 and the latter in brown hexagonal plates. Both macroscopically and 

 microscopically the rock possesses the habit of the older series of eruptive 



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