228 J. E. SPURR — ORIGIN AND STRUCTURE OF THE BASIN RANGES 



minor anticlinal fold of Treasure bill evidently belongs to tbe same re- 

 cent period of deformation, and also determines directly tbe topograpb3^ 

 The faul-ts in tbis district are nortb-and-soutb, east-and-west, and oblique, 

 one noted being nortbwest-and-soutbeast. 



Quinn Canyon and Grant ranges. — Tbe Grant range is a soutbern ex- 

 tension of tbe Wbite Pine range, and at its own soutbern end is directl}^ 

 connected witli tbe Quinn Canyon mountains. Tbese ranges are inter- 

 esting because tbey bave on botb sides comparatively steep scarps, wbicb 

 are by no means so common in tbe Great basin as bas been believed. 



Tbe Quinn Canyon range consists at its nortbern end of a broad sballow 

 syncline, wbile tbe anticline adjacent on tbe east lies in tbe valley, sepa- 

 rating tbese mountains from tbe Grant range. Tbe Grant range fit tbis 

 point is also essentially synclinal, but tbe anticline wbicb lies east of tbis 

 second syncline is often exposed in its eastern face. Tbus tbere are in 

 general two adjoining synclinal ranges, separated b}' an anticlinal valley. 

 On tbe east face of tbe Grant range and on tbe west face of tbe Quinn 

 Canyon range, moreover, tbe structure is anticlinal, and ai)pears to de- 

 termine tbe limit of tbe mountains (see plate 25, figure 1). 



Tbe nortb end of tbe Quinn Canyon range is along a fault, but in tbis 

 case tbe relatively uptbrust rocks to tbe nortb constitute tbe footbills, 

 wbile tbe downtbrust Silurian rocks on tbe soutb form an abrupt moun- 

 tain scarp. 



It is plain, tberefore, tbat in tbese ranges tbe cbief topograpby is 

 due to erosion, wbicb bas worked so powerfully as to overbalance any 

 deformation. Some of tbe scarps bave no connection witb faults; for 

 example, in tbe case of tbose nortb-and-soutb scar})S wbicb form tbe 

 east-and-west faces of tbe ranges it bas been demonstrated tbat no great 

 governing faults exist. In tbe case of tbe nortb end of tbe Quinn Canyon 

 range, wbicb is along an east-and-west fault, tbe fact above stated shows 

 tbat tbe steep scarp is not directly due to faulting, being indeed tbe re- 

 verse of what it would l)e if tbis were tbe case, and must be directly due 

 to erosion. As a matter of fad, tbe scarps wbicb bound tbese mountains 

 are no more ruggeU than tbe interior topograpby. Tbe canyons are deep, 

 witb precipitous walls, and bear witness to tbe localized or basal erosion 

 wbicb operates so powerfully, as contrasted witb general erosion, in an 

 arid and mountainous region. 



Diamond range.— The Diamond range consists chiefly of an anticlinal 

 fold with an attendant syncline. The main axis of the range cuts across 

 tbe strike of these folds in their minor deviations, but is in general par- 

 allel to it. In tbe Eureka district there is a condition often found in 

 mining regions, where complicated topography is dependent upon in- 

 creased complications of structure. Such topograpby may be due directly 



