140 



University of California Publications. 



[Geology 



the map are shown the west slopes and foothills of a north-south 

 mountain range, divided ahout midway by the Carson River. To 

 that portion north of the river the name Virginia Range is given, 

 including the Washoe Mountains, as delineated on the map. 

 South of the river is the Pine Nut Range, east of Carson, some- 

 times called the Como Mountains. As noted on a previous page, 

 these two ranges, structurally one, are a spur of the greater 

 Sierra Nevada. The greater part of their areas is covered with 

 Tertiary lavas, but along their western parts they exhibit struc- 

 tural, physiographic and tectonic features that prove their kin- 

 ship to the Sierra Nevada. At the north the volcanics extend 

 across from the Virginia Range to the Sierra Nevada, but a mile 

 south of Washoe the granodiorite appears beneath the later 

 rocks. Prom this latter part to the south limit of the map a 

 fringe of the old metamorphics and intruded plutonic appears 

 along the Nevada ranges on their west side. Throughout this 

 portion of the ranges most of the main faults are apparent from 

 an inspection of the map, as for instance, at Lakeview, Prison 

 Hill, and in the Washoe Mountains north of Carson. A good ex- 

 ample of a longitudinal fault parallel to the one just east of 

 Washoe Slope occurs in the granodiorite area east of the lake. 

 A prominent north-south ridge has been formed, that in a well- 

 watered region would have been occupied by a longitudinal 

 stream as in the Sierra Nevada. Fault scarps are common and 

 are best developed in the Washoe Mountains. The steep scarp 

 in the rhyolite area east of Washoe Lake bears every evidence 

 of being an original scarp in the granodiorite and schist covered 

 over by a thin flow of the rhyolite. This is on the line of faulting 

 to the south, near Eagle Valley, and probably represents an ex- 

 tensive line of displacement. The Hot Springs north of Carson 

 are on a line of movement, as is shown by their being easily af- 

 fected by earthquakes. The fault across Prison Hill is apparently 

 a normal one, with downthrow of the north metamorphic area. 

 This fault is well expressed in the topography. The normal re- 

 lation of the schist and plutonic is shown by the small schist 

 area on Carson River east of the hill-crest, that rests upon the 

 granodiorite. 



In the vicinity of Lakeview the Sierra Nevada and Virginia 



