An Unique Region 187 



of cellular lava, red in color. Spirally twisted volcanic bombs 

 occur, as do also other bombs as much as 4 feet in size. A 

 plateau of basaltic lava and cinders stands out on the plain of 

 Owens Valley north of Independence, below the mouth of Saw- 

 mill Canyon. Lava flowed down Sawmill Canyon in the inter- 

 val between the two ice epochs. Among all the profound 

 canyons incised in the great escarpment of the Sierra Nevada 

 none shows in more impressive fashion the striking contrast 

 between its glaciated and unglaciated portions, the upper can- 

 yon U-shaped and that below deeply incised as a V-shaped 

 gorge. 



Valuable Ores in Inyo and Sierra 

 Ranges 



The mineral resources of the region occur chiefly in the 

 Inyo Range, and most abundantly in the southern part, coin- 

 ciding with the occurrence of the intrusive granite. The 

 principal mineral resources are silver, lead, zinc, tungsten, gold, 

 copper, and marble, and sodium carbonate, which is derived 

 from Owens Lake. In the Sierra Nevada the principal ore 

 body is that of the Bishop Creek gold mine, on the middle fork 

 of Bishop Creek. The gold occurs in a quartzite band which 

 forms part of a downward projecting mass of the sedimentary 

 roof rocks which overlie the granitic masses of the range. 

 Later large deposits of tungsten ore have been discovered west 

 of Bishop, in the zone of metamorphic rocks where the intruded 

 granite is in contact with the sedimentary roof rocks. 



The premier producing mine in the Inyo Mountains is the 

 Cerro Gordo. It has yielded more silver-bearing lead ore than 

 any other mine in California. The mine is at the foot of the 

 scarp forming the western face of Cerro Gordo Peak. A broad 

 band of white marble is surmounted by dark-gray limestone 

 which forms the summit of Cerro Gordo Peak. The white 

 marble is the principal repository of the ore. It is a white 

 marble, essentially a pure calcite rock, of Carboniferous age. 



