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RESUME AND THEORETICAL DISCUSSION. 



observed by any of our parties, there are certainly no hydraulic mines in 

 that part of the Sierra. Volcanic rocks are not entirely absent, but there 

 are none of those long lava-flows like that of the Tuolumne Table Mountain 

 anywhere south of the immediate vicinity of the San Joaquin River, where a 

 flat, table-like mass of lava occupies a considerable area, extending off to the 

 north for a dozen miles, and then disappearing, having apparently been 

 roded away in this direction, so that the place where it originated is un- 

 known. The highest part of the range, from Kearsarge Mountain south, 

 and all the western slope at the head of the Kern and of the South Fork of 

 King's River, seems to be destitute of volcanic rocks. But north of Kear- 

 sarge, both on the crest of the range and on its eastern slope, lava-flows 

 abound. All along near Owen's River, for six miles in both directions from 

 Fish Springs, which is directly east of that part of the crest of the Sierra 

 called the Palisades, there are large and finely preserved basaltic cones, from 

 which great streams of lava have run clown on the slope of the " wash," or 

 detrital mass which lies piled up to a great thickness all along the eastern 



F 



base of the range, from Owen's Lake north for a great distance. Indeed, 

 from here to the north, through Inyo and Mono counties, on the east side of 



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the Sierra, the evidences of former volcanic activity exhibit themselves on 

 the grandest scale, as described in the Geology of California, Vol. I. None 

 of the detrital materials on this side, however, contain any appreciable 

 amount of gold ; neither are there any important or regular veins, containing 

 the precious metals or any metalliferous ores, although occasional bunches 

 of such are found a little to the north of Mono Lake, around Aurora and 

 Bodie, none of which are of permanent value, while some of them have led 

 to large expenditures with but little proportionate return. 



All through the range on its western slope, as far as the Fresno River at 

 least, all the conditions for favorable mining for gold have been wanting. 

 There is no body of slaty rock there ; the volcanic flows have not descended 

 on that side ; and most of the detrital materials eroded from the grand and 

 rugged mass of mountains which here makes up the range have, as it appears, 

 been carried entirely down into the Great Valley. This, it seems, is reason- 

 able to suppose, since the Sierra is here nearly twice as high as it is farther 

 north in the heart of the gold region, while the distance from the foot-hills 

 to the crest is considerably less, so that the inclination of this part of the 

 range is very rapid. And when we notice that farther north, where the 

 slope is so much less steep, great masses of gravel have been swept down 











