312 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 
eroded 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 voleanic 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 down on the slope of the “ wash,” or 
detrital mass which lies piled up to a great thickness all along the eastern 
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 
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 1s 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 
