Whitney's Geology of California. 353 
chain, not however continuous, but occurring in patches, some 
very small and others large, the larger lying nearer the two ex- 
tremities, the central portions, as might be expected, having 
nh more extensively swept away by denudation. Portions 
quently in the mining regions, which sometimes extend up to a 
Great height, and often contain the precious metal in quantities 
Sufficient for profitable extraction. 
0 the south of the latitude of Sacramento they are entirely 
Tertiary. The most considerable mass commences’ near White 
Tl 
. rn ri 
from 200 to 600 feet high; the rock is soft, easily decomposing, 
and the hills dry and treeless, They rest on a floor of granite 
Which is exposed by denudation at frequent intervals. Wher- 
ever fossils have been found, they are in poor preservation and 
ave been referred to the Miocene. South of Kern river the de- 
posits are widely distributed, but are not so extensively denuded. 
Passing north, occasional patches occur at intervals to the 
American river at Folsom. Here the first Cretaceous rocks 
Sverlaid by beds of lava, but in a number of streams, cafions 
have been worn to such a depth that they cut through into the 
fossiliferous beds beneath, so that the formation was found at 
Intervals nearly to Pitt river. 
more interest to the general reader is the great aurierous 
belt along the western slope of the chain. 
Auriferous Belt,—The auriferous region of the state is not ex- 
Clusively confined to the western slope; but this portion will be 
first noticed, 
Aw. Jour. Scr.—Szconp Series, Vou. XLI, No. 123.—Mar, 1866. 
45 
