390 Prof. Blake on the Diluvial Deposits in California. 
the farther side of the obstruction. Another similar instance oc- 
curs near the same spot, where the rock, a clay stone, has been 
washed out to some extent on the southwest side of a barrier 
caused by a dyke of harder porphyry. 
have also been informed by the miners, that gold is formd in 
greater quantities on the east side of the elevations. in the bed 
rock, a fact that would indicate that the current from which it 
was deposited, came from that direction. ‘There were however 
frequent periods in which the ocean must have been almost still, 
when its waters deposited the extensive strata of clay and sand 
that are found interstratified with the conglomerates. 
-'The principle geological interest attached to these diluvial de- 
posits is the evidence they afford of that portion of the moun- 
tain chain on which they are found having been the bottom of 
an ocean at a comparatively recent period, and: also that it must 
now be many ages since the country has been the seat of any 
reat disturbance. The elevation they here attain (probably 
four thousand feet above the level of the ocean) would indicate 
a considerable rise in the level of the land on this part of the 
continent. A more extended examination will undoubtedly iden- - 
tify them by their organic remains, with the diluvial’ drift found 
on the eastern portion of the continent and which is so exten- 
sively developed in South America along the eastern slope of the 
Andes. The origin of these deposits or the locality from which 
they have been brought, presents a question of great interest 
both to the geologist and also to the miner, for on its solution 
most probably depends the discovery of a region where auriferous 
quartz must exist in large: quantities. Many of the localities in 
which they are at present found, abound in veins of auriferous 
quartz, and it is possible that the gold which these deposits 
contain, has not been carried far from the spot where it was 
originally thrown up; but the great abrasion that large boulders 
of the hardest rocks have been submitted to, evidently indicates 
hey at least must have been carried ‘a considerable distance 
by powerful currents, and it is probable that the gold has been 
brought with thems Should they have come from the higher 
lars have been taken from a claim of fifteen feet sqnare; and there 
are many instances where ten and fifteen thousand dollars have 
