%S^ The American Geologist.. Novombor, iae& 
depression. Land existed in the Klamath mountains but it 
was not greatly elevated. Becker* has held that land existed 
also in the Clear Lake region during the Miocene. From the 
region of San Francisco bay southward it appears that at the 
beginning of the Miocene there were numerous detached land 
areas extending in the direction of the San Emedio mountains, 
which although now rising 9,000 feet were then nearly sub- 
ifierged. At the base, the Miocene consists very generally of 
a coarse arkose sandstone or conglomerate. These shore de- 
posits occur in many places, a few of which will be enumera- 
ted. They are found along the flanks of the Santa Cruz 
range, in Alum Rock canon on the northern slopes of the 
Mount Hamilton range, east of Monterey in the Palo Escrito 
hills according to Whitney, | along the slopes of the Santa 
Lucia range in southern Monterey county, etc. The almost 
buried granitic axis extending from the Santa Lucia range 
to the San Jose range in northern San Luis Obispo county is, 
bordered for nearly 100 miles by coarse arkose sandstones and 
conglomerates derived from the granite on which they rest. 
Much of the southern and western sides of the San Joaquin 
valley is bordered by argillaceous sandstones and clays of 
Miocene age. They are richly impregnated with alkalies, in- 
dicating dep(5sition in quiet waters partly shut off at least, 
from the open ocean. 
The facts at present known seem to warrant the statement 
that at the beginning of the Miocene the region of the cen- 
tral and southern Coast ranges was occupied by an archipel- 
igo of islands, some of them being of large extent. Enough 
is known of the Miocene to trace out the position of these, 
^reas with some accuracy but it will not be attempted here. 
In the foregoing presentation of a few of the facts bearing; 
upon the history of the Coast ranges the writer hopes to have 
^hown reasons for believing in a great age for this system of 
mountains. The mere fact that a subsidence took place at 
^ome period, even if as a result the mountains wholly disap- 
peared beneath the sea, is no reason for affirming that the 
mountains first originated with the following re-elevation. 
The upheaval at the close of the Jurassic in all probability 
♦Quicksilver Deposits of the Pacific Coast, p. 23.8, 
•j-Geol. of Cal., vol. i, p. 154. 
