238 Whitney’s Geology of California. 
: 
ties to be profitably wo ra aulic cement Weotnd in the : 
Cretaceous shales, sete near ie Maristas may yet be turned to a 
count; but thus far it isnot worked. Asphaltum and oil occur | 
near the two extremities of the chain, but thus far they do not 
bid fair to be profitable. . 
North of the bay of San Francisco, we have a continuation 
of the Cretaceous, also mostly metamorphosed, being a aie - 
een ee, Te 
same mineralogical and lithological features, and quicksilver 0¢- 
curs in many localities, in some > of which it has been worked, but 
thus far with questionable profit. It occurs generally as the - 
sulphuret, but considerable ehh of the native metal are 
ners in certain localities in Lake county. oS 
sre is a smaller proportion of aaivered rock than in the 
Tertiary rests uneonformably on the highly diagarbed and tenet 
Gold as Boon but the extent of the formation is rather rc 
in pierce coho to. commerce. athe of the 2 valleys 
are among the most fertile and ‘beattifal of the stat ee 
Between the bay of San Francisco and San José valley on the E 
east and the Pacific on the west, and extending from the Golden — 
Ba he y of Monterey, are ; a series of ridges known und r - 
a is about. 16 oe Jes in length, and has a maxi- 
25 mil Bee = quite narrow ane 
