Whitney's Geology of California. 237 
the west, already noted, it is separated to the northwest, by 
the narrow strait of Carquines from ridges of the same age and 
Tanges; only its eastern edge seems to be well defined, where it 
€ : lain. 
The great mass of the chain is Cretaceous, and the most of 
tent, especially in its northern part, are very fertile and many of 
its lower hill afford pasturage ss limited herds and flocks. No 
oe eur il its length, but the center is covered 
With scattered timber or chapparal, and scattered trees occur on 
_ 8ome of the lower hills. Coal is its most valuable mineral, and = 
_ this occurs in workable conditions only at Pe ae 
near Mt. Diablo. Quicksilver occurs 10 
I~ 
MM 
