244 Whitney’s Geology of California. 
the same series that sink beneath the plain on the south side, 
from the northern flanks of the Santa Monica. : 
The chain known as the Santa Monica is of less extent, its 
ut 
mingled with the mountains that close around the western end 
of the San Fernando valley. The chain is especially interest- 
ing from its having a well-defined anticlinal axis, with a mass 
of granite forming the center, the strata dipping away from its 
center on either side. In places they are altered quite exten- 
sively, especially near the contact with the granite. Tbe strata 
consists of both the sandstones and the bituminous slates of the 
of the Coast Ranges with the Sierra Nevada near Fort Tejon. 
Strata supposed to be of Tertiary age, of great thickness, he 
along the southern flanks, which have been greatly disturbed - 
and are traversed by numerous dikes of granite. The whole of 
this side of the chain shows most extensive disturbances an 
powerfal metamorphic action to have taken place since the de- 
position of the Miocene. 
- The region south of this is also little known. The ranges 
known as the Santa Anna chain and the Temescal range were 
visited. The latter has attained some celebrity from the exist- 
ence of tin ore in it, forming the so-called Temescal Tin Mines, 
which were the scene of considerable excitement five years 
ago. Enough tin ore has been found here to justify some hopes 
of its occurring in paying quantities; but thus far explorations 
y any deposits of workable value. 
The geological age of the rocks in which it occurs has not bee® s 
satisfactorily determined. 
The islands that lie off the lower 
