Page 10 - 1915, Springs of CA.

10 SPRINGS OP CALIFORNIA.

San Francisco Bay, and granite is exposed at several points. Lime-
stone and slate also outcrop at a few localities near the coast.
The rocks that make up these ranges are usually folded into anti-
clines (archlike folds) and synclines (inverted arches). They are
also faulted in many places, so that their structure is complex. The
deposits of oil and of natural gas in these ranges and about their bor-
ders are of great economic importance, and their occurrence is closely
related to the structure of the rocks.
A few carbonated springs and some scattered sulphur and saline
springs are found in the unaltered sediments. In the arid region in
the southern part of the Temblor Range, along the southwest side of
San Joaquin Valley, a number of surface springs that yield small
amounts of water of poor quality are of local importance because
they furnish watering places for travelers and for stock. The springs
of chief geologic interest in this region are, however, thermal, and like
the others they issue mainly from the unaltered sediments.
The representatives of the Sierran and Coastal systems south of
the Tehachapi are not so clearly differentiated nor so readily recog-
nized as in middle California. At the southern end of the San
Joaquin Valley the Sierra swings westward as the Tehachapi Range,
separating the Great Valley lowland on the northwest from the desert
lowland on the southeast. Mount Pinos, the culminating point on
the divide between the Cuyama, the San Joaquin, and the southern
Santa Clara drainage systems, lies at the center of a mountain
group in which Coast Range and Sierran characteristics are both
displayed. Extending southeastward from this central point, the
San Gabriel, San Bernardino, and San Jacinto mountain groups
resemble the Sierra, while the Santa Monica and the Santa Ana
mountains are properly regarded as of the Coast Range type. The
Santa Ana Mountains, however, merge southward with the spurs of
the San Jacinto and Santa Rosa groups, to form the Peninsula
Range,1 which extends southward through San Diego County and
forms the backbone of the peninsula of Lower California. This range,
although lower than the Sierra, closely resembles it in geologic and
physiographic characteristics.
Moderate altitudes are attained in these southern groups. Mount
Pinos is about 9,000 feet high; San Antonio and San Jacinto peaks,
the culmmating points respectively in the San Gabriel and the San
Jacinto mountains, are each more than 10,000 feet in elevation;
and San Gorgonio, the highest point south of the Sierra, in the
San Bernardino Mountains, is nearly 11,500 feet above sea level.
Those of the southern mountains which have been described as be-
longing to the Sierran type are composed mainly of granitic and

t Fairbanks, H. W., Geology of San Diego County: California State Mineralogist Eleventh Kept.,
p 76, 1893.