Page 14 - 1915, Springs of CA.

14 SPEINGS OP CALIFOENIA.

Among the valley areas the Colorado Desert, in the southern part
of the State, and the Mohave Desert and Death Valley region farther
north, are the principal subdivisions.
The Colorado Desert, an abandoned and dried-out portion of the
valley of the Gulf of California, is a great basin whose sides slope
gently to the lowest point, 273^ feet below sea level, in Salton Sink.
The Mohave Desert is a broken desert area of indefinite boundaries,
lying mainly between the southern Sierra, the San Bernardino Moun-
tains, and Colorado River. Death Valley, lying north of Mohave
Desert, in Inyo County, is one of many similar arid valleys in south-
eastern California and southwestern Nevada and is the lowest point
on the continent, being 276 feet below sea level. There are relatively
few springs in this southeastern region that are worthy of note,
except as their scarcity gives all sources of water in desert areas
peculiar value. A few hot springs in the northern portion are the
ones of chief geologic interest, while several artesian springs in the
Colorado Desert are of considerable economic value. There are also a
few saline springs that are of interest, while many surface springs of
slight flow are of local importance to travelers as watering places.
FAULTS.
Several of the principal structural features in the State are related
to faults, and these features also appear to be the most prominent
ones associated with the springs, especially the hot springs. Of the
major fault lines that have been traced in the State the San Andreas
fault forms one of the principal zones of displacement, and is the one
along a portion of which the movement took place that caused the
earthquake of April 18,1906. As a structural feature it extends from
Humboldt County southeastward a distance of 600 miles to the
Colorado Desert, and is marked throughout the greater part of this
distance by long, trough-like valleys and steep mountain slopes.
Another great fault extends along the eastern base of the Sierra.
Displacement that took place along a portion of it in 1872 produced
the Owens Valley earthquake of that year. The San Jacinto fault
extends along the western base of San Jacinto Mountains. Along it
also displacement has taken place within recent years, the latest
movement having caused the San Jacinto earthquake of December
25, 1899. Other fault lines are shown on Plate III (in pocket), and
still others that have not been traced probably exist in the Sierra and
the northern Coast Ranges. Their close relation to the hot springs
of the State is shown on Plate III by the proximity of the springs
to the fault lines, and the relation of the individual springs to fault
lines is mentioned m their descriptions. This map was originally
prepared for reproduction on a smaller scale, and the positions of a
few of the symbols showing springs are therefore less accurate than
those on Plate I.