a
little over nine thousand feet high, and the passes seven thousand to
eight thousand feet; Donner Pass, through which the Central Pacific
Railroad is built, being seven thousand feet high. The range here
divides into two crests between which lies Lake Tahoe, a body of water
twenty miles long, eight to twelve miles wide, and a little over six
thousand feet above sea-level.
At
the head-waters of the Merced and Tuolumne rivers, in Tuolumne and
Mariposa counties, the main peaks are twelve thousand to thirteen
thousand feet high, and the passes nine thousand to ten thousand feet.
The width of the western slope is fully eighty miles.
The highest Sierra is between lat. 370 31' N. and lat. 360 N.,
in the region of the head-waters of the Kern, King's, and San Joaquin
rivers. Here the main crest is twelve thousand to thirteen thousand
feet high, with numerous points exceeding fourteen thousand feet, Mount
Whitney being the culminating peak. The west slope is some fifty miles
wide, with an average descent of two hundred and fifty feet to the mile.
Still
further south the range turns to the west, and from this point is less
marked in its character. In the southern part of the State is a mass of
high, broken ranges (the San Bernardino range being the most
extensive) allied in their general structure and formation to the main
Sierra Nevada, but as yet insufficiently explored.
General Geological Structure.— The Sierra Nevada is made up of:
(1) a central intrusive core of granite, flanked by
(2) metamorphic slates of triassic and Jurassic age (the so-called auriferous slate formation), over which lies
(3) a covering of cretaceous, tertiary, and post-tertiary deposits, which are either
(4) the
river deposits which form the material which is washed, either by
hydraulic or drift process, to extract the gold contained therein; or
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