splendid valley of imperial extent, and
outside all this a great area of barren, arid lands, belonging partly to
the Great Basin and partly to the Open Basin region.

Along the Pacific, and some 20-40 m. in width, runs the mass of the
Coast Range, made up of numerous indistinct chains--most of which have
localized individual names--that are broken down into innumerable ridges
and spurs, and small valleys drained by short streams of rapid fall. The
range is cut by numerous fault lines, some of which betray evidence of
recent activity; it is probable that movements along these faults cause
the earthquake tremors to which the region is subject, all of which seem
to be tectonic. The altitudes of the Coast Range vary from about 2000 to
8000 ft.; in the neighbourhood of San Francisco Bay the culminating
peaks are about 4000 ft. in height (Mount Diablo, 3856 ft.; Mount St
Helena, 4343 ft.), and to the north and south the elevation of the
ranges increases. In the east part of the state is the magnificent
Sierra Nevada, a great block of the earth's crust, faulted along its
eastern side and tilted up so as to have a gentle back slope to the west
and a steep fault escarpment facing east, the finest mountain system of
the United States. The Sierra proper, from Lassen's Peak to Tehachapi
Pass in Kern county, is about 430 m. long (from Mt. Shasta in Siskiyou
county to Mt. San Jacinto in Riverside county, more than 600 m.). It
narrows to the north and the altitude declines in the same direction.
Far higher and grander than the Coast Range, the Sierra is much less
complicated, being indeed essentially one chain of great simplicity of
structure. It is only here and there that a double line of principal
summits exists. The slope is everywhere long and gradual on the west,
averaging about 200 ft. to the mile. Precipitous gorges or canyons often
from 2000 to 5000 ft. in depth become a more and more marked feature of
the range as one proceeds northward; over great portions of it they
average probably not more than 20 m. apart. Where the volcanic
formations were spread uniformly over the flanks of the mountains, the
contrast between the canyons and the plain-like region of gentle slope
in which they have been excavated is especially marked and
characteristic. The eastern slope is very precipitous, due to a great
fault which drops the rocks of the Great Basin region abruptly downward
several thousand feet. Rare passes cross the chain, opening