Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 5, Pt. 2

GEOLOGY.
Qui-quaiqngo rancho.-At this place the road from,os Angeles branches, one passing to
the Cajon Pass, and the other to the Mormon settlement. The last had been recently laid out
and constructed by the Mormons, and led in a straight line over a broad plain, covered with
chamisal, to the valley of the Santa Anna, where the city is located. The chamisal is principally
Larrea Mexicana, and forms a dense growth, which it is almost impossible to break through.
The country between Los Angeles and San Bernardino was passed over very rapidly, and few
opportunities for geological examinations were presented. The surface is generally level, and
in many places has the appearance of a broad plain. Its sloping character has, however, been
mentioned, and a more correct conception of the nature of the region can be obtained by keeping
this peculiarity in mind. The mountains, (the Bernardino Sierra,) which are flanked by this
extended slope, have a nearly east and west trend, and rise to the height of about 6,00 feet.
Near the rancho of Qui-quai-mungo they are called Qu-quai-mmungo mountains, but this name
is not known beyond the locality.
By reference to the map, it will be seen that this slope, or the region between the base of the
Bernardino Sierra and the shore of the Pacific, is about 30 miles in width at San Gabriel, and 50
at San Bernardino, while at San Diego it is only about 20 miles. Slopes or plains of this extent
are unusual on the western coast, the mountain ranges at other points being flanked by a comparatively narrow slope, or descending abruptly to the ocean. The existence of ridges of intrusive rocks has been noted, and it is probable that others will be found in different parts of the
slope, forming low ridges, or ranges of hills. The strata which underlie and form the slope
are doubtless Tertiary, and are overlaid by marine drift and beach-shingle, and by the more
recent alluvial deposits along the streams.
VALLEY OF SAN BERNARDINO.
The valley of San Bernardino, which has been selected by the Mormons as the site for their
new city (San Bernardino) in California, is connected with the series of beautiful valleys and
slopes just described. It is situated at the southern base of the high, and during the greater
part of the year snow-capped, peak of San Bernardino, and is irrigated by the waters that
condense on its summit and flow in many channels down its sides. The northern boundary of
the valley is formed partly by this mountain, and partly by the adjoining ridges of the mountain chain that trends westward, and has already been described as the Bernardino Sierra. At
the peak of San Bernardino the trends of the mountains change, and become more southerly in
direction, and these form the eastern boundary of the valley. Through these bounding ranges
of mountains there are two passes which communicate with the valley, one leading northward
up to the surface of the Great Basin, called the Cajon Pass, and the other leading eastward over
-the mountains south of San Bernardino, called the San Gorgono or San Bernardino Pass.
The principal stream of the valley is the Rio Santa Anna, which is formed by the union of
several streams that rise in the mountains at distant points between the Cajon Pass and San
Bernardino Pass, and have their point of junction at the city. These numerous streams wind
about, and thus form a wide area of bottom-land which is peculiarly rich and well adapted to
agriculture. The valley may, in fact, be considered as a broad and shallow excavation, formed
by the action of the streams upon the slopes that formerly flanked San Bernardino and the
adjacent mountains, these slopes having been a continuation of those that now remain in
detached po tions between the mountains and the Pacific.
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