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ELEVATION OF THE SURFACE—SLOPES AROUND THE MOUNTAINS. 215 
of ascent, and their length is determined by the distances between the ridges or frame-work upon 
which the materials forming them are deposited. 
When travelling on these extended slopes, the descent is scarcely perceptible, but becomes 
remarkably distinct where a distant and projecting angle of the mountains throws the slope 
outward, so that it can be viewed at right angles to its direction of descent.’ When these oppor- 
tunities offered, the clinometer was used to measure the amount of inclination, and five degrees 
and six degrees was generally obtained as the result. The almost entire absence of vegetation 
sufficient to obscure the vision, and the clear air of that region, permit all the inequalities of 
the surface to be distinctly seen, even at great distances. The explorer of the Basin has, there- 
fore, peculiar facilities for studying its topography. The gently ascending or descending slopes 
permit rapid travelling, and the occasional ridges and peaks offer inviting points of view. 
The general characters and aspect of the slope from the Sierra Nevada, at the eastern end of 
the Tejon Pass, are described in Chapter VI. It is furrowed by a long valley of erosion leading 
from the Tejon, so that the view is limited on each side by the low banks or rounded hills 
formed out of the sedimentary deposits of the slope. A representation of this long valley, with 
its peculiar vegetation, accompanies this Chapter, View XI. The upper margin of the slope is four 
thousand feet in elevation, and it descends out into the Dasin very uniformly. The slope at the 
Caiiada de las Uvas is of the same character; the inclined surface or slope being continuous 
between the two places. The slope flanking the Bernardino Sierra is similar in its characters 
and very uniform in its surface. It extends northwards into the Basin until broken at intervals 
by the Lost Monntains, or an intersection with their slopes. This broad slope, extending for 
nearly one hundred miles, with a breadth of from fifteen to twenty is, in some respects, not 
unlike that which flanks the same chain on its opposite side and extends to, and under, the 
waters of the Pacific. It is, however, very different from that slope in its appearance and eleva- 
tion, and is not so much modified or destroyed by the action of streams. On the side of the 
Pacific the streams are not only more numerous, but have a greater volume, and have excavated 
broader channels, which coalesce, and thus produce wide valleys; while, in the Basin, the streams 
are few, and widely separated ; their channels are short and deeply cut, and extend but a short 
distance from the mountains. 
In eur journey over this inland slope, we were, in some places, obliged to descend with the 
wagons to its lower portions, in order to avoid these deeply-cut channels, which seemed like 
great grooves in the plain. 
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CHANNELS IN THE SLOPE OF THE GREAT BASIN. 
The general form of these channels near the mountains may be illustrated by an outline 
. Sketch from my note book, taken from a point between Johnson's River and the Cajon Pass. 
The regularity of the slope and its nearly uniform inclination was exhibited in the most 
striking manner in the descent from the summit of the Cajon Pass to the first camp on the 
Mojave River, a distance of 19 miles. It appeared very much like a plain when we were 
