214 l GEOLOGY. 
abstract what little moisture may be offered by the loose and porous soil. The necessary condi- 
tions for luxuriant vegetation are therefore wanting ; and the only plants found there have a 
most peculiar and extraordinary appearance, and are seldom seen in localities where the air is 
charged with vapor. 
The barren ridges by which the surface of the Basin is diversified are much lower than the 
Sierra Nevada, and consist, apparently, of isolated peaks. The term Lost Mountains has, not 
inappropriately, been applied to these elevations ; for they do not form continuous ridges, or an 
unbroken line of elevation, but consist of disconnected and rugged peaks, or very short ridges, 
rising at intervals of from five to twenty miles. They are surrounded on all sides by the long 
and gentle slopes which form the apparent plateau of the Basin. 
These observations are made with reference to the mountains of the southern part of the 
Basin only, but they will doubtless truthfully apply to much of the northern and central 
portions. We are, however, aware that in the more extended and broad parts of the Basin to 
the northward there are long and lofty ranges—as, for example, the Humboldt Mountains, and 
others—which have all the characteristics of mountain chains. These are, however, believed 
to be but more enlarged and extended examples of the same peculiarities of structure that are 
observable in the minor ridges of the southern portion of the Basin. 
The isolated and broken character of theše ridges permits the traveller to avoid them by 
making frequent detours around their bases ; and, in the event of the construction of a railroad 
over this surface, a nearly uniform grade can be obtained by winding about on the slopes. 
These Lost Mountains, in the part of the Basin explored by the Survey, are separated by 
intervals of several miles; the principal ridges being from six to ten and twenty miles or more 
apart. Several which were visited were about eighteen miles north of the Bernardino Sierra. 
From the tops of these ridges the mountains further north appeared to be more numerous 
and nearer together ; but this appearance was, in great part, due to perspective. It was difi- 
cult to determine the exact trend of the short ranges ; but there is little doubt that the general 
or average direction is nearly north and south, or parallel with the eastern ranges of the Sierra 
Nevada. 4 
The most striking feature of the Basin, next to the absence of drainage to the sea, is the great 
elevation of its surface, as compared with the extensive valley of the San Joaquin and Sacra- 
mento, or the slopes of the coast further south. The elevation was estimated by Col. Fremont to 
range from four to six thousand feet; the Great Salt Lake, near its eastern limit, has an eleva- 
tion of four thousand five hundred feet.! The southern part of the Basin, however, although 
elevated, does not attain this altitude, but is considerably lower, as will be shown subsequently . 
The great elevation of the surface produces a great difference in the appearance of the bounding 
ranges, compared with their aspect from the plains at their seaward base. The eastern slope 
or ascent of the Sierra Nevada from the plateau is thus rendered very short, as compared with 
that towardsthe Pacific. Along the Bernardino Sierra, the surface of the Basin reaches, in many 
places, nearly to the summit of the chain, forming, in one instance, the crest of a pass. The 
Basin may thus be said to be filled nearly to the brim. ۱ 
The surface thus elevated is not, as is generally supposed, a nearly level plain or plateau, p 
is rather a combination of slopes flanking the bounding mountains and all of the intermediate 
ranges, ridges, or Lost Mountains. These slopes are of slight inclination, but of uniform rates 
1 Report of Colonel J. C. Fremont. 
