DESERT REGIONS OF NORTH AMERICA. 29 
the Humboldt River isan example. The Great Salt Lake of Utah is an 
illustration of the survival of a lake in the bottom of the basin. In either 
case the soil of the basin in many places becomes highly charged with 
salts, especially in the sinks and in the vicinity of the lakes, which show 
a decreasing or widely varying volume. 
In addition, the precipitation on areas outside of the mountain peaks 
and slopes is low in comparison with the annual rate of evaporation. This 
is true also of regions in these two States in the drainage system of the 
Colorado River, with the result that a highly xerophilous vegetation of 
great extent is encountered. The predominant forms in this flora con- 
sist of perennial compositaceous shrubs, of which the genus Artemisia 
furnishes three or four species. These constitute the most prominent 
feature of the deserts in question under the local appellations of sage- 
brush, greasewood, and desert-sage (plate 24). 
Such a flora is to be seen to advantage in the vicinity of Great Salt 
Lake, Utah. To the southwest of this lake lies the area formerly known 
as the Great American Desert, in which the soil is so highly charged with 
salts that extensive areas are devoid of any covering of seed-plants (plate 
24). The main stretch of this arid area is about 125 miles from north 
to south and is about 50 miles at its greatest width. It was traversed 
by one of the main routes of the old emigrant trail to California, and con- 
sequently finds prominent mention in the descriptions of travel and sur- 
veys of half a century ago. Perhaps no better characterization of the 
general aspect of the region could be given than by the following citations 
from Bryant (What I saw in California, 1848, New York). He says: 
From the western terminus of this ominous-looking passage we had a view of 
the vast desert-plain before us, which, as far as the eye could penetrate, was of a 
snowy whiteness and resembled a scene of wintry frosts and icy desolation. Not a 
shrub or object of any kind rose above the surface for the eye to rest upon. * * #* 
Descending the precipitous elevation upon which we stood, we entered upon the 
smooth, hard plain we had just been surveying with so much doubt and interest, 
composed of bluish clay, incrusted in wavy lines with a white saline incrustation. 
* * %+* ¥* Beyond this we crossed what appeared to have been the beds of 
several small lakes, the waters of which have evaporated, thickly incrusted with 
salt and separated from each other by small mound-shaped elevations of white, 
sandy or ashy earth, so imponderous that it has been driven by the action of the 
winds into these heaps, which are constantly changing their positions and their 
shapes. Our mules waded through these ashy undulations, sometimes sinking 
to their knees and at other times to their bellies, creating a dust that rose above 
and hung over us like a dense fog. 
At elevations of about 4,000 feet the soil, which is subject to the 
leaching action of natural drainage, bears the sage-brush, Artemisia 
tridentata (plate 25), as the predominant form, both as to general land- 
scape effect and actual population, over many thousands of square miles, 
in which but little else besides low annuals occur. Succulents are rare 
and comprise not more than two or three species of cacti. 
