6 LANDS OF THE ARID REGION OF THE UNITED STATES. 
lands, however, are usually supplied with living streams, and their irriga- 
tion can be readily effected, and to secure greater certainty and greater 
yield of crops irrigation will be practiced in such places. 
IRRIGABLE LANDS. 
Within the Arid Region only a small portion of the country is irriga- 
ble. These irrigable tracts are lowlands lying along the streams. On the 
mountains and high plateaus forests are found at elevations so great that 
frequent summer frosts forbid the cultivation of the soil. Here are the 
natural timber lands of the Arid Region—an upper region set apart by 
nature for the growth of timber necessary to the mining, manufacturing, 
and agricultural industries of the country. Between the low irrigable 
lands and the elevated forest lands there are valleys, mesas, hills, and 
mountain slopes bearing grasses of greater or less value for pasturage 
purposes. 
Then, in discussing the lands of the Arid Region, three great classes 
are recognized—the irrigable lands below, the forest lands above, and the 
pasturage lands between. In order to set forth the characteristics of these 
lands and the conditions under which they can be most ‘profitably utilized, 
it is deemed best to discuss first a somewhat limited region in detail as a 
fair type of the whole. The survey under the direction of the writer has 
been extended over the greater part of Utah, a small part of Wyoming and 
Colorado, the northern portion of Arizona, and a small part of Nevada, but 
it is proposed to take up for this discussion only the area embraced in Utah 
Territory. 
In Utah Territory agriculture is dependent upon irrigation. To this 
statement there are some small exceptions. In the more elevated regions 
there are tracts of meadow land from which small crops of hay can be 
taken: such lands being at higher altitudes need less moisture, and at the 
same time receive a greater amount of rainfall because of the altitude; but 
these meadows have been, often are, and in future will be, still more 
improved by irrigation. Again, on the belt of country lying between 
Great Salt Lake and the Wasateh Mountains the local rainfall is much 
greater than the general rainfall of the region. The water evaporated 
