russell] IRRIGATION AND AGRICULTURE. 31 
the plains on the north side of Snake River, and for a few miles flows 
through a narrow, steep-sided canyon. The fact that Bruneau Valley 
is comparatively wide above the narrow canyon in basalt through 
which it enters Snake River is due to the check in downcutting 
afforded by the basalt, which permitted the stream above the obstruc- 
tion to meander and broaden its valley. In this broader portion farm 
lands form a belt averaging about a mile wide and about 9 miles 
long. Water for irrigation is, for the most part, derived from the 
river by means of canals, but warm springs, and to a small extent 
artesian wells, are also utilized. 
The variations in geological conditions and in topographical develop- 
ment which favor the utilization of streams for irrigation are again 
illustrated along the lower portion of Boise River. This river, on 
leaving its narrow and rather high-grade canyon in the mountains and 
entering the comparatively wide valley it has excavated in the soft 
rocks of the plain, where its gradient is low, is unable to bear along 
the cobbles, gravel, sand, and other material brought from above and 
has spread out a wide flood plain bordered by terraces, through which 
it flows with many curves and frequently divides and reunites so as to 
inclose islands. These conditions have favored the construction of 
irrigating ditches and high-level canals, and a large area has been 
brought under cultivation. From the hills near Boise, a thousand feet 
in height, one may look down on that beautiful city embowered in 
trees, and toward the west, as far as the eye can reach, behold green 
fields and orchards surrounding comfortable farm houses. Owing to 
the abundance of water available for irrigation, as well as the favorable 
soil conditions, this region has become the most extensive of the highly 
fruitful areas of Idaho. 
The most valuable crop cultivated on the Snake River Plains, where 
water is now available for irrigation, is hay, principally alfalfa. 
Cereals, including maize, are also grown, bu + in minor quantities. 
Orchards and vineyards thrive and yield abundant returns, especially 
along Snake River below Shoshone Falls, and in Bruneau Valley, 
where shelter is afforded by the neighboring canyon walls. Owing to 
the isolation of the orchards in many instances, the injuries caused by 
insects are much less severe than in more generally cultivated regions. 
The greatest obstacle that fruit raisers have to contend with is the late 
frosts in spring or early summer. 
STOCK RAISING. 
The greatest of the industries as yet established on the Snake River 
Plains is stock raising. To this a large part of the cultivation of the 
soil, the raising of grass, is incidental. In the counties of Idaho which 
include within their borders portions of the Snake River Plains there 
