GEOLOGY AND WATER RESOURCES OF THE SNAKE 
RIVER PLAINS OF IDAHO. 
Bv Israel C. Russell. 
PART 1.— PHYSIOGRAPHY AND GEOLOGY. 
INTRODUCTION. 
NATURE AND OBJECT OF THE RECONNAISSANCE. 
The field work which furnished the basis for this report was carried 
on from July 5 to September 12, 1901, under the general direction of 
Mr. F. H. Newell, hydrographer of the United States Geological 
Survey. The region examined is in southern Idaho, and is included 
for the most part in the area that is commonly termed the Snake 
River lava plains. On account of the general absence of water this 
region is also frequently designated the Snake River Desert. As 
the vast tract of approximately level country referred to is not 
entirely occupied by lava and as by far the greater portion of it is 
clothed with vegetation, and includes large tracts of open forest, it is 
evident that neither of the names just mentioned is appropriate, and 
to avoid conveying false impressions it will be termed in this report 
the Snake River Plains. The region does not constitute a single level 
plain, but exhibits considerable variation in altitude, slope, and char- 
acter of surface, etc., in its various, although indefinitely bounded, 
parts. In a general way it may be considered as a series of plains 
which merge one with another and have many characteristics in 
common. 
The main objects of the reconnaissance were to ascertain how far 
the geological conditions, particularly beneath the broad lava-floored 
plains bordering Snake River, favor the hope of obtaining flowing 
water by drilling wells, and where test wells should be put down in 
order to determine the correctness of inferences based on geological 
and other conditions. As is well known, in order to ascertain the 
artesian conditions in any region, it is necessaiy to have an intimate 
knowledge of the physical condition of the rocks below the surface, 
especially as regards the presence of alternate pervious and impervious 
13 
