NOTES ON THE GEOLOGY OF SOUTHWESTERN IDAHO 
AND SOUTHEASTERN OREGON. 
By Israel C. Russell. 
INTRODUCTION. 
During the summer of 1902 I made a rapid reconnaissance through 
portions of southwestern Idaho and southeastern Oregon for the pur- 
pose, principally, of ascertaining in what localities, if any, the geolog- 
ical conditions are favorable to obtaining flowing water by drilling 
wells. This search was more successful than had been hoped, and a 
preliminary report on the artesian basins discovered has already been 
published. a The explorations referred to were in continuation of 
similar work done the preceding summer in southern Idaho, a report 
on which was published as Bulletin No. 199 of the United States Geo- 
logical Survey. The aim of the present paper is to put on record such 
observations relating to the general geology of the region traversed 
as it is thought may be of interest, more particularly to the people of 
Idaho and Oregon, and also in certain instances serve to supplement 
the report referred to on artesian conditions. 
During the reconnaissance I was assisted by Mr. Scott Turner and 
Mr. Robert H. Dawson, students of the University of Michigan. Our 
journey began at Boise, Idaho, on July (3, and ended at the same place 
on September 6, 1902. The route followed was planned so as to 
traverse as many as possible of the valleys of southwestern Idaho and 
southeastern Oregon, in which rich agricultural land is plentiful and 
where artesian conditions are most likely to be present. Portions 
of Canyon and Owyhee counties, Idaho, and of Malheur and Harney 
counties, Oreg., were examined \ but it is not to be understood that 
anything like a geological survey of the immense territory included 
in these counties was undertaken. This paper is simply an account 
of observations made during a rapid reconnaissance, principally in 
the way of supplementing the study of artesian conditions, and should 
not be judged in any other light. 
« Water Sup. and Irr. Paper No. 78, U. S. Geol. Survey, 1903. 
