Wright.] 
430 
[Jan. 1, 
days to the Boise region, in the summer of 1887, made for the pur- 
pose of looking into the merits of a scheme for diverting the wa- 
ters of the Boise river at a point about ten miles above Boise cit} r , 
where it emerges from the Upper Boise basin through a canon in 
the basalt, so as to irrigate a triangular area of country between 
Boise and Snake rivers, some fifty miles in length from the junc- 
tion of these rivers southeastward, and thirty miles wide at its base 
or southeastern end. To the engineers of the Irrigation Company, 
Messrs. A. D. Foote and C. H. Tompkins, jr., I am indebted for 
valuable topographical data with regard to this area. 
Nampa, where the boring was made from which the image is said 
to have been obtained, is a station on the Oregon Short Line R. R. 
about midway in this area and, as you state, about twelve miles 
north of the Snake river and seven miles south of the Boise river. 
It was obtained, you tell me, from a bed of coarse sand 320 feet 
below the surface after passing through beds of quicksand divided 
by thin beds of clay and one bed of lava ten to fifteen feet thick, 
and below this coarse sand was found vegetable soil and then what 
is described as the “ original sandstone.” 
My experience with data given by persons sinking drill holes a3 
to the material passed through leads me to accept with consider- 
able reserve the descriptive names they give to this material unless 
I have an opportunity of verifying it by personal observation, yet 
those given by you accord very well with the general idea I was able 
to form of the material underlying the Boise region. Stream ero- 
sion has been very slight in this region, and its topographical form, 
characterized by a succession of broad, level terraces descending 
in gentle steps, shows that it is underlain by practically horizontal 
deposits of recent age. Owing partly to the character of the ero- 
sion and partly to the loose, crumbly nature of the beds themselves 
no good cliff exposures were found where I could obtain a continu- 
ous section of these beds. The important point in the section, 
namely, whether the definition of the lowest stratum, as vegetable 
soil, is well taken or not, it would have been impossible to verify, 
since it must be at a lower level than the beds of either the Snake 
or Boise rivers at any point within the region. 
I could see that the basin, in which these beds were deposited, 
extended for a considerable distance to the south and west, but to 
the nhrth it was bounded by a mountainous country not farbe 3 T ond 
the Boise river. As to how far it extended eastward toward the 
