russell.] PETROLEUM. 79 
accumulation and storage of petroleum and gas are in general the 
reverse of those which lead to the accumulation of water in artesian 
basins. The most promising localities in the search for relatively 
light hydrocarbon, are in upward folds or anticlines and the most 
favorable localities for storing water in the rocks under pressure are 
in downward folds or synclines. This difference in the conditions 
leading to accumulation of oil and water, as an effort has been made 
above to explain, is due to the differences in the specific gravities (or 
weight of equal volumes) of the substances named. If a fluid heavier 
than water should be present in the rocks, the other conditions con- 
sidered being the same, the water would be forced upward and would 
accumulate in anticlines, and the most favorable localities for search- 
ing for artesian water would be in the upward folds, instead of as now, 
in the downward folds. 
APPLICATION. 
In attempting to apply the principles just considered in Idaho and 
Oregon, it is evident that the search for petroleum should be confined 
to regions where the rocks have been but moderately disturbed, and 
in such regions drill holes should be put down in the crests of anti- 
clinal folds. The downward folds or synclines should be avoided, as 
water is everywhere present in the rocks and all the downward folds 
may be expected to be filled with it. Experience in southern Idaho 
has fully sustained these deductions, and much time and expense 
might have been saved if they had been given proper consideration 
when the search for petroleum began. All of the drill holes thus far 
put down with the hope of obtaining petroleum are located in broad 
synclinal basins, and in nearly all instances have resulted in obtain- 
ing a surface flow of water. Even after several artesian wells had been 
obtained, the drilling of holes for petroleum was continued in the 
same basin, as in Snake River Valle} 7 , between Guffey and Weiser, 
and uniformly with the same result. Although there has been a total 
failure to obtain petroleum, what in the end will prove to be a much 
more valuable result, so far as the development of the region is con- 
cerned, has been secured, namely, the demonstration of the value of 
the Lewis artesian basin. 
While the region crossed by Snake River in western Idaho and the 
adjacent portion of Oregon, in the vicinity of Owyhee, Vale, and 
Ontario, is a broad syncline, nearly flat in its central portion, it does 
not follow that the entire region is a single great fold. There may be 
secondary wrinkles, and beneath the small upward folds, if such are 
present, petroleum and gas might occur, and be under the pressure of 
the water in the broader and in general trough-shaped depression. 
The only locality in the Snake River Valley in western Idaho, so 
far as I can judge from the explorations I was enabled to make, at 
which one would be justified in drilling for the purpose of prospecting 
for petroleum, is the southern part of Canyon County, in the vicinity 
