russell.] FISSURE SPRINGS. 169 
line of displacement which defines the junction of the Snake River 
lava with the rhyolite of Mount Bennett, there is a small group of hot 
springs, rising through lava. For the sake of brevity, I shall term 
them the Mountain Home hot springs. Their combined discharge is 
about 2 cubic feet per second and their range in temperature is from 
103° to 167° F. The water from this group of springs forms Hot 
Spring Creek, which flows to Bennett Creek. 
Small springs, with a temperature of 131° F., occur at the right or 
southern banks of Snake River, about -I miles above the mouth of 
Salmon River. The water rises through recent alluvium deposited by 
the river, and the true orifice from which it comes is not visible. 
Most probabty there is a fissure in the solid rocks beneath the alluvial 
floor of the valley. A small warm spring, known as Poison Spring, 
occurs in the canyon of Salmon River, about 8 miles above its junction 
with Snake River Canyon. 
Near the head of Little Valley, about 9 miles west of Bruneau, there 
is a small hot spring, which rises through soft, white lake beds (prob- 
ably sediment deposited in Lake Idaho) which has a temperature of 
101° F. Five drill holes, put down to a depth of 40 feet in the imme- 
diate vicinity of this spring, resulted in a marked increase in the out- 
flow. The discharge is now about one-half cubic foot per second. 
The wells are not cased, and there is reason to believe that larger holes, 
with proper casing, would lead to a greater discharge. 
In reference to the development of fissure springs, the fact should 
be borne in mind that the water in most instances rises through nearly 
vertical cracks, and may not have great freedom of discharge. When 
the water rises through stratified sedimentary beds or lava sheets, the 
chances are that there is great lateral dispersion or leakage, only a 
small part of the discharge that comes from the more deeply seated 
portions of the fissure actually reaching the surface. In general, 
fissure springs are similar to uncased artesian wells, but owing to 
[probable irregularities in the fissures and the many chances they are 
exposed to of becoming clogged, it is to be presumed their surface 
outflow, in many instances, can be increased. 
In the case of each of the warm or hot springs mentioned above, 
to which may be added a mud spring situated northwest of Moun- 
tain Home, and on the Overland road midway between Dry and 
Canyon creeks, there is no doubt that an increase and possibly a 
great discharge can be secured by drilling vertical wells. Such wells 
should be put down within a few feet of the springs, and continued, if 
practicable, to the depth indicated by the temperature of the spring 
water unless success is attained at less depth, in the case of Mud 
and Mountain Home hot springs the pioneer drill holes should be put 
down to the south of the spring in each case, and about 50 feet from 
it. The reason for this is that most probably these springs are sit- 
