SPR cy eeecees 
Geological Survey of the Territories in 1872. 201 
rusty-brown, and are most abundant in pools of comparatively 
moderate temperatures ; while the more slender forms are com- 
monly white, and are most abundant in the rapidly-flowing 
outlets of the hot pools, where they are continually reproduced 
as the channels fill up with newly deposited silica which buries 
the older fibers, so that, in breaking the crust, we frequently 
perature of 180. Very numerous skeletons of Diatoms occur 
in the sediment of even the hottest pools; but no living ones 
were found in springs of much over 100°. 
e process of silicification of wood and other tissues is well 
shown in many cases: all stages of the process may frequently 
be seen in the same pool. 
The eruptions of a few of the larger geysers are accompanied. 
by violent subterranean pulsations, from 70 to 78 per minute: 
while others give no sound, except that of the mere rush and 
splash of the water. 
Neighboring vents exhibit various degrees of sympathy. In 
some cases, a large vent is surrounded by several small ones, 
which are active when it is quiet and quiet when it is active. 
Again, the large and the small may be active together and quiet 
together. Large vents side by side are sometimes in full sym- 
Snake River drainage, and therefore called it Shoshone Lake, 
adopting the Indian name of the Snake. 
_ At the western extremity of the lake, we found the valley of 
its principal tributary occupied by a large number of hot springs, 
ca 
