92 GUIDEBOOK OF THE WESTERN UNITED STATES. 
range. Here it is tinted a deep, rich red, which adds a warmth and 
beauty to the otherwise somber mountain slope. 
At Miner the river valley makes an abrupt bend to the southeast 
and the rocks on the right show clearly the smoothing action of the 
: glacier that once passed over them. Each project- 
—_— ing mass of rock has been rounded and smoothed, 
pogo om especially on the upriver side, which the glacier 
struck first in its course down the valley. 
A short distance above Miner the stream passes through a narrow 
rugged canyon, the walls of which are composed of gneiss and show 
clearly the intricate folds into which this rock has been bent and the 
character of the different layers composing it. Through most of this 
canyon the tracks are on the very brink of the river channel, and the 
traveler can look down on the left into the boiling flood which dashes 
and foams about the bowlders that have fallen into it from the roc 
slopes above. The grade through this canyon is very steep, but the 
gorge is short and the slope of the valley beyond is more gentle. 
At Corwin Springs is a hotel for the accommodation of those 
who wish to use the hot waters. Above this place Cinnabar Moun- 
tain, on the west, is the most conspicuous object, 
Corwin Springs. byt the wonderful structure of the mountain and 
rigteaip tye aig its peculiar appearance can not be fully appreciated 
until the traveler reaches Electric. Cinnabar Moun- 
tain was named in the early days, when the bright-red streak that 
marks it from top to bottom was supposed to be due to the mineral 
cinnabar, a red ore of mercury. It is now known that this red 
streak, called the Devil’s Slide, is a bed of shale and that there is 
no cinnabar i in the mountain. Almost the entire geologic column 
of this part of Montana is here exposed, and the rocks are turned 
up on edge so that they can be studied without the exertion of 
making a difficult climb. The oldest rocks are seen first, as one 
ascends the valley, and then others come in orderly succession, 
ranging from Cambrian to Upper Cretaceous.! 
-e Apt sae section exposed at Electric, if placed in its correct position, would 
as fo 
Feet. 
Montana formation (Upper Cretaceous)........................... 955 
Colorado shale (Upper Cretaceous). ............................ 2,775 
eer sues Sees 277 
Quadrant formation PS See ee ies oe eek 200 
Madison limestone erupts oe eee -: 1,500 
Threeforks shale (Devonian)..................... "240 
Jefierson limestone pn 200 
Cambrian 700 
