DENVER & RIO GRANDE WESTERN ROUTE. 163 
of the last bends the traveler may look down upon Poncha Pass, but 
from a distance so great that good eyesight is needed to distinguish 
even the telegraph poles that mark the line of the railroad. The 
chain of high peaks which lies behind the pass and which is known 
as the Sangre de Cristo Range here begins to loom up, and as the 
journey continues it grows steadily in apparent magnitude until it 
is lost to view over the summit of Marshall Pass. 
As the train continues to climb upward the traveler will observe 
that the slopes become less and less rugged, and he soon begins to 
realize that the mountain masses about him, which looked so formid- 
able when seen from below, are really only the foothills of the higher 
range and that many of these foothills have a nearly common height 
and are relatively flat topped. These flat tops stand at an altitude of 
9,300 to 9,500 feet and may correspond with the rolling plain at the 
north foot of Pikes Peak and with the tops of the Front Range 
as seen from Denver. Their equivalence with those features can not 
be regarded as proved, but they suggest that at one time much of 
the mountain region of Colorado was a rolling plain above whose 
generally even surface only a few high knobs projected. Later this 
surface was upraised to its present position, and the mountains as 
we know them to-day were carved from the uplifted mass. 
As soon as the railroad reaches the top of the hills that front the 
valley it changes its course to one directly toward Mount Ouray, 
which is the most conspicuous feature in the landscape. The road 
Winds considerably, but from time to time the peak can be seen 
from either side of the train, though the best views are from the 
left. The peak is not symmetrical, but looks as if some giant had 
taken a great bite out of the side next to the traveler, as shown in 
Plate LXIX, B. And, indeed, a giant has taken a bite out of the 
Side of the mountain, but the giant was a glacier that once lay high 
up on its slopes and that gradually ate out a great amphitheater or 
cirque, as it is called by geologists.** This cirque looks large even 
times, tends to produce a hole in the 
51The exact method by which a t 
. As the tendency is to 
glacier excavates an amphitheater or 
ee is not very well understood, as 
all the work is done under the ice and 
hence can not be seen. It can be | the point of outlet the cirque has a 
udged only by the form of the cirque 
after the glacier has melted away. 
Weight and finally becomes so heavy 
that it begins to move down the slope. 
In doing so it takes with it some of 
the underlying rock to which it has 
frozen, and this action, repeated many 
semicircular shape and the plucking 
tends to cut’ back horizontally, so that 
the floor of the cirque is nearly level 
or it may be slightly deepened so as 
to form a rock basin, The walls of 
cirques in many kinds of rocks stand 
nearly vertical, but the walls of the 
cirque in Ouray Peak, which are com- 
posed of granite, take on a more gentle 
slope, as shown in Plate LXIX, B. 
