STUDIES OF THE CYCLE OF GLACIATION Bf y| 
The two districts which are here contrasted, the Bighorn Range 
and the Glacier National Park, furnish also the opportunity to 
contrast the effects of rock structure in modifying the forms of 
relief shaped by mountain glaciation. Whereas the high upland 
of the Bighorn Range has a core of massive rock, thus resembling 
the Wasatch and Uinta ranges and the Alps, the rocks of Glacier 
National Park are sediments and dominantly shales and limestones. 
It was to be expected that the characteristic structures of these 
J 
Fic. 9.—Cirque at head of Panther Creek, Yellowstone National Park, with 
pair of monumented peaks at entrance—Antler Peak and Bannock Peak. 
sediments, their bedding planes and their joint system, should 
exert a strong influence upon the topographic forms produced, 
as indeed they have. The influence of the bedding planes 
is displayed in the Glacier National Park in the accentuation of 
the rock terraces at the upper ends of valleys within the cirques 
themselves. As in the Canadian Rockies across the international 
boundary, this character reaches an extreme (Fig. 11). An excel- 
lent instance is shown also in an illustration by Alden.? 
t Glaciers of Glacier National Park, Fig. 11. 
