GLACIATION OF THE UINTA MOUNTAINS 799 
6) In three canyons there appears to have been ice only at a much 
earlier period than that of the later epoch. 
7) In some cases two distinct valley trains have been determined, 
one being associated with the outer and the other with the inner 
moraines. 
The alternative interpretation of the glacial deposits in the range 
is that the so-called younger moraines are recessional moraines 
deposited by the same ice that built up the outer older ridges. The 
marked differences in the age of these two series of moraines make 
this interpretation unsatisfactory. The time necessary for the 
removal of the outer terminal moraine, and the excavation of broad 
valleys in which the younger valley trains were deposited, must have 
been many times, perhaps ten, or twenty times, as long as the period 
that has elapsed since the final melting of the ice. 
THE INFLUENCE OF TOPOGRAPHY UPON THE ICE 
In an earlier paragraph it has been pointed out that the formation 
of the Uinta glaciers has been controlled by the size and elevation of 
the catchment areas. The case is equally clear that the movements 
of the ice were, in a large measure, dependent upon the topography 
of the range. At some places the divides were covered by ice, and 
yet in such places the underlying rock divides controlled the direction 
of ice movement, causing movement in opposite directions in a con- 
tinuous ice mass. In the catchment areas the movement was in 
general pointed toward the canyon. From certain catchment areas 
the ice was forced to pass around isolated peaks and ridges that rose 
above the ice as nunataks; in some cases, to divide and move down 
different canyons on the same slope. ‘The canyon ice was frequently 
forced by some projecting rock spur to swing to one side or the other. 
At constricted portions in the canyons the ice responded somewhat as 
rivers do and worked its way through the narrows, to deploy as soon 
as the walls of the canyon permitted. At several points the canyon 
ice was required to turn at right angles in order that it might move 
down valley. 
THE INFLUENCE OF ICE ON THE TOPOGRAPHY 
While the ice responded to topography, and in a large measure 
was controlled by the physical features of the range, yet at the same 
