798 WALLACE W. ATWOOD 
2) The outer moraines are much more deeply eroded than the 
inner. Usually the outer terminal moraine has been entirely removed 
by erosion. 
3) In some cases, where an older lateral moraine rests on a canyon 
slope above a younger moraine, the difference in the amount of erosion 
which each has suffered is very marked. Often there are valleys 
crossing the upper moraine which fail to cross the lower, and there- 
fore appear as blocked valleys in drift above the lower moraines, 
Fic. 4.—A glacial cirque in the western portion of the Uinta Mountains. The 
vertical walls and comparatively even floor are common characteristics of the catchment 
areas in the range. 
just as blocked valleys inrock appear in the rock above the upper 
moraines. 
4) Corresponding to the greater erosion in the outer moraines, 
there has been greater deposition. In many of the canyons, immense 
alluvial fans have been developed by side-streams that enter the main 
valleys at points below the terminal moraines of the later epoch and 
above the terminal moraine of the earlier epoch. 
5) Depressions in the older drift have commonly been filled with 
alluvium. In this way, possible lakes or marshes have been oblit- 
erated. In the older moraines there are but few lakes and marshes 
while in the younger moraines lakes and marshes are common. 
