48 
The Colorado River 
only by an increase of precipitation on the mountain summits. 
During the Glacial Epoch, the Rocky Mountain summits were 
considerably glaciated, the amount varying according to alti¬ 
tude and latitude. The general topography of the Colorado 
River was about as it is to-day, and the rainfall m the valleys 
probably nearly the same, or at least only a little greater. In 
other words, the 
conditions were 
those of to-day 
intensified. In 
summer, then, the 
amount of water 
seeking outlet by 
these drainage 
channels to the sea 
was enormously 
multiplied, and the 
corrasive power 
was correspond¬ 
ingly augmented. 
When the ice caps 
finally began to 
permanently dim¬ 
inish, the summer 
floods were doubt¬ 
less terrific. The 
waters of the Colo¬ 
rado now rise in 
the Grand Can¬ 
yon, on the melt- 
from forty to one 
hundred feet; the rise must then have amounted to from one 
hundred to four hundred or more. The Kanab heads in two 
very high regions—the Pink Cliffs and the Kaibab. Though 
probably not high enough to be heavily glaciated they were 
high enough to receive an increased snowfall and to hold it, or a 
portion of it, over from one year to another. Thus the canyons 
having their origin on these high regions would be given peren- 
In Lower Kanab Canyon. 
Width about 75 feet, depth 2500 to 3000. 
Photograph by E O Beaman 
ing of the snows in the distant mounta 
