When the ice caps finally began to permanently diminish, the summer floods were doubtless terrific.

The waters of the Colorado now rise in the Grand Canyon, on the melting of the snows in the distant mountains, 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 perennial streams, with torrential floods each summer, compared with which anything that now comes down the Kanab would be a mere rivulet.