4 EXPLORATION OF THE CANONS OF THE COLORADO. 
lower third is but little above the level of the sea, though here and there 
ranges of mountains rise to an altitude of from two to six thousand feet. 
This part of the valley is bounded on the north by a line of cliffs, which 
present a bold, often vertical step, hundreds or thousands of feet to the 
table-lands above. 
The upper two-thirds of the basin rises from four to eight thousand feel 
above the level of the sea. This high region, on the east, north, and west, is 
set with ranges of snow-clad mountains, attaining an altitude above the sea 
varying from eight to fourteen thousand feet. All winter long, on its mount 
ain-crested rim, snow falls, filling the gorges, half burying the forests, and cov 
ering the crags and peaks with a mantle woven by the winds from the waves of 
the sea a mantle of snow. When the summer-sun comes, this snow melts, and 
tumbles down the mountain-sides in millions of cascades. Ten million cas 
cade brooks unite to form ten thousand torrent creeks; ten thousand torrent 
creeks unite to form a hundred rivers beset with cataracts; a hundred roar 
ing rivers unite to form the Colorado, which rolls, a mad, turbid stream, into 
the Gulf of California. 
Consider the action of one of these streams: its source in the mount 
ains, where the snows fall; its course through the arid plains. Now, if at 
the river's flood storms were falling on the plains, its channel would be cut 
but little faster than the adjacent country would be washed, and the general 
level would thus be preserved; but, under the conditions here mentioned, the 
river deepens its bed, as there is much through corrasion and but little 
lateral degradation. 
So all the streams cut deeper and still deeper until their banks are tow 
ering cliffs of solid rock. These deep, narrow gorges are called canons. 
For more than a thousand miles along its course, the Colorado has cut 
for itself such a canon; but at some few points, where lateral streams join it, 
the canon is broken, and narrow, transverse valleys divide it properly into 
a series of canons. 
The Virgen, Kanab, Paria, Escalante, Dirty Devil, Sari Rafael, Price, 
and Uinta on the west, the Grand, Yauipa, San Juan, and Colorado 
Chiquito on the east, have also cut for themselves such narrow, winding 
gorges, or deep canons. Every river entering these has cut another canon; 
