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Show 4 EXPLORATION OF THE OARONS OF. THE OOLORADO. 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 thousa~ds of feet to the table-lands above. The upper two-thirds of the basin rises from four to eight thousand feet 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 mountain- crested rim, snow falls, filling the gorges, half burying the forests, and covering 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 cascade brooks unite to form ten thousand torrent creeks; ten thousand torrent creeks unite to form a hundred rivers beset with cataracts; a hundred roaring 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 mountains, where the snows fall; its course through the arid plains. Now, if at the river's flood Htorms 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 con·asion and b.nt li ttle lateral degradation. So all the streams cut deeper and still deeper until their banks are towering 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; btlt 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, San Rafael Price . ' ' and Uinta on the west, the Grand, Yampa, San Juan, and Colorado Ohiquito on the east, have al~o cut for themselves such narrow, winding gorges, or deep canons. Every river entering these has cut another canon; I•' igure 2.-Lowor Cunou of tho Kauub. (:1,000 foot deop.) |
