The low desert, with its desolate mountains, which has thus been described is plainly separated from the upper region of plateau by the Mogollon Escarpment, which, beginning in the Sierra Madre of New Mexico, extends northwestward across the Colorado far into Utah, where it ends on the margin of the Great Basin. The rise by this escarpment varies from 3,000 to more than 4,000 feet. The step from the lowlands to the highlands which is here called the Mogollon Escarpment is not a simple line of cliffs, but is a complicated and irregular facade presented to the southwest. Its different portions have been named by the people living below as distinct mountains, as Shiwits Mountains, Mogollon 28 CANYONS OF THE COLORADO. Mountains, Piñal Mountains, Sierra Calitro, etc., but they all rise to the summit of the same great plateau region. The upper region, extending to the headwaters of the Grand and Green Rivers, constitutes the great Plateau Province. These plateaus are drained by the Colorado River and its tributaries; the eastern and powell-canyons-9.jpg OUR MESSENGER. southern margin by the Rio Grande and its tributaries, and the western by streams that flow into the Great Basin and are lost in the Great Salt Lake and other bodies of water that have no drainage to the sea. The general surface of this upper region is from 5,000 to 8,000 feet above sea level, though the channels of the streams are cut much lower. THE VALLEY OF THE COLORADO. 29 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 8,000 to 14,000 feet. All winter long snow falls on its mountain-crested rim, 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. When the summer sun comes this snow melts and tumbles down the mountain sides in millions of cascades. A million cascade brooks unite to form a thousand torrent creeks; a thousand torrent creeks unite to form half a hundred rivers beset with cataracts; half 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 is in the mountains, 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. continually deepens its beds; so all the streams cut deeper and still deeper, until their banks are towering cliffs of solid rock. These deep, narrow gorges are called canyons.