Formation of mesas with deep canyons in between
Flowing water can cut sharply through layers of rock. The area shown on the photo above is the Colorado River in Marble Canyon, about 20 miles downstream from Page, AZ. The view is to southeast. This photo was taken on April 12, 1966.
What John Wesley Powell had to say about the origin of these formations -
"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."
From Powell, John Wesley, 1895. Canyons of the Colorado.
Questions for thought
- Powell mentions high snow-clad mountains to the east, north, and west. Where does the Colorado River begin its downhill journey to the Gulf of California?
- Powell mentions high snow-clad mountains to the east, north, and west. Where does the Colorado River begin its downhill journey to the Gulf of California?
Web exploration
- Powell mentions high "snow-clad" mountains to the east, north, and west. Where does the Colorado River begin its downhill journey to the Gulf of California?
- How much water makes its way to the Gulf of California today? Would you call it a "mad, turbid stream"?
© 2008 Earthguide at Scripps Institution of Oceanography.
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