FIG. 1.—THE GRAND CAÑON OF THE COLORADO
The work of a river
The Colorado is a wonderful stream. It is fed by the perpetual snows of the Rocky Mountains. For some distance the tributary streams flow through fertile valleys, many of them now richly and widely cultivated. But soon the branches unite in one mighty river which, seeming to shun life and sunlight, buries itself so deeply in the great plateau that the traveller through this region may perish in sight of its waters without being able to descend far enough to reach them. After passing through one hundred miles of cañon, the river emerges upon a desert region, where the rainfall is so slight that curious and unusual forms of plants and animals have been developed, forms which are adapted to withstand the almost perpetual sunshine and scorching heat of summer.
Below the Grand Cañon the river traverses an open valley, where the bottom lands support a few Indians who raise corn, squashes, and other vegetables. At the Needles the river is hidden for a short time within cañon walls, but beyond Yuma the valley widens, and the stream enters upon vast plains over which it flows to its mouth in the Gulf of California.
No portion of the river is well adapted to navigation. Below the cañon the channels are shallow and ever changing. At the mouth, enormous tides sweep with swift currents over the shallows and produce foam-decked waves known as the "bore."
Visit the Colorado River whenever you will, at flood time in early summer, or in the fall and winter when the waters are lowest, you will always find it deeply discolored. The name "Colorado" signifies red, and was given to the river by the Spaniards. Watch the current and note how it boils and seethes. It seems to be thick with mud. The bars are almost of the same color as the water and are continually changing. Here a low alluvial bank is being washed away, there a broad flat is forming. With the exception of the Rio Grande in New Mexico, and the Gila, which joins the Colorado at Yuma, no other river is known to be so laden with silt. No other river is so rapidly removing the highlands through which it flows.
FIG. 2.—LOOKING DOWN THE COLORADO RIVER FROM ABOVE THE NEEDLES
Over a large portion of the watershed of the Colorado the rainfall is light. This fact might lead one to think that upon its slopes the work of erosion would go on more slowly than where the rainfall is heavy. This would, however, be a wrong conclusion, for in places where there is a great deal of rain the ground becomes covered with a thick growth of vegetation which holds the soil and broken rock fragments and keeps them from being carried away.
The surface of the plateaus and lower mountain slopes in the basin of the Colorado are but little protected by vegetation. When the rain does fall in this arid region, it often comes with great violence. The barren mountain sides are quickly covered with trickling streams, which unite in muddy torrents in the gulches, carrying along mud, sand, and even boulders in their rapid course; the torrents in turn deliver a large part of their loads to the river. As the rain passes, the gulches become dry and remain so until another storm visits the region. It is storming somewhere within the basin of the Colorado much of the time, for the river drains two hundred and twenty-three thousand square miles. So it comes about that whether one visits the river in winter or summer one always finds it loaded with mud.