Among the other many important irrigation works may be mentioned the Shoshone and Rio Grande Dams. The Shoshone Dam in Wyoming impounds sufficient water to irrigate one hundred and fifty thousand acres in the valley below. This dam was completed January 10, 1910, and is the highest in the world, its height being three hundred and eighty-four feet. Twelve miles below the dam proper a diversion dam was built across the river which turns the stream into a tunnel connected at the other end with a canal, which delivers water upon one hundred thousand acres of fertile land. The Rio Grande Dam involving the construction of a storage dam opposite Eagle, New Mexico, across the Rio Grande River will irrigate one hundred and eighty thousand acres of land in New Mexico, Texas, and Mexico. CHAPTER II THE GRAND CANYON OF THE COLORADO Nowhere else on the face of the globe is one so vividly impressed by the vastness of the work of corrasion as in the northwestern part of Arizona. Here the mutilated breast of Mother Earth discloses a chasm from three thousand feet to seven thousand feet deep, cut through horizontal strata of sandstone, shale, limestone, and granite, chiefly by the agency of water. This stupendous chasm is the Grand Canyon of the Colorado River. It is more than two hundred miles long; and from rim to rim its walls measure in places twenty miles across. It is not a clean-cut open channel from wall to wall, but, on the contrary, it is filled with castellated peaks, buttes, pinnacles, ridges, seams, and lesser canyons. Down deep in its lowest part, hurrying onward with impetuous speed, is the river itself. Geologists tell us that this stream was an ancient river before the Mississippi was born and that it formerly watered a valley as fertile. Ages ago when Time was young the river found its channel closed by an obstruction--just how, or where, or by what, no one knows. So it spread out into a great lake, or, perhaps, into an inland sea several thousand feet deep. The rock waste carried into its basin hardened into sandstone--red, pink, and white of many shades.