Its depth is not great, at least as compared with the canyons upon the Colorado river system; it ranges from 600 ft.
Provpee The province was uplifted and divided into great blocks by faults or monoclinal flexures and thus exposed to long-lasting denudation in a mid-Tertiary cycle of erosion; and then broadly elevated again, with renewed movement on some of the fault lines; thus was introduced in late Tertiary time the current cycle of erosion in which the deep canyons of the region have been trenched.
There are also deep canyons which have been cut by the rivers in their present courses, especially by the Snake river and its tributaries.
In the valleys there are usually about two snows a year and these quickly disappear; but on the mountain peaks and in the canyons the snow accumulates to great depths and forms a steady source of water-supply for the rivers.
The few rivers of the region must have reached the quiescence of old age iii the earlier cycle, but were revived by uplift to a vigorous youth in the current cycle; and it is to this newly introduced cycle of physiographic evolution that the deep canyons of the Plateau province are due.
It appears in the cores of some of the western mountains, in some of the deep canyons of the west, as in the Grand Canyon of the Colorado in northern Arizona, and over considerable areas in northern Wiscpnsin and Minnesota, in New England and the piedmont plateau east of the Appalachian Mountains, and in a few other situations.
On its slope, which rises abruptly from the Bitterroot Basin, glaciers have cut canyons between high and often precipitous walls, and between these canyons are steep and rocky ridges having peaked or saw-toothed crest lines.
Her laugh echoed down the rocky canyons of Zzz as the essence of abomination breathed his bloody last below her.
The largest rivers of Mexico are: the Rio Grande de Santiago, called the Lerma above Lake Chapala, rising in the state of Mexico and flowing westward across Guanajuato, Jalisco and Tepic to the Pacific coast, with a total length of 540 m., celebrated for its deep canyons and waterfalls; the Rio de las Balsas, or Mescala, which rises in Tlaxcala and flows south and west to the Pacific with a course of 426 m.; the Yaqui, which rises in western Chihuahua and, after breaking through the northern ranges of the Sierra Madre Occidental, flows south-westerly across Sonora to the Gulf of California, with a length of 390 m.; the Grijalva, also called the Chiapas on its upper course, which has its sources in the state of Chiapas and flows north-west and north across Tabasco to the Gulf of Mexico, with a total length of 350 m.; the Fuerte, which rises in southern Chihuahua and, after breaking through the sierras, flows south-west across Sinaloa to the Gulf of California, with a course of 340 m.; the Usumacinta, which is formed by the confluence of the Chixoy and Pasion on the east frontier of Chiapas, and flows north-west across Tabasco to the Grijalva, with a course of 330 m.; and the Panuco, which has its source in the north-west of the state of Mexico and flows north-eastward to the Gulf of Mexico.
There are stony wastes, or alluvial fans, where mountain streams emerge upon the plains, in time of flood, bringing detritus in their torrential courses from the mountain canyons and depositing it along the mountain base.