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Show CHAPTER I THE COLORADO RIVER BASIN GENERAL DESCRIPTION From Gannet Peak in the Wind River Mountains of Wyoming and the 14,000- foot mountain peaks in Colorado to the Salton Sea in southern California, 248 feet below sea level, stretches the vast region of forests, deserts, plains, mountains, canyons, and plateaus drained by the Colorado River. The outline of the Colorado River Basin as it follows the crests of adjacent mountain masses is irregular, but its general shape may be compared with the ear of a horse. The lower end of the basin in southern California, Arizona, and New Mexico, corresponding to the base of the ear, is broad, being some 500 miles wide at one point, and is bounded for the most part by low, desert ranges. Northward, in Utah and Colorado, the basin becomes progressively narrower, edged by loftier mountain ranges, until at the extreme northern tip of the ear, 830 miles from the Mexican border, it is reduced to a width of 25 miles as it culminates in the magnificent Wind River Range of western Wyoming. The Colorado River Basin not only is ringed with mountains but contains within its boundaries many extensive ranges and lofty plateaus. In the north, these interior ranges run in an east- west, or else a northwest- southeast direction, forming a series of more or less parallel mountain barriers and high plateaus across the basin. Between these barriers lie great valley systems, also running more or less east and west. Only the mighty Green and Colorado Rivers have cut deep gorges in a southerly direction through the barriers to unite all the streams into one drainage. Toward the south, the interior ranges pivot gradually from the northwest- southeast direction, until in southern Arizona, Nevada, and New Mexico they run nearly north and south. The physiography of the basin can be most readily described in terms of these various mountain barriers and their intervening valleys. Farthest to the north lies the spacious but bleak valley of the southward- flowing Upper Green River in Wyoming, with the elevated and still more barren Red Desert to the east. These areas have long, cold winters and short, dry summers. They extend south into northern Utah and Colorado where they encounter the first of the mountain barriers. This barrier is formed by the Uinta Mountains and Yampa Plateau as they extend eastward toward, but do not quite meet, the Danforth Hills and White River Plateau- which in turn are westward exten- tions from the main Rocky Mountain Divide. Winters are still longer and colder than in the valleys, with a heavy snowfall. Summers are cool, with frequent afternoon thunderstorms. Beyond this first barrier to the south lies the broad, east- west valley of the Duchesne River, elevated and bleak, but farmed, and its counterpart on the opposite side of the Green River, the wilder but similar valley of the White River. These valleys have long cold winters and short dry summers like the Upper Green River Valley. They are bounded on the south by the second mountain barrier, comprising the Tavaputs Plateaus which, with the Roan Plateau, form an 8,000- to 9,000- foot wall all the way across the basin from the Wasatch Mountains on the west to the White River Plateau of the Rockies on the east. Only the Green River has been able to cut a cleft through this wall to join with the stream systems still farther south. The climate of this mountain barrier resembles that of the first, being characterized by deep, long- lasting winter snows and cool summers with afternoon thunderstorms. About 50 miles south of the Tavaputs- Roan Plateau barrier, the southward- flowing Green River joins the Colorado River which, with its great tribu- 1 |