NORTH AMERICAN DESERT

Physical features of western North America. vast, irregular belt of inhospitable terrain that stretches north to south down the western side of the North American continent from southern Oregon and Idaho to northern Mexico. It roughly corresponds to the sheltered, and hence rain-starved, intermontane region lying between the soaring barrier of the Rocky Mountains to the east and the fertile coast ranges fringing the Pacific Ocean to the west. Estimates of the size of the region vary from about 500,000 to more than 730,000 square miles (1,300,000 to 1,900,000 square kilometres). The physical geography and human utilization of this huge area exhibit great internal variety, but its overall aridityassociated with an excess of evaporation over precipitation, great temperature extremes, frequent winds, localized storms, and a predominance of starkly eroded sun-beaten landscapesgive it an unquestioned unity. Scientists, in naming this whole ecological complex, or biome, the North American Desert, are merely echoing the legend of a Great American Desert established as early as the 1820s by the vivid reportage of an expedition led by the American pioneer explorer and engineer Stephen H. Long. Sandstone formations rising above the desert floor of Monument Valley Navajo Tribal Park, which All forms of life, from lowly plants and insects to people, have had to struggle to survive in the region, and the North American Desert thus has had enormous importance in the development of the continent. Descendants of the earliest inhabitants, the desert-culture Indians, are still found in the area. Their ranks were swollen in the 19th century by tribes thrust westward in the great dispossession that followed the advance of European settlement from the Eastern Seaboard into the continental interior, and the region is now the home of most of the U.S. Indian population. The legacy of much earlier population movements from farther south has lent a distinctly Spanish element to the area, while modern American settlement has added its own contribution in the form of sheep and cattle grazing, military installations, and small but often rapidly expanding oases of mining and manufacturing. All the peoples of the North American Desert, whatever their origin, have their lives molded by the basic and all-pervading lack of water. ecological complex in western North America that basically consists of an arid region lying in the rain shadow of the Pacific mountain system to the west and bounded by the Rocky Mountains to the east. The North American Desert extends nearly 2,000 miles (3,200 km) from northern Mexico to southern Oregon and Idaho. Estimates of its size range from 500,000 square miles (1,300,000 square km) to 730,000 square miles (1,900,000 square km). The North American Desert is actually a complex of desert plains or basins that are separated from each other by northsouth-trending mountain ranges or other types of terrain. The North American Desert can be subdivided into regions of cold mid-latitude (north) and hot mid-latitude desert (south). The Great Basin Desert is classified as a cold mid-latitude desert. It includes the Great Sandy Desert of southeastern Oregon, the Snake River Plains of southern Idaho, nearly all of Nevada, most of Utah, and the Painted Desert of northern Arizona and the Red Desert of southern Wyoming (the latter two considered extensions of the Great Basin Desert). Around the southern end of the Sierra Nevada the Great Basin Desert of Nevada merges into the hot mid-latitude desert region characterized by the Mojave (Mohave) Desert, which is bounded on the south and southeast by the arid Sonoran Desert. From the coast of western Mexico to the east, the Sonoran Desert extends inland to blend into the southern Arizona Upland Desert. Farther east is the Chihuahuan Desert, stretching across the Mexican states of Chihuahua, Coahuila, and San Luis Potos. Because of long periods of erosion, the landforms of the North American Desert are characteristically sharp and angular and contain some beautiful scenery. Most of the soils are aridisols (a dry-soil group), but local variations occur, reflecting differing salt and mineral composition and the presence or absence of organic matter. The vegetation of the North American Desert includes xerophytes, sagebrush, saltbrush, Joshua tree, and creosote bush. The Arizona Upland Desert is noted for the giant saguaro cactus. Fauna include coyote, bobcat, fox, skunk, and various lizards and snakes. Additional reading On the natural setting of the North American Desert, historical works include Daniel Trembly MacDougal, Botanical Features of North American Deserts (1908, reprinted 1971), early investigations in the southwestern United States and in Mexico; Daniel Trembly MacDougal et al., The Salton Sea: A Study of the Geography, the Geology, the Floristics, and the Ecology of a Desert Basin (1914); and John Wesley Powell, Report on the Lands of the Arid Region of the United States, new ed., edited by Wallace Stegner (1962). A massive survey of geographic research on deserts is presented in William G. McGinnies, Bram J. Goldman, and Patricia Paylore (eds.), Deserts of the World: An Appraisal of Research into Their Physical and Biological Environments (1968). Other relevant works are Slater Brown, "The Great American Desert, in his World of the Desert (1963); Edmund C. Jaeger, The North American Deserts (1957); and Ann Sutton and Myron Sutton, The Life of the Desert (1966), an abundantly illustrated volume focusing on desert biology. Other special studies include William A. Burns (ed.), The Natural History of the Southwest (1960); and Carle Hodge and Peter C. Duisberg (eds.), Aridity and Man: The Challenge of the Arid Lands in the United States (1963). Gordon L. Bender (ed.), Reference Handbook on the Deserts of North America (1982), is an informative source. Roy Eugene Cameron