GREAT AMERICAN DESERT, a term formerly used to designate the arid parts of the West. It is now used only in historical reference. A large part of the region which formerly bore this designation has been reclaimed through the construction of railroads, the development of its abundant min eral resources, the foundation of per manent agricultural communities, and the irrigation of vast stretches of waste land.
The topography, scenery, and geolog ical structures are extremely varied. The climate, though excessively hot in many parts, is, generally speaking, healthful and enjoyable, as the exces sive heat is much tempered by the dry atmosphere. The boundaries of the Great American Desert, of course, can be indicated only in a general way. They are the Rockies, and the mountain ranges continuing from the Rockies in New Mexico and Texas on the east, and the Sierra Nevadas and Cascade ranges on the west. Roughly speaking, the country included between these, some 700 miles across at its greatest width, and extending from British Columbia in the north to the Mexican border in the south, forms the Great American Desert, although a region of similar aspect is to be found south of the Mexican fron tier. However, only a part of the re gion thus indicated actually consists of arid country, and the total area is es timated at about 550,000 square miles within the United States, and a some what smaller area in Mexico. The
desert parts lie at various altitudes, ranging from below the level of the sea to the extreme elevations of 13,000 feet, but averaging between 2,000 and 4,000 feet. The most extensive stretches of waste lands are included within the Great Basin, possessing an area of 210,000 square miles and containing the larger part of the State of Nevada and parts of California, Utah, Idaho, and Oregon. Perhaps the best known part of the Great American Desert is the so called Colorado Plateau, with its famous Colorado caflyon. Other well known deserts are Death Valley in eastern Cali fornia, the Salton Desert in southern California, the Black Rock Desert in northwestern Nevada, etc. The water resources of the region are very limited, considering its vast extent. Such re sources, however, as are available, have been extensively developed for irrigation, especially in recent years. Vegetation is comparatively limited. Various kinds of grasses known as bunch grass, as a result of their habit of growing in tufts, are to be found in most of the deserts. Numerous members of the cactus family are abundant, especially the prickly pear. In the south the giant cactus abounds, frequently reaching a height of 30 to 40 feet. Sagebrush, yucca, and mesquite are other characteristic desert forms.