The Great American Desert is a region in the United States roughly triangular in shape, including the area between the Rocky Mountains on the E, the Sierra Nevada on the W, the Salmon Mountains on the N, and the Sonoran Desert of Mexico to the S. Historically the name was applied to the entire western portion of the United States until careful exploration and settlement revealed the smaller limits of the area. The Great American Desert includes the GREAT BASIN, a major physiographic region, and several sub-regions which have been delimited because of individual characteristics. At the apex of the triangle in southern Oregon is the Great Sandy Desert, a high, treeless, chill area about 5,000 feet above sea level. Its floor is an ancient lake bed broken by volcanic cones. Malheur River is the only source of water, feeding Harney Lake (fresh) and Malheur Lake (saline). Burns, the only settlement, is one of the most remote cattle centers in the nation.
To the east is the Red Desert of southwest Wyoming, a basin surrounded by the Wind River Range, the Medicine Bow Range, and the Uinta Mountains. There is no drainage into the basin, a fact which limits its productive capacity. Some antelope graze the flats; sheep stations truck in supplementary winter fodder. The Painted Desert of northeast Arizona lies at the eastern base of the triangle. A narrow sandy desert, it is bordered on the east by mesas and buttes and on the west by the Little Colorado River, whose course it follows for 300 miles. Shifting sands of yellow, red, magenta, brown, and mauve, and fantastic sand sculptures make this a scenic spot.
The middle and western portion of the base of the triangle is a desert area of more than 60,000 miles. Yuma, Ariz., is at the center of the region. These deserts may be grouped into the SALTON SEA-Sonoran system. They are brought into productivity by irrigation from the COLORADO RIVER. Of especial interest is the Mojave Desert of California. It is a salt, gypsum, soda, and borax desert that formerly was a lake bot-tom. Mojave River, a mere trickle, connects ponds that are remnants of the lake. To the north is Death Valley, the lowest point in the desert, 276 feet below sea level; to the southwest the desert slopes upward to the San Bernardino and San Gabriel mountains.
Near the apex, on the western leg of the triangle, is the Black Rock Desert of northwest Nevada. It, too, is an ancient lake bed, the shore of glacial Lake Lahontan. Spring rains turn the desert into a lake with an area of 450 square miles and a depth of four to five inches. Rapid evaporation turns it into a typical alkali flat. Thus it is similar to the GREAT SALT LAKE Desert.
