Mojave Desert

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The Mojave Desert covers some 38,850 km² (15,000 sq miles) of low, barren mountains and flat valleys in the south of California. The region is between 610 and 1,524 m (2,000 to 5,000 feet) above sea level and part of the Great Basin of the United States. The Mojave Desert is bordered on the north and west by the Sierra Nevada and the Tehachapi, San Gabriel and San Bernardino mountains. It is connected with the Colorado Desert in the southeast. About 587,250 hectares (1,450,000 acres) of the desert are protected in Mojave National Preserve. Other preserves in the Mojave Desert include Death Valley National Park and Joshua Tree National Park.

The Mojave Desert was formed from material deposited by the Colorado River and volcanic action. Lava surfaces with cinder cones are present. The area was once part of an ancient interior sea. Temperatures in the desert are uniformly warm throughout the year, although there is a wide variation from day to night. Strong, dry winds usually blow in the afternoons and evenings. The Mojave Desert is located in the rain shadow of the Coast Ranges and receives an average annual rainfall of only 12.7 cm (5 inches). Most precipitation occurs in winter. On the higher, outer mountain slopes, Juniper and Joshua trees are found. Other desert-type vegetation, as well as numerous intermittent lakes and streams are present in the valleys. The Mojave River is the region's largest stream. Several minerals are found in the desert, including gold, silver, iron and saline such as borax.

Two rail lines and two highways cross the Mojave Desert. During WWII, several military installations were established in the desert, of which Edwards Air Force Base is probably the best known. North from Edwards, on the western edge of the desert, is Mojave Airport, a civilian test facility and aircraft storage center. Federal legislation from 1978, aimed at developing alternate energy sources, provided for the resources needed to build a geothermal energy plant. There is also a low-level nuclear waste site in the desert. The 1995 transfer of federal land in Ward Valley to the state of California was an important step in the establishment of that site. Environmentalists have fiercely opposed the project, as they fear that radioactive material might contaminate the water table that supplies drinking water to southern California.