White Sands National Monument is a U.S. National Monument located about 25 km (15 miles) southwest of Alamogordo in western Otero County and northeastern Dona Ana County in the state of New Mexico, at an elevation of 4235 feet (1291 m). The area is in the mountain-ringed Tularosa Basin valley area and comprises the southern part of a 710-km² (275-mi²) field of white sand dunes composed of gypsum crystals.
The first exploration was led by a party of US Army officers in 1849. The Mescalero Apache were already living in the area at the time. Hispanic families started farming communities in the area at Tularosa in 1861 and at La Luz in 1863.
The idea of creating a national park here goes back at least to 1898, when a group in El Paso proposed a Mescalero National Park. Their idea was for a game hunting preserve, which conflicted with the idea of preservation held by the Department of the Interior, and their plan was not successful. In 1921-1922 Albert Bacon Fall, United States Secretary of the Interior and owner of a large ranch in Three Rivers near White Sands, promoted the idea of a national park there an "All-Year National Park" that, unlike more northerly parks, would be usable all year round. This idea ran into a number of difficulties and did not succeed. Tom Charles, an Alamogordo insurance agent and civic booster, was influenced by Fall's ideas. By emphasizing the economic benefits Charles was able to mobilize enough support to have the park created.
On January 18, 1933, President Herbert Hoover created the White Sands National Monument, acting under the authority of the Antiquities Act of 1906. The dedication and grand opening was on April 29, 1934.
Gypsum is rarely found in the form of sand because it is water-soluble. Normally, rain would dissolve the gypsum and carry it to the sea. Since the Tularosa Basin has no outlet to the sea, rain that dissolves gypsum from the surrounding San Andres and Sacramento Mountains is trapped within the basin, and the rain either sinks into the ground or forms shallow pools which subsequently dry out and leave gypsum in a crystalline form, called selenite, on the surface. During the last ice age, a lake known as Lake Otero covered much of the basin. When it dried out, it left a large flat area of selenite crystals which is now the Alkali Flat. Another lake, Lake Lucero, at the southwest corner of the park, is a dry lake bed, at one of the lowest points of the basin, which occasionally fills with water.
The ground in the Alkali Flat and along Lake Lucero's shore is covered with selenite crystals which reach lengths of up to three feet (1 m). Weathering and erosion eventually breaks the crystals into sand-size grains that are carried away by the prevailing winds from the southwest, forming white dunes. The dunes constantly change shape and slowly move downwind, covering the plants in their path. Some species of plants, however, can grow rapidly enough to avoid being buried by the dunes.
