New Mexico
New Mexico is known as the Land of Enchantment and one of the most enchanting—and otherworldly—places in the state is White Sands. This sea of stark white crystals is piled in ever-shifting dunes, seen from altitude as a barren, sandy expanse ringed by mountains, about fifteen miles southwest of Alamogordo, New Mexico.
The dunes here aren’t made from typical sand, which is usually composed of minute grains of silica. All that white stuff is actually gypsum—hydrous calcium sulfate—originally deposited 250 million years ago in an inland sea. Gypsum is highly water soluble and easily dissolved by rainwater. White Sands exists in part because it’s one of the driest deserts on Earth, receiving less than ten inches of rain a year. Gypsum crystals that do get dissolved by the occasional rainstorm are usually recrystallized and eventually eroded back into sand again, as the dune field is a closed basin—no streams exist to carry the dissolved gypsum away. White Sands boasts the largest gypsum field in the world, stretching more than 250 square miles.
This dune field is contained within the Tularosa Basin, a fault-block depression in the crust surrounded by mountains (the San Andres Mountains to the west and the Sacramento Mountains to the east). White Sands is trapped in the middle. The bulk of the gypsum sand comes from Lake Lucero, in the southwest corner of the dune field, which only rarely holds surface water. Here, selenite crystals, which are eroded by wind into gypsum crystals, are transported into the dune field in the northeast direction of the prevailing winds. A cycle of erosion, evaporation, and dune building dates back 6500 years, after Lake Lucero’s predecessor, Lake Otero, dried up following the end of the last glacial period—relatively recently in geologic time.
Four types of dunes are found at White Sands—dome, crescent, parabolic, and transverse—each reflecting a different mechanism of formation. Dome dunes take shape along the margins of dune fields, in this case on the leeward shores of Lake Lucero. Crescent dunes form in windy areas and are the fastest-moving type. Parabolic dunes, the slowest-moving variety, are generally found along the perimeter of dune fields in areas with the least loose sand. Transverse dunes are created in areas with large amounts of loose sand stretching into long, wavy ridges.
This region in south central New Mexico is also home to exotic oryx—African antelopes imported for hunting in the 1960s—and the remote and inaccessible White Sands Missile Range, where the world’s first atomic bomb was detonated in 1945.
The dunes of White Sands are gradually advancing to the northeast. The missile range occupies the northern half of the dunes and White Sands National Monument is confined to the southern half.
Look for White Sands en route to Alamogordo or Albuquerque, New Mexico. The area is divided into White Sands National Monument, in the southern part of the dune field, and the White Sands Missile Range to the north, which is closed to the public.
