Frequently Asked Questions About White Sands
Gypsum is a common mineral in the surrounding San Andres Mountains. Like salt gypsum dissolves in water, and then flows into Lake Lucero in the Tularosa valley below. No river drains the valley so the water is trapped in the basin. As this mineral-rich water evaporates in the dry desert air, gypsum crystalizes. Weathering reduces these crystals to sand-sized grains. Strong winds blowing across Lake Lucero pick up the gypsum particles and carry them downwind. As the gypsum grains accumulate into dunes they bounce up the gentle windward side of the dune, creating ripples on the surface. At the steep leading edge of the dune, gypsum builds up until gravity pulls the gypsum down the slip face, moving the dune forward.
Four types of sand dunes can be found in the white sands dune field.
- Barchan or Crescent Dunes: These are crescent-shaped dunes that form in areas with strong winds, with their nose pointed into the wind and arms pointing downwind. They may travel more than 330 feet (100 m) in a year.
- U-shaped or Parabolic Dunes: These are found along the edges of the dune field. Plants anchor the arms of barchan dunes as the bulk of the sand inches forward.They are the slowest moving dunes, crawling less than 8 feet annually.
- Transverse Dunes: These dunes form in areas with plenty of sand.Barchan dunes join together into long wavy ridges of sand.
- Dome Dunes: These are the first dunes to form downwind of Lake Lucero. They are low mounds that move up to 30 feet per year.
The dune fields began to form about 25,000 years ago.