The primary dunes you see in White Sands South are white sand dunes composed of gypsum crystals. This dunefield is the largest of its kind on Earth.
White Sands National Park, encompassing White Sands South, is almost entirely made of gypsum sand. This gypsum originates from the dissolution of gypsum-rich deposits in the surrounding San Andres and Yeso Formations. Rainfall dissolves the gypsum, and it is then carried by streams and rivers into Lake Lucero and the Tularosa Basin. When the water evaporates, gypsum crystals are left behind. These crystals are broken down by wind and water action into fine sand grains that are then transported and sculpted into various dune formations by the prevailing winds.
While the park focuses on gypsum dunes, it's worth noting that the wind shapes these sand grains into a variety of dune types. The exact classification of dunes can vary based on wind patterns, sand supply, and vegetation, but within White Sands, you can find examples of:
-
Transverse Dunes: These are long, wavy ridges that are perpendicular to the prevailing wind direction. They form where there is a large supply of sand and a consistent wind direction.
-
Barchan Dunes: These are crescent-shaped dunes with horns pointing downwind. They form when there is a moderate sand supply and a consistent wind direction. Barchan dunes are less common in White Sands due to the vegetation that often stabilizes them.
-
Parabolic Dunes: These are U-shaped dunes with the open end facing upwind. They are often stabilized by vegetation and are formed when the wind erodes sand from vegetated areas.
-
Dome Dunes: These are small, rounded dunes with no slipface (the steep, downwind side of a dune). They are often found in areas with variable wind directions.
The unique mineral composition (gypsum) and the interplay of wind, water, and vegetation create the dynamic and ever-changing landscape of White Sands South.
