White Sands National Monument is in the northern Chihuahuan Desert in the U.S. state of New Mexico. It's known for its dramatic landscape of rare white gypsum sand dunes. 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.
The Tularosa Basin is enclosed, meaning that it has no outlet to the sea and that rain that dissolves gypsum from the surrounding San Andres and Sacramento Mountains is trapped within the basin. Thus water 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. A truly amazing place. Once more the couple of strollers helped give scale and depth to the image