Easily mistaken for snow, these brilliantly white rolling drifts are actually the world’s largest gypsum dunefield.

The 275 square mile New Mexico desert, known as White Sands National Monument, is a remarkable place both for its beauty and its improbability. Gypsum dissolves in water and normally is washed out to sea before it can grow into such large dunes. In White Sands, however, gypsum washed down from the San Andres and Sacramento Mountains remains trapped in the Tularosa Basin, where it accumulates into a snow white desert.