This is a shot from White Sands National Monument in New Mexico. WS is a field of bright white sand dunes composed of gypsum crystals. The dunes constantly change shape and slowly move downwind, covering the plants in their path. Some species of plants, like the Yucca, however, can grow rapidly enough to avoid being buried by the dunes. What looks like grass in this picture is actually the very top of such Yucca.