Photos from a few visits to the White Sands National Monument. There are many dune formations which present many interesting photo opportunities. The white sand is not beach(quartz)sand,but pure gypsum sand. Gypsum is widely mined and is used as a fertilizer, and as the main constituent in many forms of plaster, blackboard chalk and wallboard. The origin of the white sand is Lake Lucero, at the base of the San Andres Mountains. Seasonal rains fill the ancient bed. As the water evaporates the fine gypsum sediments dry and are blown downwind. The wind moves small sand grains by bouncing them along the surface in a process called "saltation." Saltating sand grains create a beautiful pattern of ripples on the dune surface. Larger sand grains are struck by saltating grains and slowly roll forward, a process known as "surface creep." In this manner, the vast gypsum dunes are slowly advancing south and east. Roads have to be plowed regularly to prevent the windblown gypsum from making the roads impassable. For more info about this beautiful National Park, visit www.nps.gov/whsa