WHITE SANDS, N.M. -- Gypsum sands roll endlessly into the horizon of the Tularosa Basin in southern New Mexico. The massive sea of glistening dunes called White Sands National Monument engulfs nearly 125 square miles of desert.
This waterless beach attracts thousands of visitors each year from all over the world, and most of them want to know, "Where did all this sand come from," says Joan Gaul, a volunteer with the National Park Service.White Sands was formed by gypsum, hydrated calcium, deposited at the bottom of a shallow sea that covered the area 250 million years ago.
Normally, rivers would carry dissolved gypsum into the sea. But no river drains the Tularosa basin. The water and gypsum are trapped within the basin.
As the water evaporates, the dissolved gypsum is deposited on the surface where the forces of nature take over and turn the sand-size particles into dunes of various shapes and sizes.
"Visitors are amazed at the peacefulness and the starkness of the white dunes against the blue sky, " Gaul says.
The massive sand is silently ever-changing, moving and advancing with the winds. As New Mexico's intense sun reflects off the white sand, the dunes resemble mountains in winter.
"It reminded me of the roads in Austria when it snows," said Patricia Stehoibl, of Salzburg, Austria. She and her family of five visited the park for the first time in August. "Our jaws dropped in amazement as we peered out the window. It was just spectacular."
Slowly but relentlessly the sand in the world's largest gypsum dune field, driven by strong southwest winds, covers everything in its path. Within the extremely harsh environment of the dune field, even plants and animals adapted to desert conditions struggle to survive.
Only a few species of plants grow rapidly enough to survive burial by moving dunes, but several types of small animals have evolved a white coloration that camouflages them in the sand.
While the tracks of rabbits, foxes and coyotes can been seen, the animals remain mostly underground during the heat of the day and emerge in the evening.
"The people are amazed that so many animals live in the park with so little water," Gaul says.
Visitors to the park for the first time should stop at the White Sands visitors center, which has a museum, information desk, book store, gift shop and restrooms. It also offers refreshments and snacks.
An eight-mile scenic drive on Dunes Drive leads from the visitors center into the heart of the dunes. Wayside exhibits at pullouts along the drive provide information about the natural history of the park.
Numerous parking areas along the drive allow visitors to stop and walk in the white sands.
Allow 30 minutes driving time for the 16-mile roundtrip, plus additional time for walking and taking pictures. The Interdune Boardwalk has interpretive exhibits.
For those who would like to explore the dunes on foot, the Big Dune Trail is a one-mile self-guided nature trail. A booklet, available at the trailhead, discusses the plants and animals that live within the dunes.
The Alkali Flat Trail, which starts from the end of the Dunes Drive, is a 4.6-mile (round-trip) backcountry trail that traverses the heart of the dunefield.
The most common activity, besides sightseeing and sunbathing, is sledding down the side of the larger dunes.
Near the end of the scenic drive are picnic areas with tables and charcoal grills. There is no campground in the park, but three campgrounds are a short drive away.
The park runs an evening slide show program at the amphitheater. There are also daily sunset tours guided by park rangers. When there's a full moon, there are guided tours at night.