White Sands National Park

Kneel down and press your palm into the sand. It feels cool, even under a hard desert sun. That surprises almost everyone. This is not ordinary sand made of quartz. It is gypsum, a soft mineral that reflects most of the sunlight instead of soaking it up. So the ground stays comfortable to walk on barefoot, while the air above it shimmers with heat. Look around you. In every direction, white dunes roll toward a ring of distant mountains.

You are standing in the Tularosa Basin of southern New Mexico. The San Andres Mountains rise to the west, and the Sacramento Mountains rise to the east. Between them lies the largest gypsum dunefield on Earth. The dunes cover an area of roughly 700 square kilometres. The national park protects a large part of that field. The rest lies inside military land that surrounds the park. On a clear day, the white ground and the deep blue sky can make it hard to judge distance at all.

So where does all this gypsum come from? The answer is water. Gypsum dissolves in water, which is why you almost never find gypsum sand anywhere else. Rain usually washes it away. But this basin has no outlet to the sea. Water that falls on the surrounding mountains carries dissolved gypsum down into the valley, and then it has nowhere to go. It sits, and it evaporates under the sun.

Thousands of years ago, during the last ice age, a large lake filled much of this basin. Geologists call it Lake Otero. As the climate warmed and dried, the lake shrank. The gypsum it held was left behind as crystals. Today a remnant called Lake Lucero, in the southwest of the park, still collects water after rains. When it dries, clear crystals of a gypsum form called selenite grow in the mud. Wind breaks them down, grain by grain, into the sand under your feet.

The wind here usually blows from the southwest. It pushes the sand into dunes and moves them slowly northeast. Some dunes travel several metres in a single year. Yet the field does not simply blow away. Just below the surface, the water table sits close to the top. It keeps the lower layers of sand damp and heavy. Dig a little with your fingers in the base of a dune, and you may feel that moisture yourself.

Life in this white world has had to adapt. Several small animals here are pale, almost bleached, compared with their relatives elsewhere. The bleached earless lizard is one example. The Apache pocket mouse is another. Their light colouring helps them hide from hawks and other predators against the white sand. Scientists have studied these creatures for decades as a living example of how animals change to match their surroundings.

Plants face a different problem. They must avoid being buried. The soaptree yucca solves this by growing its stem taller as the sand rises around it. Some yuccas stand on stems that are mostly hidden inside the dune. Other plants hold on in a different way. Their roots bind the gypsum together. When a dune moves on, it can leave behind a firm column of sand with the plant still on top, like a small pedestal.

Now for one of the most remarkable discoveries in American archaeology. On the dried lakebeds of this park, researchers have found fossil footprints. Some belong to ice age animals such as mammoths and giant ground sloths. Others belong to people. Studies published in 2021 suggested that some human footprints here are more than twenty thousand years old. If that is correct, they are among the oldest known signs of people in the Americas. Debate continued, but later studies supported the early dates.

The human story of this landscape continued long after those footprints. Native peoples hunted and travelled through the basin for thousands of years. Much later, ranchers and settlers arrived. In the early twentieth century, local residents began to push for protection of the dunes. In 1933, President Herbert Hoover declared White Sands a national monument. In December 2019, it became a national park, one of the newest in the United States.

There is another neighbour here, and it is a surprising one. The park is surrounded by White Sands Missile Range, a large military testing area. The first atomic bomb test, in July 1945, took place on that range, well to the north of the dunes. Even today, missile tests sometimes close the park road and nearby highway for a few hours. Visitors are often startled to learn that this quiet white world sits beside such a different kind of history.

The visitor centre near the entrance is worth a closer look. It is built in the Pueblo Revival style, a design that copies the thick adobe walls and rounded edges of traditional Pueblo buildings in the American Southwest. It was built in the 1930s as part of a government work programme during the Great Depression. From there, Dunes Drive leads you deeper into the field. The paved road turns into a road of packed gypsum, white and hard, a little like driving on snow.

Along the drive, you can choose how deep you want to go. A raised boardwalk crosses the space between dunes, with signs about plants and animals. Longer trails head out across open sand, marked only by tall posts. The longest leads toward the old lakebed. Out there, it is easy to lose your sense of direction. And many families come for a simple pleasure: sliding down the steep sides of the dunes on plastic sleds, laughing all the way to the bottom.

Before you leave, pause for a moment. Stand still and listen. Often there is almost no sound at all, only the wind moving across the crests. Watch the light. In the late afternoon, the white sand turns soft pink and gold, and the shadows in the ripples grow long and blue. Look down at the small wind patterns near your feet. By tomorrow, they will be gone, and new ones will be in their place.