Millions of years ago, before the continents separated, the Permian sea covered most of the southwestern United States. Layers of gypsum were deposited on the
seabed as the sea level rose and fell. Over time the sea vanished. Plate tectonics, earthquakes and volcanoes form the mountain ranges of New Mexico. Rain and snow-melt from those mountains fill Lake
Lucero with gypsum-laden water.
Lake Lucero is a playa: a dry lake that
periodically fills with water. When the gypsum-laden water
evaporates under the hot sun,
selenite crystals form in the mud. Wind and water break down these crystals into smaller
and smaller particles. The wind pushes the particles across the desert floor, grinding them into fine grains of
white gypsum sand.
The formation of sand at Lake Lucero
and Alkali Flat is on a smaller scale than it was when Lake Otero
existed, but Lake Lucero and Alkali Flat are the primary sources of
new dunes at White Sands.
The gypsum doesn’t have the silica associated with regular sand. It doesn’t retain heat in the same way that sand on a beach does. In fact the ‘sand’ at White Sands couldn’t exist on a beach, because water breaks down gypsum, more or less melting it. If you dig into the sand at White Sands, it is usually cool just beneath the surface, with the gypsum retaining water.
Beyond the extraordinary geology, White Sands is consistently photogenic, surrounded by mountains with spectacular sunrises and sunsets. Sledding at White Sands is a local past time, though if you go during the summer, please be aware of heat and hydration. The dry climate tends to evaporate perspiration. It is easy to become dehydrated, because you aren’t aware of how much water you are losing absent perspiration. Temperatures are commonly over 100 during the summer.
In the summer my preference is to stay in Cloudcroft or Ruidoso to take advantage of lower temperatures (9000 foot elevation, alpine environment), heading to White Sands for the sunset (only about a 30 minute drive from Cloudcroft), go on a full moon hike if possible, and head back up to higher elevations before the sun comes back up.
White Sands is currently under consideration by UNESCO for World Heritage designation (natural). If it is deemed a UNESCO site, it will be New Mexico’s 4th.