White Sands National Monument, New Mexico

After leaving the Gila Wilderness, we drove to Las Cruces, New Mexico. For being the 2nd largest city in NM, there wasn't much going on there. It was just a place to get a hotel room and shower up. The next day, with temperatures forcast to approach 100 degrees, we left really early in the morning and headed to White Sands National Monument arriving around 7am.

San Andres Mountains in Distance

(notice the white gypsum layers near the top)

White Sands is located in an endoheric basin called the Tularosa Basin between two fault-block mountains, the San Andres Mountains to the west and the Sacramento Mountains to the east. Gypsum (Calcium Sulfate) deposits from the San Andres dating back to when the region was under a shallow sea erode from the mountains and collect in the basin below.

These cottonwoods survive where groundwater seeps near the surface

Since there is no outlet for the water that drains from the mountains, the dissolved minerals collect at the bottom of the basin. When the water evaporates, they collect in sedimentary layers at the bottom of the basin. During the Ice Age, there was a large lake that collected thick layers of this gypsum.

The few plants that grow here can hold the sand together with their roots while the rest of it blows away

But, after the lake dried up, the winds broke up and blew the gypsum crystals around until it formed great sand dunes. White Sands is the largest gypsum dune deposit in the world.

We absolutely loved our hike there. The "trail" was basically hiking directly across the sand with large posts sticking up ever few hundred feet to prevent you from getting lost.

The sand is actually soluble in water, so you can literally eat it (and generally calcium sulfate is harmless). As the heat increased in the late morning, we knew it was time to head up in elevation to escape the heat.

Life survives even in this harsh environment

So, we headed up the 9,000 foot Sacramento Mountains. At the summit ridge, we found a nice place to disperse camp amongst the firs and spruces in a completely different world than the searing desert below.

White Sands below from the Sacramento Mountains

9500 feet in the cool air of the Sacramento Mountains