- White Sands National Monument, NM
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- October 16th, 2011
Sunday, October 16, 2011
Another day in paradise! A cloudless, brilliantly blue sky greeted us this morning. Last night it did not drop below 58 in the coach. I think today will be a hot day.
After a leisurely morning we finally bestirred ourselves and left for White Sands. On the way we passed the Holloman Air Force Base and also the White Sands Missile Range. Actually the White Sands Missile Range surrounds the park. It was first used as a military proving ground after WWII for testing rockets captured from German armed forces. The 4,000-square-mile range is still an important site for testing experimental weapons and space technology. Even now there is a test on the average of twice a week.
The Visitor Center was a lovely adobe building with a cool and inviting courtyard with a cottonwood tree and other indigenous plants. There was an excellent short video that introduced us to the White Sands Monument and told us how it formed. We have found that it is almost always a good idea to go to the Visitor Center first. They often have great videos and give you information you otherwise would never have received. The Park covers 275 square miles but only has one road running through it. You only get to see a small portion of this unique land.
The gypsum that forms the white sand was deposited at the bottom of a shallow sea covering this area 250 million years ago. Eventually turned to stone, these gypsum-bearing marine deposits were uplifted into a giant dome 70 million years ago when the Rocky Mountains formed. Ten million years ago the center of this dome started to collapse, creating the Tularosa Basin. The remaining sides of the original dome form the San Andres and Sacramento mountain ranges that now ring the Tularosa Basin.
The common mineral gypsum is rarely found as sand because it is soluble in water. Rain and snow in the mountains dissolve gypsum from the rock and carry it into the Tularosa Basin. Rivers would usually carry dissolved gypsum to the sea, but no river drains the Tularosa Basin. The water with the gypsum and other sediments is trapped in the basin.
Crystal beds in wet periods, water evaporating on the playa floor causes the gypsum to be deposited in crystalline form as selenite. Along Lake Lucero’s shore and in the Alkali Flat, beds of selenite crystals – some three feet long – cover the ground. Freezing and wetting and drying eventually break down the crystals as sand-size particles light enough to be moved by the wind.
Strong winds blowing across the lake bed pick up gypsum particles and then carry them downwind. Actually they bump, jump, skip, hop, and tumble along. As sand grains accumulate as a dune, they bounce up the gentle windward slope and ripple its surface. At a dune’s steep leading edge, sand builds up until gravity pulls it down the slip face, moving the dune forward. Sometimes the dunes move slowly at about only ½” a year. This happens when the dune is at the edge of the dunes and has some protective covering of plants. In the middle of the dunes, however, it is a vastly different story. Here the winds swirl and howl and the lack of plants create dunes the move as much as 37’ a year. Yes, that was feet, not inches. One of the park volunteers told us there was a very nice nature center at the heart of the dunes area. In one year a shifting dune completely engulfed it and it had to be torn down.
The few varieties of plants that manage to eke out an existence here have learned how to adapt to avoid burial by moving sand. The Soaptree yucca elongates its stem to keep its leaves above the sand, growing upward a foot per year. Some plants anchor parts of a dune with their roots and keep growing on a sand pedestal even after the dune moves on.
The animals too have adapted. The lizards that once were dark colored in other parts of New Mexico are now closer to white. Butterflies, birds, mice, rats, and even the Kit Fox all have changed their color to more closely match the surrounding sand and thus not be noticed by predators. Although the dunes appear to be completely devoid of life other than plant life, there is really diverse animal life living and thriving within these harsh, unforgiving dunes.
The pristine, almost incandescent whiteness of the dunes at mid-day makes viewing them almost a painful experience. Sunglasses help but even they cannot diminish the sparkling rays bouncing off the sand. The sand itself is interesting. I thought it would have the texture of sugar but it is really much more like talcum powder. We’ve been told that the dunes are covered with a thin layer of sand. When it rains the sand becomes joined to the gypsum underneath and becomes hard, almost like concrete. (Actually, gypsum is used in wallboard and plaster so I guess it isn’t a surprise.) It is strange that something that feels so delicate could become so rocklike. In fact, when you walk on it you do not sink like you do in beach sand.
The tallest dunes are only around 60’ and aren’t anywhere near the height of the dunes we saw at Great Sand Dunes National Park, CO, but they are impressive in their own way. We had lunch at a picnic area with an aluminum shed positioned so that it shielded us from the sun. It had a flat roof and a curved back, table and bench seating, and even a charcoal grill. All the comforts of home – well, almost.
This area has also been set aside as a “play” area. Children and adults climb the dunes and slide down on disk shaped plastic slides about 30” in diameter that can be purchased at the Visitor Center. We were surprised to see that many families had come to the park to have picnics and play in the sand. Everyone seemed to really be enjoying themselves.
As we continued around the park we began to see more definition in the dunes. The sun had changed position and the shadows were improving our viewing. It made us appreciate the unique beauty of the place even more.
We had a very good time and said goodbye to White Sands before the sun had begun to set. It was a peaceful, interesting day and we were glad we had visited this unusual area.