Dunes

Traveling north from Badwater and up in elevation a few hundred feet, you'll come across the Mesquite Sand Dunes near Stovepipe Wells. The dunes have an aesthetic beauty, and their soft curves contrast dramatically with the sharp, rocky features of the surrounding mountains. The dunes are always changing and shifting as each windstorm makes its mark on these unique features.

 Dunes
Dunes, mesquite bushes, and "mud-cracked silt." Click on the photo to view larger version. Photo by Benjamin Mendelsohn.

The forces that shape the dunes are the same ones that created them in the first place. Sand dunes are created by winds that come in from different directions. When these winds converge, they drop their loads of sand. If the wind blew in the same direction the sand would just move on and would never accumulate.

The dunes near Stovepipe Wells are the largest in Death Valley, but are not particulary large as far as sand dunes go. The highest dune in the valley is about 140 feet thick. Dunes found farther south in the Imperial Valley are about three times as large. Still, Death Valley's dunes are impressive not just for the sand, but for the setting.

A hike into the dunes reveals some interesting details. Large green creosote mesquite bushes greet you as you approach the dunes. These bushes thrive on the moisture the dunes lock in. Rainwater percolates deep into them and the sand on the outside of them dries out. This process provides insulation for the moisture within.

Once in the dunes it's hard to resist the urge the play in the sand. In digging in the dunes, I discovered multicolored layers of sand. I asked Glazner about what I had seen and he told me, "What you saw are layers of cross beds that have been cemented a little bit by water percolating through and depositing gypsum or calcium carbonate, which sticks the sand grains together a little bit. You also might have seen dark layers that represent deposits of really dense minerals like magnetite and garnet that don't blow around as easily and tend to concentrate in the low spots." These layers are sometimes preserved in sandstone rocks that are millions of years old.

Occasionally, sandstone will show the ripples that are often found on the outside of the dunes. Ripples are not only beautiful, they are also revealing. They can tell us which direction the wind was blowing on the surface when they were formed, how strong the wind was, and even how coarse the sand is. Apparently, the size of the ripples varies depending on the coarseness of the grain and the strength of the wind.
Ripples in the DunesAccording to "Geology Underfoot," which Glazner coauthored with Robert Sharp, most ripples are relatively small, "from 3 to 8 inches from crest to crest--which is known as the ripple's wavelength." These wavelengths increase from 18 to 24 inches in coarse sand found near the center of Mesquite dunes.

"Geology in a Land of Extremes"

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