Into the Valley of Death (Part 2): Ventifacts and Dunes

Wind gets far more credit for shaping the surface of the Earth than it should. Contrary to popular belief, wind is a relatively poor sculptor of landscapes, especially when compared to water in its many forms.

Remove water from the equation though, and the influence of wind becomes magnified. The planet Mars is a great example. Dry for billions of years, with no streams or ocean waves to shape its landscape, Mars has become a barren land of sand dunes and sandblasted rocks.

If you want to experience a Mars-like landscape without the inconvenience of a long flight, Death Valley just might be your best bet. Here, water is so sparse that the effects of wind are more prominent and striking than anywhere I’ve ever visited.

Martian-like landscape on Ventifact Ridge, Death Valley National Park. A snow-dusted Telescope Peak (11,043′) is visible in the background.

Looking east along Ventifact Ridge toward the Black Mountains

My personal favorite wind-driven geologic phenomenon are what are geologists call “ventifacts.” Ventifacts are rocks (usually boulder-sized) that have essentially been sandblasted by wind-blown sand particles for extended periods of time. Ventifacts are consequently pockmarked with an array of pits, grooves, gouges, striations, and etchings that betray their uncomfortable past. Near Badwater in southern Death Valley, a low, linear ridge covered in boulders of dark black volcanic rock juts out into the valley, intercepting the strong winds that often blow along the valley’s length. Nearly every rock on this ridge shows these telltale signs of sandblasting. Combined with the lack of vegetation, photos from here resemble many of those taken by the Mars rovers more than just about anywhere else on Earth.

Ventifact and sand ripples, Death Valley National Park

A pair of excessively pockmarked ventifacts. Note that the top portion of the foreground ventifact has been completely eaten away near the top.

Larger ventifacts like the one below often take on an exceptionally strange shape. This is because wind (even very strong wind) is incapable of picking up anything bigger than a large grain of sand, and even then it can’t lift it more than a few feet off the ground. The result is that the bottom two or three feet of the bounder gets abraded away, while the top remains relatively intact, leading to the classic “hourglass” shape of large ventifacts.

Yours truly atop a large roadside ventifact in Death Valley

All of the sand blown along the valley has to go somewhere. In several locations around Death Valley National Park, mountain ranges act as obstacles to wind, and where the wind stops or slows, the sand is deposited in large dune fields.

Death Valley has not shortage of dunes but the most accessible are the Mesquite Flat Dunes near Stovepipe Wells. Unfortunately, the proximity of these dunes to paved highways means that they are also one of the most visited locations in the park. Upon arrival at the dunes a bit before sunset, we were immediately greeted by the high-pitched insectile buzz of an amateur drone (currently prohibited in national parks) hovering overhead. Fortunately, such devices have a limited range and we were soon free of the annoyance. Even though the Sun was getting low, our plan was to stay awhile. Before long, the Sun set, the stars came out and we had the dunes almost entirely to ourselves as the nearly full Moon illuminated our path:

A clear winter night in the Mesquite Flat Sand Dunes, Death Valley National Park. The yellowish glow on the horizon at right is light pollution from Las Vegas, nearly three hours away.

Ripples in the sand, Mesquite Flat Sand Dunes, Death Valley

One unique feature of the these dunes is the presence of large patches of dried & cracked mud between the dune crests. Having been to dozens of different sand dunes, seeing anything other than sand (and the occasional hardy bush) in a field of sand dunes in a strange sight. The origin of the mud is connected to the fact that the dunes lie nestled against the base of the Panamint Mountains. Periodically, mudflows and debris flows burst forth from the canyons at the foot of these mountains, migrating their way into the low spots between the dunes. The mud dries quickly in the arid climate, forming the large mudcracks. The sand dunes, constantly in a state of motion, eventually bury most of the mudflow deposits, leaving only portions peeking through.

Mudcracks in the Mesquite Flat Sand Dunes, the dried remains of mudflows from the Panamint Mountains that occasionally penetrate the dunes. The Pleaides star cluster is visible near the top of the photo.

Coming up in part three, we leave the valley behind and explore the myriad of canyons cut into the mountains ringing Death Valley. Then it’s on to Joshua Tree!