Pictures: What Drives Death Valley's Roving Rocks?

Lake Remains

Photograph courtesy Cynthia Cheung, GSFC/NASA

Traveling up to 1,500 feet (458 meters), the Racetrack's moving rocks sometimes push up mounds of clay at the ends of their tracks, as seen above in a summer 2010 picture.

The dried mud lining the lakebed is at least a thousand feet (300 meters) thick, according to the Death Valley National Park website. It was left behind when abrupt climate change caused the lake to evaporate about ten thousand years ago. (See pictures of desert landscapes.)

NASA scientists are studying the three-mile-long (five-kilometer-long) Racetrack as a way to understand the landscape of Saturn's moon Titan, which has similar cracked plains occasionally fed by lake water—but is much, much colder, according to NASA's Cheung.

(See "Saturn Moon Has Lakes, 'Water' Cycle Like Earth's'.")

Published September 8, 2010

Traveling Companions

Photograph courtesy Maggie McAdam, GSFC/NASA

Sometimes the traveling rocks move in pairs (pictured in a summer 2010 photo), possibly as part of a single ice sheet, Cheung said.

Because the Racetrack is on protected federal land, the researchers are limited in their techniques, she added. For example, the rocks can't be disturbed, and the few cameras allowed to photograph the rocks over the winter have to be hidden as part of the landscape, she said.

(Read about how global warming is threatening Death Valley and other national parks.)

So far, the cameras haven't snapped pictures of a rock in motion. But "newer technology may come to our aid," Cheung said. "We talk about various ways that we can embed things into rocks [so as] not to destroy the wilderness."

Published September 8, 2010

Tagged Trail

Photograph courtesy Leva McIntire, GSFC/NASA

During the summer 2010 research project, the students used thumbtacks to outline the rock trails.

The rocks occasionally tumble from the hills onto the baked plain. In other lakebeds, the rocks "would just sit there, but in this case, they don't," Cheung said.

Published September 8, 2010

Footrest

Photograph courtesy Maggie McAdam, GSFC/NASA

NASA intern Devon Miller takes notes while resting his foot on one of the bigger roving rocks, which can be as small as pebbles.

Back in the lab, the students used clay from a neighboring dry lake, Bonnie Claire, to create an artificial playa and observe how an ice collar forms around a rock, Cheung noted. "That's the closest we could do without disturbing the playa itself."

The students also set up a website, Racetrackplaya.org, to solicit photos from people who have seen these "sailing stones" during their travels.

Published September 8, 2010

Ice Indentation?

Photograph courtesy GSFC/NASA

During their summer research project, the NASA team found even more mysterious rockless trails, including this indentation that may have been made by a patch of ice, according to Cheung.

Most moving-rock trails erode away within a couple years, she added.

Published September 8, 2010

Extreme Beauty

Photograph by Pete Ryan, National Geographic

Above, the curved trail of a roving rock cuts across the Racetrack in a 2006 photograph. The Racetrack is a "place of stunning beauty and mystery" cradled into a remote valley between the park's Cottonwood and Last Chance ranges, according to the Death Valley National Park website.

Even so, the hottest and driest place in North America is "not very bearable," Cheung noted. Temperatures in July, for instance, can reach 115 degrees Fahrenheit (about 46 degrees Celsius). (See a picture of Death Valley's badlands.)

And getting there isn't easy: Roads are washed out during wintertime, and in summer, Cheung said, "it's not a nicely paved road—even with four-wheel drive."

Published September 8, 2010