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Environment & Science

Death Valley 'sliding stones' mystery solved

Stones on the Racetrack Playa in Death Valley, CA.
Stones on the Racetrack Playa in Death Valley, CA.
Flickr/Sandy Redding

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If you've ventured out to Death Valley National Park in California, chances are you've seen the so-called sailing stones at Racetrack Playa. The dry lake bed out there is littered with rocks — and some big, heavy ones, too — that appear to have been dragged across the landscape by an invisible force. 

No one had ever witnessed the rocks moving from one place to the next, however, and folks long wondered how it could be possible.

Now a scientist has figured it out, and he published his findings in Nature. Paleobiologist Richard Norris, of the Scripps Institution of Oceanography at UC San Diego, spoke with Take Two to shed some light on this longstanding mystery.

"The answer is that it is ice, but it's ice floating on a couple of inches of water. This totally blew me away. This ice is 2 or 3 millimeters thick — the width of a key — and it happens when just a light breeze is blowing. It seems like you need steady breezes, sunlight melting the floating ice sheet that forms in the wintertime at night, ... and you get ice break-up that happens around midday. "

On why it's a less subtle process than you might think:

"My cousin and I were out there in December, and we were sitting on this hill, overlooking the playa. ... One moment it was this beautiful, quiet day with this breeze blowing along, and then the whole surface, a mile-wide surface of ice, begins to pop and crackle as it broke up under the influence of these winds. And the ice is moving at this point, not terribly fast, but it just bulldozes the rocks along."

On whether his theory is truly the final answer to the mystery of the moving rocks:

"Well, this is for sure how it happens part of the time. I'd say we pretty much figured it out. There may be some other possibilities we haven't sorted out yet, but it's primarily thin ice, light breezes and not hurricane-force winds that make the rocks move."