From: Allison Winter, ENN
Published August 28, 2014 09:38 AM

Mystery Behind Slithering Rocks of Death Valley Revealed

In California's Death Valley, a geological phenomenon exists. Sailing stones, or moving rocks can be observed on the valley floor inscribing long trails on the ground without human or animal intervention.


For over 60 years of observations, no one has been able to uncover the mystery of what is actually pushing these stones across the sand. That is, until now.

For decades, scientists have trekked out to a dry lake bed in Death Valley called Racetrack Lake, to see these rocks for themselves. Some of the stones weigh as much as 500 pounds, and many do indeed leave a long trail in the sand; some paths are straight, some zigzag.

Richard Norris, a geologist at Scripps, was just as puzzled as everyone else when he first saw the rock trails. Some were even parallel, as if the rocks had moved in tandem. "They are just going every which way out there," he says, "but in a very regular kind of fashion — like they're moving in fleets."

Fleets of boulders mysteriously sliding across the lake bed, or playa caused researchers to become obsessed with the phenomenon. Some scientists said windstorms were behind it, others said ice. Multiple experiments have been conducted in the valley over the years to narrow down the causes.

So what did scientists do to get to the bottom of this mystery? They put GPS trackers on the rocks. And even though these rocks are observed moving in desert environments, ice was determined to be the culprit.

How? After rain had fallen, overnight, a thin sheet of ice can form on the desert surface. When the sun starts to melt the ice, the ice pops and thin sheets of ice start to slide atop a film of melted water, slowly pushing any rocks along.

The rocks slid several feet per minute along the muddy desert floor.

Norris says the right conditions — rain followed by cold and sunshine, a steady wind, and mud that's just slippery enough — coincide very rarely, but is the reason for these mysterious rock movements.

The details of their results in the current issue of the journal Plos One.

Read more at NPR.

Rock image via Shutterstock.

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