Solved: the mystery of Death Valley's sailing stones

Credit: Foter

A desolate, jarring four hour drive into the depths of Death Valley, CA lies a place that defies human understanding: Racetrack Playa. It's the home of Death Valley's notorious 'sailing stones,' and no one who has laid eyes on them has been able to crack the mystery of how these rocks slowly and invisibly move themselves across the desert, leaving long trails in their wake.

Well, no one except Ralph Lorenz of Johns Hopkins University. In 2006, Lorenz — a planetary scientist — was working on a project for NASA which had him setting up weather stations in Death Valley. Like those who had been there before him, Lorenz heard the call of the mysterious sailing stones and decided to try his hand at discovering the enigma of their movements.

"I was intrigued, as everyone is, and I had this instrumentation I was using in desert locations during the summer... We realized we could use it during the winter and try to understand what the conditions really are at the playa." — Ralph Lorenz

But even NASA-developed weather sensors weren't able to single-handedly resolve the mystery of the sailing stones. The real breakthrough came when Lorenz managed to find the site of what looked like a collision between two of the strange stones. Rather than smashing into one another, the two stones had not touched. It was as if one stone had deployed some crazy force field that had deflected the other.

Lorenz wasn't about to accept force fields as an explanation for the movements of rocks. Instead, the discovery reminded Lorenz of a phenomena he had read about taking place in the Arctic. Boulders in the Arctic are sometimes so encased in ice that they gain enough buoyancy to be washed onto tidal beaches by the sea. And the weather data Lorenz had collected told him that the desert got cold enough for something similar to be going on in Death Valley.

He'd need to replicate the result to be sure. So Lorenz did what any scientist would do: he broke out the tupperware and made a frozen desert on his kitchen counter. As Lorenz describes it, "I took a small rock, and put it in a piece of Tupperware, and filled it with water so there was an inch of water with a bit of the rock sticking out. I put it in the freezer, and that then gave me a slab of ice with a rock sticking out of it."

He then filled his Tupperware with layers of sand and water and then floated his stone-carrying iceberg on top. By simply blowing gently on the surface of the ice, he witnessed the same phenomena that has bamboozled humanity for decades — a rock drawing an impression in the sand. And when two of these icebergs came in contact, they'd bounce off each other, without the rocks that they were carrying touching.

No aliens, no crazy force fields — not even some crazy form of magnetism was to blame for the sailing stones. There was only ice, water and a bit of wind involved. If this had been an episode of the X-Files, we would have to give the point to Scully. But the world is still full of other mysterious phenomena. So keep the faith believers, the sailing stones are just the tip of the iceberg.

Via Smithsonian Magazine

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