The Sailing Stones of Death Valley: How Rocks Move on Their Own

Strange Science · September 29, 2026

In Death Valley National Park there is a dry lake bed called Racetrack Playa. The ground is flat and cracked like a puzzle, and scattered across it are rocks, some weighing hundreds of pounds, each with a long trail behind it in the mud. It looks like someone dragged them.

For decades, nobody knew who or what did it. The park service says the rocks range up to about 700 pounds (320 kg). People have wondered about wind, water, and ice since the 1940s. Nobody had ever seen one move.

Putting GPS in the rocks

Scientists finally decided to catch it in the act. Richard Norris, a scientist at Scripps Institution of Oceanography, and his cousin Jim Norris placed GPS units inside some rocks and set up weather stations and cameras.

In December 2013, they arrived to find the playa covered by a shallow pond about three inches deep. Cold nights froze it into ice that was only a few millimeters thick, thin as a windowpane.

What actually happened

As the sun came up and the ice began to melt, it broke into floating panels. A light breeze, around 4 to 5 meters per second, pushed the panels across the water. As the sheets drifted, they shoved the rocks along the soft mud underneath, leaving the trails.

On December 20, 2013, more than sixty rocks moved. They traveled at a few meters per minute. The researchers published their findings in the journal PLOS ONE in 2014. Richard Norris later called it "complete dumb luck" that they were there when the conditions lined up (The New York Times, 2014).

No mystery left, but don't try it yourself

The explanation is not aliens or magnets. It is a rare combination of a thin pond, thin ice, sun, and a gentle wind. That is also why the movement is rare and rarely witnessed.

The National Park Service asks visitors not to move the rocks or drive on the playa, because tracks and disturbances damage a fragile, unusual landscape.

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