DEATH VALLEY, Calif. — For decades scientists have been puzzled by the mystery of the “sailing stones” in California’s Death Valley.
Boulders, some weighing as much as 500 pounds, were spotted in the desert with long trails behind them as if the stones had been pushed across the dry lakebed called the Racetrack.
No one could figure out how the stones moved.
Geologist Richard Norris and his team from the Scripps Institution of Oceanography have found evidence that large planes of ice move the rocks as they melt.
Norris used GPS trackers and cameras around the rocks to record their movement.
In December, the lakebed freezes and on one morning after a rain storm, Norris said, the team saw a thin sheet of ice had formed on the desert surface.
As the sun came up, the ice melted and began to move around atop a film of melted water.
Sheets of ice, some 40 to 50 feet across, moved across the flat surface and moved the rocks, Norris said.
By the end of the day, some of the rocks had moved hundreds of feet. As the day went on, the ice water evaporated leaving the rocks in place and winding trails behind them.
Norris said the combination of rain, freezing temps and a steady wind are rare. He said he was lucky to see it firsthand.
The results of his study are published in the current issue of the journal Plos One.