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Caught On Camera: Mystery Of Death Valley’s ‘Sailing Rocks’ Solved, Mother Nature Is A Fan Of Curling

by Brandon Mercer
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PLOS One Journal:
The GPS unit with its battery pack is inserted into a cavity bored into the top of the rock. The GPS continuously logs its position after a switch is triggered by the stone moving away from a magnet set in the playa. The surface of the playa is frozen in this image, but the ice had melted or was floating when the trail formed. (Image by Mike Hartmann.
doi:10.1371/journal.pone.0105948.g004)

PLOS One Journal:
The GPS unit with its battery pack is inserted into a cavity bored into the top of the rock. The GPS continuously logs its position after a switch is triggered by the stone moving away from a magnet set in the playa. The surface of the playa is frozen in this image, but the ice had melted or was floating when the trail formed. (Image by Mike Hartmann.
doi:10.1371/journal.pone.0105948.g004)

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DEATH VALLEY NATIONAL PARK (CBS SF) — Using GPS-fitted boulders in the flat, parched desert of Death Valley, and tying in the data to a weather station, researchers with the Scripps Institution of Oceanography in San Diego have confirmed that rocks weighing hundreds of pounds are pushed along on a thin sheet of ice by light winds, in a sort of natural display of truly Olympic “curling.”

PLOS One Journal: The GPS unit with its battery pack is inserted into a cavity bored into the top of the rock. The GPS continuously logs its position after a switch is triggered by the stone moving away from a magnet set in the playa. The surface of the playa is frozen in this image, but the ice had melted or was floating when the trail formed. (Image by Mike Hartmann. doi:10.1371/journal.pone.0105948.g004)

PLOS One Journal:
The GPS unit with its battery pack is inserted into a cavity bored into the top of the rock. The GPS continuously logs its position after a switch is triggered by the stone moving away from a magnet set in the playa. The surface of the playa is frozen in this image, but the ice had melted or was floating when the trail formed. (Image by Mike Hartmann.
doi:10.1371/journal.pone.0105948.g004)

The sensors recorded movement of about 15 feet per hour as light winds hit the heavy rocks. The key was the night temperatures had to dip down below freezing, after a light rain had misted the area with water. The result — a slick sheet of ice, and as the sun came up and melted the top layer, the stones began sliding along the lake bed when the wind blew.

Richard and James Norris, two cousins, made the discovery, tracking 60 rocks moving across “Racetrack Playa” last year, according to results published Wednesday in Plos One

They told the Los Angeles Times that on one magical day, they were able to watch it happen with their own eyes, saying, “We found the playa covered with ice. “We also noticed fresh rock trails near shards of thin ice stacked up along the shoreline.” The next day, it happened: “We were sitting on a mountainside and admiring the view when a light wind kicked up and the ice started cracking,” said Richard Norris. “Suddenly, the whole process unfolded before our eyes.”

Diagram from the LA Times

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