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A Sailing Stone across Death Valley

How did this large rock move across the perfectly flat surface of Racetrack Playa in Death Valley? This image, taken in April 2019, shows one of these "sailing stones" beneath a dark, star-filled sky. The flatness of the playa is due to mud flow, but the movement of these heavy stones remained a mystery for a long time. Recent research suggests that ice sheets form around the rocks, and when the ice melts, wind pushes the rocks across the slippery mud.