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Boulders Moving in Death Valley: A 70-Year Mystery Solved by Thin Ice and Weak Wind

For more than seven decades, heavy rocks weighing up to 300 kg on Racetrack Playa in Death Valley, United States, have left mysterious trails without explanation. In 2013, researchers first recorded direct movement: a thin layer of ice — formed from rainwater freezing at night — was moved by weak wind (5–10 m/s), pushing the rocks across the slick mud surface. This phenomenon requires a unique combination of temperature, humidity, and topography — explaining why it rarely occurs and is hard to observe.