Long trails showing rocks’ movement make phenomenon all the stranger.

Unforgiving sun, punishingly hot days, freezing nights, no water, and a name like Death Valley keep people away from this ultra-dry section of California. Those who do venture there notice that sometimes, in some places, rocks just move. They don’t do it a lot, and they never do it when anyone is watching. Make no mistake, though, they do it. They leave behind long, even grooves in the packed dust to prove it.

When walking through Racetrack Playa, a dried up lake bed in Death Valley, it’s not unusual to see these moving rocks, with their long tracks stretched out behind them. They’re never moved into any kind of structure, so it’s unlikely that humans are doing – although scientists have not ruled out some kind of prank. The occasional rains in southeastern California can flood the lake beds. Rains can create small rivers that go for miles, so parts of the desert can flood even when there isn’t a cloud in the sky. But rocks don’t float, so how do they manage to move themselves?

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