These Rocks 'Walk' Across the Desert on Their Own — and No One Saw It Happen for Decades

On the cracked, dried-up bed of Racetrack Playa in Death Valley sit rocks — some weighing dozens of kilograms — that leave long, unmistakable trails across the earth behind them, as if they'd been crawling under their own power.

The phenomenon had been observed for decades, but for a very long time nobody ever caught the process in the act — the rocks had always "already moved" by the time researchers came back to check.

The mechanism was only cracked in the 21st century, thanks to GPS trackers and time-lapse cameras: under rare conditions — a thin sheet of rainwater freezing into a very thin layer of ice overnight, then cracking and melting under the wind by day — huge, thin ice panes form and get pushed by the wind, dragging the rocks across the slick, muddy ground beneath.

The takeaway: it's a textbook case of something that looked like a mystery demanding exotic explanations for decades, turning out to be a rare but completely natural combination of ordinary physics — someone just had to be in the right place with a camera.