The Stones That Keep a Schedule

Here's what everyone misses: the furrows in the mud last three, four years. So right now, looking at these tracks, you're most likely staring at something that happened two or three years ago. The stone has long since stopped. It's just been waiting for you to notice.

Racetrack Playa is a dried-up lakebed in Death Valley, flat as a tabletop. And across that table, boulders weighing several hundred kilograms travel on their own — no hands, no ropes, no witnesses. The paths curve, zigzag, sometimes cross each other at sharp angles, as if the stones were staging their own intersection.

Until two thousand thirteen, nobody had ever seen one move. Researchers would drive stakes into the ground beside a boulder, come back a year later, and find the same stone sitting in a new spot with a long groove trailing behind it — while the stakes stood exactly where they'd left them. One geologist wrote in his notebook that the stones seemed to wait for the moment no one was watching.

The answer came from GPS trackers on a hundred and sixty-two boulders, and a lot of patience. It takes a thin film of water on the mud. A cold night freezes it into ice, three to six millimeters thick. Then the wind picks up. These ice sheets are huge but fragile — they press against the sides of the stones and tow them along, two to five meters a minute. To the eye, it's almost nothing. Then the ice melts, the water dries, and what's left is cracked, sun-baked clay with a single long scar across it.

Everything that looked like magic turned out to be three millimeters of ice and the right gust of wind. Nature doesn't need special effects — it just needs us to leave a little too early.

What should we tell you about? Your own street would do. moygid dot online.