Deep within the scorching landscape of Death Valley in California, lies Racetrack Playa, a vast dry lakebed where an inexplicable phenomenon unfolds. Scattered across its parched surface are hundreds of heavy rocks, some weighing up to hundreds of pounds, that mysteriously move, leaving long, mesmerizing trails etched upon the cracked earth.
Also called sliding rocks, walking rocks, rolling stones, and moving rocks, these enigmatic “sailing stones” have captivated scientists and curious minds for decades, their dance fueled by speculation and fueled by the harsh winds and arid beauty of the surrounding desert.
So what causes these stones to move? For a long time, no one knew the answer to this question. Some people speculated that strong winds, magnetic fields, or even aliens were responsible for the motion of the stones.
However, in 2013-14, a team of researchers finally solved the puzzle using time-lapse photography and GPS tracking devices. The research team observed and documented the most significant rock movement on December 20, 2013, involving over 60 rocks. Some of these rocks traveled distances of up to 224 meters (245 yards) between December 2013 and January 2014 in various events of movement.
The findings contradicted previous hypotheses of strong winds or thick ice displacing rocks. The team discovered that the stones move when a rare combination of conditions occurs in winter: a thin layer of water covers the playa, freezes overnight, and then melts in the sun, creating thin floating panels of ice. These ice sheets are pushed by light winds and collide with the stones, nudging them along at speeds of up to 5 m/min (0.3 km/h, 0.2 mph).
Some GPS-measured movements lasted up to 16 minutes, and numerous stones moved more than five times during the winter of 2013–14.
This explanation may sound simple, but it took decades of observation and experimentation to reach it. The researchers who cracked the case had to be very patient and persistent, as the stones only move once every few years, and never when someone is watching. They also had to respect the fragile environment of the playa and avoid disturbing the stones or their tracks.
If you want to see the sailing stones for yourself, you can visit Racetrack Playa in Death Valley National Park. It is a remote and rugged place that requires a high-clearance vehicle and careful planning. You should also follow the park rules and not touch or move the stones or their trails. By doing so, you can help preserve this amazing natural wonder for future generations.
