January 4, 2016
Death Valley, California, in the United States is known as one of the hottest, driest places on Earth. In this desolation without much life, the problem of the “sailing stones of Death Valley” has stumped scientists for over half a century. At a dry lake bed known as Racetrack Playa, stones that weigh up to 700 pounds have been moving, seemingly without human or animal assistance, leaving tracks across the desert sands. Since their discovery in the 1940s, several theorists have attempted to solve the mystery of the rocks’ movement, but it may have only been in the last year that science has provided an answer.
The sailing rocks can be seen spread around the desert floor and make intricate and interesting patterns with their tracks. While the tracks may be parallel, they also are not uniform, and the rocks can move in any direction, including backwards over their own tracks. Until 2014, researchers weren’t sure if the movements were caused by dervishes, hurricane force winds, or some other natural phenomena, but the cause of the movement was determined to likely be from thin layers of ice that form when the conditions are just right. The thin ice across the top of the sand pushes the rocks, which then slide based on the direction of moderate winds of about 5-10 miles per hour.
Researchers observed rocks moving as far as 180 feet over the course of 2 years while running their experiments. While some rocks moved much less than that, the stones moved an average of a few inches per second, or slower than your average turtle. The discovery lends another meaning to the whimsical name behind Racetrack Playa.