The sailing stones of California’s Death Valley National Park is a fascinating phenomenon, traveling along the desert with seemingly no outside intervention.
For so long, no one has ever witnessed its movement, the trajectory is undeniable with its trail etched into the surface of the dried lake bed known as the Racetrack Playa. These trails — some stretching for as long as 860 feet — can persist for years on the desert floor, evidence of some unknown force moving the rocks on the remote and empty Death Valley.
The only question is, how?
Speculation over the mysterious sailing stones phenomenon has ranged from hurricane winds to aliens. The explanation is much more amazing though, if only for the “perfect storm” necessary to create the conditions necessary for the sailing rocks to occur.
According to a report from Gizmodo, the stones “are actually being pushed around by delicate sheets of ice skating on sand.”
A team of scientists searched for answers about the decades-long mystery of Califonia’s Death Valley sailing stones by setting up cameras and GPS, tracking the rocks on the site. It took years, but in December 2013, the perfect storm of ice and wind finally allowed the researchers to capture the phenomenon on camera and find out its cause.
The rare combination of events that causes it begins with the playa filling with just enough water to create floating ice but leave the rocks exposed, according to a report from Scripps Institute of Oceanography.
During cold winter nights, this pond freezes to form sheets of ice that are thin enough to move but thick enough for strength. Then on sunny days with warmer temperatures, the ice sheets break. Winds cause it to drift around the lake bed and behind the rocks, eventually driving it forward and leaving the mysterious trails behind that people see. The study was published in the journal Plos One back in 2014.
There’s a catch though: the largest boulders didn’t move at all during this event, so there could be another reason behind their movements. Maybe aliens really are behind the sailing rocks after all?
“People always ask, ‘what do you think causes them to move?’ But if you try to explain, they don’t always want to hear the answers,” Ranger Van Valkenburg told the Smithsonian. “People like a mystery 0– they like an unanswered question.”