Visitors to Death Valley, whether in person or via the interwebs, have noticed a strange phenomenon that takes place with some of the Valley’s rocks- they seem to be moving across the valley floor.
The rocks in Racetrack Playa move slowly enough that you can’t see the movement happening, about 15 feet per minute, but the fact that they are actually moving is reconfirmed by the trails left behind in their wake.
People have been wondering for decades what makes those rocks move like that, coming up with their own theories ranging from sporadic hurricane-force winds, little rafts made of ice, or little grey men in UFOs.
Now, thanks to a lucky discovery made last December by Richard and James Norris, we finally have an answer- weather phenomenon that surprisingly has much more in common with an arctic climate than a desert.
As this handy chart, created by Javier Zarracina from the LA Times, illustrates these sailing stones are moving due to a unique combination of weather patterns- rainfall gathers on a shallow layer above the desert floor then freezes into sheets overnight. The sheets crack under the morning sun, then the breeze pushes the rocks along on top of the muddy surface.
So, the next time you're on a road trip through Death Valley and your group comes across these seemingly miraculous sailing stones you can explain the mystery away with science!