If you were unaware, in Death Valley National Park, there is a geological phenomenon in the Racetrack Playa called sailing stones– large rocks that lie at the end of a long trail in the ground (as seen in the picture above). Interesting in-and-of themselves, the stones recently received explanation this august after being left a mystery for the better part of the twentieth century.
Before now, it was unknown how the rocks moved long distances by themselves, as no one had ever witnessed it happening. All we had to go on were the trails the rocks left behind them. It has been speculated that the process the rocks go through happens so slowly as to be difficult to observe or test. However, it’s not as much slow as it is rare. For the stones to move, they require a very specific set of conditions. There needs to be a thin layer of ice in the playa (which is rare in the desert), the ice needs to be in the process of melting, and a shallow breeze needs to blow the ice and rocks along (at a slow rate).
The discovery is thanks to a team of scientists, that while doing maintenance on GPS trackers on some of the stones, noticed the layer of ice, and stayed to observe it. They captured a time lapse video of the rocks in motion, and published their findings in Plos One.Image Credit: “Racetrack Playa (Pirate Scott)”. Licensed under Creative Commons Attribution 2.0 via Wikimedia Commons