The Mystery Behind the Sailing Stones of Death Valley

Sailing stone in Racetrack Playa

Death Valley National Park in California is home to a place called The Racetrack Playa. The Racetrack is a dry lake situated 1130m above sea level, and even though it is 4.5km long, the ground is surprisingly flat, with only a 4cm height differential between the north and south ends. The mountains surrounding the Racetrack, comprised primarily of dark dolomite, reach as high as 1731m above the lake bed. When the heavy rains come, water rushes down the mountains and onto the lake bed, forming a shallow endorheic lake. Due to the hot temperatures of the region, the water evaporates, leaving behind a layer of soft mud. When the liquid fully evaporates, the ground cracks and leaves a mosaic pattern behind. While all of this is interesting, the feature that makes this area truly unique is something that has yet to be fully understood by the scientific community.

Image: Dan Mayer

Sailing Stones in Racetrack Playa

Over time, stones have fallen from the mountainsides onto the lake bed. Some of the stones are small, though others weigh as much as 700 pounds. Once they are situated on the incredibly flat surface, one might be inclined to think that they would sit undisturbed for thousands of years. This, however, is not the case. These gigantic rocks and boulders (known as Sailing Stones, Sliding Rocks, or Moving Rocks) are found all over the dry lake bed with long trails, or racetracks, having formed behind them, extending for hundreds of meters. Since there is no evidence of human or animal intervention in the movement of these stones, one has to wonder how the phenomenon is happening.

Image: Daniel Mayer

Large sailing stone

Not only to the stones move, but they move in completely different directions. Two stones could start next to one another, and start moving at approximately the same speed, but one will suddenly stop or change directions. Sometimes the sailing stones will turn around completely, moving back towards their point of origin. The tracks left behind are generally no wider that 30 cm, and less than 2.5cm deep. The longest tracks have been forming for numerous years, though to date, nobody has ever witnessed the event.