Death Valley National Park in California and Nevada is known for its beautiful desert vistas, sand dunes, deep valleys, and extremely hot weather. It is also known for rocks that seemingly move on their own. These ambulatory rocks have been the subject of much debate and mystery, so much so that they have been named the “Sailing Stones.”
The Sailing Stones can be found in a dry lake bed known as Racetrack Playa. They were first observed in the early 1900s by prospectors and other travelers who spent enough time in the lake bed to realize that a number of rocks, some of them quite large, were moving during the night. Word about the rocks began to spread and by the middle of the century a combination of curious onlookers, supernatural buffs, and legitimate scholars made their way to Racetrack Playa to see the phenomenon for themselves.
Everyone was surprised to see that rocks as big as humans sometimes moved hundreds of feet at night, in straight lines, curves, and even at right angles.
Few people could offer any explanation and no one ever actually saw the rocks move. But it wasn’t long before people did start offering solutions to the mystery of what has become known as the Sailing Stones. Among the more reasonable-sounding explanations were gravitational and/or magnetic forces from the earth that were concentrated in the valley due to its salinity. Others thought that the winds coming into the valley were moving the rocks.
When those theories proved to be untrue, many thought the rocks were being moved by pranksters, but the park rangers pointed out that it would be difficult to do so since it was such a remote area of the park.
Of course, when all else fails, blame it on aliens!
Then, a number of scientists began noticing that the Sailing Stones only moved at night and during the winter when the desert can get fairly cold. Even under those conditions, the rocks only move about once every three years. By the 1970s, scientists began theorizing that the rocks were actually being moved by large, but thin ice sheets that melted when the sun rose —a process known as an ice shove.
In 2006, NASA scientist Ralph Lorenz decided to test this theory at home. According to Lorenz, he “took a small rock and put it in a piece of Tupperware, and filled it with water so there was an inch of water with a bit of the rock sticking out.”
Lorenz then put the container in the freezer, and the rock consequently became embedded in a slab of ice. After taking the slab of ice out of the freezer, he gently blew on the rock, which moved it, leaving a trail. It seems that the Sailing Stones were moved by a combination of ice sheets on seasonal water blown by slight winds.
This theory was finally confirmed by GPS and time-lapse photography in late 2013 and early 2014. Recorded footage showed more than sixty rocks moving, some as far as seven hundred feet, in just a sixteen-minute span.
It seems the mystery of the Sailing Stones has finally been solved. But, as park ranger Alan van Valkenburg has said regarding park visitors who ask him about the rocks, “If you try to explain, they don’t always want to hear the answers.”