Sailing stones, sliding rocks, and moving rocks all refer to a geological phenomenon where rocks move in long tracks along a smooth valley floor without human or animal intervention. They have been recorded and studied in a number of places around Racetrack Playa, Death Valley, where the number and length of travel grooves are notable.
The stones move only every two or three years and most tracks develop over three or four years. Stones with rough bottoms leave straight striated tracks while those with smooth bottoms wander. Stones sometimes turn over, exposing another edge to the ground and leaving a different track in the stone’s wake.
Various and sometimes idiosyncratic possible explanations have been put forward over the years that have ranged from the supernatural to the very complex. Most hypotheses favored by interested geologists posit that strongwinds when the mud is wet are at least in part responsible. Some stones weigh as much as a human, which some researchers, such as geologist George M. Stanley, who published a paper on the topic in 1955, feel is too heavy for the area’s wind to move. They maintain that icesheets around the stones either help to catch the wind or move in ice floes.