[FunXone] Moving Rocks: Mysterious Phenomenon of Death Valley : FunXone eMails Collection

Racetrack Playa is a seasonally dry lake (a playa) located in the northern part of the Panamint Mountains in Death Valley National Park, California, U.S.A.. It is famous for 'sailing stones', rocks that mysteriously move across its surface.

The sailing stones are a geological phenomenon found in the Racetrack. The stones slowly move across the surface of the playa, leaving a track as they go, without human or animal intervention. They have never been seen or filmed in motion. Racetrack stones only move once every two or three years and most tracks last for just 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-sized track in the stone's wake.

The sailing stones are most likely moved by strong winter winds (up to 90 mph), once it has rained enough to fill the playa with just enough water to make the clay slippery. The prevailing winds across Racetrack Playa travel blow from southwest to northeast. Most of the rock trails are parallel to this direction, lending support to this hypothesis.