Unsolved mystery of Racetrack Playa, where rocks sail

New Delhi: The Racetrack Playa in California is a place of stunning beauty and mystery. The Racetrack is a playa--a dry lakebed--best known for it's strange moving rocks. No one knows how, but the stones there somehow manage to move from their original position, leaving a track behind them. The reasons are still unknown and are subject of research. It is supposed that the winds in the valley are “responsible” for this.Although no one has actually seen the rocks move, the long meandering tracks left behind in the mud surface of the playa attest to their activity. Some of these rocks weigh several hundred pounds and have traveled as far as 1,500 feet, which leaves us with the question: "How do they move?"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.Despite a century of scientific investigation, this curious phenomenon has confounded the geological community and park visitors alike. To this day, no one has ever seen the rocks move. But in lieu of eyewitnesses, countless theories have been put forward over the years in an effort to explain the reasons behind the migrations.One early suggestion was that the rocks were driven by gravity, sliding down a gradual slope over a long period of time. But this theory was discounted when it was revealed that the northern end of the playa is actually several centimeters higher than the southern end and that most of the rocks were in fact traveling uphill.Some people have suggested attaching radio transmitters to the rocks or erecting cameras to catch them “in the act” in order to put an end to the speculation. But as Death Valley National Park is 95 percent designated wilderness, all research in the park must be noninvasive. It is forbidden to erect any permanent structures or instrumentation. Further, no one is permitted on the playa when it is wet because each footprint would leave an indelible scar.