The Sailing Stones

   Sailing stones or sliding stones are mysterious phenomenon in which the rocks move through a smooth valley floor leaving tracks behind.They have been recorded and observed in and around Death valley and Racetrack Playa.The forces behind these rock movements are mysterious and they have not been found by research.
   The stones move only every two or three years and most tracks develop over three or four years.Trails differ in both direction and length. Rocks that start next to each other may travel parallel for a time, before one abruptly changes direction to the left, right, or even back the direction it came from. Trail length also varies – two similarly sized and shaped rocks may travel uniformly, then one could move ahead or stop in its track.