Sailing Stones, Racetrack Playa, Death Valley, CA
No one has ever seen one of the “sailing stones” on Death Valley’s Racetrack Playa move, but evidence of their travels is visible in the long track marks that trail behind them in the dusty ground. Scientists aren’t sure exactly how the rocks—which can weigh hundreds of pounds—make their way across the dry lake bed. The prevailing theory is that when the rocks are wet or icy, they’re pushed along the flat playa by strong winds. The deep groove marks they leave behind indicate they may travel up to 700 feet from their point of origin.