Longest "sailing stone" trails

The Racetrack Playa in Death Valley on the Nevada-California border (USA) is famous for its bizarre "sailing stones". The flat surface of this dry lake bed is home to rocks that seemed to have moved across the ground without human intervention, leaving trails in the dried surface. No one has seen these rocks move, but monitoring results published in 1996 revealed that a rock nicknamed "Diane" had left an 880-m-long (0.5-mile) trail.

In November 2012, a team from the University of Santa Barbara (USA) placed GPS receivers on rocks at the Playa in order to measure movement. Over the course of the next year they discovered that the rocks were moving owing to a phenomenon known as "ice shove". This happens when rafts of floating ice are pushed by wind, in turn pushing the rocks gradually along the surface.