Every now and then, nature does something that's inexplicable. In the case of the moving rocks at the Racetrack playa in Death Valley National Park, rocks at the southeastern section of the dried lake bed leave tracks, some stretching for a quarter mile. At first, this would seem to be made by humans because - of course - rocks don't move by themselves. But when standing on the rock-hard lake bed, the surface is almost impenetrable. So, how do the rocks make their tracks? Nobody knows...for sure. The most likely cause is a sequence of events that is something akin to the revealing of a magic trick.
First, the stones naturally tumble off the mountains that surround the lake bed. Although Death Valley is the driest spot in North America, the Racetrack does receive a small amount of rain in the winter months. The lake bed fills with a shallow layer of water which them freezes, trapping the rocks in a large, thin sheet of ice. As temperatures warm in early spring, winds are thought to move the ice sheets with the rocks still frozen in place. The rocks make contact with the now softened lake bed, creating scars or "tracks" in the lake bed. Once dry, the lake bed rehardens, capturing the scars for years to come. The effect is other worldly - sometimes making the rocks appear as though they are racing and sometimes crossing each other's paths.