The road to the Racetrack Playa in Death Valley National Park is one long, brutal washboard past volcanic craters, Joshua Trees, and teakettles to a dry lakebed punctuated by a grandstand rock formation and sailing stones.

From an accompanying sign:

The rocks on this ancient lake bed move.

The moving rocks are something of a mystery. Scientists theorize that when this ancient lake bed—or playa—gets wet, it becomes so slippery that winds can move rocks weighing 100 pounds or more. Others suggest that winds move the rocks only when ice helps raft them along a temporary lake surface.

Lexi lives in a truck camper down by the river.