You Could Not Make This Up

There is a (usually) dry lake bed in California's Death Valley called the Racetrack.  Since 19th Century pioneers pushed their tired oxen across this arid land, diaries and travel logs have told of large rocks that appear to have slithered across the sand.  The rocks left trails behind them dredged from the hard pan.  How could this have happened?  What force slid boulders hither and yon leaving no evidence of method but the trail in the sand. Theories have been offered.  Observations and measurements made.  But until last winter, the mystery remained unsolved.  Follow this link to NPR and read how it happened.  There is even a video of a rock on walkabout.  Go to the source if you want to know more.  The research is documented in PLOS ONE, a free-access journal for peer-reviewed work.