[quote= www.bbc.co.uk/news/blogs-news-from-elsewhere-28989520]Scientists have finally solved the mystery of how rocks can move across the flat ground of a dry lake bed in Death Valley, California. Visitors have long been puzzled by the sight of boulder tracks criss-crossing a dusty bowl known as the Racetrack Playa in Death Valley National Park. But two researchers now say the rocks - which can sometimes be heavy and large - are propelled along by thin, clear sheets of ice on breezy, sunny days. They call it "ice shove". "I'm amazed by the irony of it all," paleobiologist James Norris tells the LA Times. "In a place where rainfall averages two inches a year, rocks are being shoved around by mechanisms typically seen in arctic climes."