The sliding rocks of Racetrack Playa in Death Valley, California have mystified and delighted visitors for decades ( previously ). Now planetary scientist Ralph Lorenz and colleagues think they've figured out how the rocks get around: ice rafts float the rocks out of the mud, reducing friction enough that modest winds can push them along (PDF of Lorenz, Vol. 79, 1 January 2011). Ralph Lorenz spends most of his time studying Saturn's moon Titan and often looks to Earth's geology for clues. Racetrack Playa's surface resembles a dry lakebed on Titan , so it's easy to see how Lorenz and his colleagues got interested in the mysterious sliding rocks. (To date nobody has actually seen the rocks in motion, since they only move every few years for a few seconds at a time.)Don't miss the low-tech experiment in the AJP article - in addition to theoretical calculations the authors provide experimental evidence in support of their theory using a small rock, a Tupperware container of water, a baking sheet filled with sand, and a home freezer (p 39 - 40). High school science fair project, anyone?