WHY DOES THIS ROCK MOVE? [PIC]

25ive.com — One of the most interesting mysteries of Death Valley National Park is the sliding rocks at Racetrack Playa (a playa is a dry lake bed). These rocks can be found on the floor of the playa with long trails behind them. Somehow these rocks slide across the playa, cutting a furrow in the sediment as they move. Nov 23, 2008 View in Crawl 4