The Racetrack Playa

Perhaps the most mysterious of any of the features of Death Valley are the "moving rocks" of the Racetrack Playa. The playa is a three-mile-long dry lake bed which sits at an elevation of 3,708 feet. The lake bed itself is extremely flat and smooth and contains no vegetation. Surrounding the playa are rugged mountains which not only drop rocks onto the valley below, but also help channel strong winds through the valley.

Rocks on the valley floor, some as large as 700 lbs, have carved deep tracks into the surface of the lakebed, indicating that they've been moved. Since no one has actually seen these rocks move, it's a bit of a mystery. Glazner's coauthor, Robert Sharp, professor of geology at the California Institute of Technology, has worked extensively on this question.

There are two main theories about how these rocks move across the playa. A theory that Sharp helped develop is that wind, along with a wet and very slippery surface, was enough to move these rocks. Sharp recorded the locations of the rocks and their movement over the course of a year. Sharp also recorded the weather conditions after each move. His study found that all of the rocks move in the direction of the prevailing winds. He also found that some stones move hundreds of feet in one move .