View of Racetrack Playa from Ubehebe Peak.

Racetrack Playa occupies the south end of Racetrack Valley at an elevation of just under 4000 feet. Its surface consists of light-gray mud that when dry, is cracked into countless small (5 cm to 10 cm wide) polygons. Numerous blocks of limestone lie near its south end, each of which has a track indicating that it slid across the surface. Although nobody has yet witnessed this phenomenon of "sliding rocks", various studies call on strong winds with or without ice as explanations. Most recently, Reid and others (1995) suggest that strong winds caused movement of a gigantic ice raft. They found that the beginning parts of tracks for widely separated rocks were nearly identical and reasoned that the rocks were bound together by a sheet of ice. This ice sheet then "floated" over the surface during high winds and caused the embedded rocks to scrape tracks into the playa. As the ice sheet broke up, different parts could moved in different directions. Consequently, the ending sections of tracks tend to vary.