Holiday Cycling Adventures - Panoramic Picture - 2005 - The Racetrack (Death Valley National Park)

Racetrack Playa is a seasonally dry lake (a playa) located in the northern part of the Panamint Mountains in Death Valley National Park, California, U.S.A. that is famous for rocks that mysteriously move across its surface.

The playa is nestled between the Cottonwood Mountains to the east and the Last Chance Range to the west. During periods of heavy rain, water washes down from nearby mountain slopes onto the playa, forming a shallow, short-lived lake. Under the hot Death Valley sun, the thin veneer of water quickly evaporates, leaving behind a layer of soft mud. As the mud dries, it shrinks and cracks into a mosaic of interlocking polygons.

The playa is 3708 feet (1130 m) above sea level, 2.8 miles (4.5 km) long north-south, and 1.3 miles (2 km) wide east-west. It is also exceptionally flat with the north end being only 1.5 inches (4 cm) higher than the south. Two islands of bedrock poke above the playa's surface at its north end. One of the above panoramic pictures is taken from the top of one of these islands.

Most of the so-called 'sailing stones' are from an 850 foot (260 m) high hillside made of dark dolomite on the south end of the playa, but some are intrusive igneous rock from adjacent slopes (most of those being tan-colored feldspar-rich syenite). They have never been seen or filmed in motion and are not unique to The Racetrack. Similar rock travel patterns have been recorded in several other playas in the region but the number and length of travel groves on The Racetrack are notable. Tracks are often tens to hundreds of feet (low to high tens of meters) long, a few to 12 inches (8 to 30 cm) wide, and typically much less than an inch (2.5 cm) deep. Racetrack stones only move once every two or three years and most tracks last for just three or four years. Stones with rough bottoms leave straight striated tracks while those with smooth bottoms wander. Stones sometimes turn over, exposing another edge to the ground and leaving a different-sized track in the stone's wake.