The Racetrack, is a playa (dry lake) with "sailing stones" that leave linear "racetrack" imprints; the process has never been observed. Sailing stones are most likely moved by strong winter winds, reaching 90 mph, once it has rained enough to fill the playa with just enough water to make the clay slippery. Playa is 3608 feet (1130 m) above sea level, and 2.8 miles (4.5 km) long (north-south) by 1.3 miles (2 km) wide (east-west). Also exceptionally flat and level with the northern end being only 1.5 inches (4 cm) higher than the southern. Nelson Range in background. Death Valley National Monument Est. February 11, 1933. Est. as Death Valley National Park in 1994; 5,270 square miles (13,649 km2). Inyo County, CA.