Deep in the Californian desert of Death Valley National Park lie mysterious rocks with what seems like supernatural moving powers. In an area on a flat dry lake bed, or playa, known as the Racetrack, these rocks have never been seen moving yet they leave traces, or tracks, behind them. They tumble down a mountainside and cover the far southeast corner of the 4.5-mile long playa and then, somehow, begin moving. According to the National Park Service (NPS),
“a research project has suggested that a rare combination of rain and wind conditions enable the rocks to move. A rain of about ½ an inch will wet the surface of the playa, providing a firm but extremely slippery surface. Strong winds of 50mph or more may skid the large boulders along the slick mud.”
NASA funded another program in 2010 that tested the consistency of the rocks, amount of water in the ground, temperature and air pressure, wind speeds, tremors in the earth and any other factors that may influence movement of rocks. The study confirmed that the playa rises less than 2 inches from one end to the other and arrived at the same conclusion as the one quoted above by the NPS. To read more about this study, visit the NASA website. Still, many questions were left unanswered. For instance, why do the bigger rocks (some are the size of microwaves and weigh more than 30lbs) tend to move farther than the smaller rocks?
One great read about a 1968 study that also tried to answer these questions is "Geology Underfoot in Death Valley and Owens Valley" by Robert Sharp and Dwight Carey. This study left another question unanswered: where do these rocks go? During the seven-year study, Karen, a 700lbs rock, simply disappeared. It was later found by a geologist in 1996!
Regardless of the answers (or maybe due to its mystery), the Racetrack is an impressive place and the approach to it is well worth the hassle. The nearest town to the Racetrack is Beatty, NV, two hours away from Las Vegas and still two hours away from the moving rocks. The last 26 miles of the approach are made up of a washboard dirt road that should only be attempted by a high clearance vehicle with good off-road tires. As is common in the desert, the difference between day and night temperatures is quite extreme. In winter night temperatures can drop into the teens (-8C) and rise during the day to over 70F (21C) and day temperatures in summer can get higher than 120F (49C). Maybe this is another factor that can help explain the mysterious forces acting on rock movements, but these conjectures are best left for the experts.