In Death Valley Nationa Park, surrounded by the Cottonwood and Last Chance Mountains, lays the playa or dry lake bed of Racetrack Playa. At the north end of the Racetrack Playa is an outcrop of quartz monzonite that, if you use your imagination can be a grandstand for a race track of the lake bed. This playa is famous for the mysterious moving rocks. There have been many explanations as to how they move, a recent research project has suggested that it is a rare combination of changing temperatures, rain, wind and ice that move the rocks. The playa surface is easily damaged when wet, footprints and other man made marks can take many years if not hundreds of years to erase. The road to the playa is rough requiring 4-wheel-drives to travel to and had limited tourist damage. Recent 4x4 rental companies now rent these vehicles and the playa is now subject to more damage. Tire track and footprints mar the playa and the moving rocks have even been taken, man made fake tracks have started to apear.