Even NASA could not yet explain it. These rocks just have been moving in the dry lake, Racetrack Playa, in Death Valley National Park. The bottom of the lake is almost flat, 2.5 km from north to south and 1.25 km from east to west, and covered with cracked mud. The stones slowly slide along the muddy bottom of the lake, as evidenced by long traces that remain of them. They move on their own without any help of others.