In the few minutes before sunrise, the air was still, the temperature cool, and the rocks were motionless. I had spent the night near the Racetrack Playa of Death Valley to collect star photos. It was late March and, under clear skies at 3700 ft elevation (1126 m), the nights get cold. On this morning, the temperature was about 28 deg F (-2 deg C).
Vegetation is extremely sparse in this section of the park. Trees are non-existent, grasses and low brush are sparse on the hillsides, and the playa is only populated by rocks. These rocks remain stationary for years, decades, possibly centuries. Then, when conditions are right, the rocks move.
It is believed that when the playa is covered in water, the water freezes on a cold night, the wind pushes and moves the ice, and the ice drags the rocks that are frozen in it, creating tracks on the playa. On this morning, nothing moved.
