Imagine finding a trail of enormous rocks stretching across a dry desert floor—yet no one saw them move.

For decades, the mysterious "sailing stones" of Death Valley puzzled scientists and visitors alike. Heavy rocks appeared to travel across the desert, leaving long tracks behind them as though something invisible had dragged them across the ground.

The Rocks That Move Across a Desert by Themselves explores the strange natural conditions that allow these rocks to move without people, animals, or machinery pushing them.

The mystery was eventually connected to a rare combination of water, freezing temperatures, thin sheets of ice, and wind.

After winter rain or snowmelt creates a shallow layer of water across the playa, nighttime temperatures can drop low enough for the water to freeze around the rocks.

When the sun r ...