Who moves the stones of Death Valley?

On the almost flat ground of Racetrack Playa, in the Valley of Death, stones leave long traces. The furrows prove a movement, but observing this movement requires being present at the right time.

Observations have finally shown the role of a rare combination: a thin layer of water, thin ice that fragments, and a wind capable of pushing these plates. As the ice moves, it drags stones onto the wet ground.

The mechanism requires no invisible force or extraordinary gusts. It depends mainly on specific conditions that do not meet often. The puzzle came from this shift: the traces remained long after the small scene of ice, water and wind had disappeared.