Death Valley is the USA’s hottest spot. This remote desert landscape provides a perfect backdrop for science-fiction blockbusters such as Star Wars, but something stranger than fiction happens here. Heavy rocks inexplicably move around. From magnetic fields to alien activity, theories abounded. Finally, we know the truth.
Since 1948 scientific research has left no stone unturned. The breakthrough came in 2014, when stones were seen moving on camera. Floating ice proved to be the mischief-maker. On cold nights, thin sheets of ice develop, which then melt down into smaller pieces in the daytime sunshine. Wind pushes the ice along, carrying the rocks with it and depositing them elsewhere.
Rainfall creates a shallow pool in the playa, which then freezes over as the temperature drops. A swift rise in temperature breaks up the ice into smaller, floating sheets. Wind then pushes the ice sheets over the pond. Any rocks caught in the ice sheet are easily carried along by the buoyant ice, inscribing a trail in the mud as they go.