Mystery of Death Valley’s rolling stones solved
‘Magic’ force behind rocks has been a mystery for nearly a century
Stones, weighing as much as 700lbs, can move hundreds of metres
Scientists now say they move due to mix of rain, wind, ice and sun
The lake fills with water which must be deep enough for floating ice
This creates ‘windowpane’ ice which is thin enough to move freely
On sunny days, ice begins to melt and break up into floating panels
Light winds drive across the dry lake, pushing rocks in front of them
WHAT CAUSES DEATH VALLEY’S ROCKS TO MOVE?
Scientists now believe the ‘magic’ force that moves the rocks is in fact due to the perfect combination of rain, wind, ice and sun.
First, the playa fills with water, which must be deep enough to form floating ice during cold winter nights but shallow enough to expose the rocks.
As night-time temperatures plummet, the pond freezes to form thin sheets of ‘windowpane’ ice, which must be thin enough to move freely but thick enough to maintain strength.
On sunny days, the ice begins to melt and break up into large floating panels, which light winds drive across the playa, pushing rocks in front of them and leaving trails in the soft mud below the surface.