Death Valley's mysterious 'dancing rocks' controlled by ice and wind
Friday, September 5, 2014, 7:10 PM - For years, scientists were baffled over the mysterious 'dancing rocks' in Death Valley, which seem to move great distances on their own -- but a new study in PLOS One has shed some light on the matter.
The rocks have been known to carve out trails longer than football fields.
"The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s," the study's authors write.
"Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action."
There were a few theories about what was causing the rocks to move, which range in size from pebbles to boulders.
Some scientists believed it was strong winds that set the rocks in motion while others pointed the finger at aliens.
This past December a team of researchers set up GPS trackers and time-lapse photography equipment in Death Valley National Park, which is east of the Sierra Nevada in the U.S.
On December 20 they were able to film more than 60 stones moving at speeds of 2 to 5 metres per minute.
"Some instrumented rocks moved up to 224 metres between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, 'windowpane' ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light."
Researchers believe that floating ice panels on the surface push the rocks along trajectories determined by the direction and strength of the wind.
The complete study can be read online at PLOS One.