What You Need to Know About Those Moving Stones
Out in California's Death Valley, scientists have discovered countless rocks that seem to be moving on their own. Is it just an illusion? How is it happening? Find out more below.
First thing's first, where is it happening?
Above the northwestern part of Death Valley, there's a dry lakebed known as Racetrack Playa. It's here that scientists noted these peculiar rocks and went to take a closer look.
What's different about Racetrack Playa?Thomas Dressler/imageBROKER/Corbis
Racetrack Playa measures about two miles in width and three in length. Once an actual lake, climate evolution has rendered it thick and muddy, as seen here.
Why do scientists care about these rocks?PLoS ONE
It's not exactly common to find 700-pound stones moving around, on their own, no less. Scientists were interested to see what role nature has played in the phenomenon.
In 2011, scientists at Scripps Institution of Oceanography, UC San Diego began focusing on 15 rocks. They fitted each rock with a GPS unit and utilized a high-res weather station to monitor and measure gusts.
December 2013Louis Sahagun / Los Angeles Times
Scripps paleobiologist, Richard Norris, and his cousin, James Norris, a research engineer, came to Death Valley and saw that the lake was covered with about three inches of water. It wasn't long before the rocks began their journey.
The FactorsLouis Sahagun / Los Angeles Times
According to observations, scientists believe multiple natural components have to come together in order for the rocks to move, including the wind, sun, ice, and rain.
The Beginning of the ProcessDon Bartletti / Los Angeles Times
The lake fills up, though there has to be enough depth so that floating ice can formulate during the winter. On the other hand, the lake can't be too deep, as the rocks must be exposed.
As It ContinuesErik Harrison/National Geographic Society/Corbis
Even in the Valley, it gets colder once the sun goes down. As this happens, the lake will freeze and "windowpane" ice will begin to form. The sheets have to be thin enough to move with ease, but not too thin, so as to remain strong.
How does the sun affect it all?Don Bartletti / Los Angeles Times
The warmth of the sun causes the ice to melt and separate. Light winds move these slabs across the lake and rocks are moved in front of them. Underneath, this path is visible in the mud.
Prior to this explanation for the movement of the rocks, other theories were considered. Dust devils (similar to a tornado though generally harmless) and winds with the strength of a hurricane were mentioned.
How far did the rocks move and how quickly?Louis Sahagun / Los Angeles Times
The rocks were observed as moving about ten miles per hour under light winds, driven by ice that was too thin to grasp bigger rocks and take them off of the lake.
How often do the rocks move?
It's not uncommon for these rocks to have moved around a lot before they settled, so to speak. Rock-less paths were also noted. According to Ralph Lorenz, a Johns Hopkins University researcher, it's believed that 2006 was the last time the rocks moved, which means they "may move only about one millionth of the time."
How has time affected movement?Louis Sahagun / Los Angeles Times
Given the indication that cold nights are necessary for the rocks to be affected, Professor Lorenz believes the changing climate might have resulted in more seldom movement since the '70s.
Do we have all the answers?Gord McKenna
Despite having documented hundreds of rocks in multiple instances, Professor Norris reminds us, the "really big boys" haven't been spotted moving there. He wonders how they would move and how similar they would work.
Curious Rocks Around the World
The Valley isn't the only home to mysterious rocks. Archaeologists have been looking into the perplexing Stonehenge since at least the 17th century. In Finland, Kummakivi is a massive boulder set atop another large rock; the name means "Strange Rock." Ireland has "The Dead Man," a set of islands very closely resembling a large sleeping man. The Earth has countless other peculiarities, of course, these are just a few.