Moving rocks refer to a geological phenomenon where rocks move in long tracks along a smooth valley floor without human or animal intervention. They have been recorded and studied in a number of places around Racetrack Playa, Death Valley.
The force behind their movement is not confirmed and is the subject of research for which several hypotheses exist.For years, people have been puzzled by a peculiar phenomenon in Racetrack Playa, a desolate section of California's Death Valley. Big and small rocks seem to move spontaneously, gliding across the flat landscape and leaving behind trails. Some travel in pairs, tracking each other so precisely that they leave marks that appear to have been made by car tires. Others wander back and forth alone, covering the length of several football fields.
Some photos showing the kind of movement rocks make:
Some move in strainght line ,taking turns at after
Some move in strainght line ,taking turns at after
some interval.
Other move in completely random pattern.
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| Moving Rock |
What Makes Death Valley Rocks Move by Themselves?
Are They Moved by People or Animals?
The shape of trails behind the rocks suggest that they move during times when the floor of Racetrack Playa is covered with a very soft mud. A lack of disturbed mud around the rock trails eliminates the possibility of a human or animal pushing or assisting the motion of the rocks.
Are They Moved by Wind?
Another theory is that the rocks are moved by powerful winds that rage through the desert at night. In the 1950s, a researcher tried to simulate this effect with an airplane but was unable to move any rocks very far. In the late 1960s and early 1970s, California Institute of Technology geologist Robert P. Sharp built upon the wind theory by suggesting that the rocks required precise environmental conditions to move. The Playa floor is moistened by meltwater from adjacent mountains. Sharp theorized that it had to be saturated with a quarter to three-eighths of an inch of water, just enough to make the surface slick but not enough to make it soggy.
Sharp attempted to track the movements of rocks, which has never been observed in real time. He and a colleague from UCLA placed stakes near 25 rocks of various sizes and gave them names such as "Mary Ann" and "Irene."
As this 1977 Associated Press article details, Sharp found that from 1968 to 1975, all but one of the 25 rocks moved, including seven that moved more than 300 feet.
Are They Moved by Ice?
A few people have reported seeing Racetrack Playa covered by a thin layer of ice. One idea is that water freezes around the rocks and then wind, blowing across the top of the ice, drags the ice sheet with its embedded rocks across the surface of the playa.
Some researchers have found highly congruent trails on multiple rocks that strongly support this movement theory. However, the transport of a large ice sheet might be expected to mark the playa surface in other ways - these marks have not been found.
Other researchers experimented with stakes that would be disturbed by ice sheets. The rocks moved without disturbing the stakes. The evidence for ice-sheet transport is not consistent.
Wind is the Favored Mover!
All of the best explanations involve wind as the energy source behind the movement of the rocks. The question remains is do they slide while encased in an ice sheet or do they simply side over the surface of the mud? Perhaps each of these methods is responsible for some rock movement?
Perhaps this story will remain more interesting if the real answer is never discovered!
NASA Studies on Sliding Rocks
NASA sent a team of interns and mentors to Racetrack Playa during Summer 2010. They made observations, performed tests, compiled data and developed some ideas about how the rocks might move.Check out their report and photos.
In 1976 Dr Robert Sharp of the geology department of the California Institute of Technology wrote in the Bulletin of Geological Society of America and stated that:
The secret is to catch the play of wind and water at precisely the right moment.
Not everybody is convinced of this though… Two years after the results were published, there was a severe frost after a week of heavy rain. Surely this would ‘glue’ the rocks in place? In the morning they found that several rocks had moved.
If its not nature, what then can be the secret of these rocks?
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