The Secret of Rolling Stones (USA)
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The Secret of Rolling Stones
The gravel access road to the Racetrack doesn't require a 4WD vehicle for clearance, but the sharp rocks along the road require that vehicles have heavy duty all-terrain tires -- usually available only on 4WD vehicles -- to avoid the very real threat of multiple flats.
The Racetrack Playa is a fragile area, so please do not walk on the Racetrack when it is wet to avoid leaving deep, muddy footprints. Do not pick up, move, or remove any of the rocks on the Racetrack.
Visiting the Racetrack during the heat of summer from mid-May through late September is not recommended unless one is fully prepared with two gallons of water per person and extra food.
Never before could any human being watch these stones move! Rocks in Californian Death Valley seem to change positions over night! Latest research results explain what makes these rocks move…
Death Valley is a national park and is also home of a mysterious phenomenon: Rocks at Racetrack Playa are self-moving! Some of them appear to move up to 4.5 miles per hour – faster than normal pedestrians (No proven fact! No one knows how fast the rocks move, but it has been speculated that they may move as fast as 4 or 5 miles per hour!). Some rocks weigh 350 kilograms and leave visible stress marks in the desert sand. For years scientists have been puzzling about what causes the migration and why the rocks move in different directions: upward, downward, zigzag and in pairs. What is also curious: in front of some marks you do not find a rock at all. Maybe wind? Magnetism? Smooth sheets of ice in winter? A recent expedition of NASA scientists could have solved this mystery.
Sometimes we use supernatural or alien theories to explain phenomena we don't understand. In the 1960s, UFO fans suggested that aliens move these rocks to communicate. A moot question. Did E.T. arrive home?
Mischief… from an academic point of view. Many theories draw on weather and wind which that make stones roll. But you will need wind speeds of 500 mph to move these heavy stones. Hurricane Katrina only reached 190 mph! “Wind” does not seem to be the right idea.
To catch rocks in the act of moving, scientists have suggested setting up cameras for observation. Durable installations are prohibited because Death Valley is a listed area, and 91 percent of it is still intact wilderness. Furthermore, it is not allowed to enter when it rains because footprints could cause everlasting changes of the area's surface.
Since 1948, scientists have been investigating these rambling rocks. They got to be friends and named them after women. For one, the biggest chunk which moves 18 meters in one month is called Karen. Diane is fastest and moves 880 meters a month.
One of the first scientists who camped out at this high plateau was Thomas Clement, a geologist. In 1952, he tried to solve this mystery, but he could not leave his tent because of heavy storms and rainfalls. The nNext morning he found fresh sand marks, and something important attracted his interestattention: The rainstorm left a slippery water film at this section. Could this be a kind of lubricating film for rocks? But Clement could not explain why rocks moved in different directions, leaving zigzags and even circular marks.
Geologist Bob Sharp accomplished some analyses at Racetrack Playa between 1968 and 1974. During this time he had been following 30 different rocks. He did not catch the rocks while moving, but he noticed changes in their positions. His conclusion: Certain weather conditions (slick floor and stormy nights, for example) bring cause stones to move up to one meter per second! His report contained another curious hint: “I can’t explain it myself, but seven rocks completely disappeared!”
Also, Paula Messina, a geologist from San Jose State University, analyzed the sliding rocks. For five years she had been mapping all 162 stones using a GPS device. She found that neither size or weight nor the form of the rocks could predict how far or which direction rocks move. She guesses that water flowing down from the mountains water (particularly after heavy rainfall) carries particles of clay to the Racetrack and makes it greasy. In addition, heavy winds (up to 60 mph) could make the rocks move. In her dissertation she writes: “A fascinating conclusion: There is no conclusion!”
Will Sensors shed Light on it?
Recently, 17 scientists and students under the special direction of NASA scientists examined the Racetrack phenomenon. They got special permission to spend the night in Death Valley. They analyzed GPS data and so-called Hygrochrones which measure wetness and temperature. NASA scientist Gunther Kletetschka burrowed these sensors into the ground months before starting this expedition. Examinations showed a layer of ice in March which put stones in position to glide. This "ice thesis" also explains why big and heavy rocks move more than smaller ones: Once on the move they do not brake as fast as small rocks do.
Above all, the "ice thesis" illuminates the mysterious disappearances of rocks: When ice is melting, rocks settle down in sand. The scientists determined that not only ice is responsible for the “rolling stones,” but also alga, clay, wind, and rain. How factors work together is still a mystery. Paula Messina does not believe in this theory because they did not find any traces of ice. Analyses in laboratories should bring some clarification now. Scientists have received permission to examine the sand of Racetrack Playa at university labs. To be continued…
To claim this earthcache, send a picture of yourself and/or your group at Death Valley's Racetrack and tell the cache owner how many rocks you found and what you think is reason for the “rolling stones” phenomenon.
(No hints available.)
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Coordinates are in the WGS84 datum