The Mysterious Sailing Stones

In the northwest section of Death Valley there is a place of greatest mysteries on earth called the Racetrack, where rocks ranging in size from mere pebbles to half ton boulders that regularly move without human or animal intervention in long tracks along a smooth valley floor. This Sailing stones phenomenon is documented by scientists since the 1940s, early studies of the Sailing Stones began when geologists Allen Agnew and Jim McAllister mapped the area and noted the tracks left by the boulders in 1948 however the force behind their movement is not confirmed and until now is still the subject of research.

The Racetrack is a mere two inches higher on the north end than the south. Flat as a pool table. The surface is sun-baked mud, hard as rock, and patterned in polygons the size of doughnuts, about about three miles long (4.5 kilometers) and a mile wide (2 kilometers).

Some Sailing stones made straight paths, some curved. Some traveled a hundred yards (90 meters) in one direction, stopped in a muddy muddle, apparently thought better of their direction, and made a 180-degree turn to ramble off in another direction. Some trails were wide for a while, narrow, then wide again. Occasionally, half a dozen rocks took off at once from the base of the mountain and seemed to race straight toward the Grandstand like horses at the derby. The tracks often crossed one another.

In 1968, two scientists from the Institute of Technology in California, Robert Sharp and Dwight Carrey conducted an ambitious study tracking the stones that involved painstakingly mapping their movements by noting their positions at regular intervals.

In 1972 they explain the process. The playa receives three to four inches (eight to ten centimeters) of rain a year during winter storms and summer cloudbursts. Parts of the Racetrack flood. Intensely slippery clay settles, and the winds, which may reach 90 miles an hour (40 meters per second), must overcome the forces of friction for the rocks to break free. Once that happens, it takes only about half the wind power to keep the rocks moving.

Their theory was widely accepted until 1991, when another geologist studied the enigmatic stones and brought his students to test the validity of the earlier researches. This time, John Reid from Hampshire College in Amherst, Massachusetts and a group of students converged on the stones en masse, during a time where the weather conditions matched those stated in the 1968 study. Reid and his students attempted as a group to push, shove and/or pull the rocks with ropes. Yet nothing could budge them and despite their valiant efforts, the rocks remained stubbornly immobile.

One of the factor that the previous explanations could not account for is that footprints made on the surface of the wet, muddy plain would typically be visible for years, and no tracks except for the ones made by the rocks have ever been found on the playa. Another theory, that earthquakes might move the rocks, has also been dismissed, since all quakes in the area are recorded, and none has coincided with new tracks being made by the rocks.

To date, there’s no film of the sailing stones, though several scientists have tried to capture their movement. The rocks don’t move every year, which complicates the effort, but nevertheless, several teams of scientists plan to set up camera equipment on the plain.

Sources:
http://en.wikipedia.org/wiki/Sailing_stones;
http://en.wikipedia.org/wiki/Death_Valley;
http://ngm.nationalgeographic.com/2007/11/death-valley/cahill-text/1;
http://www.scienceillustrated.com/nature/2011/11/sailing-desert-stones;
http://scienceray.com/earth-sciences/geology/the-mysterious-sailing-stones/
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Written By Tripzibit on Sep 18, 2012 | 19:37

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