The California Valley of Death has attracted mystery lovers for a hundred years now - no one has been able to fully solve the riddle of its self-propelled stones. In their book Mysteries of the World: Unexplained Miracles and Mysterious Phenomena, Herbert Gentzmer and Ulrich Hellenbrand write: “Boulders of stones in an incomprehensible way move along flat, dry ground, leaving long furrows behind them. There is nothing around that could push stones. No one has yet been able to see with their own eyes how they move."
Not all stones in Death Valley are mobile. And those that move, do it every two or three years, and without any synchronization in time or direction. Judging by the tracks, some blocks make sharp turns (up to 90 °). The furrows themselves behind the stones stretch for tens of meters. Most of the movable stones are 15 to 45 centimeters in diameter.
To explain the mysterious phenomenon, scientists have proposed several theories. One of them is a hitherto unknown magnetic effect. However, this assumption had to be abandoned rather quickly, since no substances with magnetic properties, for example, iron, were found in the stones.
The most plausible, from the point of view of scientists, is an explanation based on the combined effects of wind, temperature and water contained in the soil. Despite the fact that Racerek Playa (the region of the valley where the phenomenon is observed) is the bottom of a dried-up lake, there is not so little water there. It accumulates on the surface during rains or as a result of snow melting on the tops of neighboring mountains.
Brian Dunning, a researcher from California, is confident that water collected on the surface of the soil can freeze during cold snaps, forming a thin ice crust. Dunning believes that the wind is quite capable of moving stones along such a "roller" for noticeable distances.
NASA specialist Ralph Lorenz performed a simple experiment to test Dunning's theory. The scientist placed a small stone in a saucepan and poured some water into it, so that its level did not exceed two or three centimeters. After that, Lorenz put the pan in the freezer and waited for the water to freeze. Next, the researcher took out the stone together with the ice from the pan and put it in a tray of sand. It turned out to be easy to achieve the movement of the stone on such a surface - it was enough just to blow on it. It is curious that in this case a furrow remained in the sand, similar to those that stretch behind the stones in the Valley of Death.
Although this explanation seems logical, so far no one can verify its truth, because for this you need to personally observe the movement of stones in the Valley of Death, or at least have videos of this process.
Indeed, it is not easy to organize observations in Racetrack Playa: not everyone is ready to fast for years at a temperature of 37 ° C in the hope of seeing a stone crawling on the sand. In addition, the site stretches 4.8 kilometers in length and 1.6 in width, and no one can say in advance exactly at which point the long-awaited event will occur. Imagine the face of a man who sat by a motionless boulder for two years and then learned that several stones in another part of Racetrack Playa had moved two hundred meters.
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Fortunately, there are technologies nowadays to make observations with less casualties. In 2013, a team of scientists managed to capture the movement of stones on video using GPS. The research results were published in the journal PLOS One.
However, this work could not fully reveal the secret of the "living" stones, because only relatively small boulders were captured on the video. And here is how real boulders move on the sand, so far no one has seen.
ALEX KUDRIN
