Bottom of the California travel firms established a cash prize for anyone who can solve the mystery of the crawling stones in the American Death Valley. The company promises to pay out $ 7,500
In the valley there is a dry Lake Racetrack Playa, on the smooth bottom of which huge boulders move by themselves. Rock fragments of various sizes and weights move across a large area completely devoid of vegetation, leaving behind clearly visible traces. The trajectory of the stones can be either straight or winding, and they move at different distances
Since the middle of the twentieth century, scientists have been researching this phenomenon, trying in vain to figure out the mechanism of movement of stones. It is known that in the area of the lake there are strong winds reaching a speed of 145 km / h, and its surface freezes in winter - the ice thickness can be 6.5 cm. There are also floods caused by rainstorms, and, moreover, so much unexpected and strong that often lead to tragic results. Perhaps that is why tourists do not come to Lake Racetrack Playa very often - mainly to take pictures against the backdrop of the famous crawling stones.
Recall that at the beginning of the 20th century, scientists tried to explain the phenomenon by the presence of magnetic fields, but this version had nothing to do with reality, Membrana reports.
The first scientific works describing the trajectories of stones appeared in the late forties - early fifties of the twentieth century. However, this did not help to find out the nature of the movement: all the researchers could do was to come up with many new hypotheses, and some of them were very difficult.
Scientists almost unanimously argued that this strange phenomenon is associated with the stormy rains that occasionally occur in Death Valley, as well as the following floods and everything else that is connected with this.
Most of the concepts about the movement of these stones (as they were called: traveling, crawling, floating, moving, sliding, dancing) converged on some common points. So the researchers were able to identify a number of factors that clearly contribute to the movement of blocks.
The first factor is a rather slippery base under the stone, in other words, dirt. This argument is supported by at least the shape of the track. The paths that the stones leave behind have a clear shape with smooth edges, which means that at first the soil was soft and only then froze.
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But a slippery base is only a condition for mobility. And the main factor due to which the movement begins is the wind, which pushes the stones lying on the slimy clay.
However, not everyone supported the idea of the wind at that time. Geologist George Stanley of the University of Michigan believes the rocks are too heavy to be propelled by air masses.
The idea was put forward that the wind was pushing not the stones themselves, but also the pieces of ice that grew on the boulders, and played the role of a kind of sails, increasing the area of contact with the atmosphere. At the same time, it was assumed that ice makes it easier to slide through the mud.
In addition, there were also considerations that earthquakes could influence the movement of stones. However, this conjecture was quickly rejected, since seismic activity increases in that area extremely rarely, moreover, it is very weak in order to demonstrate such an effect.
In 1972, Robert Sharp, who became famous, by the way, as an expert in the field of geologists of the surfaces of the Earth and Mars, together with Dwight Carey made a breakthrough in the study of this anomaly. For six years, they tracked the movement of stones and learned a lot of interesting things about this phenomenon. Most importantly, they figured out that ice has nothing to do with movement.
Sharpe and Carey, after analyzing the data obtained, created a kind of rough model. According to her, in the rainy season, water accumulates in the deepening of the lake, and also its huge volumes merge into it from the slopes of the surrounding mountains.
This causes flooding, due to which the hard clay soil is soaked so much that the coefficient of friction drops sharply. As a result, even Karen, one of the largest stones, weighing about 350 kilograms, can move under the influence of the wind and travel some distance.
According to the concept, the movement of stones did not begin during a downpour, but after it - after all, it took some time to soak a fairly hard and completely dry surface.
The source of the stones is a dolomite hill in the south of Racetrack Playa and volcanic rock from the adjacent slopes.