Decoded the walking stone in the Death Valley

The phenomenon of stones moving in the death valley area is a mysterious problem that has not been answered during many years. Many hypotheses have been proposed to explain the phenomenon of mysteries including the impact of magnetic fields or even the work of aliens. Until recently, a team of researchers at Scripps Institution of Oceanography at the University of San Diego had a satisfactory answer to the strange phenomenon. The results of the research have just been published on the page of PLoS Community Science Library.

>>>Decipher the mystery of the "run" rock in Death Valley

Death Valley (Death Valley) is a long and narrow valley in the eastern part of the Mojave Desert, California. This is also the region with the lowest terrain, the dry and hottest climate in North America. Prominent here is a dry lake, large area with stones (up to 320kg can) capable of moving and leaving behind it the long streaks on the cracked ground.

Many theories have been proposed to explain the movement of rocks as a result of magnetic fields, whirlwinds, slippery algae layers, thin ice, or even the immobilization of an alien creature. Land. However, no one has confirmed these hypotheses and no one has actually seen the stone moving. Hypotheses are still controversial and this is considered one of the mysterious phenomena that science still cannot explain.

Therefore, with the goal of finding a satisfactory explanation for this phenomenon, a team of researchers at the University of San Diego decided to conduct scientific research on an unprecedented scale. Since the winter of 2011, the team has placed a meteorological station with high accuracy and reliability to measure wind power at intervals of 1 second. At the same time, the group brought here 15 stones equipped with GPS navigation system to serve the research.

In the beginning, extremely few moving rocks made scientists judge that the research could be up to 10 years or even longer. However, luck came unexpectedly. In December 2013, two leading researchers, Jim Norris and Richard Norris, surveyed the reservoir area in the dead valley. At that time, the lake was flooded with water with a depth of about 7cm. Richard said: "At noon on December 21, 2013, the only time in the day when the ice on the lake melted. We heard the crackling and popped tires all over the surface of the shallow lake . I shouted to my partner that this is the cause ".

From the above observation, the researchers found that the movement of the rocks required a perfect combination of many different events.

1. First, the surface of the valley must be covered with a water of sufficient depth to form a floating ice layer during the winter but there is still enough shallowness for the stones to rise up into the air.
2. When the temperature drops at night, the shallow lake will close a thin layer of windowpane ice above, still liquid water below. The amount of ice will then thicken to give it enough stiffness and enough force to push the rock, but it must still be thin enough to be able to move freely (in the next step). At that time, the stone will be surrounded by a thin layer of ice above, part of the rock is raised, the rest is submerged in water.
3. Finally, when the sun gradually appears, the ice will melt and crack into pieces. The ice sheets will be pushed by the gentle winds on the surface of the shallow lake and push the stones along.

Surprisingly, the above movement is quite gentle and does not need to use much force: Each sheet of ice is only 3-5mm thick, moved by the wind with a speed of 3-5m / s and push the stones away at a rate of several inches per second. At this rate, it is almost impossible for humans to see unless approaching closely to observe. Jim said: "Maybe, when tourists come here, movement is happening in a very subtle way but the problem is they don't feel it. Recognizing a moving stone is quite difficult. towels, partly because all the stones around it are moving too. "

Although most mysteries have been answered, there is still a question to be solved."We have recorded five movements over a two-and-a-half-month period in low-lying areas with the movement of hundreds of stones. Therefore, we have the right to conclude that the tapes, " Richard said . floating is the strong driving force for the stones in the dead valley to move , however, we still have not seen large sized stones moving, do they also move in this way? will be done to fully explain the last question on ".