For more than 70 years, the stones of the Valley of Death (California), crawling from place to place, have been stirring the minds of scientists. And now, it seems, the veil of this secret has been slightly opened …
Death Valley Toys
There were many speculations regarding the wandering stones of the Valley of Death: magnetic anomalies, radiation, or maybe mysterious boulders just slide down the slope? But each of these versions failed miserably: the instruments did not detect magnetic or radiation deviations. the elevation difference in the valley is small, and most of the stones, oddly enough, crawled uphill.
The "wet clay" theory lasted the longest. The fact is that the Valley of Death is not at all seasons of the year a lake that has dried up to the bottom. From time to time, rains moisten the soil abundantly, the clay bottom becomes slippery, and stones can be moved by the wind. This assumption looked quite realistic, especially since the wind in these regions sometimes reaches a speed of 150 km per hour!
But here, too, there was a discrepancy. The fact is that in order to move some boulders (weighing several hundredweight), you need a mighty hurricane with a wind speed of up to 300 km per hour! During the entire observation period, such anomalies never happened, and stones weighing hundreds of kilograms suddenly moved several tens of meters, leaving a characteristic trace behind them.
So who is "playing with stones" in Death Valley? A group of students from various US universities literally settled in the waterless desert to uncover this secret, and it seems they succeeded.
After carrying out painstaking research, future scientists came to the conclusion that the driving force is … ice. It sounds paradoxical, since Death Valley is one of the "hottest" places on Earth! It was here that an abnormally high temperature was recorded in the Western Hemisphere - 56.7 degrees Celsius!
Promotional video:
But it turned out that it is not so hot and dry there. The sensors buried for a year in the ground showed that the soil here is wet in March and April, and in March the temperature of the lake bottom … falls below zero Celsius.
Blame … ice
The main source of water needed for the creeping rock phenomenon is the snow on the mountains surrounding the valley. In late winter - early spring, the snow melts, and the melt water forms puddles at the bottom of the lake, which freeze at night. If there is a stone in such a puddle, a “collar” of ice will form around it. Ice reduces friction against the ground, and when it is picked up by the flow of melt water, it plays the role of a raft, partially lifting the stone and reducing its pressure on the soil. Water currents hitting the "raft" can move and turn stones in a variety of directions.
The students also noticed that the grooves left by the boulders from the "start" to the "finish" get deeper. They explained this by the fact that the ice covering the stone melts as it moves and the stone carves a deeper furrow in the ground.
Ice can explain the riddle of lonely paths without a boulder at the end. Previously, scientists thought that someone was simply stealing some of the stray stones as a keepsake, despite the fact that the valley lies quite far from civilized places.
Now students claim that such paths could leave large blocks of ice with small frozen stones. After the ice melts, there will be practically no traces of the "traveler".
Ice can also serve as a kind of "sail". Researchers believe that with ice build-ups, even very large stones can budge under the influence of the wind that periodically sweeps over Death Valley.
It seems that the mystery has been solved. But … no one has yet seen or filmed the very process of moving stones!
Magazine "Secrets of the XX century" № 40. Konstantin Karelov
