For almost a century, the Valley of Death, so far away, so beautiful and frightening of California, has had a mystery: it has stones that seem to move by themselves. This is happening at Racetrack Playa, an ancient lakebed now dry known for its “Moving Stones”. This effect occurs in some other parts of the world, although Death Valley is the most famous place. The mystery may have been solved, at least in part.
In their book “Mysteries of the World: Unexplained Wonders and Mysterious Phenomena“, Herbert Genzmer and Ulrich Hellenbrand state that the perfectly flat, dry soil is raked up to form paths that suggest that rocks have moved along the ground.There is no indication of how this movement could have been provoked, and no stone has ever been observed moving.
The truth is, not all the stones in Death Valley are moving. Some only move every two to three years, and not all of them move in the same direction or at the same time. In fact, some rocks appear to have made steep 90-degree bends, judging from tens to hundreds of metres in length. Most of the stones are not large boulders, but on the contrary, they have a diameter of about 15 to 45 centimetres on average.
Several theories have been proposed to explain this curious phenomenon, including some sort of localized and unknown magnetic effect. This theory has been dismissed for a variety of reasons, including that many stones do not contain significant amounts of magnetic elements such as iron, and that the stones do not go in the same direction. It has been suggested that strong winds in the area may displace rocks after the lakebed has become slippery, especially with rain or snowmelt nearby.
The most likely solution to the mystery is a combination of wind, temperature and water. Although Racetrack Playa is a dry lake, it is not always dry. Water accumulates on the surface after rainfall or when snow from the surrounding peaks melts.
Brian Dunning, a California researcher who spoke about this mystery in his podcast on Skeptoid, notes that when water is present and the temperature drops below freezing – as it sometimes is there – a thin layer of ice forms.
With the ice moving to the lake surface due to the inertia of all this surrounding glacial mass, it would have no difficulty pushing a rock along the muddy and slippery ground beneath the ice. Above that, as the wind blows, it pushes the ice that in turn pulls the rocks across the lake zigzagging and forming paths on the ground.
PD Photo/Wikimedia Commons
NASA researcher Ralph Lorenz was intrigued by the enigmatic stones while studying the weather conditions in Death Valley. He developed a simple experiment on “model” to demonstrate how rocks could slide to the surface of the not so dry lake.
“I took a small stone and put it in a Tupperware, filled it with water so that there was a few millimetres of water under the stone,”Lorenz explained to the Smithsonian Institution.
After putting the container in a freezer, Lorenz found himself with a small plate of ice in which the stone was buried. By placing the ice-bound rock in a large plateau of moist sand, all he had to do was to gently blow the rock over so that it would move through the miniature model. And as the rock moved, it formed a slight drag in the sand.
Also, technology has participated to study the mystery remotely. In 2013, a team of scientists installed motion-activated GPS devices on the rocks. In addition, real-time photographs captured the first video images of the stones slid into the desert floor.
However, and today, the mystery has not been completely solved. The video shows how the smaller rocks move, but no one has ever seen the gigantic boulders move a centimetre. All these are only hypotheses…