Sailing stones in Death Valley
How do they do it? and most importantly – why? Probably everyone has heard about these strange stones in the Death Valley. It is a natural national park in the state of California in the United States. The stones of this valley periodically move and in the literal sense crawl slowly, leaving an impressive trail behind.
The Indians of the tribe Mojave, the inhabitants of the desert of the same name which includes the park, were the first who paid attention to this amazing feature of the stones. These mysterious stones can walk in groups and individually, synchronously or in the different manner. Sometimes they come back and start moving in the opposite direction. The rocks weighing up to 30 kilograms move more often than the 300-kg ones. But even they can travel once every two or three years. Their traces are more distinct and deep than the traces of the smaller stones, and they are visible within three to four years.
The most incredible versions were examined by various scientists and enthusiasts – earthquakes, strong winds, and even evil spirits living in the stones. That version of the winds was a part the theory of two geologists. So these movements were a real mystery until the end of the 40s of the last century. Two American geologists were the first to put forth the theory explaining this phenomenon. The lowland, where the stones move, is located in the northwest of the park. This is the bottom of the dry lake Racetrack Playa, which fills up with water during the heavy rains. They believed that the stones were moved by strong winds, which could reach the hurricane speeds, and in combination with the fact that when the bottom of the lake was filled with water, it promoted to the stones’ movement. But the version wasn’t confirmed by various researches and special calculations.
A few years ago, Professor Ralph Lorenz and Professor Richard Norris made an experiment – set on the lake a meteorological station. It fixed everything – temperature, humidity, wind direction and strength. 15 stones were equipped with GPS-tracking devices to monitor their movements.
In December 2013, Richard and his brother Jim came to Death Valley and saw the results and concluded. The situation is approximately as follows. First, there is puddle on the spot where the stone lies, during the frosts, it is covered with ice, but doesn’t freeze to the bottom. Stone is in the water, but it is not covered with water completely. When the sun comes out and the ice breaks apart, with the help of the wind ice plates move the stones upon the slippery bottom of the lake. Stones gradually crawl and leave the furrows. Thus, the stones were moving for about 2-6 meters in 1 minute.
A – the stones frozen into the ice floe, B – a huge puddle formed on the bottom of a dried-up lake, C – puddle and ice along the banks, D – a stone in the ice and a pool. Photos: Scripps Institution of Oceanography.
This experiment explains why the stones move in a certain way, but the way how ice moves the huge blocks weighing of a few hundred kilograms, the researchers haven’t seen. Although the mystery which used to leave different scientists without sleep so many years is solved, the observations of stones continue till today.