Massive rocks that wander around up to 800 metres across a desiccated lake, leaving highly visible gorges? Of course, no one has ever watched that scene, but there are also no traces of external influence. That doesn't sound scientifical, rather like spook or a joke!
The mysterious place in Death Valley (one of California's most visited national parks) is called Racetrack Playa. A totally plain, four-kilometres-long racecourse for big and small stones which seem to be moved by the devil himself. Not even experienced park attendants have an explanation for the phenomenon.
There are rumours about subterranean magnetism, wind, black ice in winter. And of course there was a theory about aliens, especially in the sixties and seventies: According to that theory, the traces in the loam were symbols created by aliens, which wanted to send us a message...
Bob Sharp, a geologist, investigated the wandering stones between 1968 and 1974. In this period he observed 30 rocks and finally came to the conclusion that the movements would happen in stormy nights under special circumstances. Some of the specimens must have been wandering with a speed of more than one metre per second. At the end of his report he adds: "I can't explain it, but 7 of the 30 observed stones disappeared without a trace..."
In 1996, Paula Messina (see photo), geologist at the Jose State University, started to study the strange phenomenon that became more and more esoteric and mysterious. At first she planned to adjust cameras in order to film the stones, but according to a national park law this was prohibited. So she marked all the 162 stones at Racetrack Playa and measured and documented the movements at regular intervals.
Paula Messina told us in an interview: "The movements always happened after very strong rainfalls which made the loamy soil very slippery. As loam attracts humidity the water was also soaked up by the dry soil under the big dolomite rocks. This goes with an extremely stormy wind, which even enforces, if it comes through the valley in a particular angle and reaches more than 100 km/h. Some of the rocks even showed some sort of bow waves and wake (like boats) after the loam dried up. This leads to the conclusion of high sliding speeds."
But after a practical test (with loamy soil, a hosepipe and an even stone) other scientists concluded that – even with aquaplaning – storms with more than 280 km/h would be necessary to cause rock wanderings of this dimension.
And if a bunch of funny guys played a few jokes with the stones on the "Racetrack of the Devil"? Paula Messina: "162 rocks of this dimension? Never! And they would have left traces behind as the stones do. Only in dry condition the loam is as hard as concrete."