This is Racetrack Playa in Death Valley California. This area has been the centre of scientific controversy for decades. Why? At this location an amazingly large number or rocks and boulders (some weighing up to half a tonne) have been regularly moving across the surface, without any human or animal interference, and they are not just moving a small distance; one travel path was recorded at 880.73 metres!
Some scientists have proposed that the movement is caused by strong winds accompanied by the development of surface ice when temperatures fall. It is hypothesised that the development of ice allows the wind to move the rocks with less difficultly. This hypothesis, however, is commonly refuted. The hypothesis cannot account for rocks starting side by side and moving at different rates and in disparate directions, and sliding rock trails vary in direction and length. Some rocks which start next to each other start out travelling parallel, but one may abruptly change direction to the left, right, or even back the direction it came from. Length also varies because two similarly size and shaped rocks could travel uniform, then one could burst ahead or stop dead in its tracks.
Another hypothesis proposed is that another force is present; electromagnetism. Air passing through the valley is positively-charged, since it has passed over the highest mountains in the Lower 48 to get into the valley, and since positive charge increases with altitude. The electric charge in the air induces an opposite charge in the Earth, creating an electrostatic potential between them. Dolomite, being composed of calcium, magnesium, and sometimes with traces of iron, is a good conductor. Being in contact with the surface, it will be negatively charged, and will therefore be attracted to the positive charge in the air above. Sticking up above the perfectly flat playa, the rocks will concentrate the lines of force on themselves, accentuating the effect. The electric force will then exert an uplifting force on the rock, reducing the friction caused by gravity, and allowing it to travel more easily.
This hypothesis is also widely discredited. A team of interns from NASA’s Lunar and Planetary Science Academy went to Racetrack Playa last year to investigate. They found that there are no electromagnetic or radiation anomalies that would account for the movement, and they also found no patterns in the mass, direction and orientation in the moving stones.
There are several other explanations offered by the scientific community, but as of yet, none are set in stone!! ;)
