In Death Valley, California, the stones move: nobody has figured out how. These are sailing stones. You can find them all in one area, just around the aptly name Racetrack Playa.
Here the valley is scored with flat tracks between 8 and 30cm wide, some curvaceous whilst others straight or jagged. Their marks score rarely more than 2 cm into the earth whilst their length range from over 100 metres to and pitiful few centimetres. At the ends of each and every one, an unremarkable stone from one of the nearby towering cliffs. Without human or animal intervention the rocks have partially navigated the smooth valley floor. Bizarre.
These tracks are the cumulation of around 4 years work for each stone and its respective propulsion, whatsoever that may be. The mysterious force has been much researched but remains illusive, it makes the rough stones travel in jagged paths but lets the smooth ones wander aimlessly across the fragmented clay surface. No direction seems truly set, occasionally two adjacent rocks set out in parallel then one veers off wildly or even goes back the way it came.
The rocks are nothing special, or so it seems for the moment, the majority of the moving rocks are of the 260m high cliff nearby and made of Dolomite, a tough mineral mixture. Enthusiastically joined by some igneous rocks from the neighbouring cliffs in their wanderings of the Racetrack Playa.They weigh up to 40 kg at a time and even turn over, changing the width and structure of their paths.
This geological phenomenon is a true enigma, all suggested propulsions have been either totally wrong when tested or near negligible. The truth remains illusive.