Walking Rocks of Death Valley
Death Valley, the aptly named dried lake bed in the Californian desert is the second lowest piece of land in the world and one of the hottest, with temperatures regularly reaching into the 50 deg Celsius. Within the whole Death Valley National Park, there is an area called Racetrack Playa. The playa is actually an endorheic basin (a valley with no outflow of water, where evaporation exceeds inflow) that is over 1100m above sea level. The valley floor is occasionally covered by water runoff from the surrounding mountains but is mostly arid and patterned with hexagonal shaped dried mud.
In 1911 a prospector visiting the valley, documented a strange phenomenon, large stone blocks, some as large as a human, moving across the flat landscape and leaving a clear trail behind them. What could have caused such large heavy stones to seemingly ‘sail’ across a dried lakebed? Even if it occurred when the lake existed, rocks do not float! No one ever saw the rocks move yet they could easily be documented. Marked rocks would change positions over the period of a few days and leave a clear trail in the dried mud showing how they had moved, sometimes several meters. As usual, something so unusual and unexplained attracted the attention of the usual suspects. Explanations ranged from the natural - unique weather patterns or animal behaviour - to the outlandish - aliens, transdimensional votices or even psychic fields.
In 2006, Nasa scientist Ralph Lorenz whilst looking at Death Valley as part of his research into weather conditions on Saturn’s moon, Titan, came across the walking rocks. Using his research into how large ice bound rocks moved along beaches in the Arctic Sea and that quintessential piece of science apparatus, Tupperware, he developed an experiment that went on to prove that as in certain circumstances in Death Valley’s winter there was enough water to form ice in the muddy ground under rocks, this removed any resistance allowing the rock to move in a breeze. His experiment showed that a trail was left in the water-soaked ground.