The Sailing Stones Of Death Valley, California

Since their initial discovery in the early 1900s, the enigmatic sailing stones of Death Valley, California, have drawn the interest of both serious scientists and conspiracy theorists. The stones appear to be moving, as their name would imply, and they typically leave behind long, distinct tracks. Nobody knew why they did it for a very long time because the winds in the valley were not powerful enough to dislodge huge rocks. Some speculated aliens, although it was unclear why they would appear inconspicuously to move rocks in a secluded valley in California named "Death Valley."

That was before two researchers, Richard D. Norris and his relative James M. Norris, used GPS to set their own pebbles and record them for more than two years starting in 2011. By the end of 2013, they had discovered the root of the problem: a thin layer of wintertime ice that developed at night and broke off during the day, causing the stones to slide off and leave traces. The rocks could move more than 15 feet per minute on their finest days.