The secret of the moving stones in Death Valley<br />For years, scientists have been puzzled by the mysterious moving rocks in Death Valley National Park in California<br /><br />Heavy stones move to the bottom of a dried lake, leaving traces on the cracked muddy surface. For a long time, the mysterious movement was explained by the intervention of aliens, magnetic fields or even a joke.<br /><br />In an attempt to solve the mystery, scientists at the Scripps Institute of Oceanography observed the rocks in motion. In the winter of 2011, a team of the institute brought to the site 15 rocks equipped with GPS, which it monitors with the help of cameras.<br /><br />After three years of observation, as a result of the experiment it became clear that the displacement of the rocks is due to a combination of factors. First, the plateau fills with water deep enough to form ice in winter, but also shallow enough to see the rocks. When temperatures drop at night, thin "sheets" of ice form. Their thickness of 3 to 6 mm allows them to move freely. On sunny mornings, the ice covering the water begins to melt and shatter into large floating pieces that move on the surface by light winds.