For years, moving rocks were a mystery. Their tracks proved that rocks slide, and many believed high desert winds played a role, but no one had seen a boulder slide across dirt or mud. In 2013 and 2014, a group of scientists led by cousins James and Richard Norris used scientific instruments to monitor the rocks and discovered that with enough rain, this end of the playa becomes a shallow lake. In winter, cold night temperatures freeze the lake’s surface into a sheet of floating ice that embeds the rocks. Morning sun breaks the ice into sheets, and steady breezes push the floating ice along with the embedded rocks. This is why many rocks leave parallel tracks, shifting and turning in unison. Eventually the ice melts and the water evaporates, leaving the rocks in new locations until another event, perhaps years later, moves them again.