Those rocks move because they're carried by thin ice sheets every once in a while: > rocks move when large ice sheets a few millimeters thick floating in an ep

Those rocks move because they're carried by thin ice sheets every once in a while: > rocks move when large ice sheets a few millimeters thick floating in an ephemeral winter pond start to break up during sunny days. These thin floating ice panels, frozen during cold winter nights, are driven by wind and shove rocks at up to 5 m/min.