Ice Wedge Polygons
June 04, 2009
The photo above, taken from a helicopter in the Canadian Arctic, shows striking contraction patterns that are most likely ice wedge polygons. These fresh fractures probably developed on beach sediments that were recently under water. During the long winter season liquid water expands when it freezes near to the surface of the ground. However, for the extremely cold winters encountered at high latitudes (and high altitudes) ice that's already formed behaves like a solid and contracts to create fissures in the surface. If this process continues for several successive years, the resulting ice wedges can be huge. The ones shown above are perhaps the size of a roof top. Patterns similar to these have actually been identified on Mars by the Mars Odyssey Mission. Photo taken on September 9, 2005, somewhere around Radstock Bay, Canada.