January 07, 2009
The polygonal patterns featured above were caused by the thawing and freezing of permanently frozen ground or permafrost. These landforms can occur in periglacial areas, where cold climate and ice contributes to the evolution of the landscape. Braided streams (mid-ground) are also indicative of periglacial geology. The photo was taken on August 19, 2005, along the north slope of the Yukon Territory, between the Mackenzie River and the border of Alaska. Similarly patterned ground has been observed on Mars -- via Mars probes.