The repeated annual freezing and thawing of permafrost soils can produce very interesting geometric features called patterned ground.
These include polygons, circles, nets, steps, and stripes.
Areas that are rich in larger stones contain much less water than highly porous areas of finer grained sediments.
Patterned ground in Katmai National Park, Alaska.
Photo credit:epod.usra.edu
Photo credit:www.geol.umd.edu
Patterned Ground on Ile de la Possession in the Crozet Islands.
This picture was taken on Mars indicating the presence of water on the Red Planet.
Photo credit:NASA/JPL/University of Arizona
Patterned ground in Alaska.
Photo credit:permafrost.gi.alaska.edu
Photo credit:jbriner/Panoramio
Patterned ground permafrost pattern seen on Devon Island, CA.
Photo credit:Anthonares/Wikimedia
Photo credit:sis.agr.gc.ca
