The Frozed Wastelands

 

Ice wedges and Polygons

 
Ice wedges are structures where water has filled a crack or hole in the ground and froze over the winter. As the water freezes, it expands, making the crack bigger.
Picture from nunatak.geology.union.edu
 
As the Wedge gets bigger, the whole it creates gets bigger and gets fovered with sediments and dirt.
 
 
On the surface, these ice wedges make the ground look like a patchwork of tiles, called polygons.
Picture from http://sis.agr.gc.ca/cansis/taxa/landscape/ground/nwt.html
As the wedge gets deeper, it begins to melt and the water is then put nder high pressure from the surrounding ice and dirt. This causes the water to be forced to the surface. As it moves twards the surface, the rock and soin above it are pushed out of the way, making pingos. These pingos are usually a small hill with a ring or rock and siol at the center. Many pingos, thought, can reach the size of a house or other large building.

photo by Harald Sund