Gelisol landscape
patterned ground, Alaska

This aerial view of patterned ground, west of Prudhoe Bay, Alaska, shows the characteristic polygonal fractures that result from freezing and thawing processes. In this photo, most of the polygons are 3-7 meters in diameter.

Repeated cycles of freezing and thawing in the upper part of Gelisols along with the associated processes of frost-heaving and ice wedge formation, eventually create microrelief within individual polygons. The outer polygon becomes a frost-heaved ridge and the center becomes a collapsed depression.