Arctic Polygons

How Freaking Beautiful Is That?

How does this happen?


  • In the winter the cold causes the frozen soil to shrink, and cracks form.
  • In the spring, the active layer melts and water seeps down into the cracks. It freezes and expands when it is chilled by the still-frozen soil. The frozen water forms wedges of ice in the soil.
  • The active layer and the tops of the ice wedges melt in the summer, adding more water.
  • Each winter, cracks form again in the same places, and in the spring, more water enters and enlarges the ice wedges as the freezing water expands.
  • This cycle of crack, melt, and freeze enlarges the wedges year by year until the soil above them is pushed up, forming a blocky pattern of ridges on the ground called polygons.



2 responses to “Arctic Polygons

  1. Sheina, where was this picture taken? Isn’t it wild how water EXPANDS when it freezes unlike other liquids which contract? Check this link out where it is well explained and thus how this evolution factors into life’s perfect balance in aquatic ecosystems:
    Can I post this on the ANSC blog, linking to your site?

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