How does patterned ground form

The active layer continually freezes and melts year on year above the permafrost and talik. Over winter, as the active layer freezes down over water can become trapped between the descending freezing plane of the active layer and the permafrost that surrounds it. This promotes the growth of an ice lens which pushes the land up above it as it expands. Water underneath the permafrost can move through the talik between the permafrost areas because of capillary action the movement of water through the soil because of and hydraulic pressure.

This water migrates to the ice lens and freezes, swelling the ground above further. Both of these pingos can rupture if they become too large, and if the ground cracks it exposes the ice lens to the atmosphere and the suns energy. This can then melt the ice causing the pingo to collapse, leaving a ruptured pingo with a depression in the middle that can fill with water and a lake, and a rampart around the edge that is prone to the mass wasting process of solifluction.

The collapsed pingo is known as an ognip. Patterned ground. Ice wedges. Tedrow JCF Soils of the polar landscapes. Troll C Structure soils, solifluction and frost climates of the earth. Translation The arctic brown and related soils, vol Geoderma — CrossRef Google Scholar.

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