pingo

A pingo is an ice-cored mound that forms in periglacial landscapes where permafrost is present. The surface is a dome of soil and rock over lying an extensive core of ice, which raises the ground above the surrounding terrain. Pingos may be active, continually drawing groundwater to feed the ice core, or inactive, with melting ice and no ongoing uplift.

Two main formation mechanisms are recognized. Closed-system pingos develop in depressions that trap groundwater under an impermeable layer of permafrost. As the enclosed water freezes, the expanding ice pushes the ground upward, creating a mound with a relatively small surface drainage. Open-system, or hydrostatic, pingos form where unfrozen ground (a talik) supplies groundwater from surrounding aquifers to the freezing front beneath the permafrost; the accumulating ice also pushes the surface upward.

Pingos typically range from a few to several tens of meters in height and from tens to hundreds of meters in diameter. When active water input ceases or the ice melts, a pingo may collapse to form a circular or irregular crater, sometimes filling with water to create a small lake.

Distribution: Pingos are characteristic of Arctic and subarctic regions, including northern Canada (notably the Mackenzie and Yukon areas), Alaska, Siberia, and Greenland. The term originates from Inuit or Greenlandic languages, reflecting the feature’s northern distribution.