Pingo's are another arctic landform showing the power of permafrost to shape the land. A pingo is a conical hill with a core of clear ice a big one may be as much as 75 m high and 500 m across, making it a conspicuous feature of the landscape.

Closed-system pingos are formed only in the continuous permafrost region. They are most numerous in the Western Arctic, in the coastal plain extending westward from the Mackenzie Delta into Alaska (the Alaskan North Slope); this is because they develop best in the unfrozen silty sediments that are emerging above sea level along this coast as the earth's crust rebounds.

* from E.C. Pielou, A Naturalists Guide to the Arctic, p. 42