Ice-cored, dome-shaped hill, oval in plan, standing 2–50 m high, and 30–600 m in diameter, developed in an area of permafrost. The larger examples have breached crests in which ice may be exposed. They are probably due to local freezing of water that has migrated from adjacent uplands, or to the late freezing of the ground beneath a lake. See also palsa.
Subjects: Earth Sciences and Geography — Ecology and Conservation.