Open-system pingos in Spitsbergen

Pingos (Fig. 1) are ice-cored hills found in permafrost areas. They are generally divided in two groups, the closed and the open-system pingos. The pingos in Spitsbergen are thought to belong to the latter type (Liestol 1977). They frequently occur in groups or clusters and consist of mounds of different ages growing inside each other. Some have a perfect conical shape, but many are oblong and very irregular. The base circumfer- ence of the clusters and cones varies greatly and can exceed one kilometre. The highest measured cone in Spitbergen is 42 m above the base (Ahman 1973). Thermokarst processes are in action at almost all pingos, and flatten and destroy their regular conical form.