ABSTRACT

A very important feature of the more humid permafrost areas is the existence of permafrost mounds, e.g., the well-known pingos. The processes involved in the development of icy mounds are very varied, some developing in areas of essentially continuous permafrost, e.g., closed-system pingos, while others are found in areas of seasonal frost, e.g., thufurs. This chapter examines the main types, largely omitting those decaying mounds resulting from thermokarst. In the chapter, the main groups of pingos, palsas, lithalsas, peat plateaus, and earth hummocks are treated, together with their apparent subdivisions and look-a-likes. Unfortunately, many published descriptions do not provide enough information to precisely determine which of these landforms was studied. Studies of a given landform over time have been the most revealing, and the chapter classifies the mounds by the dominant process as well as by size. This describes the changes with fluctuations in the climatic regime.