Aspects of the genesis, geomorphology and terminology of palsas: perennial cryogenic mounds

Palsas are true perennial permafrost mounds. It is generally accepted that there are at least three mechanisms which might contribute to the initiation of their formation, although these are not necessarily mutually exclusive. These mechanisms can be termed: the ‘snow cover’ hypothesis; the ‘vegetation succession’ hypothesis; and the ‘buoyancy’ hypothesis. Furthermore, there are at least three types of palsas recognized, although the terminology relating to these different varieties is varied and disputed. It is clear that palsas are potentially extremely useful features for monitoring permafrost growth and decay in certain areas, and that a unified understanding of their growth and decay processes would aid this.