OBSERVATIONS ON NEARSHORE PINGO GROWTH, ADVENTDALEN, SPITSBERGEN

The open-system pingos of Svalbard can be divided into three groups. G roup I pingos are located over geologic faults. Group II pingos are lo cated in areas of artesian flow resulting from the migration of sub-gl acial groundwater. Pingos of group II occur usually in riverbeds, wher e the permafrost is locally thinner. Group III pingos are located in n earshore or low-lying environments of active geologic uplift, where gr oundwater flow is in response to relict conditions. In this paper grou p III pingos in the Adventdalen delta area are examined. Group III pin gos characteristically have a complex shape and occur in groups. Growt h occurs rapidly after initial emergence from marine conditions and th e establishment of a minimum permafrost thickness. Water is supplied t hrough discontinuities in the aggrading permafrost. Net influx of wate r is moderate, owing to relatively thin permafrost.