Cryogenetic mounds as indicators of permafrost conditions, northern QuCbec

Along the east coast of Hudson Bay, palsas and related cryogenic mounds are easily discernable evidence of the presence of permafrost. Analysis of their distribution shows a zonation oriented NE-SW, approximately parallel to the shore. In the first zone, within 20 km of the shore and mainly north of Richmond Gulf, peat-bogs are scarce and mineral cryogenic mounds occur in most locations where surficial deposits exist. In the second zone, peatzbogs are more widespread and permafrost is found both in surficial deposits (mineral cryogenic mounds) and peat-bogs (palsas). South of 56" N, towards the interior, string-bogs are the dominant type of peat-bogs, with occasional partially collapsed palsas. Permafrost has been more widespread in the region in the recent past, and its extent is now decreasing. In areas of discontinuous permafrost such as that of the study, the distribution of palsas and related cryogenic mounds is a good indicator of the extent and general conditions of permafrost.