CGRG Bibliography of Canadian Geomorphology
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Author : Cummings, C.E.; and Pollard, W.H.
Date : 1989.
Title : An investigation of palsas in the Schefferville area, Quebec
Publication : Student research in Canada's north : Proceedings of the Second National Student Conference on Northern Studies, Ottawa, November 23-24, 1988. Edited by J.F. Basinger and W.O. Kupsch. Musk-ox
Issue :
Page(s) : 8-18.
Abstract
The term palsa is a Fennoscandian term for a round or elongated hillock or mound having a permafrost core composed of peat and mineral soil and generally occurring in peatlands. It has been incorporated into the permafrost literature as a genetic term to distinguish a category of frost mound phenomena characterized by slow growth, the formation of segregated ice lenses, and abundant standing water. Palsas appear to occur mainly in the discontinuous permafrost zone; however, mounds morphologically resembling palsas have been documented in areas of continuous permfrost. In recent years the descriptive use of the term palsa to define similar frost mounds, independent of their genesis, has resulted in confusion in the literature. The present paper presents results of an investigation on palsas in the Schefferville area of Quebec. The study focused on the analysis of palsa setting, size, morphology, structure, summer temperature profiles, andmacrofossil stratigraphy. Palsas from three sites were investigated ranging from 6 to 30 m in length and up to 1.9 m in height. In each case the palsas were composed of peat, with minor amounts of mineral soil. Ground ice ranged from small discontinuous ice lenses to reticulate ice veins and thick ice layers. Ice contents were highly variable, with excess ice present in all palsas. The analysis of plant macrofossils suggests a successional change from species in wet settings to those in progressively drier areas. This suggests that the vegetational equilibrium was interrupted and a relatively rapid change took place from extreme hydrophilic species, such as Carex and Scirpus, to less hydrophilic species, such as Sphagnum fuscum and ericaceous shrubs such as Ledum groenlandicum and Kalmia spp., as the palsas expanded. The study of palsa characteristics and the analysis of the permafrost conditions (aggrading or stable versus degrading) based on palsaactivity provide a useful approach to the analysis of change in permafrost and climatic conditions
Bibliography of Canadian Geomorphology