Étude géographique d’un champ de palses à Poste-de-la-Baleine, Nouveau-Québec

Séguin, Maurice K.; Crépault, Jean

doi:10.7202/1000368ar

Cited by 9 publications

(1 citation statement)

References 16 publications

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“…LAGAREC (1978), LAVERDIÈRE andGUIMONT (1976), PAYETTE ef al. (1976) and SEGUIN and CRÉPAULT (1978) made extensive investigations on the evolution of permafrost in palsas and other landforms from the northern portion of the James Bay region to Poste-de-la-Baleine and further north. Southward, observations have been reported from the vicinity of Fort George (VINCENT, 1977) and Fort Rupert (DION-NE, 1978).…”

Section: Palsas and Other Peatland Featuresmentioning

confidence: 99%

Permafrost distribution in the southern part of the discontinuous zone in Québec and Labrador

Brown

2011

gpq

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The distribution of permafrost in the southern part of the discontinuous zone in Québec and Labrador is described. At the southern limit of this subzone islands of permafrost vary in extent from a few tens of square metres to several hectares and in thickness from a few centimetres to a metre or so. Northward to the middle of the discontinuous zone permafrost becomes increasingly widespread reaching a thickness exceeding 100 metres. Permafrost occurs mainly in peatlands, on some north facing slopes and above treeline on mountain summits. The relationships of permafrost distribution to climatic and terrain factors, including air temperature, vegetation, drainage and snow cover are discussed, the last being particularly important. The paper concludes with an analysis of some prominent air photo patterns.Au sud de la zone de pergélisol discontinu, la superficie des îlots de pergélisol varie entre quelques dizaines de mètres carrés et plusieurs hectares et l’épaisseur du pergélisol se situe entre quelques centimètres et environ un mètre. En se dirigeant vers le nord, jusqu’au centre de la zone discontinue, le pergélisol devient plus dense et son épaisseur dépasse la centaine de mètres. Le pergélisol se manifeste surtout dans les tourbières, sur les versants exposés au nord et sur les sommets au-dessus de la limite arboréenne. Il est ensuite question des relations entre la répartition du pergélisol et les caractéristiques du climat et du terrain telles la température de l’air, la végétation, les conditions de drainage et l’épaisseur de la neige, ce dernier aspect étant particulièrement important. L’étude se termine par une analyse des traits saillants de quelques photos aériennes.Die Verteilung des Dauerfrostes im sudlichen Teil der Unterbrochenen Zone in Quëbec und Labrador ist beschrieben. An der Südlichen Grenze dieser Subzone finded man Insein von Dauerfrost die im Durchmesser von wenigen Quadratmetern bis zu mehreren Hektaren varieren und wo er von wenigen Zentimetern bis zu ungefähr einem Meter dick ist. Weiter nördlich in der Mitte der unterbrochenen Zone wird der Dauerfrost immer häufiger und erreicht mehr als 100m Dicke. Dauerfrost kommt hauptsächlich in Mooren vor, an einigen Nordhangen und über der Baumlinie auf Berggipfeln. Die Beziehungen zwischen Dauerfrostverteilung und klimatischen und landschaftlichen factoren, einschliesslich Lufttemperaturen, Vegetation, Entwässerung und Schneedecke werden behandelt, die letztere ist von besonderer Wichtigkeit. Die Studienarbeit schliesst mit der Analyse einiger wichtiger Luftbildstrukturen

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Section: Palsas and Other Peatland Featuresmentioning

confidence: 99%

Permafrost distribution in the southern part of the discontinuous zone in Québec and Labrador

Brown

2011

gpq

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Cyclic Development and Thermokarstic Degradation of Palsas in the Mid-Alpine Zone at Leirpullan, Dovrefjell, Southern Norway

Matthews

Dahl

Berrisford

et al. 1997

Permafrost Periglac. Process.

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The palsas of Leirpullan are developed in deltaic sands and silts in the zone of alpine permafrost at an altitude of 1437 m (estimated mean annual air temperature −2.7°C). Five mounds that represent a chronosequence are analysed with particular reference to initiation, aggradation and degradation phases. It is inferred that geoecological factors control initial mound formation beneath areas of thin (< 20 cm) moss‐peat, which provide summer insulation for developing permafrost. Low summer temperatures and low summer precipitation appear to allow the survival of permafrost, the existence of stable mounds, and limited height growth, after the gradual successional replacement of moss‐peat by fellfield vegetation growing directly on the mineral substrate. Degradation occurs owing to thermokarstic processes, which result in the formation of rim‐ridge ramparts. ‘Exogenous’ processes associated with lateral thermal erosion by lake and river water are important at the site. Regeneration and the possible effects of climatic change are also discussed. Palsas with only a thin peat cover in the initial stage of formation but no peat cover during subsequent development and degradation are considered to be near one extreme of a morphological and genetic continuum of pure peat palsas to mineral permafrost mounds. The rim‐ridge ramparts characteristic of the degraded palsas of Leirpullan appear to provide appropriate modern analogues for relict Pleistocene forms in Wales and elsewhere in Europe formerly interpreted as pingo scars. © 1997 John Wiley & Sons, Ltd.

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Pingos and palsas: A review of the present state of knowledge

Pissart

1985

Polar Geography and Geology

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From: Inter-Nord, No. 17,1985, pp. 21-32. Abstract: The article presents a summary of the present state of knowledge of perennial periglacial mounds, including descriptions of the external appearance and internal composition of pingos and palsas and a discussion of the genetic mechanisms. Pingos appear to be the result of the freezing of a mass of water trapped beneath permafrost under cryostatic or hydraulic pressure. Palsas are formed by the migration of groundwater to a freezing plane (cryosuction). The existence of mineral palsas is recognized; in this case the peat cover may be extremely thin or even totally non-existent.

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Étude géographique d’un champ de palses à Poste-de-la-Baleine, Nouveau-Québec

Cited by 9 publications

References 16 publications

Permafrost distribution in the southern part of the discontinuous zone in Québec and Labrador

Permafrost distribution in the southern part of the discontinuous zone in Québec and Labrador

Cyclic Development and Thermokarstic Degradation of Palsas in the Mid-Alpine Zone at Leirpullan, Dovrefjell, Southern Norway

Pingos and palsas: A review of the present state of knowledge

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