Le felsenmeer du mont Gausta (Telemark, Norvège) : environnement, caractères morphologiques et significations paléogéographiques

Sellier, Dominique

doi:10.7202/033036ar

Cited by 13 publications

(4 citation statements)

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“…This is confirmed by Sattler et al (2016), who have attributed an unusually low per- Figure 13. Comparison of steep slope permafrost distribution in specific regions with estimations from previous studies (Hipp et al, 2014;Isaksen et al, 2002Isaksen et al, , 2008Isaksen et al, , 2011Farbrot et al, 2011Farbrot et al, , 2013Sollid et al, 2003;Westermann et al, 2013;Heggem et al, 2005;Steiger et al, 2016;Gisnås et al, 2017;Borge et al, 2017). The width of the boxes is proportional to the square roots of the number of observations in the respective groups.…”

Section: Permafrost Characteristics In the Steep Slopes Of Norway Commentioning

confidence: 86%

“…in Jotunheimen (Isaksen et al, 2002;Farbrot et al, 2011), down to 1300 m a.s.l. in Dovrefjell (Sollid et al, 2003;Isaksen et al, 2011;Westermann et al, 2013), and 1100 m a.s.l. in more eastern continental terrain in the Femunden region (Heggem et al, 2005;Westermann et al, 2013;Gisnås et al, 2017).…”

Section: Permafrost Characteristics In the Steep Slopes Compared To Omentioning

confidence: 99%

“…Gruber et al, 2004a;Fischer et al, 2006;Allen et al, 2009;Ravanel et al, 2017) and the occurrence of highmagnitude rock-ice avalanches (e.g. Haeberli et al, 2004;Sosio et al, 2008;Huggel et al, 2012;Deline et al, 2015). These increasing rock slope failures bear both fundamental and societal concerns.…”

Section: Introductionmentioning

confidence: 99%

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Permafrost distribution in steep rock slopes in Norway: measurements, statistical modelling and implications for geomorphological processes

et al. 2019

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Abstract. Permafrost in steep rock slopes has been increasingly studied since the early 2000s in conjunction with a growing number of rock slope failures, which likely resulted from permafrost degradation. In Norway, rock slope destabilization is a widespread phenomenon and a major source of risk for the population and infrastructure. However, a lack of precise knowledge of the permafrost distribution in steep slopes hinders the assessment of its role in these destabilizations. This study proposes the first nationwide permafrost probability map for the steep slopes of Norway (CryoWall map). It is based on a multiple linear regression model fitted with multi-annual rock surface temperature (RST) measurements, collected at 25 rock slope sites, spread across a latitudinal transect (59–69∘ N) over mainland Norway. The CryoWall map suggests that discontinuous permafrost widely occurs above 1300–1400 and 1600–1700 m a.s.l. in the north and south rock faces of southern Norway (59∘ N), respectively. This lower altitudinal limit decreases in northern Norway (70∘ N) by about 500±50 m, with a more pronounced decrease for south faces, as a result of the insolation patterns largely driven by midnight sun in summer and polar night in winter. Similarly, the mean annual RST differences between north and south faces of similar elevation range around 1.5 ∘C in northern Norway and 3.5 ∘C in southern Norway. The CryoWall map is evaluated against direct ice observations in steep slopes and discussed in the context of former permafrost studies in various types of terrain in Norway. We show that permafrost can occur at much lower elevations in steep rock slopes than in other terrains, especially in north faces. We demonstrate that the CryoWall map is a valuable basis for further investigations related to permafrost in steep slopes in terms of both practical concerns and fundamental science.

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Section: Permafrost Characteristics In the Steep Slopes Of Norway Commentioning

confidence: 86%

Section: Permafrost Characteristics In the Steep Slopes Compared To Omentioning

confidence: 99%

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Permafrost distribution in steep rock slopes in Norway: measurements, statistical modelling and implications for geomorphological processes

et al. 2019

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“…12c). Gaustatoppen is made of Precambrian quartzite, prone to macrogelivation and therefore to the producing of geometric blocks (Sellier, 1995). Combined with slopes rarely exceeding 55°, this results in a significant debris cover, favouring snow accumulation in winter and permafrost persistence, even with a relatively low probability value.…”

Section: Model Evaluationmentioning

confidence: 99%

Permafrost distribution in steep slopes in Norway: measurements, statistical modelling and geomorphological implication

Magnin

Etzelmüller

Westermann

et al. 2019

Preprint

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Permafrost in steep slopes has been increasingly studied since the early 2000s in conjunction with a 15 growing number of rock-slope failures, which likely resulted from permafrost degradation. In Norway, rockslope destabilization is a widespread phenomenon and a major source of risk for the population and infrastructure. However, the lack of precise understanding of the permafrost distribution in steep slopes hinders the assessment of its role in these destabilizations. This study proposes the first nation-wide permafrost probability map for the steep slopes of Norway (CryoWall map). It is based on a multiple linear regression 20 model fitted with multi-annual rock surface temperature (RST) measurements, collected at 25 rock-wall sites, spread across a latitudinal transect (59-69°N) over mainland Norway. The CryoWall map suggests that discontinuous permafrost widely occurs above 1300-1400 and 1600-1700 m a.s.l. in the north and south slopes of southern Norway (59°N), respectively. This lower altitudinal limit decreases in northern Norway (70°N) by about 500±50 m, with more pronounced decrease for south faces, in reason of the insolation patterns largely 25 driven by midnight sun in summer and polar night in winter. Similarly, the mean annual RST differences between north and south faces of similar elevation range around 1.5°C in northern Norway and 3.5°C in southern Norway. The CryoWall map is evaluated against direct ice observations in steep slopes and discussed in the context of former permafrost studies in various types of terrains in Norway. We show that permafrost can occur at much lower elevations in steep rock slopes than in other terrains, especially in north faces. We demonstrate 30 that the CryoWall map is a valuable basis for further investigations related to permafrost in steep slopes in both practical concerns and fundamental science.

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Age and significance of mountain-top detritus

Ballantyne

1998

Permafrost Periglac. Process.

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In north‐west Scotland, mountain‐top detritus forms blockfields or diamicts, depending on lithology. Clast angularity, absence of grussification and transition to underlying rock imply formation by frost‐wedging of bedrock. Age is constrained by trimlines and exposure dating of weathering zones. Mountain‐top detritus is ubiquitous on nunataks that remained above the level of the last ice sheet, but occurs only on well‐jointed rocks in areas exposed to periglacial conditions since ice‐sheet downwastage and is absent from areas exposed to weathering only during the Holocene. Most secondary clay minerals are equally represented both above and below a trimline cut by the last ice sheet, indicating formation since deglaciation, though haematite and gibbsite are preferentially represented on former nunataks. The age and significance of mountain‐top detritus are determined by lithology and glacial history. On well‐jointed rocks, such detritus has developed within a few millennia of exposure to periglacial conditions. On massive lithologies, however, it has formed over much longer timescales on nunataks above the last and possibly earlier ice sheets. In north‐east Scotland ancient (possibly pre‐Pleistocene) regolith also appears to have survived under a cover of cold‐based ice. Use of the distribution of mountain‐top detritus in palaeoglaciological reconstructions therefore requires caution. © 1998 John Wiley & Sons, Ltd.

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Le felsenmeer du mont Gausta (Telemark, Norvège) : environnement, caractères morphologiques et significations paléogéographiques

Cited by 13 publications

References 31 publications

Permafrost distribution in steep rock slopes in Norway: measurements, statistical modelling and implications for geomorphological processes

Permafrost distribution in steep rock slopes in Norway: measurements, statistical modelling and implications for geomorphological processes

Permafrost distribution in steep slopes in Norway: measurements, statistical modelling and geomorphological implication

Age and significance of mountain-top detritus

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