Aesthetic perceptions of the landscape of a shrinking glacier: Evidence from the Mont Blanc massif

2021 ◽  
Vol 35 ◽  
pp. 100411
Author(s):  
Emmanuel Salim ◽  
Ludovic Ravanel ◽  
Christophe Gauchon
Keyword(s):  
Mont Blanc Massif

scholarly journals Investigation of a cold-based ice apron on a high-mountain permafrost rock wall using ice texture analysis and micro-14C dating: a case study of the Triangle du Tacul ice apron (Mont Blanc massif, France)

2021 ◽  
pp. 1-8
Author(s):  
Grégoire Guillet ◽  
Susanne Preunkert ◽  
Ludovic Ravanel ◽  
Maurine Montagnat ◽  
Ronny Friedrich
Keyword(s):  
Radiocarbon Dating ◽  
Boundary Migration ◽  
Ice Core ◽  
Ice Cores ◽  
Shear Plane ◽  
High Mountain ◽  
14C Dating ◽  
Rock Wall ◽  
Major Mechanism ◽  
Mont Blanc Massif

Abstract The current paper studies the dynamics and age of the Triangle du Tacul (TDT) ice apron, a massive ice volume lying on a steep high-mountain rock wall in the French side of the Mont-Blanc massif at an altitude close to 3640 m a.s.l. Three 60 cm long ice cores were drilled to bedrock (i.e. the rock wall) in 2018 and 2019 at the TDT ice apron. Texture (microstructure and lattice-preferred orientation, LPO) analyses were performed on one core. The two remaining cores were used for radiocarbon dating of the particulate organic carbon fraction (three samples in total). Microstructure and LPO do not substantially vary with along the axis of the ice core. Throughout the core, irregularly shaped grains, associated with strain-induced grain boundary migration and strong single maximum LPO, were observed. Measurements indicate that at the TDT ice deforms under a low strain-rate simple shear regime, with a shear plane parallel to the surface slope of the ice apron. Dynamic recrystallization stands out as the major mechanism for grain growth. Micro-radiocarbon dating indicates that the TDT ice becomes older with depth perpendicular to the ice surface. We observed ice ages older than 600 year BP and at the base of the lowest 30 cm older than 3000 years.

scholarly journals Évolution des parois rocheuses gelées de haute montagne sous forçage climatique

2020 ◽  
pp. 034
Author(s):  
Ludovic Ravanel ◽  
Florence Magnin ◽  
Xavi Gallach ◽  
Philip Deline
Keyword(s):  
Global Warming ◽  
High Altitude ◽  
Recent Work ◽  
Time Scales ◽  
Heat Waves ◽  
High Mountain ◽  
Permafrost Degradation ◽  
Geomorphological Processes ◽  
Different Time Scales ◽  
Mont Blanc Massif

Avec le réchauffement du climat, la dégradation du permafrost est à l'origine d'une intensification des processus géomorphologiques sur les versants de haute montagne. Dans les parois rocheuses, les écroulements se multiplient et leur volume augmente, posant des problèmes de sécurité non seulement à haute altitude (infrastructures, alpinistes), mais également pour les fonds de vallée. Cet article présente les travaux récemment menés dans le massif du Mont-Blanc sur la relation entre climat et écroulements à différentes échelles de temps, les effets des épisodes caniculaires et la répartition et l'évolution du permafrost de paroi. Under global warming, permafrost degradation tends to intensify geomorphological processes on high mountain slopes. In the perennially frozen rock walls, the number and volume of rockfalls is increasing, causing safety problems not only at high altitude (infrastructure, mountaineers) but also for the valleys. This article summarizes recent work carried out in the Mont-Blanc massif on the climate-rockfall relationship at different time scales, the effects of heat waves, and the distribution/evolution of rock wall permafrost.

Evaluating the temperature dependence of bedrock hillslope erosion in the Mont Blanc massif using in situ cosmogenic 3He-10Be-14C

2021 ◽  
Author(s):  
Donovan P. Dennis ◽  
Dirk Scherler ◽  
Samuel Niedermann ◽  
Kristina Hippe ◽  
Hella Wittmann ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Erosion Rates ◽  
Close Proximity ◽  
Order Of Magnitude ◽  
Stochastic Events ◽  
Exposure Ages ◽  
Alpine Environments ◽  
Magnitude Difference ◽  
Mont Blanc Massif

<p>The erosion of cold bedrock hillslopes in alpine environments depends not only on rates of frost weathering and accumulated rock damage, but additionally on the removal of the weathered material from the bedrock surface. In the Mont Blanc massif, steep bedrock faces with exposure ages sometimes much older than 50,000 years sit in close proximity to actively-eroding rockwalls, suggesting a more complex relationship between temperature and erosion rates than encompassed by the proposed “frost-cracking window.” Stochastic events like rockfalls and rock avalanches, despite their rarity, contribute a non-trivial proportion of the total sediment budget in alpine permafrost regions, adding to the contribution from background “steady-state” erosion. Employing a methodology based on the combination of in-situ cosmogenic nuclides <sup>3</sup>He -<sup>10</sup>Be-<sup>14</sup>C, we test the temperature-dependence of high-alpine erosion while taking into account erosional stochasticity.</p><p>From cosmogenic <sup>10</sup>Be concentrations of amalgamated samples collected on the Aiguille du Midi (3842 m a.s.l.) in the Mont Blanc massif, we find an order of magnitude difference in erosion rate across the peak’s surface. Our preliminary measured erosion rates, ranging between appx. 0.03 mm yr<sup>-1</sup> and 1.0 mm yr<sup>-1</sup>, correlate neither with modern temperature measurements from borehole thermistors, nor with our current estimates of bedrock cosmogenic <sup>3</sup>He-derived paleotemperatures. The corresponding cosmogenic <sup>14</sup>C/<sup>10</sup>Be ratios (between 1.70 and 4.0) for these erosion rates indicate that our measurements are not biased by recent stochastic rockfall events. Our current results therefore suggest that on geomorphic timescales, bedrock hillslope erosion rates are not set solely by rates of frost-cracking, but rather by the combined effects of frost-cracking and permafrost thaw-induced rockfalls. These insights are relevant both for short-term monitoring of alpine permafrost and associated geohazards under a warming climate, as well as studies of proposed “buzzsaws” operating on glacial-interglacial timescales.</p>

scholarly journals Altitudinal gradient of mass-balance sensitivity to climatic change from 18 years of observations on glacier d’Argentière, France

1998 ◽  
Vol 44 (146) ◽  
pp. 93-96 ◽  
Author(s):  
M. Vallon ◽  
C. Vincent ◽  
L. Reynaud
Keyword(s):  
Mass Balance ◽  
Temperature Variation ◽  
Sea Level ◽  
Altitudinal Gradient ◽  
Statistical Study ◽  
Current Model ◽  
Simple Calculation ◽  
Meteorological Station ◽  
Climatic Variations ◽  
Mont Blanc Massif

AbstractAssessment of the contribution of small glaciers to sea-level rise or the reconstruction of past glacial mass balance requires knowledge of mass-balance sensitivity to climatic variations. The aim of this paper is to clarify this relation. The mass-balance fluctuations analyzed from measurements on glacier d’Argentière, Mont Blanc massif, France, between 1850 and 2700 m a.s.l. were compared with climatic variations at a nearby meteorological station. Statistical study of the data shows that: (1) the annual mass-balance fluctuations are dependent on elevation, and (2) the mass-balance sensitivity to temperature decreases with altitude and diverges from current model results. Consequences of a temperature variation of 1°C for global volume variations are significant. A simple calculation on glacier des Bossons, Mont Blanc massif, France, shows that the sensitivity from the model can lead to volume variations twice as high as results compatible with our observations.

Improved discrimination of subglacial and periglacial erosion using10Be concentration measurements in subglacial and supraglacial sediment load of the Bossons glacier (Mont Blanc massif, France)

2015 ◽  
Vol 40 (9) ◽  
pp. 1202-1215 ◽  
Author(s):  
Hervé Guillon ◽  
Jean-Louis Mugnier ◽  
Jean-François Buoncristiani ◽  
Julien Carcaillet ◽  
Cécile Godon ◽  
...  
Keyword(s):  
Sediment Load ◽  
Concentration Measurements ◽  
Mont Blanc Massif

scholarly journals Altitudinal gradient of mass-balance sensitivity to climatic change from 18 years of observations on glacier d’Argentière, France

1998 ◽  
Vol 44 (146) ◽  
pp. 93-96 ◽  
Author(s):  
M. Vallon ◽  
C. Vincent ◽  
L. Reynaud
Keyword(s):  
Mass Balance ◽  
Temperature Variation ◽  
Sea Level ◽  
Altitudinal Gradient ◽  
Statistical Study ◽  
Current Model ◽  
Simple Calculation ◽  
Meteorological Station ◽  
Climatic Variations ◽  
Mont Blanc Massif

AbstractAssessment of the contribution of small glaciers to sea-level rise or the reconstruction of past glacial mass balance requires knowledge of mass-balance sensitivity to climatic variations. The aim of this paper is to clarify this relation. The mass-balance fluctuations analyzed from measurements on glacier d’Argentière, Mont Blanc massif, France, between 1850 and 2700 m a.s.l. were compared with climatic variations at a nearby meteorological station. Statistical study of the data shows that: (1) the annual mass-balance fluctuations are dependent on elevation, and (2) the mass-balance sensitivity to temperature decreases with altitude and diverges from current model results. Consequences of a temperature variation of 1°C for global volume variations are significant. A simple calculation on glacier des Bossons, Mont Blanc massif, France, shows that the sensitivity from the model can lead to volume variations twice as high as results compatible with our observations.

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