ICG2022-323, updated on 01 Dec 2023
10th International Conference on Geomorphology
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Molards, a new geomorphological tool for the identification of permafrost degradation in periglacial terrains around the globe

Costanza Morino1, Susan Conway2, Philip Deline1, Florence Magnin1, Axel Noblet2, Kristian Svennevig3, Antoine Lucas4, Alexander Strom5, Stuart Dunning6, and Reginald Hermanns7
Costanza Morino et al.
  • 1CNRS UMR 5204 - Laboratoire EDYTEM, Université Savoie Mont Blanc, Le Bourget du Lac, France (costanza.morino@gmail.com)
  • 2CNRS UMR 6112 - Laboratoire de Planétologie et Géosciences, Nantes Université, Université d’Angers, Université du Mans, Nantes, France
  • 3Geological Survey of Denmark and Greenland, Copenhagen, Denmark
  • 4CNRS UMR 7154 - Institut de Physique du Globe de Paris, Université de Paris, Paris, France
  • 5Geodynamics Research Center, JSC Hydroproject Institute, Moscow, Russia
  • 6School of Geography, Politics and Sociology, Newcastle University, United Kingdom
  • 7Geohazards and Earth Observation, Geological Survey of Norway, Trondheim, Norway

Our study looks at how to use the landform called “molard” as a marker of permafrost degradation in arctic, sub-arctic and mountain environments. Molards in permafrost terrains are mound of loose debris that derive from the degradation of blocks of ice-rich sediments mobilised by a landslide. Such molards cannot form without ground ice, which cements the source material, allowing it to behave like solid during transport. Once the ground ice has thawed, its cementing action is lost, inducing collapse of the material into molards. We reconstruct the permafrost, geological, geographical settings of more than 50 landslides characterised by molards, compiling data available in the literature. We apply quantitative terrain analysis using high-resolution DEMs to describe, quantify and compare their topographic characteristics, morphometry, dynamics, and molards distribution and density. Our results show that landslides with molards can occur in terrains characterised by various permafrost distribution, from continuous to isolated. These landslides show a variety of morphological and morphometric characteristics, source materials often composed of loose debris or rheologically weak bedrock, and their molard distribution reflects the dynamics of the landslide. In this study, we show that molards are an indicator landform of permafrost degradation under different permafrost, geomorphological and geological conditions, and that they can be used to decipher landslide dynamics in cold environments.

Acknowledgements: This study is funded by the Agence Nationale de la Recherche in the framework of the project ANR-19-CE01-0010 PERMOLARDS

How to cite: Morino, C., Conway, S., Deline, P., Magnin, F., Noblet, A., Svennevig, K., Lucas, A., Strom, A., Dunning, S., and Hermanns, R.: Molards, a new geomorphological tool for the identification of permafrost degradation in periglacial terrains around the globe, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-323, https://doi.org/10.5194/icg2022-323, 2022.