Landslide-glacier interaction in a neoparaglacial setting at Tverrbytnede, Jotunheimen, southern Norway

• Main Authors: Owen, G., Hiemstra, J., Matthews, J., McEwen, L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley Online 2010
• Subjects: Norway; glacier; Ice; permafrost
• Online Access: http://eprints.uwe.ac.uk/20094/

A tongue-like, boulder-dominated deposit in Tverrbytnede, upper Visdalen, Jotunheimen, southern Norway, is interpreted as the product of a rock avalanche (landslide) due to its angular to subangular boulders, surface morphology with longitudinal ridges, down-feature coarsening, and cross-cutting relationship to ‘Little Ice Age’ moraines. The rock avalanche fell onto glacier ice, probably channelled along a furrow between two glaciers, and stopped on the glacier foreland, resulting in its elongated shape and long runout distance. Its distal margin may have become remobilized as a rock glacier, but a rock glacier origin for the entire landform is discounted due to lack of source debris, presence of matrix, lack of transverse ridges, and sparcity of melt-out collapse pits. Lichenometric dating of the deposit indicates an approximate emplacement age of ad 1900. Analysis highlights the interaction of rock-slope failures and glaciers during deglacierization in a neoparaglacial setting, with reduced slope stability due to debuttressing and permafrost degradation, and enhanced landslide mobility due to flow over a glacier and topographic channelling. Implications for the differentiation of relict landslides, moraines and rock glaciers are discussed and interrelationships between these landforms are considered in terms of an ice-debris process continuum.