Landslide‐glacier interaction in a neoparaglacial setting at tverrbytnede, jotunheimen, southern norway

Abstract

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.

A regional inventory of rock glaciers and ice‐cored moraines in norway

“…However, considering a paraglacial period with high sediment availability following deglaciation, many of the rock glaciers might have originated from landslide‐influenced deposits, which shorten their formation period (see e.g. Owen et al . 2010).…”

Small rock‐slope failures conditioned by Holocene permafrost degradation: a new approach and conceptual model based on Schmidt‐hammer exposure‐age dating, Jotunheimen, southern Norway

“…Lower voids fractions have generally been used for MRSFs, rock avalanches, talus and other mass movement types involving mixed particle sizes, fine matrix and/or compacted material (Sass & Wollny 2001;Hungr & Evans 2004;Wilson 2009;Owen et al 2010;Stock & Uhrhammer 2010;Sandøy et al 2017). Aspect and the altitude of the fan apex were estimated from topographic maps at a scale of 1:50 000 with a contour interval of 20 m, supplemented by altimeter and GPS measurements in the field.…”

“…Although some of the largest fans are thicker than 1 m in places, all are thinly spread across and down slope, and rarely involve piles of debris. Lower voids fractions have generally been used for MRSFs, rock avalanches, talus and other mass movement types involving mixed particle sizes, fine matrix and/or compacted material (Sass & Wollny 2001;Hungr & Evans 2004;Wilson 2009;Owen et al 2010;Stock & Uhrhammer 2010;Sandøy et al 2017). The value of 40% is justified given the absence of fine matrix (Fig.…”

Geomorfología paraglacial asociada a la inestabilidad de laderas en el Brazo Norte del Lago Argentino, Patagonia, Argentina

“…Los procesos de inestabilidad de laderas (deslizamientos, avalanchas de rocas, coladas de piedras, etc.) pueden generarse en zonas de montaña recientemente abandonadas por glaciares (Jarman, 2006;Hewitt et al, 2008;Kellerer-Pirklbauer et al, 2010;Owen et al, 2010;Ballantyne y Stone, 2013;Kovanen y Slaymaker, 2015, entre otros). Todas las formas de respuesta paraglacial se sustentan en un único elemento común: que la deglaciación ha dado lugar a la exposición de fuentes sedimentarias inestables o metaestables, que posteriormente se liberan y reelaboran mediante una amplia variedad y combinación de procesos a diferentes escalas de tiempo (Ballantyne, 2015).…”