An overview of the consequences of paraglacial landsliding on deglaciated mountain slopes: Typology, timing and contribution to cascading fluxes

Abstract

Three decades after the early definition of the «paraglacial» concept, a general model of paraglaciation was established, integrating the typical sediment paraglacial cascading system and the responses of associated sediment storages. The residuals of this model should now be examined and explained through controlling factors that may act at both regional (e.g. tectonics) and local (topography, lithology, etc.) scales. We compare here the patterns identified in a few mountain ranges of the northern hemisphere, located in various seismotectonic settings (especially western Alps, northwestern Scotland, central Norway, Svalbard and Iceland). By combining our field observations with a literature review, the effectiveness of the paraglacial response on mountain-slope erosion and the contribution of paraglaciation to the sedimentary cascading system are discussed. In most cases, paraglaciation generates sediment storage and aggradation in headwaters and glacial trough, as the evacuation rate into sinks remains low. Finally, paraglaciation appears to be a period of hillslope denudation, preparing reservoirs of sediments, which can only be effectively evacuated during further glaciation periods.