When connected to torrential channels, the fronts of active rock glaciers constitute important sediment sources for gravitational transfer processes. In this study, a 2013-16 time series of in situ webcam images from the western Swiss Alps was analyzed to characterize the erosion processes responsible for sediment transfer at the front of three rapidly moving rock glaciers and their temporal behavior. The main erosion processes comprised rock fall, debris slide, superficial flow and concentrated flow. These processes were induced by (i) changes of the frontal slope angle produced by rock glacier advance, and (ii) increases in water content of the sediments at the rock glacier front due to melt processes and rainfall. Erosion almost ceased during winter, when the front was frozen and snow-covered. The onset of snowmelt triggered an active period of high-frequency erosion events. After the melt period, sediment transfer continued as occasional rock falls, while other erosion processes occurred only during or following rainfall events.Intense regressive erosion phases that triggered debris flows were rare and occurred when enhanced snowmelt and/or recurring rainfall induced substantial groundwater flow on the debris slopes directly below the rock glacier fronts. -the availability of unconsolidated sediments downslope may have increased substantially, potentially affecting the sediment transfer rate within the sediment cascade.The sediment supply from the upper part of mountainous watersheds strongly influences the development of torrential hazards but its study is commonly neglected. 10 There is a general lack of information about erosion processes in the upper sections of torrential catchments, as hazard assessment is often limited to observations on the alluvial fans where most infrastructure is located (eg, 11,12 ). Identifying sediment storage and active debris inputs in the headwaters of high alpine catchments is essential to assess the magnitude and frequency of debris flow events (eg, [13][14][15] ). Along with the quantification of sediment fluxes 16 , understanding what controls erosion from the main sediment sources is the key to estimate sediment budgets 17 and to identify debris flow scenarios.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Sur-les-Creux rockshelter is located in the Prealps of southwestern Switzerland. The sequence of deposits in the rockshelter is 80 cm thick and consists of weathered gravels in a phosphaterich matrix. A few Middle Palaeolithic artifacts and the bones of cave bear (Ursus spelaeus) were recorded in the fill. We present the results of sedimentological, geochemical, and micromorphological analyses of the rockshelter sediment. All analyses suggest an endokarstic origin of the sediments. The alteration cortices of the gravels imply in situ weathering over a long period. The phosphates are essentially biogenic and have an apatitelike nature. Phosphatization and intense mixing of the sediment are attributed to cave bear (digging of lairs, input of excrements, and carcasses). Only rare carnivore coprolites (lynx) were preserved in the cave deposits. ᭧

Abstract. Le Jura tabulaire d’Ajoie est caractérisé par la présence de nombreuses vallées sèches. Afin de préciser leur morphogenèse, une étude multidisciplinaire a été conduite lors des travaux de prospection archéologique le long de l’autoroute A16 (Braillard 2006). La section transversale des vallées sèches, en forme de U, laissait supposer la présence de dépôts quaternaires en profondeur. Un remplissage de 2 à 10 m d’épaisseur a effectivement été mis au jour. L’étude stratigraphique détaillée de ce remplissage a permis une subdivision chronostratigraphique des dépôts en 10 ensembles (E1-E10): une couche très argileuse (E10) interprétée comme un horizon argilique éémien remanié, ou comme une altérite plus ancienne, est localement préservée sur le bedrock karstifié. Des graviers fluviatiles (E9, E5) constituent systématiquement la base du comblement. Ils témoignent d’un système de drainage fossile actif probablement durant le Glaciaire ancien weichsélien (SI 5), ainsi qu’au Pléniglaciaire supérieur (SI 2). Une nappe de solifluxion (E8), attribuée au Pléniglaciaire inférieur (SI 4), a été trouvée en pied de pente. Des loess (E6/7) datés par OSL du Plénigla ciaire moyen (SI 3) sont intercalés entre les graviers E9 et E5. Une partie de ces loess (E4) a été remaniée et altérée durant le Tardiglaciaire et l’Holocène ancien. Finalement, quatre épisodes fluviatiles ont été repérés dans l’enregistrement sédimentaire holocène (E1 à E3). Leur corrélation avec des périodes de hauts niveaux des lacs jurassiens (Magny 2004) suggère qu’un contrôle climatique (augmentation des précipitations) est à l’origine de ces reprises temporaires de l’écoulement superficiel.

The acceleration of surface velocities observed over the last two decades on monitored rock glaciers worldwide is a widespread signal of the probable control of warming air temperatures on long-term permafrost creep. Yet, the actual consequences of this acceleration on sediment availability in high mountain catchments have never been properly estimated at the pluri-decadal scale. The present study

High mountain environments are increasingly affected by rockfall‐related hazards, driven by climate change. Studying rockfall in these environments is, however, challenging due to the inaccessibility of mountain ridges and the complex interaction between controlling factors. In this study, the rock wall of Grosse Grabe North Pillar in the Matter valley (Western Swiss Alps) was studied in detail over a timespan of 4 years (2017–2021). Data was collected from time‐lapse photography, terrestrial laser scanning, unmanned aerial vehicle photogrammetry and seismic measurements. The presented dataset is unique because data collection started before the onset of the rock wall destabilization, allowing us to understand precursory indicators of large‐scale events. In total, we recorded 382 rock‐ and cliff fall events (100–31 300 m3), with a total volume of 204 323 ± 8173 m3, resulting in a scar depth of ~40 m. An associated rock wall retreat rate of 71.2 ± 2.8 mm year−1 was calculated for the 1991–2021 period. Highly fractured south‐exposed gneiss lithology is viewed as the main predisposition for the observed rock‐ and cliff fall events, allowing high‐temperature oscillations to cause irreversible movements at fracture level. Cliff falls (104–106 m3) were preluded by an outward movement of the rock wall that started to increase 1.5 years before any significant collapse of the rock wall, reaching locally up to 30 cm. All cliff fall events occurred in summer, exposing ice in the clefts. This is assumed to be the base of the permafrost from the north side. Rapid permafrost degradation is viewed as a triggering factor after its exposure, causing progressive failure of the rock wall, leading to very high rock wall retreat rates on a decadal timescale.