Stratified slope deposits: periglacial and other processes involved

Abstract

Stratified slope deposits occur on or at the base of slopes within a wide range of hilly or mountainous environments. Gelifraction, a lack of vegetation, and snowmelt-derived slopewash are thought to be important factors in their development. The relatively fine-grained grèzes litées found at many sites within the French Charente region are the prototype of this kind of deposit. The original, strictly limited and genetically intended definition has been enlarged by mainly non-French authors causing considerable confusion.Other assemblages of cold-climate slope deposits are more heterogeneous, sometimes less clearly stratified, and show much larger variation in grain sizes and sedimentary structures than grèzes litées. The most important of these are stone-banked solifluction (sheets or lobes), rock fall, (dry) grain flow, frost-coated clast flow, debris flow, snow avalanching and, to a lesser degree, rain-generated overland flow and (niveo-) aeolian activity. Many of these processes are azonal and occur under a wide range of environmental conditions. A periglacial context may nevertheless influence process activity in these cases, for instance with regard to their magnitude and/ or frequency.

Integrated Field Surveying and Land Surface Quantitative Analysis to Assess Landslide Proneness in the Conero Promontory Rocky Coast (Italy)

“…Stratified slope deposits are widespread within the Umbria-Marche Apennines, even along the coastline [45], principally where bedrock particularly prone to frost shattering, as Maiolica and Scaglia Rossa formations, is exposed. These deposits typify cold, periglacial environments [46] and represent in the Apennine area the termination of the last glacial slope-fluvial sedimentation cycle [47], thus their chronological collocation is at the end of Late Pleistocene [48].…”

A new CT scan methodology to characterize a small aggregation gravel clast contained in a soft sediment matrix

“…Wetsnow avalanches are typically observed in steep alpine valleys where the slope exceeds 28 • , but they have been observed on slopes as low as 15 • (Jomelli and Bertran, 2001;Ancey and Bain, 2015). They are capable of transporting sediments ranging in size from fine eolian particles up to cobbles or boulders (van Steijn et al, 1995;Blikra and Nemec, 1998;Jomelli et al, 2007;Saemundsson et al, 2008;Van Steijn, 2011). Sediment is then carried downslope by rapidly flowing water-saturated snow and deposited directly into lake water or onto the frozen lake surface (Luckman, 1975(Luckman, , 1977.…”

Biogeomorphological influence of slope processes and sedimentology on vascular talus vegetation in the southern Cascades, California

“…6A; Pérez, 2009a). Conversely, debris flows can deposit large volumes of fine debris on lower talus areas otherwise covered with large blocks where a heterogeneous diamicton of stones and fine-soil matrix develops (van Steijn, 2011); this process may cause some plant (mostly shrubs) burial by moving debris (Fig. 14. 5) or result in high density of herb species such as L. obtusilobus, M. odoratissima, or P. hastata (Fig.…”