Spatial and temporal scale imbrication in the assessment of large geomorphosites. The Sanetsch area (Western Swiss Alps)

Abstract

The assessment of large geomorphosites, i.e. geomorphological landscapes (Bussard and Reynard, 2022), is complicated by the imbrication of spatial scales (Coratza and Hoblea, 2018), as these types of sites generally combine micro- and meso-landforms depending on several geomorphological processes. Geomorphosites also combine several time scales, related to the geological time frame (rocks, lithologies, plate tectonics) and geomorphological processes, both inactive and active, as well as human history. The present study addresses the double imbrication of spatial and temporal scales in the assessment of large geomorphosites. It proposes a procedure inspired by the one developed by Ben Fraj et al. (2023) and applies it in the Sanetsch area (Switzerland). The Sanetsch area is located in the Western Swiss Alps. It is characterized by impressive structural landforms in a limestone context (Schoeneich and Reynard, 2021), by the presence of a well-studied glacio-karst listed in the inventory of Swiss geosites and a great diversity of glacial, paraglacial and periglacial deposits, processes and landforms that document the history of deglaciation and present morphogenesis. The whole constitutes a geomorphological landscape with a wide range of karstic, glacial, periglacial, gravity and fluvial landforms covering more than 20 km2. The region has already been the subject of several scientific dissemination initiatives in the field of climate and geomorphology (educational trail, educational panels, geotourism map).    The aim of the study is to understand the spatial and temporal imbrications in a process of evaluation and promotion of geoheritage on a regional scale. The procedure consists of six steps: (i) geomorphological mapping; (ii) spatial differentiation into “homogeneous” geomorphological units; (iii) description of these units in terms of processes involved, geomorphological history and current morphogenesis; (v) analysis of the temporal scale imbrication by using the method proposed by Ben Fraj et al. (2023); (vi) proposals for interpretation. For the interpretation, particular attention is paid to the double interweaving of temporal and spatial scales. The aim is: (i) to relate the regional geological and geomorphological history to Alpine and global tectonics; (ii) for recent and current morphogenesis, to understand the links between general trends (climate change) and specific phenomena (rockfalls, glacier recession); (iii) to understand the links between the geological/geomorphological history and human activities (agriculture, tourism, exploitation of water resources) in the area.