Relationships between glacier and rock glacier in the Maritime Alps, Schiantala Valley, Italy

Abstract

In the Schiantala Valley of the Maritime Alps, the relationship between a till-like body and a contiguous rock glacier has been analyzed using geomorphologic, geoelectric and ice-petrographic methodologies. DC resistivity tomographies undertaken in the till and in the rock glacier show the presence of buried massive ice and ice-rich sediments, respectively. Ice samples from a massive ice outcrop show spherical gas inclusions and equidimensional ice crystals that are randomly orientated, confirming the typical petrographic characteristics of sedimentary ice. The rock glacier formation began after a phase of glacier expansion about 2550"50 14C yr BP. Further ice advance during the Little Ice Age (LIA) overrode the rock glacier root and caused partial shrinkage of the pre-existing permafrost. Finally, during the 19th and 20th centuries, the glacial surface became totally debris covered. Geomorphological and geophysical methods combined with analyses of ice structure and fabric can effectively interpret the genesis of landforms in an environment where glaciers and permafrost interact. Ice petrography proved especially useful for differentiating ice of past glaciers versus ice formed under permafrost conditions. These two mechanisms of ice formation are common in the Maritime Alps where many sites of modern rock glaciers were formerly occupied by LIA glaciers.

Glacier retreat in the maritime alps area

“…For the Schiantalà (Mt. Tenibrés) and the Maledìa Glaciers, dedicated geophysical surveys were carried out that focused on buried ice and mountain permafrost detection (Ribolini et al 2007;2010 1879, 1901, 1924, and 1943, and, more recently, the 1957 and following editions. 4.…”

Pluri-decadal (1955–2014) evolution of glacier–rock glacier transitional landforms in the central Andes of Chile (30–33° S)

“…The readvance(s) and superimposition/embedding of glaciers or debris-covered glaciers onto/into rock glaciers, with related geomorphological and thermal consequences (Lugon et al, 2004;Haeberli, 2005;Kääb and Kneisel, 2006;Ribolini et al, 2007Ribolini et al, , 2010Bodin et al, 2010;Monnier et al, 2011Monnier et al, , 2014Dusik et al, 2015). This is the sensu stricto significance of "glacierrock glacier relationships" (Haeberli, 2005) as defined by what has been called the "permafrost school" in reference to the long-term "rock glacier controversy" (see Berthling, 2011).…”

“…5), these landforms most probably result from the (re)advance(s) of glaciers onto or in the back of pre-existing rock glaciers. Many other examples of such development of glacier-rock glacier assemblages have been studied and reported in the literature (Lugon et al, 2004;Haeberli, 2005;Kääb and Kneisel, 2006; Ribolini et al, 2007Ribolini et al, , 2010Bodin et al, 2010;Monnier et al, 2011Dusik et al, 2015). In the central part of the Navarro's western unit, the elevated lateral margins exhibit cohesive flow-evocative ridges, which probably resulted from the lateral compression exerted by the glacier during its advance ("composite ridges" of the glaciological terminology; Benn and Evans, 2010, p. 492).…”

Glacier meltwater flow paths and storage in a geomorphologically complex glacial foreland: The case of the Tapado glacier, dry Andes of Chile (30°S)

“…Between latitudes 29°and 32°S in Chile, rock glaciers cover a four times larger surface area than that occupied by glaciers, and, depending on their ice content, may consequently represent a bigger reserve of frozen water than glaciers, (Azócar and Brenning, 2010). Whereas glacier-permafrost interactions have been intensely studied from a geomorphological point of view (Bodin et al, 2010;Haeberli, 2005;Kneisel and Kääb, 2007;Monnier et al, 2011;Ribolini et al, 2007;Trombotto and Borzotta, 2009), the issue of their hydrology and to an even greater extent, their hydrological contribution to watershed streamflow is comparatively unexplored and poorly understood. The conceptual view is that rock glaciers are capable of both long term storage of frozen water and seasonal storage of meltwater.…”