19th Alpine Glaciology Meeting

Ricci M, Bertona J, Botta L, Botta V, Cella GD, Galimberti L, Ghielmetti E

Italia

Milano

MI

2015

Ghiacciaio del Belvedere

The Belvedere Glacier is a valley glacier located above Macugnaga (Piedmont, North-Western Italy). It lies at the base of the east face of Monte Rosa, the second-highest mountain of the Alps and Europe outside the Caucasus (Dufourspitze, 4,634 m). The glacier is fed by snow and ice on the east side of Monte Rosa and, particularly it collects seven minor, steep glaciers, few of them culminating above 4,500 metres. The true Belvedere Glacier, mostly covered by rocks, develops with moderate slope for almost three kilometres to its lowest point, at about 1,800 metres above sea level. Here, the Anza River forms, a 35-kilometres Alpine torrent which flows through the Valle Anzasca into the Toce River, of which it is a right tributary. Within the Belvedere Glacier, several large underground rivers, many of which originate from the tributaries glaciers, form long ice caves, not necessarily at the ice/bedrock boundary. In the years 2009-2014, cavers from Novara and Biella explored about 20 caves, including the Tre Amici one (development 137 m, depth 69 m), the Zamboni system (development >500 m) and the Effimera (ephemeral) Cave (development > 587 m, depth 73 m). As far as we know, the latter is the largest ice cave so far explored and mapped in the Alps. These caves can be arranged into three groups: 1) Moulins. Few moulins has been recently discovered in the central zone of the Glacier. Only one of them has been explored, which turned out to be ca. 30 m deep. 2) Subglacial caves, that develop at the ice/bedrock boundary. They are usually quite straight, not so long, with large, squashed, gradually narrowing sections. Subglacial caves develop most often at the glacier terminus or at the junctions with minor, tributary glaciers (Fillar, Nordend, Tre Amici). 3) Endoglacial caves. These are active, meandering caves, often quite long, with vertically elongated sections. Many of them alternate parts completely excavated into the glacier to others developed at the ice/bedrock (or even at the ice/moraine) boundary. Sometimes, the caves walls show the marks of ancient river levels. The possibility to enter into these caves (Effimera, Locce, Zamboni) is largely a result of accidental phenomena. Their exploration is only possible with significant water flow, possibly because the latter provides the heat to maintain accessible dimensions. Low temperatures and reduced flows shortly imply the significant reduction of the gallery section, due to the plastic behavior of the glacier ice. In the years 2002-2004 it was possible to trace the water of the Lago Effimero (ephemeral lake): the tests suggested the existence of a subglacial river flowing close to the western moraine. Currently, an important stream flows close to the oriental moraine, where it is partly accessible through the Zamboni system. Tracing tests showed that this stream is the underground emissary of the Locce Lake. Further tracing experiments on affluent streams point to the existence of one or more intermediate water reservoirs: it is even possible that the Locce cave allows the access to one of them. Short descriptions and topographic surveys are provided for the main caves, along with some discussion about their genesis

https://www.researchgate.net/publication/281620477_A_karst_system_in_the_Belvedere_glacier_Macugnaga_north-western_Italy

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davide

19/07/2021 19:01:45