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The Geomorphological Landscape of Robièi

The largest glacier inTicino

Svizzera, Cantone Ticino, CEVIO

Positioning

Robièi

COORDINATES
(CH 1903) E   682510 N   144070 H   1891.0
(WGS 84) Long.   8.512 Lat.   46.443
GENERAL EVALUATION
DIFFICULTY E-T2/T3
SCIENTIFIC INTEREST PRIMARY:
Hydromorphologie, Structural geology, Karst morphology, Glacial morphology

SECONDARY:
Mineralogy / petrology
OTHER INTERESTS Landscape, Didactic, Hiking, Architectural
Ethnographical, Naturalistic
GEOSITE   GEOMORPHOLOGICAL - glaciers

DESCRIPTION

Bavona Valley seems to close in a funnel shape between steep walls just above San Carlo. However, after Basòdino Hut, the angle of the slope decreases and the plains widen, dramatically changing the landscape. The scene is dominated by the Basòdino Glacier, which, along with the less striking Cavagnöö Glacier, shaped the Robièi region far below the peaks in times past. In fact, 20,000 years ago, the mass of ice was homogeneous and reached up to 2600 metres above sea level. Unfortunately, today the situation seems compromised. Although with its 2.2 square kilometres of area it is the largest in Ticino, the Basòdino Glacier is suffering the consequences of global warming. Analysis of the forms of glacial erosion, however, shows that all of the Neozoic Period was characterized by climatic changes which constantly impacted on the glaciers themselves. These precious signs which are written on the Robièi landscape deserve to be deciphered.

INSIGHT

The most reliable tests to quantify the changes in glaciers over the last millennia are provided by moraine deposits preserved in excellent condition between Valletta di Fiorina and Pizzo Pecora. The location of these deposits allows a determination of the extent of glaciers in different epochs and, consequently, to re-establishing some climatic stages in the recent history of the Earth. In the case of Robièi, this would be from 11,000 years ago, when the moraine was deposited immediately north of Pizzo Pecora. The clearest and largest signs are the extensive lateral moraines deposited during the Little Ice Age (1850). These true moraine ramparts are visible downstream of the Basòdino and Cavergno Glaciers. In the complex proglacial margin of the Cavergno Glacier, in addition to the imposing stage of 1850, one can recognize its evolution since 1600. The Robièi region is also famous for some karst of particular value and rarity developed in very localized layers of Triassic marble. The carbonatic rock has undergone joint erosion by glaciers and their melt waters which, laden with carbon dioxide, reach a very high corrosion potential. For this reason, it is easy to come upon typical shower furrows and gouges in the emerging layers within the geological site, looking like those in a plowed field, just a few hundred metres from Lake Bianco. The marble in the area near Pian Glacier in Valletta di Fiorina is also affected by this same corrosion phenomenon. Here, the weight of the glacier has dug a depression where the river vanishes without forming a pool. The water has found a way to drain through the rocks, excavating what up to now is the longest known cave in Ticino. L’Acqua del Pavone (The Peacock’s Water – its name comes from the shape of the stunning resurgence of the waterfall) – winds underground for over three kilometres from Pian del Ghiacciaio to Zött Lake.

CURIOSITIES

According to some research, it has been shown that the region experienced a warm period during the Neolithic Age in which the vegetation grew much higher than the current limit and ice was absent. At that time, it is assumed that the mountain pass connecting Robièi to the Bedretto Valley was already travelled by hunters of both animals and crystals. This deduction has been made possible thanks to evidence found at the “Buco degli Anziani” (“The Hole of the Elders”): an ancient track where crystals were extracted from a quartz vein which had only recently emerged from the Cavagnöö Glacier.
scala temporale periodi geologici

HOW TO REACH THE SITE

From Exit 47 of the A2 (Bellinzona Sud) proceed in the direction of Locarno. Follow the A13 until the exit for Vallemaggia after the Mappo-Morettina tunnel. Once in Vallemaggia, continue for another 23 kilometres until Bignasco. Then turn to the left towards Bavona Valley, at the end of which San Carlo is situated. The cable car station, with a large car park, is located above the village.

USEFUL INFORMATION FOR THE VISIT

The area is excellent for excursions of all kinds and for people of all ages. You should bring the appropriate equipment if you want to leave the road that leads to Lake Cavagnöö.

TO LEARN MORE

CORTI G. et al. (2011): Sentiero glaciologico del Basòdino. Tipografia Poncioni. Losone. 94 pp.
COTTI G. et al. (1990): Introduzione al paesaggio naturale del Cantone Ticino.Vol. 1, Le componenti naturali, Bellinzona, 484 pp.
DECUYPER H. & ANTOGNINI M. (2008): Magie di pietra. Locarno. Armando Dadò.
VALEGGIA C. et al. (2006): I ghiacciai del Ticino. Dati, statistiche e società 6(2).

www.robiei.ch
www.ti.ch/ghiacciai
http://www4.ti.ch/dt/da/sf/temi/ghiacciai/ghiacciai/sentiero-glaciologico-del-basodino/

project | contacts | links | partners
Programma di cooperazione transfrontaliera Italia - Svizzera 2007 - 2013 Progetto cofinanziato dal Fondo Europeo Sviluppo Regionale (FESR)
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