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The Greina Pass

The spectacle of the Alps

Svizzera, Cantone Ticino, BLENIO

Positioning

Passo della Greina

COORDINATES
(CH 1903) E   715320 N   163040 H   2350.0
(WGS 84) Long.   8.944 Lat.   46.609
GENERAL EVALUATION
DIFFICULTY E-T2/T3
SCIENTIFIC INTEREST PRIMARY:
Stratigraphie, Hydromorphologie, Karst morphology, Glacial morphology

SECONDARY:
Sedimentology, Structural geology
OTHER INTERESTS Landscape, Hiking
GEOSITE   GEOMORPHOLOGICAL - karstification

DESCRIPTION

The perimeter of the Greina region is broadly defined by the rectangle drawn between the high peaks of Piz Gaglianera (3121 metres above sea level), the Pizzo Coròi (2785 metres above sea level), the Piz Terri (3149 metres above sea level) and Piz Stgir (2587 metres above sea level). Its relief is characterized by three parts with distinct river basins, divided from each other by the Crap la Crusch Col and the Greina Pass. In these areas, Brenno della Greina to the west and Ri Motterascio to the south pour their waters down towards the Ticino River, while those that flow on Plaun la Greina, a high plateau, are drained to the north-east of the Rein da Sumvitg. The geomorphology of the Greina shows very common traits all around the perimeter, while contrasts create the spectacle of this alpine landscape. In this geological site there are flat, wet valley bottom areas dominated by braided streams surrounded by the intense green of the alpine vegetation.

INSIGHT

The geological composition of the Greina is made up entirely of metamorphic rocks of various types, depending on their origin. It must be said that not all of the rocks of the Greina are sedimentary. Those which delineate the northern slopes with their respective peaks are in fact crystalline. These granitic rocks of the Gotthard Massif were the bedrock upon which were recorded the events connected with the appearance of a sea in the Triassic Period. Dolomites, easily recognizable because of their whitish colour, have settled on the ground there. Today the landscape looks very different, as a result of the continental collision which caused the formation of the Alps. The enormous forces which were involved refolded the layers and pushed them up to the surface, creating unexpected situations such as the vertical arrangement of the Triassic layers in the area of the Greina Pass. Before reaching its present form, however, the whole region was considerably affected by the influence of glaciation in the Neozoic Period. It is estimated that during the Last Glacial Maximum, which occurred about 20,000 years ago, the region of the high plateau was entirely covered by ice up to a height of 2700 metres. The ice mass would then have come from the north, along the valley of the Rein da Sumvitg, to enter the Blenio Valley, passing from the Greina Pass and the Crap la Crusch Col across the Motterascio Alp. With the disappearance of glaciers, other geomorphological processes, such as the formation of karst, intensified. The karstification of Triassic dolomite, although this rock is less compact and pure than some limestone, led to the formation of sinkholes, often filled with water, and other spectacular forms near the Greina Pass. Among these, a six-metre-tall pinnacle and a 30-metre-wide arc stand out, both situated around the plain of Greina.

CURIOSITIES

During the 1970s, following a concession for the construction of a hydroelectric reservoir on the high plateau, a strong movement of opposition to the project was created. Artists and groups fought successfully against the exploitation of the Greina landscape. The plateau thus became a symbol of the fight against the exploitation of nature.
scala temporale periodi geologici

HOW TO REACH THE SITE

From the Biasca Lucomagno exit (number 44) of the A2 motorway, proceed in the direction of Lucomagno all the way through the Blenio Valley to Olivone. After the village, turn right for Campo (Blenio), after which you follow the road for Luzzone for a bit less than a kilometre. Immediately after Aquilesco take the first turning on the left and go up the Val Camadra to the parking area, after which the road is passable only by public transport.

USEFUL INFORMATION FOR THE VISIT

From Pian Geirètt the Greina Pass may be reached in about an hour, going from Capanna Scaletta (the Scaletta Hut).

TO LEARN MORE

BUZZINI R. et al. (2008): Spazio/Raum/Spazi Greina. Disentis. Desertina Verlag.
COTTI 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.

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Programma di cooperazione transfrontaliera Italia - Svizzera 2007 - 2013 Progetto cofinanziato dal Fondo Europeo Sviluppo Regionale (FESR)
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