The spectacle of the Alps
Passo della Greina
|(CH 1903)||E 715320||N 163040||H 2350.0|
|(WGS 84)||Long. 8.944||Lat. 46.609|
Stratigraphie, Hydromorphologie, Karst morphology, Glacial morphology
Sedimentology, Structural geology
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.
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.
From Pian Geirètt the Greina Pass may be reached in about an hour, going from Capanna Scaletta (the Scaletta Hut).
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.