Читать книгу Canyoning in the Alps. Graded routes in Northern Italy and Ticino, Austria, Slovenia and the Valais Alps онлайн

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The regions and their rock types

The canyons of Val d’Ossola, Ticino and the north-western shores of Lake Como are for the most part formed in gneiss, a highly metamorphic rock of the Penninic nappes. At extremes of temperature and pressure within the Earth’s interior, minerals of a similar type within the parent rock (here mainly granite) have migrated and aligned together. This gives the rock a beautiful decorative quality with swirls and bands of different colours, polished smooth by the action of glaciers and flowing water. These canyons are often sporting, with deep green pools and gently sculpted waterfalls ideal for jumps and toboggans.

Impressive limestone scenery in Rio Simon (Route 85 in the Julian Alps)

The area around Lake Como is geologically complex, and gneiss is only one of a number of rock types in the area. Valtellina, a broad valley extending east from the northern tip of the lake, is part of a long fault line – a weak point in the Earth’s crust – that runs east–west across the Alps. The fault, known as the Insubric Line, marks the boundary between the Italian and European plates. This weakness has allowed liquid magma to ascend from beneath, cooling slowly within the Earth’s crust to form coarse-grained rocks such as granite and diorite. These have been exposed in a number of places along the fault, creating some of the youngest mountains in the Alps. Among these is Piz Badile, a granite peak on the Swiss border, where a couple of canyons reside. Although granite is hard it erodes quickly on account of its grainy structure, leaving well-rounded canyons open to sunlight.