GEOLOGICAL AND GEOMORPHOLOGICAL OVERVIEW OF THE CANNOBINA VALLEY

The rocks of our territory belong geologically to the South Alpine domain of the Western Alps 'Massiccio dei Laghi'.
There are metamorphic and intrusive magmatic rocks, to the former belong the paragneisses and the micascists while to the intrusive magmatic ones belong the granulites, the gabbros and the peridotites.
They represent a portion of the Earth's continental crust in its intermediate-lower part at the transition to the upper mantle.
They formed at depths between 15 and 35 km in temperatures ranging from 550°C to 650°C.
They are between 325 million and 400 million years old.
Gurro lies just south of the Insubric Line, the fault that marks the boundary between the African plate to the south and the European plate to the north.
This means that the rocks in the Gurro area did not participate in the formation of the Alpine arc, but simply rested on it. They are part of a mountain range older than the Alps (age 60Ma) that was generated 325 m y ago.












The terrain of Gurro is composed of three/four rock types.
The most important are:
1. Micascists: this is a beige/brownish coloured rock; it is quite friable and oxidises easily in contact    with exogenous agents because it contains iron.
2. Kinzigite: two-thirds outcrops on the territory of Gurro; it was formed at a depth of about 25 km, near the transition between the continental crust and the Earth's mantle.


The most easily recognisable shapes in the Cannobina Valley are those belonging to fluvial morphology. It is generated through the flow of surface waters over very long periods of time (at least a few hundred years) that shape the territory, giving rise to valleys with a typical V shape. In this case, the modelling factor is surface water.
The erosive force of the waters of the Torrente Cannobino continually digs into the rock, deepening the V-shape and transporting the sediments downstream.
If one climbs to higher altitudes, it notice the glacial morphology that gives the valley its typical U-shape. This testifies to the fact that the shaping of the territory is not only fluvial.
In reality, a glacier came through here from the north and modified the territory over a period of time ranging from 2 million years ago to 15,000 years ago.

A part of the glacial line expanded from the lake and the pass between Monte Giove and Monte Faierone towards the interior of the Cannobina, while from the Valle Vigezzo glacier a line developed into the Valle Cannobina by passing from Finero.

From Valle Vigezzo, the glacier front occupied the entire territory around Gurro.
Land of glacial origin testify the passage of the glacier; moraine and fluvioglacial: concentrated in only a few small portions of territory, they form natural terraces corresponding, in most cases, with the areas of human settlement, Falmenta, Gurro, Crealla, Cavaglio San Donnino.

The glacier allowed the formation of terraces on which man founded villages as the landforms were such that they could cultivate and farm. The glaciers originated from the Gotthard Massif and, through the Levantine Valley and its lateral valleys, developed as far as the Po Valley, occupying the whole of Lake Maggiore (between 1 million and 20,000 years ago).