glacial erratic in gneiss stone at 1000mt, Mount Sileggio

Glacial erratic

The boulder upon which this mark (sègn) is placed is a glacial erratic.
A glacial erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests. "Erratics" take their name from the Latin word errare, and are carried by glacial ice, often over distances of hundreds of kilometres.
In the glacial eras the glaciers reached as high as 1000mt above the lake level, and they carried here an amount of boulders from the Valtellina Valley. They are harder than the calcar rocks of the nearbies and where used for roads (as here), walls (as the one on the left side of the olive trees meadow that you passed) and parts of houses.