Coal Mines

Le fossiliferous rocks of the Sanagra valley are located in the Gariasca Valley, a small tributary that descends from theAlpe Logone and flows into the Sanagra (access restricted to insiders only). The paleontological heritage in this area outcrops near the Grona Line, and is situated between the Crystalline Basement formations and the Main Dolomite.

Although they are outcrops of limited extent, the rocks enclosed by the Grona Line, referred to as the Manno Conglomerates, preserve an important record of our planet's prehistoric events. The plant remains found bring to light an environment dating back more than 300 million years, during the Carboniferous period (Middle Carboniferous-Westphalian).

The carboniferous rocks, with their characteristic blackish appearance, were discovered between 1915 and 1918, during excavation work for the construction of the military road intended to connect Val Sanagra to Val Cavargna. Ten years later, in 1928, a local entrepreneur, Cavalier Bianchi, commissioned a geological survey of the carbonaceous material, exploring the possibility of exploiting it for mining.

In 1942, at the height of the autarkic regime, Cavalier Bianchi's company started anthracite mining from four mines dug near the outcrop. However, the activity turned out to be a failure due to the low yield of ore. Nevertheless, mining surveyor Luigi Maglia discovered one of the rarest and most interesting carboniferous fossil deposits in Italy.

The numerous fossil remains found (about 2000 pieces) became the subject of a publication in 1947, written in collaboration with Sergio Venzo, then Director of the Museum of Natural History in Milan. Since then, Val Sanagra has become a reference point for paleontologists, recognized as one of Italy's most significant anthracite-related fossil deposits.