About 50 km of river environment with unique and unusual naturalistic aspects. Particularly intense geological and geothermic events have determined the structure of the current basalts. It seems that in the prehistorical period a river ran over clayey sediments; then great volcanic eruptions canalized in the riverbed a fluid magma which sank in the most clayey places, forming the current basaltic colonnades. The apotheosis of these spectacular natural sculptures can be found in the quarters Larderia in the Municipality of Motta Camastra.