The stone bridges on the po river at Turin (NW Italy): A scientific dissemination approach for the development of urban geological heritage

This paper presents a minero-petrographic study of the rocks employed in the building of stone bridges over the Po River in the city of Turin (Piemonte Region--NW of Italy). In all the bridges, the dimension stones are present in different quantities and elements, either representing the only building material or associated with several artificial materials. The total number of bridges on the Po River is six, three of which are made of natural stones (Princess Isabella Bridge, King Umberto I Bridge and King Vittorio Emanuele I Bridge) and three are built with artificial materials with minor dimension stones (Balbis Bridge, Queen Margherita Bridge and Sassi Bridge). The lithologies of the six bridges have been identified in order to find out the corresponding geological units and the original quarry site. The stones mainly consist of rocks from the western Alps, with a prevalence of metamorphic rocks such as gneisses, as well as intrusive igneous rocks. Sedimentary rocks are minor represented.