The rocks that we can observe within the Fort system were formed during the Cretaceous period (about 80 million years ago) and are the remains of the seabed of an ancient ocean up to 4000 m deep. When the mainland was still populated by dinosaurs, the rocks of the ‘Parco delle Mura’ were therefore a muddy and sandy seabed, very different from the suggestive formations that visitors can admire today!

In fact, observing the rocks with the naked eye, on the surfaces of some layers it is possible to notice curved grooves that resemble small labyrinths: they are what remains of tunnels dug by ancient marine worms in search of food contained in the mud. Worms, like all other soft-bodied organisms, rarely fossilize while it is more likely that the traces of their passage are preserved: walking along the paths of the Park is therefore like visiting an open-air Museum of Paleontology, where we can admire million-year-old fossils that help us discover the history of the evolution of the entire Liguria region.

This fossilization process not only allowed the conservation of the traces but, together with other factors, also the consolidation of the sediments (sand and mud) until they were transformed into rock. Subsequent to this consolidation these layers, originally deposited horizontally on the ocean floor, were involved in the clash between continents that generated the Alpine and Apennine chains and therefore underwent folding, translation and lifting until they reached the position in which we find them today, where they became an integral part of a mountain range.

We thank the Hydrogeology, Geotechnics and Valleys Directorate of the Municipality of Genoa for their precious collaboration and for providing part of the texts.