From Sillaro Valley to Brisighella, in Lamone Valley, the hills of Romagna are crossed by a spectacular and well-visible gray-silvery ridge suddenly interrupting the gentle silhouette of the hills, giving a unique aspect to the landscape. The outcrop, the longest and most imposing gypsum ridge in Italy, develops for 25 km and has an average width of one kilometer and a half. The area is characterized by particular karst morphologies including dolines, steephead valleys, and several caves, among which many pits stand out.