The highest point of the Giara, which rises about 20 meters above the surface of the plateau, is the result of the consolidation of a river of lava. This lava supposedly came from a flattened volcanic cone, which can be seen in the Mount Zepparedda volcanic emission center (609 meters). The point, located in the territory of Tuili, is covered by dense oak forests. The lavas are composed of hypocrystalline-subalkaline basalt stones, which date back to the Pliocene Epoch. In the center of emission, the crater wall is vaguely recognizable. It has a central depression with typical blocks of scoriaceous lava inside, probably related to the phenomena of partially-active volcanoes.