The Salse di Nirano near Fiorano are an interesting geological curiosity. Eruptions of salty mud have formed miniature volcanos with craters, explosions and emissions of inflammable gas. These are due above all to underground deposits of hydrocarbons (particularly natural gas), which escape to the surface, bringing with them salty water and mud. Together with the mud, the volcanos also emit small amounts of brown coloured liquid hydrocarbons, which used to be exploited for medicinal purposes and for lighting in the last century. However, these deposits are of no economic value today.