The Sulcis Mountains geological structure is rather intricated, due to their very ancient origin which, in the first formations, dates to more than 600 million years ago (Cambrian period). Their age is also shown by the rather mild nature of the reliefs, with a few peaks over 1000 m of altitude, presenting what remains of the superficial erosion which has partly left untouched the magmatic intrusions and the metamorphic rocks originated before the Variscan orogeny.