The Nature Reserve covers a total surface area of 171 hectares, with an altitude going from 350 to 700 meters, and involves the southernmost nucleus of Rognosi mountains, while the three northern nuclei include the mountains of Mt. Murlo, Mt. Petroso, and Poggio delle Calbane. The geological substratum of these areas is of great interest, since it is characterized by ultrabasic igneus rocks, the ophiolites, mainly formed by gabbro, and marginally by diabase and serpentinized gabbro. The naturalistic interest for this areas, once considered unproductive and infertile, mainly derives from vegetation. As a matter of fact, a long series of researches has confirmed the great importance of the cenosis vegetating on these substrata, to the extent that these habitats have been included in the list of the priority habitats according to the European Union. In the recent past the area has been interested by reforestation measures, mainly carried out with pines. As a matter of fact, these artificial habitats cover today almost the 50% of the area, while only the 12% is covered by the characteristic natural vegetation.