The protected area was founded for the protection and the enhancement of the outcrops of ophiolite rocks - rocks of volcanic origin characterized by greenish shades - which are usually covered with a particular and interesting vegetation. The protected area includes the Murlo mount (603 meters), the Petroso mount (649 meters) and Poggio delle Calbane (879 meters), all situated in south and west of the built-up area, in the upper Tiberina Valley. The typical landscape is the Garrigue, that is an environment characterized by a sparse vegetation dominated by grasses and shrubs with many outcrops and a not very deep soil.