The Nature Reserve, enlarged in 1997, protects a large area of Carseolani Mountain Chain, between the basins of the rivers Salto and Turano. The Nature Reserve is divided into two different areas. The largest one includes Mt. Navegna and Mt. Filone, which Fosso dell'Obido separates from Mt. Cervia, which is separated from the nearby Mt. S.Giovanni by Fosso di Riancoli. The second area is formed by the mountains surrounding the town of Nespolo and representing the border with the nearby territory of Carsoli, in Abruzzi.