The park extends over 116,953 hectares at the point where the Central and Iberian systems and the northeastern sector of the Tagus Basin meet.
This conjunction explains the remarkable diversity of rocks that outcrop in the park and are responsible for its unique physiognomy. Slate, quartzite and gneiss (all of them very old metamorphic rocks) predominate, forming ridges, ridges, valleys, fluvial canyons, cliffs, canyons and gullies.In the highest altitudes, glacial cirques such as Pico del Lobo and Pico Tres Provincias or Cebollera Vieja, where the remains of ancient glacial moraines are visible. But there are also limestones that have given rise to fantastic landscapes such as the enchanted city of Tamajón and gorges such as those of Retiendas and Valdepeñas de la Sierra.