The Sierra Subbética Nature Park straddles the Bética mountain range, of limestone character and with typically jagged karstic formations that form steep slopes reaching 1,500 metres in height, narrow valleys and long stony ridges. This is due to the fact the Natural Park is where the European plate and the Eurasian plate collided during the Mesozoic and Tertiary periods.
Further unique features within the Natural Park are the sinkholes at Cerro de la Ermita, almost circular in shape and with steep sides, and limestone rock “poljes”, large flat-floored depressions within karst limestone, and where rainwater collects to form artificial pools. In the Sierra Subbética there are “poljes” at La Nava and at Fuenseca, although their drainage has been altered by human activity.
Due to its sediment based limestone geological formations of between 200 and 25 million years ago, the Sierra Subbética is a fossil spotter’s paradise. The limestone is a result of the accumulation of marine shells and skeletons at the bottom of a sea that extended inland towards the Iberian plate. It is not uncommon to come across ammonites and other marine molluscs, leading to the Park being recognized on a worldwide scale for the study of the evolution of marine fossils, and indeed resulting in the Park being included in European Geoparks Network.