The geology of the Sierra Subbetica Natural Park consists of limestone formed from sediment deposited from about 200 million to 25 million years ago, in a vast sea that extended southward from the coast of the Iberian Plateau. The limestone has been formed from carbonate mud, the result of the accumulation of marine shells and skeletons at the bottom of the sea. Sediments began to be compressed, distorted, broken and stacked to emerge in a slow process that began 25 million years ago and continues today. Water, snow and wind have subsequently changed the shape the landscape which is rich in fossils especially ammonites.
This group of marine molluscs are extinct relatives of today's cephalopods, are of great interest in palaeontology. They were distributed widely in the seas around the world during the Jurassic and Cretaceous and evolved very rapidly resulting in a vast number of species similar in overall design but different in detail. The park is recognized worldwide as one of the most important to study the evolution of this group of fossils.
There are over a dozen towns and villages within the park, many of which are worth visiting. Cabra where San Juan Bautista church is said to be one of the oldest in Spain and Rute has a ruined Moorish castle and a fascinating Baroque church. Iznájar is a particularly pretty whitewashed village on the banks of a vast reservoir of the same name.
The hermitage Ermita de la Virgen in the Sierra de Cabra, is not far from Cabra. It is perched on rocky outcrop and provides stunning panoramic views of Sierra Morena and Guadalquivir river valley.
The park has one of the largest colonies of griffin vultures in Southern Spain as well Andalucia's largest population of the peregrine falcon, a bird that is the park's symbol. Other birds of prey include Bonelli's eagles, short-toed eagles and black kites. Golden Eagles can also been seen here occasionally. Wild boar, mountain goat and Cabrera shrew are just some of the mammals that inhabit the area.
Over 1200 plant species are listed in the Sierra Subbetica Natural Park with about 30 endemic species, some of which are threatened with extinction. The predominant vegetation is Mediterranean scrubland, with holm oak woods, peonies and gorses, hawthorn, spurge flax, Centaurea castellana and gall oaks. The river banks are home to poplars, willows, salt cedars amongst others.