Major geological units of Catalonia

An inland mountain range of the Catalan Mediterranean system, running parallel to the coast and separated from the Serralada Litoral by the Prelitoral depression. Its limestone and conglomerate massifs — Montserrat, Montsant, Prades, Sant Llorenç del Munt — hold much of the country's major cave systems.

A belt of folded limestone ranges between the Pirineu Axial and the Ebro depression. Its powerful karst — Cadí-Moixeró, Montsec, Boumort — hosts some of Catalonia's deepest potholes and cave systems.

A range that skirts the Mediterranean coast, from Garraf to the Empordà. It combines intensely karstified limestone massifs, such as Garraf, with granitic sectors of block caves.

The central, highest core of the Pyrenean range, made of ancient crystalline materials. Karst is concentrated in pockets of limestone and marble interleaved within it, often at high altitude.

The great inland sedimentary basin of Catalonia — the Ebro depression — of gentle relief. Sandstones, conglomerates and gypsum predominate, with a discreet but locally notable karst, such as the salt karst of Cardona.

A group of ranges linking the Prepirineu with the Serralada Prelitoral in the northeast. It includes the volcanic terrain of the Garrotxa and travertine formations, such as those of Banyoles.