Grotte e abissi in terreno Scisto

The Schist is a foliated and insoluble metamorphic rock. Cavities there are scarce and are usually linked to fractures or to the contact with carbonate rocks. The catalogue records 17 cavities in this lithology: 4 pits and 13 caves, with a total length of 528 m and a maximum depth of 46 m.

The longest cavity is the Avenc del Tinc-ca-tinc, with 98 m, a pit 43 m deep in the Pallars Sobirà, explored in 1962 and surveyed in 1974, with an entrance shaft of 22 m and stalactitic formations. It is followed by the Forat de les Gralles d'espot, with 80 m, and Lo Forat de la Campella, with 77 m. The deepest cavity is the Forat de les Gralles d'espot, with 46 m, a pit of biospeleological interest in Espot, Pallars Sobirà, opened in a doline in Devonian calco-schists, with an important clastic process and a snow ramp that reaches 30 m in depth.

Other notable cavities are the Cova de S'Infern, with 50 m, a sea cave at the Cap de Creus (Cadaqués), today a 35-metre rock bridge within the Integral Natural Reserve, and the Forat de la Canya, with 48 m, in the Vall de Cardós.