Lithologies

Limestone is the dominant lithology of Catalan cavities: 2711 recorded cavities, 1430 caves and 1281 pits, with 143398 m of total passage length and a maximum vertical drop of 571 m.

Conglomerates are detrital sedimentary rocks made of cemented rounded pebbles. In Catalonia, 1069 cavities have been catalogued, with 739 caves and 330 pits, a total length of 59902 metres and a maximum depth of 328 metres.

Dolomite is a magnesium-rich carbonate rock, related to limestone but more resistant, that dissolves more slowly and usually forms karsts with rough morphology and robust galleries. The catalogue gathers 371 cavities of this lithology, including pits and caves.

Sandstones are a sedimentary rock of cemented sand grains, poorly soluble, where cavities of mechanical origin predominate. The catalogue records 366 cavities in this lithology: 317 caves and 49 pits, with 17588 m of total passage and a maximum depth of 215 m.

The Granite group comprises 129 cavities (126 caves and 3 pits) with a total length of 3,068 m and a maximum depth of 27 m. An intrusive igneous rock, hard and crystalline, that does not dissolve: its cavities form through erosion and the displacement of blocks.

The travertines comprise 111 cavities: 96 caves and 15 pits, with a total length of 3409 m and a maximum depth of 60 m. Notable are the Coves del Mamut, the Grutes de les Deus and les Estunes.

Gypsum is a highly soluble calcium sulfate that creates rapid and active karst, with dolines and caves. The catalogue lists 32 cavities in this lithology: 12 pits and 20 caves, with 5255 metres of total passage and a maximum depth of 76 metres.

Marls are a sedimentary rock intermediate between clay and limestone, unfavourable for large cavities. The catalogue lists 31 cavities in marls: 17 pits and 14 caves, with 1061 m of total passage and a maximum depth of 52 m.

The Marbles are limestones recrystallised by metamorphism that retain carbonate solubility, which allows karst to develop. They contain 22 cavities: 12 pits and 10 caves, with 5,140 m of total passage and 169 m of maximum depth.

The Schist, a foliated and insoluble metamorphic rock, contains 17 cavities: 4 pits and 13 caves, with a total length of 528 m and a maximum depth of 46 m. The cavities are usually linked to fractures or to the contact with carbonate rocks.

Slate, a fine-grained metamorphic rock derived from clay, is impermeable and insoluble and rarely hosts cavities of notable size; the catalogue records 5 cavities, with 81 m of total passage and 7 m of maximum depth.

Clay groups 3 cavities: 2 caves and 1 pit, with 69 m of total passage and 5 m of maximum depth. Fine, plastic sediment that acts as an impermeable layer.

The salt caves of Cardona include 3 cavities, with a total length of 5200 m and a maximum depth of 187 m. The Cova dels Meandres de Sal is the longest and deepest.

Basalt is an effusive volcanic rock. In the catalogue there is 1 cavity in this lithology: the Cova de les Feixes, an 18 m tunnel in Olot.

Sand lithology: unconsolidated detrital sediment that does not form karst. It includes 1 cavity, les Cavorques, with 8 m of passage and 0 m of depth.