Grotte e abissi nell'unità geologica Serra de Lleràs

The Serra de Lleràs is a unit of the Prepirineu, in the Pallars Jussà, formed by conglomerate layers where the cavities are linked to their pebble levels. The catalogue records 66 cavities: 52 caves and 14 pits, with a total length of 20,597 metres and a maximum drop of 328 metres. The dominant lithology is conglomerate (60), with the presence of limestone (6).

The most notable cavity is the Cova Cuberes, in Serradell (Conca de Dalt), with 13,513.15 metres of length and 328 metres of drop, the longest cave in Catalonia. Other relevant cavities are the Botet de Casa Rei, 1,579 metres long with a 41-metre drop in Tremp, and the Forat del Toscà, 1,416 metres long in Tremp, known to the people of Gurp and first explored by the SIE del CE Àliga on 9 and 23 September 1973. Also listed are the Graller de Castellet, with a 116-metre drop in Tremp (Sapeira), explored since 1911, and the Font de Rivert, a spring 321 metres long with a 16-metre drop (+13/-3) in Conca de Dalt (Rivert).

Among the pits, the Graller d'en Remigi Moli and the Graller d'Espills each reach a depth of 61 metres, and the Avenc Barbuixell, in the Conca de Dalt, has a depth of 46 metres, a total drop of 46.5 metres and a length of 284.8 metres.