Grotte e abissi nell'unità geologica Val d'Aran

Val d'Aran is a unit of the Pirineu Axial, a high Atlantic Pyrenean valley with high-altitude limestone and marble karst among granite peaks. It contains 70 cavities: 16 caves and 54 pits, with a total passage length of 8,512 m and a maximum depth of 571 m. The lithologies present are limestones (53), marbles (9), granites (4), slates (2) and sandstones (2).

The Sistema de la Bargadèra, at Escunhau, Vielha, is the cavity with the greatest vertical drop in Catalonia: it links the avenc de la Bargadèra and the horat des Lòses (CE-6), with a vertical drop of -571 metres, and reaches 2,100 m of passage. Other notable cavities are the Horat Der Uelh Deth Tor, a pit 169 metres deep explored since 1977 with 1,718 m of passage, and the Sistema de Sarrahèra, an underground traverse with a vertical drop of 102 metres.

The Horat Der Unhòla is a large karst depression and sinkhole with a cavity more than 200 m deep, which includes the Hilat Bernard Magos (T-2) and the Hilat era Ansa dera Caudèra, discovered in 2018. The Horat Deth Bo comprises a 250 m underground stretch of the Malo river, to the SE of the Plan de Beret. The Cigalèra Deth Bacivèr, in Naut Aran (Alt Aran), is 163 m deep with seven shafts and two ledges, and was discovered in 1978 and explored and surveyed by the ERE-CEC in 1982.