Grotte di Les Valls d'Aguilar

Les Valls d'Aguilar, a municipality in Alt Urgell, brings together 43 catalogued cavities: 33 caves and 10 pits. The group totals 1152 m of passage and reaches a maximum depth of 36 m. The dominant lithologies are limestones, present in 41 cavities, while gypsum appears in 2.

Among the cavities most notable for their length are the Cova de la Barra, with 163 m of passage, a gallery that divides into two branches, an upper one up to +9 metres and a lower one down to -10 metres, with a total elevation difference of 19 metres; the Coves de l'Escala I Ns-19, with 144 m of passage and 36 m of elevation difference, connected with the NS-19 cave; the Cova de Boli Ermini, of 65 m, between Espaén and Castellàs, on the left bank of the riu de Castellàs; the Forat Negre de Miravall, of 59 m, with chambers and stalagmitic formation; and the Pou de les Gralles, a pit 35 m deep between Castellàs and Espaén, on the right bank of the riu de Castellàs.

As for depth, in addition to the Coves de l'Escala I Ns-19 and the Pou de les Gralles, there are the Avenc T-7, of 22 m, and the Avenc T-4, of 21 m, both explored by the GIRES in various campaigns in the 90s.