Caves and potholes in the Serra de Llaberia - Colldejou geological unit

The Serra de Llaberia - Colldejou is a unit of the Serralada Prelitoral, a limestone massif between the Camp de Tarragona and the Ebre, with rugged relief and well-developed karst. It contains 67 cavities: 30 pits and 37 caves, with a total passage of 3869 metres and a maximum depth of 87 metres.

Among the most notable cavities are the Avenc de la Miloquera, with 769 metres of passage at Marçà, with five entrance mouths and a vertical drop reaching -78 metres; the Avenc del Pastor, of 238 metres, at the Turó de la Miloquera, Marçà, explored and surveyed by the Espeleo Club de Gràcia in 1979; and the Avenc de Pratdip, of 220 metres, at the Muntanya Blanca de Pratdip, with an entrance shaft of 21 metres and a lower gallery that reaches the 68.4 level. Other relevant cavities are the Avenc de les Perles, of 188 metres, and the Avenc Grallera de l'- Ortiguer Aguiler, of 175 metres.

The deepest cavities include the Avenc de l'Estel, of 87 metres, at Pratdip, with an entrance shaft of 35 metres; the Avenc de la Miloquera, of 78 metres; the Esquerda Estreta de Mont-redon, of 74 metres, at Tivissa; the Avenc del Pastor, of 71 metres; and the Avenc Grallera de l'- Ortiguer Aguiler, of 69 metres. The lithologies present are Limestone (44), Dolomite (15), Sandstone (4), Travertine (1), Clay (1), Marl (1) and Conglomerate (1).