Grotte e abissi nell'unità geologica Serres marginals - Est

The Serres marginals - Est are a unit of the Prepirineu formed by limestone ranges on the southern edge of the Lleida Prepirineu, a transition zone toward the plain with numerous cavities. It brings together 82 cavities: 34 pits and 48 caves, with a total passage of 3235 metres and a maximum depth of 103 metres.

Among the most notable cavities are the Forat del Coscoll, in Camarasa, located in 1973, with a continuation found in 2005 that places the current depth at -103 metres; the Baborell de la Dona Morta, in the serra de Sant Mamet, Alòs de Balaguer, known since long ago and explored on 26 January 1969; the Avenc l'Estreta, in Camarasa, explored by the GELL in 1998; the Forat de l'Obaga de la Maçana, in Camarasa, with 142 metres of passage and developed lithogenesis; and the Avenc de la Dolina, in Camarasa, with a narrow entrance that blows strong air at some times of the year.

The lithologies present are Limestone (61), Conglomerate (17), Dolomite (3) and Marl (1).