Grotte e abissi in terreno Travertino

Travertine is a carbonate rock that precipitates from calcium-rich waters, often at springs and waterfalls. It can encapsulate cavities and form tufa caves, as in the surroundings of Banyoles. This group comprises 111 cavities: 96 caves and 15 pits, with a total length of 3409 metres and a maximum depth of 60 metres.

Among the longest cavities are the Coves del Mamut, with 537 metres of length and an exterior fissure of 103 metres at Cabrera d'Anoia; the Grutes de les Deus, of 223 metres, at Sant Quintí de Mediona; and les Estunes, of 210 metres, near the estany de Banyoles (Porqueres), surveyed on 17 June 1981. The maximum depth corresponds to the Avenc del Tall, of 60 metres, at Martís (Esponellà).