Grotte di Olesa de Bonesvalls

Olesa de Bonesvalls, a municipality in Alt Penedès, contains 29 cavities: 27 pits and 2 caves. Together they total 3320 m of length and reach a maximum depth of 291 m. The recorded lithologies are limestone, present in 28 cavities, and dolomite, in 1.

The avenc de l'Esquerrà, in the Garraf massif, is the most important and complex cavity, with a depth of 291.4 m and three routes: Via Normal – Anna Maria Pallejà, Via Rat-penat and Via Lamarca-Torras. At 2050 m, it is also the longest cavity. Other cavities notable for their depth are the avenc de Sant Marçal, 121 m, located by the E.I.E.-PCB in 1970 and explored in 1971; the avenc Font I Sagué, 104 m, with a main shaft, the Ramunage route, the Sala dels Proscrits and a vertical passage that reaches -104.5 m; the avenc d'en Gori, about 60 m, at the Fondo de Matabous, explored in 1966 and extended towards -60 m by the SES del GER around 2010; and the avenc d'en Parrilla, a shaft with a drop of 45 m, an entrance 4 X 2 m and a vertical of 41 m.

Other cavities by length are the avenc de Sant Marçal, with 260 m; the avenc Font I Sagué, with 210 m; the avenc dels Topògrafs, with 131 m, 45 m deep, with an entrance in an old sparry calcite working, decorated galleries and a main shaft that reaches -45 m; and the avenc d'en Gori, with 80 m.