Avenc de Can Torrella

The circular entrance, 80 centimetres in diameter, gives way to a first shaft of 4 metres which at its base forms a small chamber of 4 x 1.5 metres. On the SW side of the chamber there is an almost impenetrable crawl of just over one metre in length, while on the opposite side (NW) there is a second shaft, of 2.3 metres. Its width is only half a metre and it leads to the maximum depth of the pit at – 6.3 metres. At the NW end of this second shaft there is a narrow chimney 3 metres high.

It is a swallow hole of the riera de les Arenes when it flows in flood and the level reaches the entrance. This happens very occasionally, but at some point it could become blocked due to dragged materials.

The pit has been excavated following a NW joint within the Eocene conglomerates (puddingstones), predominant throughout the massif. But in this cavity it must be noted that the entrance and the first metre and a half of the entrance shaft are excavated in Vallesian conglomerates (upper Miocene) which have not been affected by the joint, but being a softer material, it gave way to the erosion of the riera, opening the entrance and connecting it with the lower part of the pit.