Aven du Trépadone

The entrance opening, with an average diameter of 1 metre, is at ground level. The aven du Trépadone is located next to a small lens of marly limestone of the lower Barremian; the presence of faults explains the rise of this clayey lens, and the aven itself occupies one of these absorbent faults. The large chamber measures 15 m x 7 m x 4 m.

Un slight trickle of water flows almost permanently at the lowest point of the cavity, at -72 m.

The opening leads directly onto a 13-metre shaft. One then lands on a clayey ledge, and the descent continues through a 6.5-metre shaft opening into a vast joint. There, descend the scree slope to a shaft blocked at a depth of 3 metres. Two equivalent options are then available: on the right, one can reach the -35 level (crowbar) via a wide 10-metre shaft; by going around the blind shaft on the left, a short meander and 2 steps of 4 and 5 m lead to a rock bridge where the crowbar is wedged (-35 m). This crowbar will subsequently help to descend the following R 5. One will then make one's way along a small passage to a constriction behind which a 4-metre step and a steeply descending crawl will lead into the large chamber (15 m x 7 m x 4 m). By searching a little among the blocks, on the right, one will find a well-threaded R 5 leading to the lowest point of the cavity at -72 m. In the centre of the chamber, using the large block, one reaches an upper branch of the network by a 4-metre climb.

WARNING: possible presence of CO2 in this cavity from the first shafts onwards.