Aven des Gentianes

The pit develops in an east/west fissure parallel to the mountainside. It is a typically tectonic cavity: blocks, décollement, numerous fault mirrors. The collapse of the entrance corresponds to the intersection of a perpendicular fissure with the main fissure. One lands in a chamber 3 metres in diameter, on a scree cone covered with humus. a steep slope between high walls leads to -13 in a cul-de-sac between blocks. An opposition above a suspended block allows one to climb back up to -4 where a choke obstructs the passage.

To the west, a cleared narrow passage gives into a small chamber where a large block occupies most of the floor. Towards the west, the walls widen to more than 2 metres. The ceiling, where it is not made of blocks, is not visible, the walls converging upwards as they incline. a descending start is obstructed by blocks. At the bottom, the fissure becomes too narrow, behind a rising passage.

The descent of the shaft (du puits) passes beneath a ceiling of enormous suspended blocks. The bottom is at this point one metre wide. Towards the East, a chicane coming from a perpendicular fissure leads beneath large blocks that must be climbed to descend again a little further on. There, the passage is almost entirely obstructed by a choke. To the West, a significant décollement narrows the passage, and one descends to a small step, the lowest point being below it, in a small damp chamber with earthy floor (sandy earth). Two small descending starts are noted, to the right and to the left, both impenetrable.

One notes, in particular on the ceiling inclined towards the west, beautiful fault mirrors: the polished, as if vitrified, part detaches in fine plates, black and sometimes striated (it could in fact be calcite occupying earlier fissures, these fissures having been the preferential site of more recent movements). To the right, one finds some of the very rare speleothems of the cavity, if one excepts the fine film of calcite covering part of the walls.

Behind the block, a narrow vertical passage led onto a fissure. This one, after blasting, allowed one to gain a footing on a floor of blocks, above a shaft. To the left, one must pass beneath the wall that curves in, leave a vertical fissure blocked at the bottom, and enter a crawlway, still towards the west. After a small niche, it gives onto another narrow passage: behind it, one can advance for 2 metres in a tight joint, where the combined horizontal and vertical décollements make continuation difficult, probably dangerous.