Caunha de Rouairoux

The cave begins with a vast conical doline at the edge of the track, dotted with beeches and succulents. At -11 m a small hole opens between the blocks, which is the actual entrance to the cavity. One descends over concretioned blocks to find oneself in a low, straight gallery. On the south side is a semi-circular chamber situated beneath the doline, traversed by a small active stream coming from the entrance. This active stream splits in two: one part thus takes this route and continues through a lowered gallery that arrives almost beneath the first large chamber, the other part flows into a low gallery that one follows due north for 40 metres. These two galleries are separated only by clay fillings.

One emerges at the threshold of a vast chamber (salle René Nelli) surprising for the region and given the enclosing terrain (rotten marls). The ceiling consists of a single-piece slab of about 600 m². The floor forms a funnel in the marls; at the lowest point, the ceiling is 15 m above our heads.

The downstream section flows into a fine gallery that takes a west-northwest direction roughly conformable to the dip. The gallery of good proportions (6 m x 4 m on average) with widenings to 15 - 20 metres descends in a gentle slope broken by small steps down to -67 m. At -31 and -50 m, the stream is entrenched in an overdeepened meander in a layer of harder marls. In places, lenses of puddingstone are visible in the ceiling.

Back at the confluence, one enters one of the vastest parts of the cavern, cluttered with large masses of clay. This part has an upstream branch parallel to the arrival branch and joining it through a small hole; further on it ends in a narrow meander. In the large gallery where the stream passes beneath clayey blocks, one follows clay terraces ending on a muddy slope. On the left is the start of a tributary that can be ascended for 50 metres and which ends in a chamber with no continuation. At the bottom of the slope, one rejoins the stream, which immediately disappears beneath blocks. Above, the gallery continues for 10 metres and stops abruptly (terminus 1970). A muddy hole, funnel-style, against the left wall allows one to find the stream again in a pool. One progresses through a fairly low gallery with a few steps and basins. The ceiling lowers and a small passage at ground level opens onto a perpendicular meander: the « méandre Fébrile », 28 metres long. The start is rather scabrous and sets the tone for this section that some describe as anthology material. The average width does not exceed 30 cm with several more severe passages. The meander ends in a large gallery dug in the marls once more. 20 metres further on, collapsed blocks create a very tight crawl. Just before, on the right, a small tributary of 25 metres. The water arrives from the ceiling through an impenetrable meander. After the crawl, one emerges into a chamber even more astonishing than the first (salle Arnaud). A large balcony overhangs it, causing a 10-metre fall for the stream. It measures 30 m x 20 m and 15 metres high. At the bottom, large blocks detached from the overhanging stratum and two large clay funnels form the decor. On the edge of one of them is a small shaft that allows one to descend beneath the blocks. The stream is there again but loses itself in the mud at -109 m.

The only decorated chamber in the cave is found at the outlet of a smaller gallery of 30 metres, reached by the cascade tributary.

The cavity is still active. The stream consists of several rivulets: entrance gallery, salle R. Nelli, cascade tributary, tributary of -66, tributary of the salle Arnaud, all rapidly impenetrable moreover. The low-water flow is almost nil, a few litres/minute approximately. The average flow is around 4 litres/second and in flood it must reach 150 - 200 litres/second. A dye tracing will have to confirm the logical supposition that the waters emerge at the Coume Escure spring (source de Labastide-en-Val) 3.5 km away and 310 metres lower.

One crosses the salle René Nelli by the west flank, then a descent among large blocks gives access to the river. Upstream, arrival of the entrance stream beneath the blocks of the chamber on the left bank; one ascends a cascade of gours then the gallery narrows; a tributary arrives on the right bank from an impenetrable meander. After a short damp low vault, one finds the large gallery again. On the right arrives a fairly important tributary, the cascade tributary, coming from a smaller gallery of 30 metres that opens into the only decorated chamber in the cave. The stream falls from the ceiling through a 10-metre chimney but emerges from an impenetrable fissure.

Geology: the cavity is entirely dug in the variegated (or versicoloured) marls of the Cusien (Eocene). Over a large part of the cave, the ceiling and floor consist of a layer of more compact, harder marls. Sandwiched between the two, the much more friable marl layer has been cleared out. A few lenses of puddingstone or sandstone are visible and the « méandre Fébrile » crosses one of them. One notes fine cross-bedding forms and curious erosion forms on the puddingstones and sandstones. From a tectonic point of view, one notes the small influence of fracturing on the digging of the galleries, rather governed by the dip. The entrance gallery is dug along a diaclase nord (north/south joint) visible in the ceiling but which dies out below in the softer layers. At the entrance to the salle R. Nelli, one notes a folding-back of the soft marls, certainly tectonic (in relation to the entrance fissure?). Thereafter, tectonics no longer influences the cave but four fault mirrors are observed in the ceiling with a north 210° direction and a dip of about 30 to 40°, due to small shears. They are located at the exit of the salle R. Nelli, at -31 m between cross-section 5 and 6 and at the level of the tributary of -66 m. The north 210° direction is also found at the cascade tributary and at that of the salle Arnaud but without visible displacement, and also on several occasions in the ceiling, associated with fissures of north 300° direction and forming an orthogonal mesh.