Trou à Philippe

The entrance joint gives very rapid access to a small chamber cluttered with clastic collapse debris, then to the Gallery proper, low and wide (Galerie des Ossements). This Gallery, single for about a hundred metres up to the Salle de la Séparation (-50 m), divides there into two parallel galleries (the Galerie des Deux and the Galerie des Dents de Cochon) which rejoin at the Salle du Repos (-95 m). The Galerie des Deux continues to develop mainly along the joint, while the Galerie des Dents de Cochon presents a morphology made more irregular by the double presence of a meander and a bedding joint.

A low, narrow passage, at the Salle du Repos, gives access to a wide inclined Gallery (25°) interrupted at the Salle du Dada by a difficult squeeze. This can be bypassed by a meander in which a slide also brings us to this chamber. Here an inclined block (the Dada) facilitates the passage of a small upward step and introduces the progression into the Méandre de la Pile. This progression is characterised by the crossing of two small steps and by the route around collapse blocks. A cramped passage due to the abundance of these clastic deposits invites us to descend the « Tourniquet » into a narrow but more regular meander.

Further downstream, after a widening of the latter (Salle des Perles), the walk is interrupted by a stalagmitic flow (Ressaut des Acharnés) which can only be crossed after a rather perilous opposition climb. Behind this flow, the meander widens into a small chamber before intersecting another network: the active network.

Downstream, progress being made difficult by the abundance of flint beds and by the narrowness of the meander, we leave it in order to continue the exploration in an upper widening (Salle des Rapides). We thus arrive at the Saut de Ski and rejoin the stream which, 20 metres further on, abandons the meander for good, absorbed by the strongly inclined bedding joint over 100 metres and interrupted by two small watered steps (6 and 4 metres). We then reach a chamber where the stream is lost in an impenetrable squeeze at -283 m.

The wide, low Gallery offers in places pretty, fairly discreet concretions. The Méandre des Excentriques is adorned with beautiful crystallisations. A stalagmitic flow (Ressaut des Acharnés) interrupts the walk.

The floor of a meander is followed by a small stream (1 l/s in the low-water period). The Méandre des Excentriques is pierced by two tributaries. Downstream, the stream abandons the meander for good, absorbed by the strongly inclined bedding joint over 100 metres, and is lost in an impenetrable squeeze at -283 m.

« Tourist » visit

It is advisable to descend 2-3 metres by downclimbing to reach the narrow passage that marks the entrance. One then descends a wide, low Gallery. After 100 metres, two galleries can be followed: the wider one is the one on the right as you go down. On several occasions it is moreover necessary to shift the progression to the right so as not to find oneself in narrow passages. Arrived in a chamber, one continues the progression in a meander that presents no difficulty. Beyond, the descending Gallery resumes to reach a step which is climbed thanks to a rope in place. On the other side one descends two steps thanks to a rope to bring. A low passage in the blocks allows one to reach a meander where we stopped our progression.

Active network

A descent of 5 to 6 metres, in opposition, allows us to reach the floor of a meander followed by a small stream. Then two possibilities are open to us: either continue the descent by the Méandre des Silex, or go up the watercourse by the Méandre des Excentriques. The latter offers a rapid progression but quickly slowed by a rather dangerous boulder choke. Once this is crossed, we reach the base of two watered shafts, twinned by a small step of 4 metres behind which the progression in a small meander is quickly interrupted by a sump.

Equipment

For the Gallery in the terminal bedding joint: 1 rope of 100 metres + 3 plates (the rigging should perhaps be reviewed) + a natural anchor. A rope of 20 metres for the Ressaut des Acharnés (preferable). Provide a retrieval ring. For the 4-metre step, upstream of the Méandre des Excentriques, provide a length of ladder. A spit is in place.