Grotte du Cirque

A short, near-vertical crawlway leads to a small rubble pocket followed by a horizontal 25-metre passage that gradually becomes muddy.

A vertical passage between blocks allows one to traverse a stretch of gallery at the bottom of a four-metre flowstone. The Salle des Puits appears after a bend; its floor consists of an enormous mound of hard clay. At the back of the chamber, a large stalagmitic flowstone rises 8 metres and ends at an impenetrable joint.

A spacious, nicely decorated gallery, oriented N-S, leads, after a flowstone, into the Galerie du Mondmilch, which is traversed on all fours; this gallery is paralleled by a conduit that begins before the flowstone. At the start of the gallery, lower down on the left, a large mondmilch pool is followed by a short gallery that pinches out. At the end of the gallery is the access to the Réseau des Ailes de Papillons, between 2 blades on the left.

A little further on, a hole 3m x 1m and 1 metre deep perforates the floor; it leads into a 10-metre flat-out passage that ends at a step. At its base, a chimney appears on the right, then a small branch followed by a P 5 on the left. 20 metres further on, the gallery continues with numerous zigzags up to an ascent where a ladder facilitates the climb. At the top are found, at the same level, a dynamited crawlway that is sometimes very draughty; higher up, the access to the Salle des Lames; on the right a window giving onto the continuation of the gallery. Over 30 metres, the route passes between a vertical blade and the right-hand wall, or directly on the blade. An abrupt descent (ladder recommended) arrives in the terminal gallery, which contains a few insignificant small branches.

After a gour, the gallery turns into a forced conduit that is blocked, 20 metres further on, by a mega-colmatage composed of alternating stalagmitic floors and clayey gravel at -11. Facing the gour, on the right, a small narrow passage opens onto a muddy lake five metres long that continues, behind a low point at water level, by a 7-metre ascent on the left and an impenetrable fissure on the right.

Réseau des Puits: the access is between two blades on the south side of the Salle des Puits. An inclined passage of about fifteen metres leads to the top of a P 8. At its base, behind a local constriction, a conduit descending at 35° ends at a 2-3 metre step after a 180° bend. The step forms the top of the 2nd shaft, 12 metres deep, which is choked by rubble at -36, the lowest point of the cave. In the first third of the inclined entrance passage, a horizontal gallery following a joint in meander form, thirty metres long, ends at -8 at a small passage soon impenetrable after a 1.5-metre collapse.

Galeries des Triangles Creux: the start is made by straddling three parallel blades 5-6 metres above the floor of the Salle des Puits. Oriented N-S, this side passage is heavily decorated: soda straws and especially helictites abound. The slope becomes nil after a letterbox (triangles creux at 20 centimetres from the floor on the right) while the speleothems become dead and roots appear. The side passage pinches out definitively after several narrow passages at +3, the highest point of the cavity. On the right, a narrow 5-metre shaft has two impenetrable branches.

Réseau des Ailes de Papillons: it begins, at the end of the Galerie du Mondmilch, with an ascending joint that turns into a chimney in bare rock after 4 metres. At the top, a crawlway leads after a few metres into a small chamber 3m x 6m whose floor consists of blades and rock pillars. On the left, a flowstone followed by a 2-metre step leads to the top of a P 9. At the base of the shaft, towards the S-SE, a conduit opened with explosives, 10 metres long, begins at floor level; after a step, it descends 3-4 metres. This passage, sometimes well ventilated, is certainly connected with an interesting continuation. Opposite this conduit, a series of flowstones ends at a 2-metre step lined with speleothems. A muddy crawlway opens into the terminal chamber, vaguely circular, made up of a succession of small steps covered with red clay.

The Salle des Puits contains a large 8-metre stalagmitic flowstone. The Galerie du Mondmilch is nicely decorated. The Galeries des Triangles Creux are heavily decorated, with an abundance of soda straws and especially helictites; further on, the speleothems become dead. In the Réseau des Ailes de Papillons, a 2-metre step is lined with speleothems.

The horizontal 25-metre passage gradually becomes muddy. A large mondmilch pool precedes a short gallery. A muddy lake five metres long continues behind a low point at water level. After a gour, the gallery turns into a forced conduit blocked by a mega-colmatage composed of alternating stalagmitic floors and clayey gravel at -11.

A short, near-vertical crawlway leads to a small rubble pocket. A vertical passage between blocks allows one to traverse a stretch of gallery. The Galerie du Mondmilch is traversed on all fours. A hole 3m x 1m and 1 metre deep perforates the floor and leads into a 10-metre flat-out passage. At the base of a step, a chimney appears on the right, then a small branch followed by a P 5 on the left. An ascent where a ladder facilitates the climb leads to the top. An abrupt descent (ladder recommended) arrives in the terminal gallery. The start of the Triangles Creux is made by straddling three parallel blades 5-6 metres above the floor of the Salle des Puits. In the Réseau des Puits, an inclined passage of about fifteen metres leads to the top of a P 8; a conduit descending at 35° ends at a 2-3 metre step after a 180° bend. In the Réseau des Ailes de Papillons, a flowstone followed by a 2-metre step leads to the top of a P 9; a conduit opened with explosives, 10 metres long, descends 3-4 metres after a step.

Geology: the cave develops in white-patinated limestones of the Lower Devonian. The galleries mostly follow the N-S fractures inherited from late Hercynian brittle tectonics, a short distance from the Roc d'Agnel fault of the same direction. All the NE-SW joints are entirely filled with more or less calcified and siliceous sheets that stand out in relief after dissolution of the host rock by corrosion.

Karstology: the mean level of the main gallery corresponds, with a small offset, to that of the Réseau III of the Trassanel cave. It is thus the most easterly representation of this level known to date (1992) under the southern flank of the Cabrespine syncline.