Aven Cresp

a 12-metre shaft opening in a rocky slab through a 2 m x 3 m opening. At the bottom, a 10-metre meander filled with concretions opens to the east. To the north, a wider meander leads to the top of a very vast 23-metre shaft, with an inclined ledge at -25. This shaft opens into the ceiling of a large gallery, gently sloping, 180 metres long, with a floor formed either of concretions or of clay. In the ceiling, generally about ten metres high, several large chimneys open. Their climbing with a mast allowed the discovery at their top of a whole network of small galleries or meanders, some of which several hundred metres in development, located 25 metres higher than the floor of the large gallery.

At 20 metres from the bottom of the P23, in the left wall of the Grande Galerie, a high ascending meander starts, leading to the bottom of a vast shaft: the "Puits du Lapin", so named because at the time of discovery there was a fresh rabbit carcass on the floor. In the ceiling of this shaft several galleries open: to the north, the galerie du Rasoir, 3 m x 4 m in section, descending to a low point where it was filled (-42). On the side opposite that of the trench, an ascending meander leads into a dead-end chamber: the "salle des Colonnettes", traversed by a draught; in the ceiling, a chimney communicates through an extremely narrow meander with the small shaft of the 37-D6. In the west wall of this chamber, a fissure gives into the middle of a P 11 with a blocked bottom. Opposite the galerie du Rasoir, on a ledge of the Puits du Lapin, two small galleries begin. The larger leads into a small chamber which is in fact a shaft bottom filled with large blocks 3 metres higher; it is certainly the lower part of the 37-C2, opening 35 metres south-west of the Aven Cresp. At floor level, in this chamber, a low passage leads to a small chamber followed by very narrow crawls emerging at the top of a large calcite flow forming the southern end of the Grande Galerie. On the same ledge of the Puits du Lapin, a meander with a fairly dry clay floor opens, filled with earth after 20 metres. a distance of 17 metres separates it from the bottom of a small cave located 55 metres south of the aven Cresp, the "Trou du Renard", which would be another entrance if it were not filled[ref]Fiche cavité du Congrès 2015 de la FFS > "37-B2 -- Aven Cresp" : https://congres2015.ffspeleo.fr/pdf/FicheCresp.pdf[/ref].

The large gallery is very rich in concretions towards the end, its floor being formed either of concretions or of clay. a large calcite flow forms the southern end of the Grande Galerie.

The horizontal galleries correspond to former drains of the Caussols plateau, at the time when the flooded zone was only a few tens of metres below the floor of the polje. At low water, the water was at the level of the galleries; in flood, they were drowned and the water flowed back up to the surface, flooding the whole polje in a temporary lake. During the flood, corrosion completed the levelling of the surface of the polje. Seen from Calern, this work of corrosion appears clearly, in the form of a perfectly flat surface cutting the inclined layers of the Caussols syncline. At present, the flooded zone is several hundred metres deep[ref]Fiche cavité du Congrès 2015 de la FFS > "37-B2 -- Aven Cresp" : https://congres2015.ffspeleo.fr/pdf/FicheCresp.pdf[/ref].

The digging of a 10-metre trench at the low point of the galerie du Rasoir allowed the continuation of this silted sump to be reached, unfortunately filled again 30 metres further on. The climbing with a mast of the large chimneys in the ceiling of the large gallery allowed the discovery at their top of a whole network of small galleries or meanders.