Gouffre du Gros Pif

It is through a window at -12 m that one enters the pit proper to descend a circular shaft 10 metres deep. At the base of this shaft, a deobstructed double constriction leads to a steep slope of 10 metres that opens onto a shaft 30 metres deep. At -62 m, at the bottom of this shaft, the diaclase is much more visible; it starts from the chamber (bottom of the shaft) and runs south-east with a characteristic cross-section (see plan) for 15 to 20 metres. There, it widens to form a shaft at -73 m. At -112 m, a ring goes 3/4 of the way around the shaft; it corresponds to a reduction in the diameter of the shaft, which ends at -152 m on a flat floor of sand and gravel. The diaclase, at -152 m, is only 5 to 10 centimetres wide. To the south-east, the diaclase est appears to deepen and widen, but it is flooded.

In this shaft, at -85 m, a trickle of water arrives through the rubble wedged in the diaclase. The movements of the sand suggest that during the snowmelt period, the water flows into the diaclase and crosses the bottom of the shaft in a north-west/south-east direction. This pit dug into the Urgonian along a diaclase probably reaches an impermeable layer at -152 m, the rest of the system being flooded. It should be noted that on the Solaison side springs emerge at this altitude.

It is much more practical to descend at this point, either by anchoring on a diaclase piton or by "spitting" since the rock is excellent.