Trou à Roger

It opens in a joint on the same axis as the RL 21 fault via a 4-metre drop that immediately leads to a P 8. A high gallery, 2 metres wide (enlarged joint), brings us 15 metres further to a vertical constriction that leads via an R 3 into a chamber at the bottom of which is found a fine P34 with a belay at -25. This is in fact the base of a shaft rising (-40 m) that is reached at this point. At the top of the R 7, the meander appears to continue upwards and it seems possible to bypass the P 11; in fact, after traversing along a ledge, we realised that this is not the case, the only passage of water in the formation of this pit having evidently been the shaft.

From the base of the P 34 a very narrow meander is reached through a window, into which arrives a small stream of 0.25 l/s (this is the dry season now; in 1971: 1 l/s). This is the same flow as that of the RL 21. At the bottom of the terminal P11 we reach the lowest point of the pit at a small muddy sump (1.2 x 1 m) where the stream disappears. This sump seems to widen with depth and can, it seems, be dived; the great difficulty would be bringing the equipment because of the narrowness of the meander.

A difficult fifty-metre progression at mid-height in this meander brings us to an R 7 (widening of the meander) at the base of which opens the terminal P11.

WARNING: this hole is particularly exposed to floods; indeed, if we only reach the stream at the base of the P 34, it can be observed that already at mid-height of it there must be a significant inflow of water in the event of a flood. This cascade, as well as that of the R 7 and the following P 11, cannot be avoided and must be difficult to climb back up, since we are not far from the surface and this pit seems to be the main collector of this sector, so floods must be very rapid and violent.