Grotte Henry

The old network, on the right, extends about a hundred metres and includes a wet bedding plane, fine phreatic tubes and a small stream flowing at the bottom of a fault. The new network, on the left, comprises a wet squeeze, a decidedly narrow, dirty and wet crawl, a third wet squeeze, then about sixty metres on all fours in a greasy, creamy mixture of water, clay and mondmilch. The phreatic tube turns into a meander followed for 170 metres. The Bruno shaft (P31) leads, after an R3, into the collector. Upstream of the collector, a gallery measures 2 to 4 metres in width by 2 to 8 metres in height. Along all the phreatic-tube galleries, upstream sections with vertical development branch off, quickly impenetrable (centimetre-scale fractures).

The crawl of the new network is permanently fed by a small stream (the "Fosse Septique"), and the whole is permanently fed by two small streams on the right bank. The meander has two tributaries on the right bank and one on the left bank. Downstream of the collector, one quickly meets a sump; a wet squeeze then a narrow sump end the collector (zone saturated with CO2). Upstream, the water emerges from an impenetrable fault. The overflow of the collector meets a large sump that can fill to a height of 3 metres and flood 20 metres of gallery, which becomes active when the collector discharges more than about forty litres per second.

One climbs up into the porch on fixed equipment (E8, E19) to +31 m. On the left begins the new network: after a few metres on all fours, one immerses oneself in a wet squeeze; a few more metres, a decidedly narrow, dirty and wet crawl, permanently fed by a small stream (the "Fosse Septique"); then follows a crawl through mud, a third wet squeeze, and finally about sixty metres on all fours in a greasy, creamy mixture of water, clay and mondmilch, in which one sinks knee-deep to the hips. At the level of the third stream, just before the gallery completely seals up, take the right; after a few metres on all fours, one can finally stand up. One follows the meander for 170 metres to the top of the Bruno shaft (P31), which after an R3 leads into the collector. Before the R3, a gallery on the right bypasses the downstream sump. Upstream of the collector, one can ascend it for 200 metres, after passing a duck under a wet arch through a gallery 2 to 4 metres in width by 2 to 8 metres in height. By a climb on the left bank, one can reach the overflow of the collector.

All the people who have visited the cave swore that they had just done the dirtiest cave of their existence.

Sources: Philippe Audra, "La Grotte Henry", Scialet: bulletin du CDS de l'Isère, Grenoble, Comité départemental de spéléologie de l'Isère, no. 13, 1984, p. 15-18: https://cds38.org/wp/wp-content/uploads/2020/10/Scialet-13-1984.pdf; Philippe Audra, "La Grotte Henry (suite et fin)", Scialet: bulletin du CDS de l'Isère, Grenoble, Comité départemental de spéléologie de l'Isère, no. 17, 1988, p. 12-15: https://cds38.org/wp/wp-content/uploads/2020/10/Scialet-17.pdf