Embut de Caussols

A group of 12 crevasses joining 2 metres lower in a labyrinth of galleries swallows the stream draining the waters of the closed basin of Caussols. These galleries join into a single one which almost immediately widens into a chamber occupied by a lake.

Beyond, the gallery continues towards the north-east for 30 metres, with no appreciable slope, makes a hairpin turn and is cut by a 4-metre pit where the water plunges. On the other side of the pit, a sloping crawl allows one to rejoin the main course, doubled by a small parallel gallery.

The cave continues towards the west, with several deep potholes, and meets a narrow tributary meander penetrable for 15 metres. This meander is certainly the downstream continuation of a small entrance situated a few metres north of the crevasses at the start of the Embut de Caussols. This one continues as a meander penetrable for 10 m and almost totally choked with stones and debris; the inaccessible part should not exceed 10 metres.

After the tributary, the course runs a few metres to the north-west, is cut by a 3-metre cascade and then runs due north. A steep and slippery slope, the toboggan, leads 7 metres lower to the foot of an ancient, heavily decorated pit. The gallery continues, wider, almost horizontal, to a sump at -22 m and 150 m from the entrance. This sump, very short, was breached with explosives and gives access to a straight gallery, where the water is fairly deep, leading to a dead-end labyrinth.

To the left a gallery departs whose floor is pierced by numerous potholes, some of which are 3 metres deep. It opens into a chamber 10 metres long, partly occupied by a lake sumping in all directions.

l'Embut drains the lower part of the marly plain of Caussols (partly meadow and ploughed land), which corresponds to a recent level, inset within the vast polje of Caussols.

At low water, a meagre streamlet disappears into l'Embut, but during exceptional floods the cavity is totally flooded and the water can flow back, causing a flood of the meadow that cuts the road! As it is a polje loss, l'Embut can be described as a "ponor".

The waters of l'Embut emerge in the gorges du Loup, at the springs of Bramafan and at the grotte du Revest (overflow). The drop is 534 metres over a distance of 6.5 km.

Inside, the work of running water is clearly visible: erosion waves, potholes, cascades. The terminal sump corresponds to a local flooded zone, perched well above the main flooded zone.

A tracing carried out in the 1950s, using 50 kg of fluorescein, emerged at the springs of Bramafan and partly at the grotte du Revest, in the gorges du Loup.

Source: Cave data sheet for the FFS 2015 congress > "37-A -- Embut de Caussols": https://congres2015.ffspeleo.fr/pdf/FicheEmbutCaussols.pdf

Survey: see the cave data sheet for the FFS 2015 congress > "37-A -- Embut de Caussols": https://congres2015.ffspeleo.fr/pdf/FicheEmbutCaussols.pdf