Résurgence du Bœuf

A vast, richly decorated gallery with an average cross-section of 6 × 10 metres is swept by a strong draught.

From the terminal sump, which quickly floods both upstream and downstream, several passages branch off and are accessible. Very clayey and heavily choked, they require climbing short ascents or squeezing through constrictions.

About thirty metres below the Trou du Bœuf are two porches 1 to 2 metres in diameter.

The gallery leads to an active watercourse that can be followed for a few tens of metres. The observed flow varies with hydrological conditions, from 20 to nearly 200 litres per second. Identifying the spring corresponding to this active flow would be a particularly interesting study objective.

The two porches located below the Trou du Bœuf are usually dry; they become active during flood periods, even before the Trou du Bœuf fills. Their role in the hydrological functioning of the area was demonstrated following a tracing test.

After about 250 metres of progression from the entrance, the gallery leads to the active watercourse.