Grotte du Funiculaire

The “grotte du Funiculaire” or “grotte Le Bail” (named after its discoverer) or “grotte du Mesnil” is composed (in 2017) of two collectors: an initial conduit or “Grand Collecteur”, and a conduit intersected after two affluent zones, or “Petit Collecteur”.

The “Grand Collecteur” is a large conduit, on average two metres wide and high, intersected upstream and downstream by the retreat of the Seine valley. This wide conduit, subject to regular changes of orientation, develops over 77 metres in a long arc towards the south-east. The departures of conduits towards the east quickly become impenetrable owing to the proximity of the slope.

The “Petit Collecteur” is of smaller dimensions. While the width varies only from 0.6 metre to 1.5 metres, the height depends essentially on the state of désobstruction of the Galerie. At the very upstream end, the fill limits the visit, while moving downstream, the cleared height varies from 0.35 metre at the lowest, up to 1.20 metres near the junction with the “Galerie des Anastomoses”.

This conduit is much more irregular in its course. It presents numerous changes of direction, sometimes very abrupt; and while its general orientation is roughly west-east, this is by describing significant displacements towards the north or towards the south.

The still simple pattern it presents is due in large part to the state of clearance of the conduit, whose fills must still conceal many developments. In particular, the departures of conduit towards the south are still not explored, whereas their number is proving increasingly important. They punctuate a zone of underground development still unknown.

After 93 metres of Galerie, the “Petit Collecteur” gives out again through a remarkable keyhole conduit into the “Salle des Ampoules”. Numerous soutirage phenomena punctuate its development. At two points, they have enabled the junction with the “Grand Labyrinthe”.

Two ensembles ensure the connections between the two collectors. The first is the “Galerie des Anastomoses”. The second is materialised by the labyrinthine ensemble that frames the “Salle des Ampoules”.

General description (see also chapter II of the first bibliographic reference).

Gérard Coquerel, Jean-Claude Staigre, Joël Rodet, « La grotte du Funiculaire (Le-Mesnil-sous-Jumièges, Seine Maritime, France), spéléogenèse et étude d'un remplissage... », chapter II, in Karstologia n°22, 2/1993, juillet 1993: https://www.researchgate.net/publication/260460323_La_grotte_du_Funiculaire_Le-Mesnil-sous-Jumieges_Seine_Maritime_France_speleogenese_et_etude_d%27un_remplissage_ferro-manganique

See the continuation in chapter II of the first bibliographic reference.