Grande Grotte

The large cave consists mainly of two strictly north-south oriented, parallel galleries: the Galerie Principale, the westernmost, developed for tourism, and the Galerie Est, active and rarely visited.

The Galerie Principale has abundant speleothems that have earned the cavity a fine reputation. It is entered through a porch 9 metres long by 1.50 metres. On several occasions, the abundant speleothems partly obstruct the passage, thus dividing the gallery into several “rooms”. After a zone of scree, a series of gours graces the end of the route. Behind it, a narrow passage leads to the ultimate point of the cavity: a pile of blocks rises in steps up to a stalagmitic cascade.

The Galerie Est is overall lower-ceilinged than the Galerie Principale, and a new scree marks its northern end. It begins with a clayey corridor. After a route of 140 metres, an 80-metre-long joint fissure hides behind an opening that can be seen high up. At 210 metres from the entrance, the ceiling rises 10 metres above the river. On the right, overlooking a stalagmitic cascade crowned with gours, opens a skylight which, in the vault, leads to the Salle de l'Amphithéâtre. This is certainly the largest known room in the département: it reaches 30 metres in its greatest length and 18 metres in width. It is extended to the south by a gallery that is quickly traversed and narrows as it goes.

The Galerie Est continues still northward, the height being markedly less. At water level, a narrow crawlway opens into a last parallel gallery, called “salle Parat”. It ends to the south at a concretion-covered scree that prevents any progress, and to the north a rocky squeeze remains impenetrable.

The Galerie Principale has abundant speleothems that have earned the cavity a fine reputation; a series of gours graces the end of the route, and a pile of blocks rises in steps up to a stalagmitic cascade. In the Galerie Est, a stalagmitic cascade crowned with gours overlooks the opening of a skylight. The Salle de l'Amphithéâtre is richly decorated, despite a floor covered with scree.

The Grande Grotte is the eastern part of the hydrological network that crosses the Arcy-sur-Cure massif. Various experiments have shown the relation with the Moulinot spring. However, this spring is an integral part of the Réseau des Fées (human junction), a network also linked with the grotte des Goulettes–grotte de Barbe-Bleue system, as proved by a dye trace.

The Galerie Est is an active gallery, traversed by a stream. The small stream, issuing from the pool, first runs along the edges of the gallery before occupying its entire width.

In the Galerie Principale, beyond the porch, a fork leads on the right to a body of water called the Lac. Going around it along the edge of a clayey beach and after a few metres of concretion-covered gallery, one rejoins the Galerie Principale. On the right, one quickly reaches a body of water behind which the Galerie Est hides. On the left, one rejoins the Galerie Principale, which continues to sink into the massif.