Jecy (Aven-grotte)

The cavity opens in direct proximity to a locally important fault: an overlap of Provençal age, from south to north. The route of the Jecy seems to follow the axis of a gravitational slip of the wall, oriented EW. It is the excavation that seems responsible for the movement of the wall by a phenomenon of decompression or "call to the void". The rupture plane follows the orientation and dip of the layers: it may have been triggered on a bedding joint. The phenomenon seems relatively recent, that is to say posterior to the cessation of exploitation.

The cavity now seems to obey 2 axes of "digging": still a subvertical orientation linked to the dip of the limestone and now associated with a plane that continues as a "fault". This one sinks towards the south with a dip of about twenty degrees. The second axis could correspond to the overlap of the anticline north of Camps la source. We find on the ground red rocks, with a glassy luster, which seem to have been heated and crushed. Perhaps mylonites?

A karst phenomenon may also have helped: we will find traces of digging by water (the only ones in the cavity) in an ascending chimney directly above the slip. We finally arrive in a very large room that ends with a small lake. The cavity continues beyond for about fifty meters. Note that the level of the lake varies in the dry season. It can therefore drop by nearly 4 m, thus revealing a small room located below the large room.

To enter we slip between 2 blocks and the wall. The interior progression is made in a chaos between the limestone walls. We chain narrow passages between the collapsed blocks and increasingly large rooms.

WARNING DANGER: Dangerous cavity because of many unstable blocks and risks of collapse. Its exploration is therefore reserved for confirmed explorers[ref]Guillaume CHARDIN - CDS83, Fichier des cavités du Var > « Aven-grotte Jecy » (numéro 3023004) : https://www.fichiertopo.fr/display.php?details=1&indexid=2177[/ref].

(Extract from the internship report of Mourau Fabrice published on the ACV blog - blog link: http://avenclub83.over-blog.com/article-stage-topo-au-jecy-97615052.html )