L'Aven Grotte de la Forestière

Aven des Cristaux

Useful Information

photography — The cave entrance, only a few steps down, Grotte de la Forestière, France. Public Domain.

Location:	Located at the road D217, between Vallon Pont d'Arc and Orgnac. (44°19'768N, 4°24'252E)
Open:	APR to SEP daily 10-19, last tour 18. [2006]
Fee:	Adults EUR 5.50, Children (3-18) EUR 3.50. Groups (+): Adults EUR 4.50, Children (3-18) EUR 2.50. [2006]
Classification:	Karst cave
Light:	Incandescent Electric Light System
Dimension:	L=4,000 m, T=14 °C, H=96%..
Guided tours:	L=500 m.
Photography:	allowed
Accessibility:	no
Bibliography:
Address:	L'Aven Grotte de la Forestière, Départ. 217, F-07150 Orgnac l'Aven, Tel: +33-4753-86308, Fax: +33-4753-86308. E-mail:
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then. Please check rates and details directly with the companies in question if you need more recent info.

History

19-FEB-1966	discovered by two hunters.
1966	explored by Antoine Sonzogni.
1967	start of development.
1969	opened to the public.

Description

Cave coral, Grotte de la Forestière, France.

Stalactites with cave coral, Grotte de la Forestière, France.

L'Aven Grotte de la Forestière (Pothole and Cave of the Forest) is really located in the forest. The karstic plateau south of the Ardeche river is covered by a green forest, which consists mostly of almost impenetrable shrubs and bushes. This forest makes the visitation of the area really difficult, it is a rather unexplored white spot on the map until today. The only visitors of the forests are hunters, which follow the trails of the animals. Two of those hunters discovered the huge doline which is the entrance to the cave. Their nefue Antoine Sonzogni was a caver and after they told him the location he started to explore it. The beauty and the size of the cave convinced him to develop the cavve as a show cave. This was financed by the village of Issirac, which is also owner of the forest. Probably the proximity to the successful Showcave Aven d'Orgnac made the responsible people think a show cave could draw money to the village. Soon the cave was opened to the public, and in subsequent years the tourist path was enlarged.

During the development of the cave, a huge amount of animal bones were found. The findings included bones of ren, bison, horse, giant deer (Megaceros), rhinoceros, cave bear, and mammoth. Those animals, some are now extinct, lived in this area during the last ice age, between 40,000 and 10,000 before present. Although cave bear and humans are known too have visited caves frequently, it seems rather unliekely for this cave. The bones may be a result of accidential cave visits, animals which fell into the entrance doline, and were not able to leave again. Or the bones were transported from the surface into the cave by floods.

The cave system has four diffferent levels. They were formed during pauses of the Ardeche cutting into the limestone plateau. The speed a river cuts in depends on the amount of water, and the energy of the water (as a result of the steep gradient). If the level of the river stays about the same for some time, caves form at the level of the ground water table. The deepest level of the Grotte Forestière is about 200 m below ground. An underground river flows toward the sink, the Ardeche river. The location where it meets the Ardeche, some five kilometers from the show cave, was determined by dye tracing experiments.

The upper three levels are dry, the deposition of limestone by the dripping water has formed a wealth of calcite conctetions. Beneath rather common stalagmites and stalactites, this cave is famous for an abundance of cave coral. It covers walls, floor, stalagmites, and bones. Those strange speleothems with their dark brown and white colour are one of the things which make this cave unique in the area. The cave ceiling collapsed during the Pleistocene, about one Million years ago. Since then the huge rocks, which form the new cave floor, were again covered by speleothems. The most abundand formation of speleothems is found at the end of the tour, where a platform of crystals was formed by a cave lake filled with oversturated water.

At one place of the tour several aquariums can be seen. They are a cave zoo containing various troglobionts, animals which live in the cave and have adapted to this environment and became eyless and colourless. There are fish, amphibians, insects and scallops. Obviously most of them are not from the Grotte de la Forestière as it has no cave rive.

A part of the tour is very close to the surface, there are only a few meters of limestone. Here are much less stalactites, but instead there are the roots of various trees from above. They grow into the cave to participate from the constant supply of water. There are roots of green oak, boxwood, and sandberry tree, the roots of the mulberry are the deepest, growing up to 35 m below surface. Sometimes the roots grow along speleothems, sometimes speleothems grow on top of them.

L'Aven Grotte de la Forestière Gallery