The site

Vaulnaveys-le-Bas is a rural district of Isère, of 1243 inhabitants.
The fossiliferous unit, known for centuries, probably 1880, spread on the slopes of Belledonne moutain range. It is prospected on a regular basis by our team since 2015.

With the agreement of the municipality, in collaboration with the Natural History Museum of Grenoble and the National History Museum of Paris, we particpate to the preservation of this outstanding fossiliferous deposit.

Rebuilding this former environment

Approximately three hundred million years ago, Vaulnaveys-le-Bas was located near the equator in the middle of a single supercontinent, The Pangea, which comprised almost all the emerged lands. Two oceans bordered this continent, the Tethys Ocean on the east and Panthalassa Ocean on the west. The movement of two tectonic plates, one from the South and the other from the North, caused the collision of two supercontinents which created the Pangea. An enormous mountain range extending thousands of kilometers in length and hundreds in width, rose up all along the border where the collision occurred. This mountain-chain is called the Hercynian Massif (otherwise known as the Variscan orogeny) and Vaulnaveys-le-Bas would eventually be located inside, forming an intramountain sedimentary basin.

There was global warming during the Carboniferous. Climate, in an oscillatory manner, alternated from glaciation to dryer phases. Floral assemblages are testimonials of these climate changes as seen in Vaulnaveys-le-Bas which is a very peculiar example.

The Hercynian chain is now entirely eroded and fossiliferous sediments deposited during the Carboniferous are completely hidden under thousands of meters of more recent secondary and tertiary era sediments. But due to their outcropping associated with the tectonic shift and the formation of the Alpine mountain range which carried them to the slopes of the mountain and sometimes up to its summits (Grande Lauzière at 2700 meters), they have become once again accessible for research. In the Belledonne Massif, “l’Accident Médian de Belledonne” caused these sediments to be separated from each other by a large crack. We are studying the fossilized contents found in Vaulnaveys-le-Bas which are some of these remaining fragments of carboniferous deposits.

contact :

Akcnowledgments to :

Mr Jean-Marc Gauthier, Mayor of Vaulnaveys-le-Bas and his municipal team who support our group. Mrs Marie-Pierre Davallet-Pin for her logistic involvement in our projects.

Photographs and drawings :

Photos are from our team but for the village view from C.S.G. Communauté de Communes du Sud Grenoblois 2011. The Town hall square drawing is from Mrs France ROSSET.

Webmaster : Mr Pascal Goutte-Solard ( )