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The Stephanian flora of Graissessac (Fr)

Click on the photos for enlargement and more information.
Graissessac is a former miners' village in the Languedoc (south of France), not far from Bédarieux. In the course of years many fossils from the Upper Carboniferous have been found there, but the mining was stopped years ago. At the waste heaps some fossils can still be collected.

Old pit near GraissessacThe coal excavation in Graissessac was done in opencast coal pits. This means that first the overlaying layers were removed. This material was deposited on slopes at other places. Then the coal was extracted.
When we went collecting there for the first time, we could simply look on the slopes along the roads. Nowadays these slopes are almost completely overgrown and it is not possible to find fossils there anymore, except perhaps with great effort. Still there are some possibilities at places where waste heaps are being dug away.

About the geology
The coal has come into existence in a so-called intramontane basin. During the Westfalian (the last but one level of the Carboniferous) the Hercynian process of mountain building (orogeny) was at its maximum. In the Stephanian the process came to an end and as a consequence of the 'relaxation' of the earth's crust small depressions, bordered by faults, came into existence, e.g. around and in the Massif Central. Graissessac is situated in such a depression. The new mountains suffered from a severe erosion and pieces of rock, sand and mud were transported downwards by mountain streams and rivers. Geological map of GraissessacIn the valleys large swamps with abundant growth of plants came into existence. The peat layers were converted into coal seams in the course of 300 million of years and above these coal layers sediments with plant fossils were formed.
There are more intramontane basins in the south of France, e.g. near Alès (where the winning is still going on and where fossils can be found), Decazeville, Carmaux and Montceau-les-Mines. The latter sites have only poor possibilities nowadays.

In Graissessac the coal has already been extracted since the 18th century and in 1918 the productivity reached its top. Around the year 2000 the last quarry was shut down.

The flora
Histogram GraissessacThe depositions of Graissessac certainly can said to be rich in fossils. Especially the group of Pecopteris, real ferns, is dominant in the flora, as can be seen in the histogram on the right. Many of the fernlike fossils originate from seed ferns, gymnosperm plants. But in Graissessac (and in the Stephanian in general) the real ferns form an important part of the flora.
The total number of species we have found is about 40 and this is an average result compared with other finding places. Many species of these 40 however are rather rare and some of them we have found only once.

Because of the fact that my wife and I have only collected in a small number of sites, the overview given below will probably not be representative for the entire basin.
Animal remains do occur, but they are very rare.

Click on the photos below to proceed.

Club mosses


Real ferns
(Real) ferns



Seed ferns
Seed ferns

The overview is certainly not complete. Our collection contains still many pieces that could be something different, but that are too unclear to identify.
Still it is possible to get a good impression of a number of important plants of the Stephanian: Pecopteris, Odontopteris, Dicksonites, Pecopteridium, Sigillaria brardii and Sphenophyllum oblongifolium, to mention some of them. The club moss trees are strongly declining, the tree fern Psaronius with its Pecopteris-leaves is in a flowering time, the seed ferns Neuropteris and Alethopteris are getting less numerous, but they are replaced by other seed ferns like Odontopteris.

Nice place for fossils, this Graissessac! A pity that the coal winning has been shut down. But if the oil prices will rise enough, the mining will become attractive again!