Givetian strata in the Rochefort area

Middle Devonian of the Ardennes

The calcareous limestones that were deposited in the Middle Devonian were produced by marine organisms such as stromatoporoids, corals, crinoids and brachiopods which populated the ancient sea. During the Middle Devonian the sea was shallow in this region and its waters warm and clear, comparable to present day subtropical areas.

Lower Devonian  Middle Devonian  Upper Devonian

The lower Middle Devonian is characterised by mixed siliciclastic and carbonate layers with a biostrome at the basis west of the river Meuse. Small mounds occur in the Eifelian east of the Meuse with crinoidal-coral limestones (Formation X) locally being abundant. In the north, the Eifelian consists of clastic sequences with red conglomerates at the basis which are part of a major transgression. The Givetian marks the arrival of reef complexes which were already recognised in the older literature and which were probably comparable to extant barrier reefs.

Middle Devonian strata outcrop along the southern to eastern borders of the Dinant Synclinorium (Belgium, northern France) and the Eifel synclines (Germany).