FAMENNIAN STAGE

all those rocks deposited worldwide during the Famennian Age (367 to 360 million years ago). The Famennian and the underlying Frasnian Stage together constitute the Upper Devonian Series. The stage's name is derived from the region of Famenne in southern Belgium that historically served as the type district. Under the authority of the International Commission on Stratigraphy, the name Famennian was retained but the global stratotype section and point (GSSP) defining the base of this unit was reestablished at Coumiac, 1.5 km (1 mile) west-southwest of the village of Cessenon in the Noires Mountain region of southern France. The boundary sequence is preserved in a quarry exhibiting lower Frasnian to upper Famennian pelagic limestones. The boundary point corresponds to the extinction of all conodont species belonging to the genera Ancyrodella and Ozarkodina and to all but a few species in the genera Icriodus, Ancyrognathus, Palmatolepis, and Polygnathus. Three-quarters of all known upper Frasnian trilobite species are represented at the GSSP, many of which subsequently became extinct. Upper Frasnian brachiopods and goniatites are also well represented at Coumiac. The extinction is widely associated with black limestones known as the Upper Kellwasser Kalk, thought to represent a global hypoxic sedimentary perturbation. The boundary point between the Frasnian and Famennian also corresponds to the first appearance of the conodont Palmatolepis triangularis. The top of the Famennian Stage is defined by the base of the overlying Carboniferous System and its first stage, the Tournaisian.