EIFELIAN STAGE

all those rocks deposited worldwide during the Eifelian Age (387 to 380 million years ago). The top of the Eifelian Stage is defined by the base of an overlying subdivision, the Givetian Stage. Together the two subdivisions constitute the Middle Devonian Series. The name is derived from the Eifel Hills in western Germany, near Luxembourg and Belgium. As formally defined in 1985 under the authority of the International Commission on Stratigraphy, the global stratotype section and point (GSSP) for this boundary is established in a trench section across pastureland near the town of Schnecken-Wetteldorf. The trench exposes siltstones and mudstones in the upper part of the Heisdorf Formation and alternating limestones and mudstones in the overlying strata of the Lauch Formation. The boundary point is situated 1.9 m (6.25 feet) below the base of the Lauch Formation, which is fixed by the first occurrence of the conodont Polygnathus costatus partitus. This conodont is the second subspecies in a documented conodont phyletic lineage, the predecessor subspecies being P. costatus patulus and the successor subspecies being P. costatus costatus. The intermediate species is known from the Eifelian strata in Morocco, Spain, Germany, Austria, the Czech Republic, Central Asia, China, Malaysia, Australia, Nevada, Alaska, and the Canadian Arctic. A parastratotype sequence with conodonts typical of the Polygnathus biofacies is established in the Trebotov Limestone of the Barrandian region in the Czech Republic.