The stage is named after the small river Rupel in Belgium, a tributary to the Scheldt. The Belgian Rupel Group derives its name from the same source. The name Rupelian was introduced in scientific literature by Belgian geologist André Hubert Dumont in 1850. The separation between the group and the stage was made in the second half of the 20th century, when stratigraphers saw the need to distinguish between lithostratigraphic and chronostratigraphic names.
Stratigraphic definition
The base of the Rupelian Stage (which is also the base of the Oligocene Series) is at the extinction of the foraminiferangenusHantkenina. An official GSSP for the base of the Rupelian has been assigned in 1992 (Massignano, Italy). The transition with the Chattian has also been marked with a GSSP in August 2017 (Monte Conero, Italy).[5]
The top of the Rupelian Stage (the base of the Chattian) is at the extinction of the foram genus Chiloguembelina (which is also the base of foram biozone P21b).
Dumont, A.H.; 1850: Rapport sur la carte géologique du Royaume, Bulletins de l’Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique 16(2), p. 351-373. (in French)