Rupel Formation

Formal (Kuyl 1975; NAM & RGD 1980). Amended (Van Adrichem Boogaert & Kouwe 1997; De Lang & Ebbing 2003).
Lithological description

Heavy, dark brown-grey silty clays, rich in pyrite and relatively glauconite-poor. Towards both base and top, the clays grade into silts and rather abruptly into sands along the southern basin margin (Vis et al. 2016). The sands are moderately fine-grained (150-210 µm) to coarse-grained (150-300 µm) and glauconitic. Flint pebbles and phosphorite nodules commonly occur at the base. The formation is expected to contain septarian carbonate concretions which are well documented from Belgian quarries (De Craen et al. 1999).

Depositional setting

Middle to outer neritic marine setting (water depths of up to 500 m). The sands are of a shallow-marine origin with intercalated lagoonal sediments.

Definition of lower boundary

Unconformably overlies the Tongeren Formation, the Dongen Formation or older sediments. In those areas where the sandy development at the base is missing, the clays of the Rupel Formation rest directly on the Asse or Engelsche Hoek members, which complicates definition of the boundary. However, on wire-line logs, the Rupel clays show a somewhat higher gamma-ray response compared to the clays of the Lower North Sea Group. Biostratigraphic data may assist in establishing this boundary.

Definition of upper boundary

Conformably or mildly unconformably overlain in the central and eastern Netherlands, and part of the northeastern offshore by the sands and silty shales of the Veldhoven Formation. In the southern Netherlands the latter has a typical, thin clay interval at its base. The upper limit is usually sharp in those parts of the Netherlands where the Rupel Formation is partly eroded (in the early Kenozoic on the high between Nijmegen and Leiden) and is overlain by the Breda Formation or the Naaldwijk Formation. The Breda Formation often is richer in glauconitic sands and clays. The upper boundary is arbitrary in areas where the macroscopic characteristics of the covering clays are the same as those of the Boom Member.

Thickness indication
Up to more than 250 m.
Geographical distribution
Regional correlation
UK: Lark Formation; GER: Rupel Formation (Lower Rhine Embayment); BEL: Rupel Group largely corresponds with the Rupel Formation (Marechal & Laga 1988). The latter locally comprises slightly older beds as well (see Vessem Member).
early Oligocene (Rupelian).
Depth (thickness) AH:
1103 - 1229 m (126 m)
Type areas:
- Ratum Member: the area between Winterswijk and Ootmarsum where this units crops out (Van den Bosch et al. 1975);
- Other members: type areas are located in Belgium;
- Bilzen Member: the area around the town of Bilzen (Belgium);
- Clayey units are exposed in quarries for brick manufacturers along the River Rupel and Scheldt (Marechal & Laga 1988).
Depth (thickness) AH:
715 - 779 m (64 m)
Depth (thickness) AH:
1300 - 1410 m (110 m)
Origin of name
Named after the River Rupel in Belgium.
Previous name(s)
Dumont (1849) first used this name to indicate the middle part of the Belgian Oligocene sequence.
Reviewed by (date)
Dirk Munsterman (2018).
De Craen, M., Swennen, R., Keppens, E. 1999. Petrography and geochemistry of septarian carbonate concretions from the Boom Clay Formation (Oligocene, Belgium). Geologie en Mijnbouw 77, 63–76.
De Lang, F.D., Ebbing, J.H.J. 2003. Beschrijving lithostratigrafische eenheid. Nederlands Instituut voor Toegepaste Geowetenschappen TNO. Utrecht.
Dumont, A.H. 1849. Rapport sur la carte géologique du Royaume. Bulletin de l’Académie royale des Sciences, des Lettres et des Beaux-Arts de Belgique, 16 (2), 351-373.
Kuyl, O.S. 1975. Lithostratigrafie van de Mio-Oligocene afzettingen in Zuid-Limburg. In: Zagwijn, W.H., Van Staalduinen, C.J. (eds.), Toelichting bij geologische overzichtskaarten van Nederland. Rijks Geologische Dienst, Haarlem, 56-63.
Maréchal, R., Laga, P. (eds.) 1988. Voorstel lithostratigrafische indeling van het Paleogeen - Nationale Commissies voor Stratigrafie. Commissie: Tertiair, Belgische Geologische Dienst, Brussel, 208 p.
NAM & RGD 1980. Stratigraphic nomenclature of The Netherlands. Verhandelingen van het Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap 32, 77 p.
Van Adrichem Boogaert, H.A. & Kouwe, W.F.P. 1997. Stratigraphic nomenclature of The Netherlands, revision and update by RGD and NOGEPA, Section I, Tertiary. Mededelingen Rijks Geologische Dienst, 50, 1-39.
Van den Bosch, M., Cadée, M.C., Janssen, A.W. 1975. Lithostratigraphical and biostratigraphical subdivision of Tertiary deposits (Oligocene - Pliocene) in the Winterswijk-Almelo region (eastern part of The Netherlands). Scripta Geologica 29, 1-167.
Vis, G.-J., Verweij, H., Koenen, M. 2016. The Rupel Clay Member in the Netherlands: towards a comprehensive understanding of its geometry and depositional environment. Netherlands Journal of Geosciences 95 (3), 221-251. [OPEN ACCESS].
Cite as
TNO-GDN ([YEAR]). Rupel Formation. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from