Ieper Member

Formal (NAM & RGD 1980). Amended (Van Adrichem Boogaert & Kouwe 1997).
Lithological description

Generally soft, tough and sticky to hardened and friable clay. A subdivision into two parts can be recognised regionally. The lower part is characterised by its brown-grey colour, tending to beige or red-brown locally. The unit contains pyrite, is non-calcareous, and coalified plant remains are locally present at the base (possibly reworked material). The upper two-thirds have a characteristic green-grey colour. It has a sandy upper part with a number of larger sandstone intercalations and it is somewhat calcareous and glauconitic. Along the palaeo-coastline the clays are silty with some sand stringers, which become less common distally.

Depositional setting

Open-marine environment. Estimated waterdepth up to 200 m.

Definition of lower boundary

Generally shows as a sharp transition from the underlying Oosteind Member or De Wijk Member to the clay of the Ieper Member.

Definition of upper boundary

Very variable trasition to overlying Brussels Sandstone Member. Regionally there is an unambiguous boundary between the clay, sand and sandstone. However, near the palaeo-coastline and on palaeo-highs in the southern and eastern part of the basin, the boundary is gradual and complex, because locally, different parts of the succession are missing as a result of various phases of erosion and/or non-deposition. The nature of these breaks in sediments is not well documented.

Thickness indication
Locally more than 1000 m.
Geographical distribution
Regional correlation
UK: ?; GER: ?; BEL: the name Ieper is used to designate a group Marechal and Laga (1988), which is approximately the equivalent of the Dutch Ieper Member.
early Eocene (Ypresian).
Depth (thickness) AH:
844 - 985 m AH (141 m)
Depth (thickness) AH:
1099 - 1524 m AH (425 m)
Origin of name
The name refers to the Belgian city of Ieper in western Flanders.
Previous name(s)
Reviewed by (date)
Geert-Jan Vis (2019).
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.
Cite as
TNO-GDN ([YEAR]). Ieper Member. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from