Tongeren Formation

Formal (Kuyl 1975).
Lithological description

From bottom to top three successions can be distinguished: 

  • Sand, very fine to moderately coarse (105-300 µm), weakly to moderately silty, predominantly glauconite-bearing, sometimes containing mica. Green grey to grey green;
  • Clay, slightly, moderately to strongly sandy, glauconite and mica-bearing. Dark green to grey;
  • Clay with shells and with thin intercalations of very fine sand (105-150 µm) and lignites at the top. Grey to green grey.
Depositional setting

Shallow-marine environment (sands), and lagoonal to coastal-plain environment (clays).

Definition of lower boundary

Unconformably overlies the Dongen Formation or older deposits.

Definition of upper boundary

Sharp, when the top contains a layer of flat and rounded flint pebbles. Sharp, when overlain by fluvial sands and gravels or aeolian sediments of the Upper North Sea Group, but gradual when these consist of the sands and clays of the Walcheren Member (Naaldwijk Formation) in Zeeland. Sharp, when overlain by the clays of the Boom Member. Gradual when the overlying unit consists of the sands and clays of the Rupel Formation.

Thickness indication
Up to 125 m, thickness increases in a northwesterly direction.
Geographical distribution
Restricted to the southern part of the province of Limburg and the southern part of the province of Zeeland.
Regional correlation
UK: Solent Group; GER: Tongeren Formation; BEL: classified as the Sint Huibrechts-Hern Formation and the Borgloon Formation (Marechal & Laga 1988).
Priabonian - early Rupelian.
Depth (thickness) AH:
9.5 - 23.7 m (14.2 m)
TD in Tongeren Fm. so not very well suited!
Depth (thickness) AH:
14.1 - 21.4 m (7.3 m)
Outcrop 62A-014 in quarry 'De Heek'.
Depth (thickness) AH:
1 - 24.7 m (23.7 m)
Origin of name
Named after the Belgian town of Tongeren.
Previous name(s)
Dumont (1839) introduced the name Tongerian for equivalent deposits in Belgium. The Kallo complex and Berg Sands. The Vessem Member in the southwestern part of the Netherlands.
Reviewed by (date)
Dirk Munsterman (2018).
Dumont, A. 1839. Rapport sur les travaux de la carte Géologique pendant l'année 1839. Bulletins de l'Académie royale des sciences, des lettres et des beaux-arts de Belgique (1), 6, 2e partie, 464-485.
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.
Cite as
TNO-GDN ([YEAR]). Tongeren Formation. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from