Peelo Formation

Formal (Zagwijn 1973). Amended (Doppert et al. 1975; Ebbing 2003).
Lithological description

Light grey, yellowish grey and brownish grey very fine to very coarse sand, micaceous, slightly calcareous, with subordinate gravel layers (lags) and dropstones. Grey to black or brownish black clay, (very) firm, silty or sandy, commonly calcareous, with local shells.

Depositional setting

Subglacial channel or valley (coarse sand and gravel), ice-marginal fluvial and lacustrine (sand and clay), glaciomarine (clay with in situ shells).

Definition of lower boundary

For sandy facies, unconformable but gradual to diffuse (in case of reworking) transition into multi-coloured and gravelly fluvial sand (Veenhuizen Member, Urk Formation). For clayey facies, sharp contact with fluvial sand (Appelscha and Peize Formations;, Veenhuizen Member, Urk Formation) and, where deeply incised, with shallow-marine pre-Quaternary units.

Definition of upper boundary

Locally exposed at the surface. Elsewhere, for sandy facies gradual to diffuse transition into less calcareous and micaceous periglacial sand (Drachten Formation), sharp contact with coarser and more multi-coloured fluvial sand (Tynje Member, Urk Formation); for clayey facies sharp contact with fluvial sand (Tynje Member, Urk Formation), glacial sand and till (Drente Formation), marine sand and clay (Eem Formation), periglacial sand (Drachten and Boxtel Formations), tidal sand and clay (Naaldwijk Formation) or modern marine sand (Southern Bight Formation).

Thickness indication
Highly variable. Up to 400 m in filled glacial valleys, generally 20-30 m on valley shoulders.
Geographical distribution
Regional correlation
North Sea: Swarte Bank Formation (defined and mapped in conjunction with the British Geological Survey; Cameron et al. 1986); UK: part of the Lowestoft Formation (McMillan et al. 2011); GER: Lauenburger Ton (Kuster & Meyer 1979); BEL: not present.
Middle Pleistocene (Elsterian).
Excavation in the village of Peelo
Depth (thickness) AH:
3.5 - 5.5 m (2.0 m) below land surface (Zandstra 1975; Ruegg 1975).
Depth (thickness) AH:
4.70 - 43.70 m (39 m) below land surface
Depth (thickness) AH:
19.50 - ≥175 m (>155 m) below land surface
Origin of name
Named after a neighbourhood in the city of Assen, northeastern Netherlands.
Previous name(s)
Potclay Formation (Van der Heide & Zagwijn 1967), Emmen Deposits (Doppert et al. 1975).
Reviewed by (date)
Wim Dubelaar (2018), Sytze van Heteren (2019).
Cameron, T.D.J., Laban, C., Mesdag, C.M. & Schüttenhelm, R.T.E. 1986. Indefatigable, Sheet 53°N/02°E. Quaternary Geology, 1 : 250 000 Series, British Geological Survey and Geological Survey of the Netherlands.
Doppert, J.W.Chr., Ruegg, G.H.J., Van Staalduinen, C.J., Zagwijn, W.H., Zandstra, J.G. 1975. Formaties van het Kwartair en Boven-Tertiair in Nederland. In: Zagwijn, W.H., Van Staalduinen, C.J. (eds.): Toelichting bij geologische overzichtskaarten van Nederland. Rijks Geologische Dienst, Haarlem, 11-56.
Ebbing, J.H.J. 2003. Beschrijving lithostratigrafische eenheid. Nederlands Instituut voor Toegepaste Geowetenschappen TNO. Utrecht.
Kuster, H., Meyer, K.D. 1979. Glaziäre Rinnen im mittleren und nord-ostlichen Niedersachsen. Eiszeitalter und Gegenwart 29, 135-156.
McMillan, A.A., Hamblin, R.J.O., Merritt, J.W. 2011. A lithostratigraphical framework for onshore Quaternary and Neogene (Tertiary) superficial deposits of Great Britain and the Isle of Man. British Geological Survey Research Report, RR/10/03, 343 p.
Ruegg, G.H.J. 1975. Sedimentary structures and depositional environments of Middle- and Upper- Plesitocene glacial time deposits from an excavation at Peelo, near Assen, The Netherlands. Mededelingen Rijks Geologische Dienst, Nieuwe Serie, 26 (1), 17-37.
Van der Heide, S., Zagwijn, W.H. 1967. Stratigraphical nomenclature of the Quaternary deposits in the Netherlands. Mededelingen van de Geologische Stichting, Nieuwe Serie, 18, 23-29.
Zagwijn, W.H. 1973. Pollenanalytic studies of Holsteinian and Saalian Beds in the Northern Netherlands, Mededelingen Rijks Geologische Dienst, Nieuwe Serie, 24, 139-156.
Zandstra, J.G. 1975. Sediment-petrological investigations of a boring and an excavation at Peelo (northern Netherlands). Mededelingen Rijks Geologische Dienst, Nieuwe Serie, 26 (1), 1-15.
Cite as
TNO-GDN ([YEAR]). Peelo Formation. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from