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