Mostly an alternation of thin sand layers and humic clay layers, containing small pieces of coalified plant remains and locally, in its upper reaches, thin lignite beds. The sand is yellowish grey-brown. The clay is hard and flaky, light to dark grey-brown to black, and contains pyrite nodules. The lower sandy layers, locally contain gravel and may contain shells and/or glauconite. Locally, very characteristic, bright red and olive-green spots and flames occur in the clays.
Brackish to lagoonal. The lignite beds point to the occasional occurrence of paralic or limnic conditions.
Sharp lithologic and log break due to the unconformable contact with the underlying Houthem Formation of the Chalk Group.
Sharp lithologic transition to the glauconitic sand of the Orp Member.
