Sequence of typically dark or light grey, red or variegated claystones, fine- to medium-grained sandstones and coarse- grained, thick-bedded sandstones. Coal/lignite beds are associated with grey claystones, and are most common in the Rodenrijs Claystone Member and the youngest occurrences of Alblasserdam Member in the Rotterdam area. Dispersed lignitic matter, siderite spherulites and concretions are common. Variegated claystones are extensively mottled. Sands occur in sheets, isolated or stacked channels.
Both braided-river valley fills and meandering single-channel fills, and as crevasse-splays in a flood-plain to lower-coastal-plain setting. Fines have been laid down in an overbank setting during floods. Mottling and concretions reflect soil formation caused by fluctuating water-tables and long periods of non-deposition.
Unconformably overlies the Altena Group. Especially along the southern margin of the West Netherlands Basin, it rests on deposits of Triassic or older age.
The Rijnland Group typically onlaps onto this formation.