Sequence of rapidly alternating grey-brown, sandy claystones, siltstones, and fine-grained, light-grey sandstones, with common disseminated lignitic matter. Coal beds are scarce.
Lower coastal-plain to fluvial-plain. Upwards, an increase of marine influence is seen. Fines settled on flood-plains and in small lakes. Sands were deposited by fluvial channels, crevasses, and lacustrine deltas. Swamps did not develop, or that they were eroded and reworked by fluvial processes.
Unconformable contact with the marine shales or sandy carbonates of the Altena Group.
Conformable contact with the clay-dominated Fourteens Claystone Member, which can generally be seen as a sharp upward increase in GR-log readings. The boundary is placed at the top of the last clear sandstone bed. In truncated settings, the top can be the unconformable contact with the Neomiodon Claystone Member, Rijnland, Chalk or Lower Noordzee Groups.
