From bottom to top three successions can be distinguished:
- Sand, very fine to moderately coarse (105-300 µm), weakly to moderately silty, predominantly glauconite-bearing, sometimes containing mica. Green grey to grey green;
- Clay, slightly, moderately to strongly sandy, glauconite and mica-bearing. Dark green to grey;
- Clay with shells and with thin intercalations of very fine sand (105-150 µm) and lignites at the top. Grey to green grey.
Shallow-marine environment (sands), and lagoonal to coastal-plain environment (clays).
Unconformably overlies the Dongen Formation or older deposits.
Sharp, when the top contains a layer of flat and rounded flint pebbles. Sharp, when overlain by fluvial sands and gravels or aeolian sediments of the Upper North Sea Group, but gradual when these consist of the sands and clays of the Walcheren Member (Naaldwijk Formation) in Zeeland. Sharp, when overlain by the clays of the Boom Member. Gradual when the overlying unit consists of the sands and clays of the Rupel Formation.