Mainly light-grey to brownish and black limestones, and medium-grey to dark-brown dolomites. Intercalations of thin to medium-thickness fissile claystone and chert beds are common.
Towards the east, the number of these claystones increases gradually. In areas where the Zeeland Formation was truncated by later erosion, the upper part of the formation may be strongly leached and subsequently silicified. An enrichment in organic carbon is frequently observed under these circumstances.
Marine carbonate platform. The deposits have a trangressive character, in contrast to the overall regressive nature of the overlying Epen Formation. ln places sabkha-like deposits occur. Most dolomites are of secondary origin.
The lower part: shallow sea with intermittent restricted circulation.
Middle part: more open shallow-marine environment, showing an alternation of carbonates deposited just below and just above the wave base.
Upper part: platform as well as slope deposits occur. These facies interdigitate depending on palaeogeographic position.
Formed by the contact with the clastic sediments of the earliest Carboniferous Bosscheveld formation or the Late Devonian Bollen Claystone formation. The former can be a gradual transition (well Kastanjelaan-2), the latter a disconformable boundary (e.g. S02-02). More towards the east, on the northern flank of the London-Brabant Massif, the base of the formation may be the unconformable contact with Middle Devonian or even older rocks.
Placed where the calcareous deposits change into the fine clastics of the basal Epen Formation of the Limburg Group. This boundary may be gradual (borehole Geverik-1). However, in many places a sharp, disconformable contact is observed when the transitional layers are absent. Where severe post-Carboniferous erosion took place, the Zeeland Formation can be overlain unconformably by younger formations.