Houthem Formation

It has also been found in borings in the northeastern part of the Campine Basin.

The formation consists of calcareous sandstone and was formed about 60 million years ago, in the Paleocene epoch.

The arenite can contain calcareous concretions, fossils and hardgrounds with shell fragments.

At other places lenses of boundstone occur, formed by red algae.

Belgian stratigraphers see it as part of the Hesbaye Group, which contains Paleocene formations.