The heterogeneous formation consists of clay and sand that was deposited lagoonally and fluvially during the early Selandian (Middle Paleocene, about 60 million years old).
[1] The Opglabbeek Formation's thickness ranges between 25 metres (82 ft) and 60 metres (200 ft), reaching its greatest thickness as it abuts the Roer Valley Graben.
[1][2] It lies stratigraphically on top of the Houthem Formation (early Paleocene calcareous sandstone).
[3] On top of it lies the Heers Formation (Middle Paleocene sands and marls).
This article about a specific stratigraphic formation in Europe is a stub.