The Middle North Sea Group (abbreviation: NM) is a group of geologic formations in the Dutch subsurface, part of the North Sea Supergroup.
The three formations of this group form a thick sequence of sediments in the Dutch subsurface, they crop out in parts of the southern Netherlands.
The Middle North Sea Group was deposited from the late Eocene to late Oligocene, between 37 and 23 million years ago.
The Tongeren Formation has a continental to paralic facies, the other two consist mainly of shallow marine clays and sands.
This article about a specific stratigraphic formation in Europe is a stub.