Formations, members and layers Stratum In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...  after NITG-TNO
marine Marine (ocean) Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
Dongen Formation Dongen Formation The Dongen Formation is a geologic formation in the subsurface of the Netherlands. The formation consists of early Eocene marine clay and sand. It is named after the town of Dongen in North Brabant.-Lithology and stratigraphy:...  DO	Asse Member DOAS
	Brussel Member DOBR
	Ieper Member DOIE
	Oosteind Member DOOO	Basal Dongen Tuffite DOOOBT
Landen Formation Landen Formation The Landen Formation is a lithostratigraphic unit in the subsurface of the Netherlands. This formation shares its name with the Belgian Landen Group, but the Belgian unit is thinner and has different definitions...  LA	Gelinden Member LAGE
	Liessel Member LALI
	Orp Member LAOR
	Reusel Member LARE
	Swalmen Member LASW

The Lower North Sea Group (abbreviation: NL) is a group

Group (stratigraphy)

A group in stratigraphy is a lithostratigraphic unit, a part of the geologic record or rock column that consists of defined rock strata. Groups are divided into formations and are sometimes themselves grouped into "supergroups"....

 of geologic formations in the subsurface

Subsurface

Subsurface is the seventh studio album by British progressive metal band Threshold. The album was released in August 2004, and received an Album of the Month award in several European music magazines....

 of the Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 and adjacent parts of the North Sea

North Sea

In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

.

The group is part of the North Sea Supergroup and consists of two marine formations of early Paleogene

Paleogene

The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...

 age, the older Landen Formation

Landen Formation

The Landen Formation is a lithostratigraphic unit in the subsurface of the Netherlands. This formation shares its name with the Belgian Landen Group, but the Belgian unit is thinner and has different definitions...

 and younger Dongen Formation

Dongen Formation

The Dongen Formation is a geologic formation in the subsurface of the Netherlands. The formation consists of early Eocene marine clay and sand. It is named after the town of Dongen in North Brabant.-Lithology and stratigraphy:...

. It is in most places stratigraphically on top of the Late Cretaceous

Late Cretaceous

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

 Chalk Group and overlain by the late Paleogene Middle North Sea Group

Middle North Sea Group

The Middle North Sea Group 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 Lower North Sea Group crops out

Outcrop

An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...

in a few spots in the south of the Netherlands but is mostly overlain by younger deposits. It can be found in the subsurface of most of the Netherlands.