The Landen Group is a

lithostratigraphic Lithostratigraphy is a sub-discipline of stratigraphy, the geology, geological science associated with the study of stratum, strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are ...

unit (a "

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

" of

rock strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...

) in the

Belgian Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct language ...

subsurface. The group consists of two formations of

Thanetian The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Serie ...

(late

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

) to Ypresian (early Eocene) age. The Landen Group is named after the town of Landen in

Flemish Brabant Flemish Brabant ( nl, Vlaams-Brabant ; french: Brabant flamand ) is a province of Flanders, one of the three regions of Belgium. It borders on (clockwise from the North) the Belgian provinces of Antwerp, Limburg, Liège, Walloon Brabant, Haina ...

Subdivision

The Landen Group is subdivided into two formations: * The

Hannut Formation The Hannut Formation (french: Formation de Hannut; nl, Formatie van Hannut; abbreviation: Hn) is a geologic formation in the subsurface of northern Belgium. The formation consists of marine clay and silt, alternating with more sandy layers. On to ...

, an alternation of

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

clays, sands and limestones; * The

Tienen Formation The Tienen Formation ( nl, Formatie van Tienen; french: Formation de Tienen; abbreviation: Ti) is a geologic formation in the subsurface of northern Belgium. The formation crops out in the province of Hainaut and the Hesbaye region in the provinc ...

, a lagoonal- continental alternation of clay, sand and

lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...

. This formation is known for its fossils. Both formations can be found in the subsurface of all northern Belgium. They crop out in the

province of Hainaut Hainaut (, also , , ; nl, Henegouwen ; wa, Hinnot; pcd, Hénau), historically also known as Heynowes in English, is a province of Wallonia and Belgium. To its south lies the French department of Nord, while within Belgium it borders (clock ...

Stratigraphy

The Landen Group is stratigraphically on top of the Bertaimont Formation or

Heers Formation The Heers Formation ( nl, Formatie van Heers; french: Formation de Heers; abbreviation: Hs) is a geologic formation in the subsurface of Belgium. The formation consists of sand and marl and was deposited in the shallow sea that covered Belgium durin ...

(marine

marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...

s, sands and clays of Selandian to Thanetian age). In the Belgian lithostratigraphy, the Landen Group is overlain by the Ieper Group, marine clays and sands of Ypresian age. The Landen Group shares its name with the

Landen Formation The Landen Formation (abbreviation: LA) is a lithostratigraphic unit (a set of rock strata) 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 defin ...

in the lithostratigraphy of the Netherlands. However, this Dutch formation contains not only the equivalents of the Belgian Landen Group but also strata that correlate with the Belgian

Opglabbeek Formation The Opglabbeek Formation is a geologic formation in the subsurface of the eastern part of Belgian Limburg. The heterogeneous formation consists of clay and sand that was deposited lagoonally and fluvially during the early Selandian (Middle Pal ...

and Heers Formation.

References

* (eds.); 2001: ''Paleogene and Neogene lithostratigraphic units (Belgium)'', Geologica Belgica 4(1-2), p. 135-152 Lithostratigraphy of Belgium Eocene Series of Europe Paleocene Series of Europe Paleogene Belgium {{Europe-geologic-formation-stub