The Gentbrugge Formation (, abbreviation: Ge; named after the town of

Gentbrugge Gentbrugge (; ) is a sub-municipality of the city of Ghent located in the province of East Flanders, Flemish Region, Belgium. It was a separate municipality until 1977. On 1 January 1977, it was merged into Ghent. Neighborhoods The sub-munici ...

East Flanders East Flanders ( ; ; ; ) is a Provinces of Belgium, province of Belgium. It borders (clockwise from the North) the Netherlands, Dutch province of Zeeland and the Belgian provinces of Antwerp (province), Antwerp, Flemish Brabant, Hainaut (provinc ...

) is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

in the west of

Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...

. The formation crops out in

and

West Flanders West Flanders is the westernmost province of the Flemish Region, in Belgium. It is the only coastal Belgian province, facing the North Sea to the northwest. It has land borders with the Dutch province of Zeeland to the northeast, the Flemis ...

and also occurs in the

subsurface In geology, bedrock is solid rock that lies under loose material (regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bedro ...

of the

Province of Antwerp Antwerp Province (; ; ; ), between 1815 and 1830 known as Central Brabant ( , , ), is the northernmost province both of the Flemish Region, also called Flanders, and of Belgium. It borders on the North Brabant province of the Netherlands to the ...

. It consists of marine

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually ...

and

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

, deposited in the shallow sea that covered northern Belgium during the

Ypresian In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

(around 50 million years ago, part of the early

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

).Steurbaut, 2006, p.76Gentbrugge Formation
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Description

The Gentbrugge Formation reaches its greatest thickness in the north of Belgium, where it can be maximally thick. It is subdivided into three

members Member may refer to: * Military jury, referred to as "Members" in military jargon * Element (mathematics), an object that belongs to a mathematical set * In object-oriented programming, a member of a class ** Field (computer science), entries in ...

. The base of the formation is formed by silty clay and clayey silt (Merelbeke Member). On top of this are

lamina Lamina may refer to: People * Saa Emerson Lamina, Sierra Leonean politician * Tamba Lamina, Sierra Leonean politician and diplomat Science and technology * Planar lamina, a two-dimensional planar closed surface with mass and density, in mathem ...

e of silt (Pittem Member) and beds of very fine sand, disturbed by

bioturbation Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a ...

(Vlierzele Member). The sands can have horizontal bedding as well as

cross bedding In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The original ...

, and are often

lithified Lithification (from the Ancient Greek word ''lithos'' meaning 'rock' and the Latin-derived suffix ''-ific'') is the process in which sediments compact under pressure, expel connate fluids, and gradually become solid rock. Essentially, lithificati ...

into

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

Stratigraphy

The Gentbrugge Formation is part of the

Ieper Group The Ieper Group (; ) is a group (stratigraphy), group of stratum, rock strata in the Subsurface (geology), subsurface of northwest Belgium. The group is subdivided into three marine (ocean), marine formation (stratigraphy), formations, all formed ...

and is stratigraphically on top of the older Mons-en-Pévèle Formation (

micaceous Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as ''perfect basal cleavage''. Mica is co ...

sandstone), another formation of the same

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 ...

. On top of the Gentbrugge Formation are deposits of the

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it ...

Zenne Group. In the north of Belgium this is often the Aalter Formation (marine clays and sands). In the south the Aalter Formation often lacks and the younger Brussels Formation (marine sand and

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

) and Lede Formation (marine calcareous sand) can be found directly on top of the Gentbrugge Formation.

References

Bibliography

* * * {{citation , last1=Laga , first1=P. , last2=Louwye , first2=S. , last3=Geets , first3=S. , year=2001 , title=Paleogene and Neogene lithostratigraphic units (Belgium) , url=https://popups.uliege.be/1374-8505/index.php?id=1954 , journal= Geologica Belgica , volume=4 , issue=1–2 , pages=135–152 , doi=10.20341/gb.2014.050 , accessdate=2020-09-07, doi-access=free Geologic formations of Belgium Eocene Series of Europe Paleogene Belgium Ypresian Stage Sandstone formations Siltstone formations Shallow marine deposits Formations Formations Formations Claystone formations

Description

Stratigraphy

See also

References

Bibliography