The Brussels Formation (; ; abbreviation: Br) 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

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 central

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 is named after the Belgian capital,

Brussels Brussels, officially the Brussels-Capital Region, (All text and all but one graphic show the English name as Brussels-Capital Region.) is a Communities, regions and language areas of Belgium#Regions, region of Belgium comprising #Municipalit ...

. It consists of shallow marine

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 ...

and

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

sands, deposited in the sea that covered Belgium 45 million years ago, in the

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 ...

. The Brussels Formation crops out in

Walloon Brabant Walloon Brabant ( ; ; ) is a province located in Belgium's French-speaking region of Wallonia. It borders on (clockwise from the North) the province of Flemish Brabant (Flemish Region) and the provinces of Liège, Namur and Hainaut. Walloon Br ...

and the north of the provinces of

Namur Namur (; ; ) is a city and municipality in Wallonia, Belgium. It is the capital both of the province of Namur and of Wallonia, hosting the Parliament of Wallonia, the Government of Wallonia and its administration. Namur stands at the confl ...

and Hainaut. It is normally about 30 metres in thickness. In

Flemish Brabant Flemish Brabant ( ; ) 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, Hainaut and East Flanders. Flemish Brabant also ...

and

Antwerp Antwerp (; ; ) is a City status in Belgium, city and a Municipalities of Belgium, municipality in the Flemish Region of Belgium. It is the capital and largest city of Antwerp Province, and the third-largest city in Belgium by area at , after ...

the formation can be found in the subsurface. The Brussels Formation is subdivided into five

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 Archennes Member ( conglomerates), the Bois de la Houssière Member (

quartzite Quartzite is a hard, non- foliated metamorphic rock that was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tecton ...

s), the Chaumont-Gistoux Member ( glauconiferous quartzites), the Diegem Member (glauconiferous quartzite) and the Neerijse Member (glauconiferous calcareous sand). The formation consists either of

cross-bedded 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 ...

non-calcareous sands alternating with thin beds of

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

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 ...

or calcareous fine sands with traces of

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 ...

. The formation was formed during the early

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 ...

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 ...

(about 46 million years ago) and is part of the Zenne Group. Stratigraphically on top of the Brussels Formation is the Lede Formation (also part of the Zenne Group), or when this formation is absent the Maldegem Formation (

Bartonian The Bartonian is, in the International Commission on Stratigraphy's (ICS) geologic time scale, a stage or age in the middle of the Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is follow ...

) or Tongeren Group (

Priabonian The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene Epoch or Series. It spans the time between . The Priabonian is preceded by the Bartonian and is followed by the Rupelian, the lowest stage ...

Rupelian The Rupelian is, in the geologic timescale, the older of two age (geology), ages or the lower of two stage (stratigraphy), stages of the Oligocene epoch (geology), Epoch/series (stratigraphy), Series. It spans the time between . It is preceded b ...

). The Brussels Formation is normally lying stratigraphically on top of the Aalter Formation (part of the Zenne Group) or deposits 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 ...

References

Bibliography

* Laga, P.; Louwye, S. & Geets, S. (eds.); 2001: ''Paleogene and Neogene lithostratigraphic units (Belgium)'', Geologica Belgica 4(1-2), p. 135-152 Geologic formations of Belgium Eocene Series of Europe Paleogene Belgium {{Europe-geologic-formation-stub

See also

References

Bibliography