The Maldegem Formation ( nl, Formatie van Maldegem; old name: Kallo Complex) 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 Belgian

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 ...

. The formation consists of alternating marine

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay part ...

and

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

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 e ...

, deposited during the late

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

. The Maldegem Formation crops out in the provinces of

East Flanders , native_name_lang = , settlement_type = Province of Belgium , image_flag = Flag of Oost-Vlaanderen.svg , flag_size = , image_shield = Wapen van O ...

and

West Flanders ) , settlement_type = Province of Belgium , image_flag = Flag of West Flanders.svg , flag_size = , image_shield = Wapen van West-Vlaanderen.svg , shield_size = , image_map ...

and in the area between the Zenne and

Dender The Dender ( Dutch, ) or Dendre (French, ) is a 65-kilometre (40 mi) long river in Belgium, the right tributary of the river Scheldt. The confluence of the two rivers is in the Belgian town of Dendermonde. The Western or Little Dender is 22 kilome ...

rivers. In the northern parts of Flanders it forms an up to 50 meters thick sequence in the subsurface. Further south and to the east (in the

Campine The Campine (French ) or De Kempen ( Dutch ) is a natural region situated chiefly in north-eastern Belgium and parts of the south-eastern Netherlands which once consisted mainly of extensive moors, tracts of sandy heath, and wetlands. It encom ...

of the province of Antwerp) the formation pinches out and can be only a few meters in thickness.

Lithology

The Maldegem Formation is an alternating sequence of grey glauconiferous fine sands and greyish blue glauconiferous heavy clay. It was deposited during the late

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 ...

and

Bartonian The Bartonian is, in the ICS's geologic time scale, a stage or age in the middle Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is followed by the Priabonian Age. Stratigraphic defin ...

ages Ages may refer to: *Advanced glycation end-products, known as AGEs *Ages, Kentucky, census-designated place, United States * ''Ages'' (album) by German electronic musician Edgar Froese *The geologic time scale, a system of chronological measuremen ...

(between 42 and 37 million years old).

Stratigraphy

Seven

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 ...

can be recognized within the Maldegem Formation: Wemmel Member,

Asse Member Asse () is a municipality located in the Belgian province of Flemish Brabant. It comprises the towns of Asse proper, Bekkerzeel, Kobbegem, Mollem, Relegem and Zellik. Asse is also situated in the Pajottenland. As of 2020, Asse had a total popu ...

Ursel Member Ursel is a Flemish surname: Place Ursel, town in Flanders, part of Knesselare. Name * Noble house d'Ursel, Duke of Ursel, see too: D'Ursel Castle. ** Lancelot II of Ursel ** Charles-Joseph, 4th Duke d'Ursel ** Marie Joseph Charles, 6th Duk ...

, Onderdale Member,

Zomergem Member Zomergem () is a town and former municipality located in the Flanders and in the province of East Flanders, in Belgium. The municipality comprises the towns of Oostwinkel, Ronsele and Zomergem proper. On 1 January 2018, Zomergem had a total popul ...

, Buisputten Member and Onderdijke Member. The Maldegem Formation is not part of a stratigraphic group and forms an independent unit in the

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

of Belgium. Stratigraphically on top of it is usually the Zelzate Formation (green grey sand with a

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 ages or the lower of two stages of the Oligocene Epoch/ Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chattian ...

age), part of the Tongeren Group. The Maldegem Formation is usually found on top of the Lede Formation (calcareous grey sand with a middle Lutetian age), which belongs to the

Zenne Group The Zenne Group ( nl, Zenne Groep) is a group of rock strata in the subsurface of central and northwest Belgium. The group consists of three formations, all from the Ypresian and Lutetian ages (early Eocene, 50 to 40 million years old). These form ...

References

Bibliography

* Jacobs, P.; 1988: ''Formatie van Maldegem'', in: Maréchal, R. & Laga, P. (eds.): ''Voorstel lithostratigrafische indeling van het Paleogeen'', Belgische Geologische Dienst, pp. 141-160 ({{in lang, nl) * 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