The Aachen Formation (, ) is an

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cret ...

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 southern

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

and northeastern

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 ...

and adjacent

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

.Aachen Formation
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org It is

stratigraphically Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostrati ...

equivalent to the middle part of the

Chalk Group The Chalk Group (often just called the Chalk) is the lithostratigraphic unit (a certain number of rock strata) which contains the Upper Cretaceous limestone succession in southern and eastern England. The same or similar rock sequences occur ac ...

of England, and named after the German city of

Aachen Aachen is the List of cities in North Rhine-Westphalia by population, 13th-largest city in North Rhine-Westphalia and the List of cities in Germany by population, 27th-largest city of Germany, with around 261,000 inhabitants. Aachen is locat ...

Geography

The formation crops out in southern Belgian and

Dutch Limburg Limburg (; ), also known as Dutch Limburg, is the southernmost of the twelve provinces of the Netherlands. It is bordered by Gelderland to the north and by North Brabant to the west. Its long eastern boundary forms the border with the German sta ...

and adjacent areas in

. The formation can also be found 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 ...

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 ...

, where it forms an

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

from which

drinking water Drinking water or potable water is water that is safe for ingestion, either when drunk directly in liquid form or consumed indirectly through food preparation. It is often (but not always) supplied through taps, in which case it is also calle ...

is won.

Geology

The Aachen Formation consists of

glauconite Glauconite is an iron potassium phyllosilicate ( mica group) mineral of characteristic green color which is very friable and has very low weathering resistance. It crystallizes with a monoclinic geometry. Its name is derived from the Greek ...

bearing

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 ...

. It was deposited during the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

and

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

ages (85.8 to 70.6 million years ago) of the Cretaceous Period. The formation rests

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

on top of

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

rocks of the Limburg Group, which are more than three times as old. Overlying the Aachen Formation is the Vaals Formation, equivalent to the upper part of the Chalk Group of England.

Fossil content

Among others, the following fossils have been reported from the formation:

Corals

* '' Cunnolites''Leloux, 1999

Flora

* '' Nicolia'' * '' Verrutriletes'' ;Conifers * '' Cycadeospermum'' ;Pollen * '' Chrysotheca''Dijkstra, 1949 * '' Geleenites'' * '' Spherites'' * '' Triletes''

References

Bibliography

* * * * {{citation , last=Dijkstra , first=S. J , year=1949 , title=Megaspores and some other fossils from the Aachenian (Senonian) in South Limburg, Netherlands , journal=Mededelingen van de Geologische Stichting, Niewe Serie , volume=3 , pages=19–32 Upper Cretaceous Series of Europe Cretaceous Germany Cretaceous Netherlands Mesozoic Belgium Campanian Stage Santonian Stage Sandstone formations Shallow marine deposits Paleontology in Belgium Paleontology in the Netherlands Formations Formations Formations Geologic formations of Germany Geologic formations of the Netherlands Geologic formations of Belgium