geological 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 expo ...
in the
subsoil
Subsoil is the layer of soil under the topsoil on the surface of the ground. Like topsoil, it is composed of a variable mixture of small particles such as sand, silt and clay, but with a much lower percentage of organic matter and humus. The su ...
in the central and south area of the
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 ...
. The formation was formed during the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58BP). The formation was named after the city of
Oosterhout
Oosterhout (; from ''ooster'', "eastern", and ''hout'', "woods") is a Municipalities of the Netherlands, municipality and a city in southern Netherlands. The municipality had a population of in .
Population centers
The municipality of Ooste ...
in the province of
North Brabant
North Brabant ( ; ), also unofficially called Brabant, Dutch Brabant or Hollandic Brabant, is a province in the south of the Netherlands. It borders the provinces of South Holland and Gelderland to the north, Limburg to the east, Zeeland to ...
.
The Oosterhout Formation mainly consists of
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 ...
, often containing
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 ...
. In the upper layers,
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 ...
is also present. The Oosterhout Formation is usually right on top of the
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
Breda Formation
The Breda Formation (; abbreviation: BR) is a geologic formation in the subsurface of the Netherlands. The formation consists of marine glauconiferous sands and clays that were deposited during the Miocene epoch. Although the formation is not ve ...