Westphalian (stage)
Encyclopedia
The Westphalian is a stage in the regional stratigraphy
of northwest Europe with an age between roughly 313 and 304 Ma (million years ago). It is a subdivision of the Carboniferous
system or period and the regional Silesian series
. The Westphalian is named for the region of Westphalia
in western Germany
where strata of this age occur. The Coal Measures
of England
and Wales
are also largely of Westphalian age though they also extend into the succeeding Stephanian
.
The Westphalian age is preceded by the Namurian
stage/age (which corresponds to the Millstone Grit Series
of Great Britain) and succeeded by the Stephanian stage/age (which corresponds to the uppermost part of the Coal Measures
of Great Britain). In the official geologic timescale of the ICS
, the Westphalian is placed within the Pennsylvanian
epoch (318-299 Ma).
The (regionally defined) Westphalian stage corresponds to the upper part of the (internationally used) Bashkirian
stage together with the whole of the Moscovian
and Kasimovian
stages. Frequent references appear in scientific literature to a Westphalian epoch or Westphalian series
reflecting the stage's earlier status.
s were diverse and dominated communities. The collapse of the rainforest ecology
between the Moscovian and Kasimovian removed many amphibian species who did not survive as well in the cooler, drier conditions. Reptiles, however prospered due to specific key adaptations and underwent a major evolutionary radiation, in response to the drier climate that proceeded the rainforest collapse.
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
of northwest Europe with an age between roughly 313 and 304 Ma (million years ago). It is a subdivision of the Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
system or period and the regional Silesian series
Series (stratigraphy)
Series are subdivisions of rock layers made based on the age of the rock and corresponding to the dating system unit called an epoch, both being formally defined international conventions of the geological timescale. A series is therefore a sequence of rock depositions defining a...
. The Westphalian is named for the region of Westphalia
Westphalia
Westphalia is a region in Germany, centred on the cities of Arnsberg, Bielefeld, Dortmund, Minden and Münster.Westphalia is roughly the region between the rivers Rhine and Weser, located north and south of the Ruhr River. No exact definition of borders can be given, because the name "Westphalia"...
in western Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
where strata of this age occur. The Coal Measures
Coal Measures
The Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...
of England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
and Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
are also largely of Westphalian age though they also extend into the succeeding Stephanian
Stephanian (stage)
The Stephanian is a stage in the regional stratigraphy of northwest Europe with an age between roughly 304 and 299 Ma . It is a subdivision of the Carboniferous system or period and the regional Silesian series...
.
The Westphalian age is preceded by the Namurian
Namurian
The Namurian is a stage in the regional stratigraphy of northwest Europe with an age between roughly 326 and 313 Ma . It is a subdivision of the Carboniferous system or period and the regional Silesian series. The Namurian is named for the Belgian city and province of Namur where strata of this age...
stage/age (which corresponds to the Millstone Grit Series
Millstone Grit
Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the Northern England. The name derives from its use in earlier times as a source of millstones for use principally in watermills...
of Great Britain) and succeeded by the Stephanian stage/age (which corresponds to the uppermost part of the Coal Measures
Coal Measures
The Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...
of Great Britain). In the official geologic timescale of the ICS
International Commission on Stratigraphy
The International Commission on Stratigraphy , sometimes referred to by the unofficial "International Stratigraphic Commission" is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, geological, and geochronological matters on a global...
, the Westphalian is placed within the Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
epoch (318-299 Ma).
The (regionally defined) Westphalian stage corresponds to the upper part of the (internationally used) Bashkirian
Bashkirian
The Bashkirian is in the ICS geologic timescale the lowest stage or oldest age of the Pennsylvanian, the youngest subsystem of the Carboniferous...
stage together with the whole of the Moscovian
Moscovian (Carboniferous)
The Moscovian is in the ICS geologic timescale a stage or age in the Pennsylvanian, the youngest subsystem of the Carboniferous. The Moscovian age lasted from 311.7 ± 1.1 to 306.5 ± 1.0 Ma, is preceded by the Bashkirian and is followed by the Kasimovian...
and Kasimovian
Kasimovian
The Kasimovian is an geochronologic age or chronostratigraphic stage in the ICS geologic timescale. It is the third stage in the Pennsylvanian , lasting from 306.5 ± 1.0 to 303.9 ± 0.9 Ma. The Kasimovian stage follows the Moscovian and is followed by the Gzhelian.-Name and definition:The Kasimovian...
stages. Frequent references appear in scientific literature to a Westphalian epoch or Westphalian series
Series (stratigraphy)
Series are subdivisions of rock layers made based on the age of the rock and corresponding to the dating system unit called an epoch, both being formally defined international conventions of the geological timescale. A series is therefore a sequence of rock depositions defining a...
reflecting the stage's earlier status.
Life
AmphibianAmphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
s were diverse and dominated communities. The collapse of the rainforest ecology
Rainforest collapse
Rainforest collapse refers to the actual past and theoretical future destruction of rainforests through a process of habitat fragmentation to the point where little rainforest biome is left, only to survive in isolated refugia....
between the Moscovian and Kasimovian removed many amphibian species who did not survive as well in the cooler, drier conditions. Reptiles, however prospered due to specific key adaptations and underwent a major evolutionary radiation, in response to the drier climate that proceeded the rainforest collapse.