The Stephanian is a

stage Stage, stages, or staging may refer to: Arts and media Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly Brit ...

in the regional

stratigraphy 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: lithost ...

of northwest Europe with an age between roughly 307.5 and 299 Ma (million years ago). It is a subdivision of the

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 ...

system A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its open system (systems theory), environment, is described by its boundaries, str ...

or period and the regional Silesian

series Series may refer to: People with the name * Caroline Series (born 1951), English mathematician, daughter of George Series * George Series (1920–1995), English physicist Arts, entertainment, and media Music * Series, the ordered sets used i ...

. The uppermost units of the Coal Measures of

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

and

Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...

are probably of Stephanian age, though the larger part of this formation is referred to the earlier Westphalian. The stage derives its name from the city of

Saint-Étienne Saint-Étienne (; Franco-Provençal: ''Sant-Etiève''), also written St. Etienne, is a city and the prefecture of the Loire département, in eastern-central France, in the Massif Central, southwest of Lyon, in the Auvergne-Rhône-Alpes regi ...

for its coal mining basin in eastern central

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

(which itself derives from associations with

Saint Stephen Stephen (; ) is traditionally venerated as the protomartyr or first martyr of Christianity."St ...

) where strata of this age occur. In the official

geologic timescale The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochron ...

of the ICS, the Stephanian is placed within the Pennsylvanian epoch (323-299 Ma). The (regionally defined) Stephanian stage corresponds to the (internationally used)

Kasimovian The Kasimovian is a geochronologic age or chronostratigraphic stage in the ICS geologic timescale. It is the third stage in the Pennsylvanian (late Carboniferous), lasting from to Ma.; 2004: ''A Geologic Time Scale 2004'', Cambridge Unive ...

and Gzhelian stages. References appear in scientific literature to a Stephanian epoch or Stephanian

reflecting the stage's earlier status. Sediments younger than the Stephanian are sometimes termed the Autunian, a regional stage which includes the Carboniferous-Permian boundary.

Stratigraphy

From youngest to oldest, the proposed substages of the Stephanian are: * Stephanian C * Stephanian B * "Saberian" orrelation uncertain* Barruelian (Stephanian A) * Cantabrian

Base of the Stephanian

The Westphalian-Stephanian boundary is controversial and has not been formally defined. The early part of the Stephanian is difficult to recognize in much of Europe, due to sediment hiatuses or a transition from coal to unfossiliferous

red beds Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain t ...

. This issue is most apparent in the Lorraine- Saar-Nahe Basin of France and Germany, where a long hiatus occupies several million years between the Westphalian D and Stephanian A substages. Several workarounds have been proposed, but many bring forward their own problems. Many sources air on the side of caution and position the start of the Stephanian at the end of the hiatus. By that time, Kasimovian-type plant species are well-established, suggesting that part of the Westphalian D is Kasimovian in age. Other studies disagree with this approach, instead defining the Westphalian-Stephanian boundary at a major transition of plant faunas prior to the hiatus. Northwest Spain seems to offer a potential solution to the debate, since the regions of

Asturias Asturias (; ; ) officially the Principality of Asturias, is an autonomous communities of Spain, autonomous community in northwest Spain. It is coextensive with the provinces of Spain, province of Asturias and contains some of the territory t ...

and

Cantabria Cantabria (, ; ) is an autonomous community and Provinces of Spain, province in northern Spain with Santander, Cantabria, Santander as its capital city. It is called a , a Nationalities and regions of Spain, historic community, in its current ...

offer undisrupted and fossil-rich sediments which appear to fill in the gap between Westphalian D and Stephanian A. Most Carboniferous stratigraphers accept the utility of this interval, which has been named as the "Cantabrian" substage, the earliest substage of the Stephanian. Kasimovian-type plants first appear just above the base of the Cantabrian, arguing that the base of the Stephanian is slightly older than the start of the Kasimovian (around 307 Ma).

References

{{Geological history, p, p, state=collapsed Carboniferous geochronology Pennsylvanian geochronology . Gzhelian Stratigraphy of Europe