The Bashkirian is in the

International Commission on Stratigraphy The International Commission on Stratigraphy (ICS), sometimes unofficially referred to as the International Stratigraphic Commission, is a daughter or major subcommittee grade scientific organization that concerns itself with stratigraphy, strati ...

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 ...

the lowest

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 ...

or oldest

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

of the Pennsylvanian. The Bashkirian age lasted from to Ma, is preceded by the

Serpukhovian The Serpukhovian is in the ICS geologic timescale the uppermost stage or youngest age of the Mississippian, the lower subsystem of the Carboniferous. The Serpukhovian age lasted from Ma to Ma. It is preceded by the Visean and is followed ...

and is followed by the Moscovian. The Bashkirian overlaps with the upper part of the

Namurian The Namurian is a stage in the regional stratigraphy of northwest Europe, with an age between roughly 331 and 319 Ma (million years ago). It is a subdivision of the Carboniferous system or period, as well as the regional Silesian series. The Na ...

and lower part of the Westphalian stages from regional European stratigraphy. It also overlaps with the North American Morrowan and Atokan stages and the Chinese Luosuan and lower Huashibanian stages.

Name and definition

The Bashkirian was named after Bashkiria, the then Russian name of the republic of

Bashkortostan Bashkortostan, officially the Republic of Bashkortostan, sometimes also called Bashkiria, is a republic of Russia between the Volga river and the Ural Mountains in Eastern Europe. The republic borders Perm Krai to the north, Sverdlovsk Oblast ...

in the southern

Ural Mountains The Ural Mountains ( ),; , ; , or simply the Urals, are a mountain range in Eurasia that runs north–south mostly through Russia, from the coast of the Arctic Ocean to the river Ural (river), Ural and northwestern Kazakhstan.

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

, home of the Bashkir people. The stage was introduced by Russian stratigrapher Sofia Semikhatova in 1934. The base of the Bashkirian is at the first appearance of

conodont Conodonts, are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning " cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known from their hard ...

species ''Declinognathodus noduliferus''. The top of the stage (the base of the Moscovian) is at the first appearance of the conodonts ''Declinognathodus donetzianus'' or ''Idiognathoides postsulcatus'', or at the first appearance of fusulinid '' Aljutovella aljutovica''. The

GSSP A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. ...

( type location for the base of a stage) for the Bashkirian is in the lower Bird Spring Formation at Arrow Canyon,

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

.; 1999: ''The IUGS boundary in the middle of the Carboniferous: Arrow Canyon, Nevada, USA'', Episodes 22(4), pp 272–283.

Subdivision

The Bashkirian contains six

biozone In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxon, taxa, as opposed to a Lithostratigraphy, lithostratigraphic unit which is defined by the ...

s based on conodont

index fossil Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. "Biostratigraphy." ''Oxford Reference: Dictionary of Biology ...

s: * '' Neognathodus atokaensis'' Zone * '' Declinognathodus marginodosus'' Zone * '' Idiognathodus sinuosus'' Zone * ''Neognathodus askynensis'' Zone * '' Idiognathoides sinuatus'' Zone * ''Declinognathodus noduliferus'' Zone

References

Literature

*; 2006: ''Global time scale and regional stratigraphic reference scales of Central and West Europe, East Europe, Tethys, South China, and North America as used in the Devonian–Carboniferous–Permian Correlation Chart 2003 (DCP 2003)'', Palaeogeography, Palaeoclimatology, Palaeoecology 240(1-2): pp 318–372.

External links

Carboniferous timescale
at the website of the Norwegian network of offshore records of geology and stratigraphy

{{coord, 36.7333, N, 114.7778, W, source:wikidata, display=title Pennsylvanian geochronology