In the

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 Sakmarian is an age or stage of the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

period. It is a subdivision of the Cisuralian

Epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...

or Series. The Sakmarian lasted between 293.52 and million years ago (Ma). It was preceded by the Asselian and followed by the Artinskian.; 2004: ''A Geologic Time Scale 2004'',

Cambridge University The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

Press

Stratigraphy

The Sakmarian Stage is named after the Sakmara River in the Ural Mountains, a

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...

to the Ural River. The stage was introduced into scientific literature by Alexander Karpinsky in 1874. In Russian

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 ...

, it originally formed a substage of the Artinskian Stage. Currently, the ICS (International Commission on Stratigraphy) uses it as an independent stage in its international geologic timescale. The base of the Sakmarian Stage is defined by the first appearance of conodont species '' Streptognathodus postfusus'' in the fossil record. A global reference profile for the stage's base (a

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. ...

), located in the southern Ural Mountains, Russia, was ratified in 2018. The top of the Sakmarian (the base of the Artinskian) is defined as the level in the stratigraphic record where fossils of conodont species '' Sweetognathus whitei'' and '' Mesogondolella bisselli'' first appear.

References

External links

GeoWhen Database - Sakmarian

Upper Paleozoic stratigraphic chart
at the website of the subcommission for stratigraphic information of the ICS {{Geological history, p, p Permian geochronology .