The Stenian Period (, from grc, στενός, stenós, meaning "narrow") is the final
geologic period
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 geochr ...
in the
Mesoproterozoic
The Mesoproterozoic Era is a geologic era that occurred from . The Mesoproterozoic was the first era of Earth's history for which a fairly definitive geological record survives. Continents existed during the preceding era (the Paleoproterozoic), ...
Era and lasted from
Mya to Mya (million years ago). Instead of being based on
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 ...
, these dates are defined
chronometrically. The name derives from narrow
polymetamorphic belts formed over this period.
Preceded by the
Ectasian Period and followed by the
Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago.
It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is prec ...
Era.
The
supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leav ...
Rodinia
Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago.
were prob ...
assembled during the Stenian. It would last into the
Tonian
The Tonian (from grc, τόνος, tónos, meaning "stretch") is the first geologic period of the Neoproterozoic Era. It lasted from to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined by the ICS based o ...
Period.
This period includes the formation of the
Keweenawan Rift at about 1100 Mya.
Fossils of the oldest known sexually reproducing organism, ''
Bangiomorpha pubescens
''Bangiomorpha pubescens'' is a red alga.
It is the first known sexually reproducing organism. A multicellular fossil of ''Bangiomorpha pubescens'' was recovered from the Hunting Formation in Somerset Island, Canada
Canada is a countr ...
'', first appeared in the Stenian.
See also
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Notes
References
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Geological periods
Proterozoic geochronology
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