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Orosirian

Events of the Orosirian PeriodVertical axis scale: Millions of years agoEtymologyName formalityFormalUsage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitPeriodStratigraphic unitSystemTime span formalityFormalLower boundary definitionDefined chronometricallyLower GSSA ratified1990Upper boundary definitionDefined chronometricallyUpper GSSA ratified1990The Orosirian (; Ancient Greek: ὀροσειρά, romanized: oroseirá, meaning "mountain range") is the third geologic period in the Paleoproterozoic Era.

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