The Orosirian (from Greek orosira, "mountain range") is the third geologic period in the Paleoproterozoic Era and lasted from 2050 million years ago to 1800 million years ago. Instead of being based on stratigraphy, these dates are defined chronometrically. Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... In geology, a period or age is a time span of many millions of years that are assumed to have had similar characteristics. ... The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between 2500 to 1600 million years ago. ... ERA is an abbreviation for several different things, including: the Equal Rights Amendment, a proposed, but unratified, Constitutional amendment in United States Earned run average, a baseball statistic Engine Room Artificer Education Reform Act Engineering Research Associates, a pioneering computer firm from the 1950s Academy of European Law Trier Explosive... Stratigraphy, a branch of geology, is basically the study of rock layers and layering (stratification). ...

Latter half of the period was an episode of intensive orogeny on virtually all continents. In geology, orogeny is the process of mountain building. ... Dymaxion map by Buckminster Fuller shows land mass with minimal distortion as only one continuous continent A continent (Latin continere, to hold together) is a large continuous land mass. ...

Probably during this period Earth's atmosphere changed to oxygen-rich due to photosynthesis of cyanobacteria. Earth, also known as the Earth or Terra, is the third planet outward from the Sun. ... Atmosphere may refer to: a celestial body atmosphere, e. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Leaf. ... Cyanobacteria (Greek: cyanos = blue) are a phylum of aquatic bacteria that obtain their energy through photosynthesis. ...

Two largest known impact events on Earth occurred during the Orosirian. At the very beginning of the period, 2023 mya, a large asteroid collision created the Vredefort impact structure. The event that created the Sudbury Basin structure occurred near the end of the period, 1850 mya. Artists impression of a major impact event. ... In astronomy, geology, and paleontology, mya is an acronym for million years ago and is used as a unit of time to denote length of time before the present. ... An asteroid is a small, solid object in our Solar System, orbiting the Sun. ... Vredefort is a meteor crater in the Free State Province of South Africa. ... The Sudbury Crater or Basin is the oval structure visible in this image. ...

External link

• GeoWhen Database