The Siderian (from Greek sideros, "iron") is the first geologic period in the Paleoproterozoic Era and lasted from 2500 million years ago to 2300 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). ...

Abundance of banded iron formations (BIFs) peaked early this period. BIFs were formed as algae produced waste oxygen, which combined with iron forming magnetite (Fe₃O₄, an iron oxide). This process cleaned the oceans from iron and formerly reddish seas become clear. Eventually the process created the oxygen-rich atmosphere of today. Banded Iron Formations are a distinctive type of rock often found in old sedimentary rocks. ... The algae (singular alga) comprise several different groups of living things that produce energy through photosynthesis. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metal Group, Period, Block 8 (VIIIB), 4, d Density, Hardness 7874 kg/m3, 4. ... Magnetite is a magnetic mineral form of both iron(II) oxide and iron(III) oxide or (iron(II,III) oxide), with chemical formula , one of several iron oxides and a member of the spinel group. ... Iron oxide pigment There are a number of iron oxides: Iron oxides Iron(II) oxide or ferrous oxide (FeO) The black-coloured powder in particular can cause explosions as it readily ignites. ... Atmosphere may refer to: a celestial body atmosphere, e. ...

Huronian glaciation began in Siderian 2400 mya and ended in late Rhyacian 2100 mya. Glaciation, often called an ice age, is a geological phenomenon in which massive ice sheets form in the Arctic and Antarctic and advance toward the equator. ... 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. ... From the GeoWhen Database: Rhyacian Period From 2300 +/- 0 To 2050 +/- 0 Ma Start Defined By: Fixed Date End Defined By: Fixed Date Start Based On: Gradstein, Ogg, Smith, et. ...

External link

• GeoWhen Database