What is Eoarchaean?
The '''Eoarchaean''' ('''Eoarchean''') is the first [[geology|geological]] [[era]] in the [[Archaean]] [[eon]] that began 4 [[billion]] years ago, and ended 3.6 billion years ago.<ref>http://www.stratigraphy.org/ICSchart/ChronostratChart2013-01.pdf</ref> Before it was the [[Hadean]] It is followed by the [[Palaeoarchaean]]. The Eoarchaean is the earliest [[Geologic time scale|period of geology]] after the solidification of [[Earth's crust]]. The abiotic origins of life ([[abiogenesis]]) have been dated to a time window from 4 to 3.6 billion years ago when atmospheric pressure values ranged from {{c.}} 100 to 10&nbsp;bar.<ref>{{cite journal |last=Mulkidjanian |first=A. Y. | year=2009 | title=On the origin of life in the zinc world: 1. Photosynthesizing, porous edifices built of hydrothermally precipitated zinc sulfide as cradles of life on Earth. |journal=Biol. Direct |volume=4 |pages=26|doi=10.1186/1745-6150-4-26 |pmid=19703272 |pmc=3152778 |doi-access=free }}</ref><ref>{{cite journal |authors=Mulkidjanian, A. Y.; Bychkov, A. Y.; Dibrova, D. V.; Galperin, M. Y.; Koonin, E. V.| year=2012 | title=Origin of first cells at terrestrial, anoxic geothermal fields |journal=Proc. Natl. Acad. Sci. USA| volume=109 | issue=14 | pages=E821–E830 |doi=10.1073/pnas.1117774109 | pmid=22331915 | pmc=3325685 |bibcode = 2012PNAS..109E.821M | doi-access=free }}</ref><ref>{{cite journal | last=Mulkidjanian |first=A. Y. |year=2011 |title=Energetics of the First Life |pages=3–33 | journal=In R. Egel, D.-H. Lankenau, and A. Y. Mulkidjanian (Ed.), Origins of Life: The Primal Self-Organization. Springer Verlag, Heidelberg.(book)}}</ref> == Chronology == It was formerly officially unnamed and usually referred to as the first part of the ''Early Archaean'' (now an obsolete name) together with the later [[Palaeoarchaean]] Era. It is the first part of the [[Archaean]] Eon, preceded by the [[Hadean]] Eon. The Eoarchaean was followed by the Palaeoarchaean Era. The name comes from two [[Greek language|Greek]] words: ''eos'' (dawn) and ''arc