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Eoarchean
Sign in to savethumb|Eoarchaean (3.8 b.y.) Greenlandite specimen (fuchsite-quartz gneiss), Nuup Kangerlua, Greenland. thumb|Garnet paragneiss, Nuvvuagittuq Greenstone Belt, Canada. 4.28 Ga old: the oldest known Earth rock of which direct samples are available. The Eoarchean ( ; also spelled Eoarchaean) is the first era of the Archean Eon of the geologic record. It spans 431 million years, from the end of the Hadean Eon 4031 Mya to the start of the Paleoarchean Era 3600 Mya. Some estimates place the beginnings of life on Earth in this era, while others place it earlier. Evidence of archaea and cyanobacteri
Key facts
- Geologic timespan.color
- Eoarchean
- Geologic timespan.top_bar
- all time
- Geologic timespan.time_start_uncertainty
- 3
- Geologic timespan.timeline
- Eons
- Geologic timespan.name_formality
- Formal
- Geologic timespan.alternate_spellings
- Eoarchaean
- Geologic timespan.celestial_body
- earth
- Geologic timespan.usage
- Global (ICS)
- Geologic timespan.timescales_used
- ICS Time Scale
- Geologic timespan.chrono_unit
- Era
- Geologic timespan.strat_unit
- Erathem
- Geologic timespan.timespan_formality
- Formal
- Geologic timespan.lower_boundary_def
- Ten oldest U-Pb zircon ages
- Geologic timespan.upper_boundary_def
- Defined Chronometrically
- Geologic timespan.lower_gssa_location
- Along the Acasta River, Northwest Territories, Canada
via Wikipedia infobox
Article
8 sectionsContents
- Chronology
- Geology
- Atmosphere
- Proposed subdivisions
- See also
- References
- Further reading
- External links
thumb|Eoarchaean (3.8 b.y.) Greenlandite specimen (fuchsite-quartz gneiss), Nuup Kangerlua, Greenland. thumb|Garnet paragneiss, Nuvvuagittuq Greenstone Belt, Canada. 4.28 Ga old: the oldest known Earth rock of which direct samples are available. The Eoarchean ( ; also spelled Eoarchaean) is the first era of the Archean Eon of the geologic record. It spans 431 million years, from the end of the Hadean Eon 4031 Mya to the start of the Paleoarchean Era 3600 Mya. Some estimates place the beginnings of life on Earth in this era, while others place it earlier. Evidence of archaea and cyanobacteria date to 3500 Mya, comparatively shortly after the Eoarchean. At that time, the atmosphere was without oxygen and the pressure values ranged from 10 to 100 bar (around 10 to 100 times the atmospheric pressure today).
==Chronology== The Eoarchean Era was formerly officially unnamed and informally referred to as the first part of the Early Archean Eon (which is now an obsolete name) alongside the Paleoarchean Era.