Archean

Also known as Archaean, Archaeozoic, Archeozoic, Archean Eon, Archæan, Archaeozoic Eon, Archeozoic Eon

The Archean ( , also spelled Archaean or Archæan), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth's history, preceded by the Hadean Eon and followed by the Proterozoic and the Phanerozoic. The Archean represents the time period from (million years ago). The Late Heavy Bombardment is hypothesized to overlap with the beginning of the Archean. The oldest known glaciation occurred in the middle of the eon.

AI overview

The Archean is the second major division of Earth's history, spanning from roughly 4.0 to 2.5 billion years ago, and it followed the Hadean Eon and preceded the Proterozoic. This eon is significant because it saw some of Earth's earliest known events, including the possible tail end of heavy asteroid impacts and the oldest recorded glaciation.

AI-generated from the Wikipedia summary — may contain errors.

Key facts

Geologic timespan.top_bar: all time
Geologic timespan.color: Archean
Geologic timespan.image_art: File:Archean.png
Geologic timespan.caption_art: Artist's impression of an Archean landscape
Geologic timespan.timeline: Eons
Geologic timespan.name_formality: Formal
Geologic timespan.alternate_spellings: Archaean, Archæan
Geologic timespan.synonym1: Eozoic
Geologic timespan.synonym1_coined: J.W. Dawson, 1865
Geologic timespan.celestial_body: earth
Geologic timespan.usage: Global (ICS)
Geologic timespan.timescales_used: ICS Time Scale
Geologic timespan.chrono_unit: Eon
Geologic timespan.strat_unit: Eonothem
Geologic timespan.timespan_formality: Formal
Geologic timespan.lower_boundary_def: Ten oldest U-Pb zircon ages
Geologic timespan.lower_gssa_location: Along the Acasta River, Northwest Territories, Canada
Geologic timespan.upper_boundary_def: Defined Chronometrically

via Wikipedia infobox

Wikidata facts

Image: Archean.png

Show 5 more facts

Commons category: Archean
end time: 2500000000
start time: 4031000000
sRGB color hex triplet: F0047F
IPA transcription: /ɑːrˈkiːən/

Sources (5)

via Wikidata · CC0

~12 min read

Article

7 sections

Contents

Etymology and changes in classification
Geology
Environment
Early life
See also
References
External links

The Earth during the Archean was mostly a water world: there was continental crust, but much of it was under an ocean deeper than today's oceans. Except for some rare relict crystals (Hadean zircon), today's oldest continental crust dates back to the Archean. Much of the geological detail of the Archean has been destroyed by subsequent tectonic activity. The Earth's atmosphere was also vastly different in composition from today's: the prebiotic atmosphere was a reducing atmosphere rich in methane and lacking free oxygen.