Archean
Sign in to saveThe 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.
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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
Article
7 sectionsContents
- Etymology and changes in classification
- Geology
- Environment
- Early life
- See also
- References
- External links
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.
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.