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The first eon in Earth’s history (4.6–2.5 billion years ago).
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited
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|Noun||1.||Archean eon - the time from 3,800 million years to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life|
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