archean

Noun
  1. The time from 3,800 million years to 2,500 million years ago;
    Earth's crust formed;
    Unicellular organisms are earliest forms of life (synset 115154172)
    is an instance of: aeon, eon - the longest division of geological time
    is a part of: precambrian, precambrian aeon, precambrian eon, precambrian period - the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago
    same as: archaeozoic, archaeozoic aeon, archean aeon, archean eon, archeozoic, archeozoic eon
Adjective
  1. Of or relating to the earliest known rocks formed during the Precambrian Eon (synset 300817642)
    referred to in: geology - a science that deals with the history of the earth as recorded in rocks
    similar to: early - at or near the beginning of a period of time or course of events or before the usual or expected time
    same as: archaean

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