Archean
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Archean — [är kē′ən] adj. [< Gr archaios, ARCHAIC] [sometimes a ] designating or of the geologic eon characterized by the development of the first igneous and metamorphic rocks and the first marine microorganisms; Precambrian, esp. early Precambrian… … English World dictionary
Archean — The Archean (pronEng|ɑrˈkiːən, also spelled Archaean, formerly called the Archaeozoic (IPA|/ɑrkiəˈzoʊɪk/), also spelled Archeozoic or Archæozoic) is a geologic eon before the Proterozoic and Paleoproterozoic, before 2.5 Ga (billion years ago, or… … Wikipedia
Archean — or Archaean adjective Etymology: Greek archaios Date: 1872 1. of, relating to, or being the earliest eon of geological history or the corresponding system of rocks see geologic time table 2. Precambrian • Archean noun … New Collegiate Dictionary
Archean Eon — or Archaean Eon or Archeozoic Eon Older of the two divisions of Precambrian time. The Archean begins with the formation of the Earth s crust с 3.8 billion years ago and extends to с 2.5 billion years ago, up to the start of the Proterozoic Eon,… … Universalium
Archean aeon — noun the time from 3,800 million years to 2,500 million years ago; earth s crust formed; unicellular organisms are earliest forms of life • Syn: ↑Archean, ↑Archean eon, ↑Archeozoic, ↑Archaeozoic, ↑Archeozoic eon, ↑Archaeozoic aeon •… … Useful english dictionary
Archean eon — noun the time from 3,800 million years to 2,500 million years ago; earth s crust formed; unicellular organisms are earliest forms of life • Syn: ↑Archean, ↑Archean aeon, ↑Archeozoic, ↑Archaeozoic, ↑Archeozoic eon, ↑Archaeozoic aeon •… … Useful english dictionary
archean protaxis — noun Usage: usually capitalized A : the area or mass of Archean rocks in any continent that throughout post Archeozoic time remained a land area … Useful english dictionary
Archean — … Википедия
archean — adj. (Geology) of or pertaining to the earliest known forms of rocks; of or belonging to the earlier of the two divisions of Precambrian time … English contemporary dictionary
Archean — adjective US spelling of Archaean … English new terms dictionary
