the Archean

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• 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 — [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 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 — 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 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 — 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 — /ahr kee euhn/, adj. Geol. noting or pertaining to rocks of the Archeozoic portion of the Precambrian Era. Also, Archaean. [1870 75; < Gk archaî(os) ancient (see ARCHAEO ) + AN] * * * …   Universalium

• Archean — Ar•che•an [[t]ɑrˈki ən[/t]] adj. gel of or pertaining to rocks of the Archeozoic portion of the Precambrian Era • Etymology: 1870–75 …   From formal English to slang

• History of the Earth — For the history of modern humans, see History of the world. Geological time put in a diagram called a geological clock, showing the relative lengths of the eons of the Earth s history The history of the Earth describes the most important events… …   Wikipedia