|
Search over 100 encyclopedias and dictionaries: |
Research categories | Follow us on Twitter |
Research categories
View all topics in the newsView all reference sources at Encyclopedia.com |
|||
eon
eon
1. The largest geologic-time unit, incorporating a number of eras. The equivalent chronostratigraphic unit is the (little used) eonothem. Originally, two eons were proposed in 1930 by G. H. Chadwick. The younger was the Phanerozoic Eon (the time of evident life), comprising the Cenozoic, Mesozoic, and Palaeozoic Eras, and this term is still used. The term suggested for the preceding eon was the Cryptozoic (the time of hidden life). This time has also been called the Archaeozoic (the time of most ancient life), but most commonly has been known simply as the Precambrian. Three eons have been proposed for Precambrian time: the Priscoan for time before 4000 Ma ago; the Archaean for 4000–2500 Ma ago; and the Proterozoic for 2500–590 Ma ago; the term ‘Precambrian’ is still in frequent use but is informal. 2. A time unit of 109 present Earth years. |
|
|
Cite this article
MICHAEL ALLABY. "eon." A Dictionary of Ecology. 2004. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "eon." A Dictionary of Ecology. 2004. Encyclopedia.com. (February 10, 2012). http://www.encyclopedia.com/doc/1O14-eon.html MICHAEL ALLABY. "eon." A Dictionary of Ecology. 2004. Retrieved February 10, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-eon.html |
|
eon
eon
1. The largest geologic-time unit, incorporating a number of eras. The equivalent chronostratigraphic unit is the eonothem. Originally, two eons were proposed in 1930 by G. H. Chadwick. The younger was the Phanerozoic Eon (time of evident life), comprising the Cenozoic, Mesozoic, and Palaeozoic Eras, and this term is still used. The term suggested for the preceding eon was the Cryptozoic (time of hidden life). This time has also been called the Archaeozoic (time of most ancient life), but most commonly has been known simply as the Precambrian. Three eons have been proposed for Precambrian time: the Priscoan for time before 4000 Ma ago; the Archaean for 4000–2500 Ma ago; and the Proterozoic for 2500–590 Ma ago; the term ‘Precambrian’ is still in frequent use but is informal. 2. A time unit of 109 present Earth years. |
|
|
Cite this article
AILSA ALLABY and MICHAEL ALLABY. "eon." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "eon." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (February 10, 2012). http://www.encyclopedia.com/doc/1O13-eon.html AILSA ALLABY and MICHAEL ALLABY. "eon." A Dictionary of Earth Sciences. 1999. Retrieved February 10, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-eon.html |
|
eon
e·on / ˈēən; ˈēˌän/ (chiefly Brit. also ae·on) • n. (often eons) an indefinite and very long period of time, often a period exaggerated for humorous or rhetorical effect: he reached the crag eons before I arrived. ∎ Astron. & Geol. a unit of time equal to a billion years. ∎ Geol. a major division of geological time, subdivided into eras: the Precambrian eon. ∎ Philos. (in Neoplatonism, Platonism, and Gnosticism) a power existing from eternity; an emanation or phase of the supreme deity. |
|
|
Cite this article
"eon." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>. "eon." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (February 10, 2012). http://www.encyclopedia.com/doc/1O999-eon.html "eon." The Oxford Pocket Dictionary of Current English. 2009. Retrieved February 10, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-eon.html |
|
eon
eon see AEON.
|
|
|
Cite this article
T. F. HOAD. "eon." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>. T. F. HOAD. "eon." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (February 10, 2012). http://www.encyclopedia.com/doc/1O27-eon.html T. F. HOAD. "eon." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved February 10, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-eon.html |
|
eon
eon See Aeon.
|
|
|
Cite this article
"eon." A Dictionary of Astronomy. 1997. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>. "eon." A Dictionary of Astronomy. 1997. Encyclopedia.com. (February 10, 2012). http://www.encyclopedia.com/doc/1O80-eon.html "eon." A Dictionary of Astronomy. 1997. Retrieved February 10, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-eon.html |
|
eon
eon
•Eritrean, Ghanaian, Himalayan, Malayan, Tigrayan
•Actaeon, Aegean, aeon (US eon), Augean, Behan, Cadmean, Caribbean, Carolean, Chaldean, Cyclopean, empyrean, epicurean, European, Fijian, Galilean, Hasmonean, Hebridean, Herculean, Ian, Jacobean, Kampuchean, Laodicean, lien, Linnaean (US Linnean), Maccabean, Mandaean (US Mandean), Medicean, monogenean, Nabataean (US Nabatean), Orphean, paean, paeon, pean, peon, Periclean, piscean, plebeian, Pyrenean, Pythagorean, Sabaean, Sadducean, Sisyphean, skean, Tanzanian, Tennesseean, Terpsichorean, theodicean, Tyrolean
|
|
|
Cite this article
"eon." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 10 Feb. 2012 <http://www.encyclopedia.com>. "eon." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (February 10, 2012). http://www.encyclopedia.com/doc/1O233-eon.html "eon." Oxford Dictionary of Rhymes. 2007. Retrieved February 10, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-eon.html |
|
Search over 100 encyclopedias and dictionaries:
HighBeam™ Research, Inc. © Copyright 2012. All rights reserved.
The Encyclopedia.com advertising network includes:
