|
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 |
|||
Eocene Epoch
Eocene EpochThe Eocene Epoch, second of the five epochs into which the Tertiary Period is divided, lasted from 54 to 38 million years ago. Mammals became the dominant land animals during this epoch. The Eocene Epoch (meaning dawn of the recent period, from the Greek eos, dawn, and koinos, recent), like the other epochs of the Tertiary Period, was originally defined in 1833 by the English geologist Charles Lyell (1797–1875) on the basis of how many modern species are found among its fossils . The Eocene Epoch was defined by Lyell as that time where 1–5% of the species were modern (i.e., are still alive today). The Eocene Epoch's boundaries are therefore arbitrary, not set by mass extinctions or other clear-cut events. For most of the Eocene Epoch, the global climate was warm and rainy. Ice caps were small or nonexistent. Early Eocene Epoch sea levels were low, creating land bridges between Asia and North America via the Bering Strait, North America and Europe via Greenland, and Australia and Antarctica . Late in the epoch Antarctica drifted south, opening a deep-water channel between it and Australia that caused a global cooling trend by allowing the formation of the circum-Antarctic current. The Eocene Epoch saw the replacement of older mammalian orders by modern ones. Hoofed animals first appeared, including the famous Eohippus (dawn horse) and ancestral rhinoceroses and tapirs. Early bats, rabbits, beavers, rats, mice, carnivorous mammals, and whales also evolved during the Eocene Epoch. The earliest Eocene Epoch mammals were all small, but larger species, including the elephant-sized titanothere, evolved toward the end of the epoch. Many flowering plants evolved in the Eocene Epoch. Especially important are the grasses, which had first appeared in the late Cretaceous Period but did not become diverse and ubiquitous until the Eocene Epoch. Abundant grass encouraged the evolution of early grazing animals, including Eohippus. Familiar tree species such as birch, cedar, chestnut, elm, and beech flourished during the Eocene Epoch; aquatic and insect life were much the same as today. See also Archean; Cambrian Period; Carbon dating; Cenozoic Era; Dating methods; Devonian Period; Fossil record; Geologic time; Historical geology; Holocene Epoch; Jurassic Period; Mesozoic Era; Miocene Epoch; Mississippian Period; Oligocene Epoch; Ordovician Period; Paleozoic Era; Pennsylvanian Period; Phanerozoic Eon; Pleistocene Epoch; Pliocene Epoch; Precambrian; Proterozoic Era; Quaternary Period; Silurian Period |
|
|
Cite this article
"Eocene Epoch." World of Earth Science. 2003. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. "Eocene Epoch." World of Earth Science. 2003. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1G2-3437800197.html "Eocene Epoch." World of Earth Science. 2003. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3437800197.html |
|
Eocene
Eocene Originally coined by Charles Lyell (1833), the term ‘Eocene’ was at first used for the oldest of the Cenozoic epochs. The subsequent discovery of older Cenozoic rocks (the ‘Paléocene’ of Wilhelm Schimper, 1874) relegates it to the second place with a time-span of 15 million years. It is suceeded by the Oligocene at 33.7 Ma. It was originally distinguished by Lyell on the basis of its molluscan fauna in the Paris basin, with 3.3 per cent of living species present. Four stages are present, the last being represented by two different facies developments, the Priabonian and Latdorfian.
Plate-tectonic activity saw a northward motion of the continents and the closure of the Tethyan region with the main Alpine orogenic event towards the end of the epoch. Sea-floor spreading also brought about the split between Greenland and Scandinavia. Australia and Antarctica remained joined at the Tasman Rise but were moving northwards. World climate was generally warm. In the seas, the calcareous nannofossils were still in evidence but in shallow waters the benthonic nummulite and other larger foraminifera became very abundant. Mammals became the dominant tetrapods, replacing those of the Paleocene and Mesozoic. By 40 Ma there were advanced whales in the seas. In the lower latitudes, broadleaved forests were widespread; conifers dominated at higher latitudes and the grasses continued to diversify and reach new territory. Palaeomagnetic activity was considerable, with reversals of polarity for about 50 per cent of the time. The imprint of this behaviour of the geomagnetic field on igneous rocks in particular has been useful in the correlation of ocean floor basalts in many parts of the world. Eocene formations are important source or reservoir rocks for petroleum or gas in several parts of the world. The tropical seas of the time were highly productive in hydrocarbon materials, and the stratigraphy and structures of areas of continental shelf around Europe and North America have been responsible for many oilfields. The Near and Middle East have also seen the benefit of Eocene formations yielding abundant hydrocarbons. D. L. Dineley Bibliography Pomerol, C. (1982) The Cenozoic Era: Tertiary and Quaternary. (Trans. D. and and E. E. Humphies .) Ellis Horwood, Chichester. |
|
|
Cite this article
PAUL HANCOCK and BRIAN J. SKINNER. "Eocene." The Oxford Companion to the Earth. 2000. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. PAUL HANCOCK and BRIAN J. SKINNER. "Eocene." The Oxford Companion to the Earth. 2000. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O112-Eocene.html PAUL HANCOCK and BRIAN J. SKINNER. "Eocene." The Oxford Companion to the Earth. 2000. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O112-Eocene.html |
|
Eocene
Eocene A Tertiary epoch, from about 56.5–35.4 Ma ago, which began at the end of the Palaeocene and ended at the beginning of the Oligocene. It is noted for the expansion of mammalian stocks (horses, bats, and whales appeared during this epoch), and the local abundance of nummulites (marine protozoans of the Foraminiferida). In southern Britain a humid, subtropical climate allowed rain forests to flourish. The name means ‘dawn of the new’ and is derived from the Greek eos, meaning ‘dawn’, and kainos, meaning ‘new’.
|
|
|
Cite this article
MICHAEL ALLABY. "Eocene." A Dictionary of Ecology. 2004. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Eocene." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O14-Eocene.html MICHAEL ALLABY. "Eocene." A Dictionary of Ecology. 2004. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-Eocene.html |
|
Eocene
Eocene The second geological epoch of the Tertiary period. It extended from the end of the Palaeocene epoch, about 54 million years ago, to the beginning of the Oligocene epoch, about 38 million years ago. The term was first proposed by Sir Charles Lyell (1797–1875) in 1833. In some classifications of geological time the Palaeocene is included as part of the Eocene. Mammals were dominant in the Eocene: rodents, artiodactyls, carnivores, perissodactyls (including early horses), and whales were among the groups to make their first appearance.
|
|
|
Cite this article
"Eocene." A Dictionary of Biology. 2004. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. "Eocene." A Dictionary of Biology. 2004. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O6-Eocene.html "Eocene." A Dictionary of Biology. 2004. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-Eocene.html |
|
Eocene
Eocene A Tertiary epoch, from about 54.9–38 Ma ago, which began at the end of the Palaeocene and ended at the beginning of the Oligocene. It is noted for the expansion of mammalian stocks and the local abundance of nummulites (marine protozoans of the Foraminiferida). In southern Britain, a humid, subtropical climate allowed rain forests to flourish. The name is derived from the Greek eos meaning ‘dawn’, and kainos meaning ‘new’.
|
|
|
Cite this article
MICHAEL ALLABY. "Eocene." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Eocene." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O7-Eocene.html MICHAEL ALLABY. "Eocene." A Dictionary of Plant Sciences. 1998. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O7-Eocene.html |
|
Eocene
Eocene A Tertiary epoch, about 55.8–33.8 Ma ago, which began at the end of the Palaeocene and ended at the beginning of the Oligocene. It is noted for the expansion of mammalian stocks (horses, bats, and whales appeared during this epoch), and the local abundance of nummulites (marine protozoans of the Foraminiferida). The name means ‘dawn of the new’ and is derived from the Greek eos, ‘dawn’, and kainos, ‘new’.
|
|
|
Cite this article
MICHAEL ALLABY. "Eocene." A Dictionary of Zoology. 1999. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "Eocene." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O8-Eocene.html MICHAEL ALLABY. "Eocene." A Dictionary of Zoology. 1999. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-Eocene.html |
|
eocene
eocene (geol.) second lowest division of the tertiary. XIX. f. Gr. ēṓs dawn + kainós new, recent.
So miocene following the oligocene. f. Gr. meíōn less. oligocene following the eocene. f. Gr. olígos OLIGO-, palaeocene lowest division of the tertiary. See PALAEO-, pleistocene following the pliocene. f. Gr. pleîstos most. pliocene highest division of the tertiary, following the miocene. f. Gr. pleíōn more. |
|
|
Cite this article
T. F. HOAD. "eocene." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. T. F. HOAD. "eocene." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O27-eocene.html T. F. HOAD. "eocene." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-eocene.html |
|
Eocene
Eocene of, relating to, or denoting the second epoch of the Tertiary period, between the Palaeocene and Oligocene epochs. The Eocene epoch lasted from 56.5 to 35.4 million years ago. It was a time of rising temperatures, and there was an abundance of mammals, including the first horses, bats, and whales.
The term is recorded from the mid 19th century, and comes from Greek ēōs ‘dawn’ + kainos ‘new’. |
|
|
Cite this article
ELIZABETH KNOWLES. "Eocene." The Oxford Dictionary of Phrase and Fable. 2006. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. ELIZABETH KNOWLES. "Eocene." The Oxford Dictionary of Phrase and Fable. 2006. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O214-Eocene.html ELIZABETH KNOWLES. "Eocene." The Oxford Dictionary of Phrase and Fable. 2006. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O214-Eocene.html |
|
Eocene
Eocene Tertiary epoch which began at the end of the Palaeocene (56.5Ma) and ended at the beginning of the Oligocene (35.4Ma). It is noted for the expansion of mammalian stocks (horses, bats, and whales appeared during this epoch), and the local abundance of nummulites (marine protozoans of the Foraminiferida). The Eocene Epoch is divided into the Ypresian, Lutetian, Bartonian, and Priabonian Ages.
|
|
|
Cite this article
AILSA ALLABY and MICHAEL ALLABY. "Eocene." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "Eocene." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O13-Eocene.html AILSA ALLABY and MICHAEL ALLABY. "Eocene." A Dictionary of Earth Sciences. 1999. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Eocene.html |
|
Eocene
E·o·cene / ˈēəˌsēn/ • adj. Geol. of, relating to, or denoting the second epoch of the Tertiary period, between the Paleocene and Oligocene epochs. ∎ [as n.] (the Eocene) the Eocene epoch or the system of rocks deposited during it. |
|
|
Cite this article
"Eocene." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. "Eocene." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O999-eocene.html "Eocene." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-eocene.html |
|
Eocene
Eocene Second of the five epochs of the Tertiary period, c.55–38 million years ago. The fossil record shows members of modern plant genera, including beeches, walnuts, and elms, and indicates the apparent dominance of mammals, including the ancestors of camels, horses, rodents, bats, and monkeys.
|
|
|
Cite this article
"Eocene." World Encyclopedia. 2005. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>. "Eocene." World Encyclopedia. 2005. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O142-Eocene.html "Eocene." World Encyclopedia. 2005. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-Eocene.html |
|
|
Search over 100 encyclopedias and dictionaries:
HighBeam™ Research, Inc. © Copyright 2012. All rights reserved.
The Encyclopedia.com advertising network includes:
