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atoll
atoll, a word derived from the Maldivian word atollon used to describe a ring of coral islets and reefs enclosing a shallow lagoon. They occur exclusively in the tropical seas of the Pacific and Indian Oceans. Charles Darwin first postulated that atolls form initially on the summits of volcanoes as fringing coral reefs. The ocean crust then subsides under the weight of the new volcano and the waves wash away the ash of the central cone leaving the ring of coral. As the volcano continues to subside the reefs keep above sea level by continual growth. Islands form in the lee of the reefs through the accumulation of coralline sand voided by fish that graze on the coral. Deep boreholes drilled by the Americans into Eniwetak Atoll during preparations for nuclear weapon testing found hundreds of metres of coralline rocks sitting atop the remains of a volcano, thus demonstrating Darwin's theory was correct.
Most atolls are only a few metres above sea level, and are threatened by any rapid rise in sea level. Increases in the concentration of carbon dioxide in the atmosphere will inhibit the ability of the corals to lay down calcium carbonate, so the corals may no longer grow fast enough to keep pace with future rises in sea level. Climate change may also result in an increased frequency and ferocity of tropical storms. So, many atolls may be inundated within the next century. Bibliography Nunn, P. , Oceanic Islands (1994). M. V. Angel |
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"atoll." The Oxford Companion to Ships and the Sea. 2006. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "atoll." The Oxford Companion to Ships and the Sea. 2006. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O225-atoll.html "atoll." The Oxford Companion to Ships and the Sea. 2006. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O225-atoll.html |
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atoll
atoll Ring-shaped reef of coral enclosing a shallow lagoon. An atoll begins as a reef surrounding a slowly subsiding island, usually volcanic. As the island sinks, the coral continues to grow upwards until eventually the island is below sea level and only a ring of coral is left at the surface.
http://nasa.gov/Study/Maldives/maldives.html |
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"atoll." World Encyclopedia. 2005. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "atoll." World Encyclopedia. 2005. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O142-atoll.html "atoll." World Encyclopedia. 2005. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-atoll.html |
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atoll
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MICHAEL ALLABY. "atoll." A Dictionary of Ecology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "atoll." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O14-atoll.html MICHAEL ALLABY. "atoll." A Dictionary of Ecology. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-atoll.html |
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atoll
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AILSA ALLABY and MICHAEL ALLABY. "atoll." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "atoll." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-atoll.html AILSA ALLABY and MICHAEL ALLABY. "atoll." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-atoll.html |
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atoll
at·oll / ˈatˌôl; ˈatˌäl; ˈāˌtôl; ˈāˌtäl/ • n. a ring-shaped reef, island, or chain of islands formed of coral. |
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"atoll." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "atoll." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O999-atoll.html "atoll." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-atoll.html |
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atoll
atoll ring-shaped coral reef enclosing a lagoon. XIX (in XVII as atollon). — Maldive atoḷu.
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T. F. HOAD. "atoll." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. T. F. HOAD. "atoll." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O27-atoll.html T. F. HOAD. "atoll." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-atoll.html |
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atoll
atoll see coral reefs . |
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"atoll." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "atoll." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1E1-X-atoll.html "atoll." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-X-atoll.html |
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atoll
atoll
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•Dettol, metol
•sorbitol • capitol • Athol • menthol
•benzol
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"atoll." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "atoll." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O233-atoll.html "atoll." Oxford Dictionary of Rhymes. 2007. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-atoll.html |
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