Difference between revisions of "Continent" - New World Encyclopedia

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(New page: {{Started}} [[Image:Continental models.gif|thumb|300px|Animated, colour-coded map showing the various continents. [[Continent#Separation of continents|Depending on the convention and mod...)
 
 
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[[Image:Continental models.gif|thumb|300px|Animated, colour-coded map showing the various continents. [[Continent#Separation of continents|Depending on the convention and model]], some continents may be consolidated or subdivided: for example, [[Eurasia]] is often subdivided into [[Europe]] and [[Asia]] (red shades), while [[North America|North]] and [[South America]] are sometimes recognized as one [[Americas|America]]n continent (green shades).]]
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[[Image:Continental models.gif|thumb|400px|Animated map showing the continents according to various models. [[Eurasia]] is often subdivided into [[Europe]] and [[Asia]] (red shades), while [[North America|North]] and [[South America]] are sometimes recognized as one [[Americas|America]]n continent (green shades).]]
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[[Image:Dymaxion map unfolded-no-ocean.png|thumb|300px|right|[[Dymaxion map]] by [[Buckminster Fuller]] shows land masses with minimal distortion as nearly one continuous continent]]
 
  
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A '''continent''' is one of several large [[landmass]]es on [[Earth]]. They are generally identified by convention rather than any strict criteria, but seven areas are commonly reckoned as continents – they are (from largest in size to smallest): [[Asia]], [[Africa]], [[North America]], [[South America]], [[Antarctica]], [[Europe]], and [[Australia (continent)|Australia]].
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A '''continent''' is one of several large [[landmass]]es on [[Earth]]. Seven areas are commonly considered as continents: [[Asia]], [[Africa]], [[North America]], [[South America]], [[Antarctica]], [[Europe]], and [[Australia (continent)|Australia]]. However, they are generally identified by convention rather than any strict criteria. Some geographers divide the world into six, five, or fewer continents.  
  
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[[Plate tectonics]] is the [[geology|geological]] process and study of the movement, collision and division of continents, earlier known as ''[[continental drift]]''.
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The term "the Continent" (capitalized)—used predominantly in the European isles, such as the [[British Isles]], [[Sardinia]] and [[Sicily]]—means [[mainland Europe]], although it can also mean Asia when said in [[Japan]].
  
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The term "the Continent" (capitalized), used predominantly in the European isles, such as the [[British Isles]], [[Sardinia]] and [[Sicily]], means [[mainland Europe]], although it can also mean Asia when said in [[Japan]].
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The [[geology|geological]] process and study of the movement, collision and division of continents, earlier known as ''[[continental drift]],'' is known as [[plate tectonics]]. Geologists believe that the continents were once one huge landmass, an idea with conforms with the belief that the earth itself is indivisible except conceptually and that humankind will one day achieve unity in a world of peace.
  
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== Definitions and application ==
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==Definitions and application==
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Continents may be defined as "large, continuous, discrete masses of land, ideally separated by expanses of water." <ref>Martin W. Lewis and Kären E. Wigen. ''The Myth of Continents: a Critique of Metageography.'' (Berkeley: University of California Press, 1997  ISBN 0520207424), 21</ref> However, some of the seven most commonly recognized continents are identified by convention rather than adherence to the ideal criterion that each be a discrete landmass, separated by water from others. Likewise, the criterion that each be a ''continuous'' landmass is often disregarded by the inclusion of the [[continental shelf]] and [[island#oceanic islands|oceanic island]]s.
  
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"Continents are understood to be large, continuous, discrete masses of land, ideally separated by expanses of water."<ref>{{cite book |last=Lewis |first=Martin W. |authorlink= |coauthors=Kären E. Wigen |title=The Myth of Continents: a Critique of Metageography |date=1997 |publisher=University of California Press |location=Berkeley |id=ISBN 0-520-20742-4, ISBN 0-520-20743-2 |pages=p. 21 |chapter= |quote= }}</ref>  However, many of the seven most commonly recognized continents are identified by convention rather than adherence to the ideal criterion that each be a discrete landmass, separated by water from others. Likewise, the criterion that each be a continuous landmass is often disregarded by the inclusion of the [[continental shelf]] and [[island#oceanic islands|oceanic island]]s. Relatedly, the Earth's major landmasses are washed upon by a single, continuous [[World Ocean]], which is divided into a number of principal [[ocean]]ic components by the continents and various geographic criteria.<ref>"[http://www.answers.com/Ocean#Encyclopedia Ocean]." ''[[Columbia Encyclopedia|The Columbia Encyclopedia]]'' (2006).  New York: [[Columbia University Press]].  Retrieved 20 February 2007.</ref><ref name="UNAoO">"[http://www.oceansatlas.com/unatlas/about/physicalandchemicalproperties/background/seemore1.html Distribution of land and water on the planet]." ''[http://www.oceansatlas.com/ UN Atlas of the Oceans]'' (2004).  Retrieved 20 February 2007.</ref>
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Geologists believe that there once existed on Earth one huge landmass which separated into the areas known today as continents. Similarly, the Earth's major landmasses today are actually washed upon by a single, continuous [[World Ocean]], which is divided into a number of principal components by the continents and various human conceptual criteria.  
  
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=== Extent of continents ===
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===Extent of continents===
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The narrowest meaning of ''continent'' is that of a continuous area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. In this sense the term ''[[continental Europe]]'' is used to refer to mainland Europe, excluding [[island]]s such as [[Great Britain]], [[Ireland]], and [[Iceland]], and the term ''continent of Australia'' may refer to the [[Australia (continent)|mainland of Australia]], excluding [[Tasmania]]. [[Image:IBCAO betamap.jpg|thumb|left|350px|The Arctic continental shelves, in light blue, encompass many coastal islands.]] Similarly, the ''[[continental United States]]'' refers to the 48 contiguous [[United States]] in central North America and may include [[Alaska]] in the northwest of the continent (both separated by [[Canada]]), while excluding [[Hawaii]] in the middle of the [[Pacific Ocean]].
  
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The narrowest meaning of ''continent'' is that of a continuous<ref>"continent n. 5. a." (1989) ''[[Oxford English Dictionary]]'', 2nd edition. [[Oxford University Press]] ; "continent<sup>1</sup> n." (2006) ''The [[Concise Oxford English Dictionary]]'', 11th edition revised. (Ed.) Catherine Soanes and Angus Stevenson. Oxford University Press ; "continent<sup>1</sup> n." (2005) ''The [[New Oxford American Dictionary]]'', 2nd edition. (Ed.) [[Erin McKean]]. Oxford University Press ; "continent [2, n] 4 a" (1996) ''[[Webster's Dictionary#Webster's Third New International|Webster's Third New International Dictionary, Unabridged]]''. [[ProQuest|ProQuest Information and Learning]] ; "continent" (2007) ''[[Encyclopædia Britannica]]''. Retrieved January 14, 2007, from Encyclopædia Britannica Online.</ref> area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. In this sense the term ''[[continental Europe]]'' is used to refer to mainland Europe, excluding [[island]]s such as [[Great Britain]], [[Ireland]], and [[Iceland]], and the term ''continent of Australia'' may refer to the [[Australia (continent)|mainland of Australia]], excluding [[Tasmania]].  Similarly, the ''[[continental United States]]'' refers to the 48 contiguous [[United States]] in central North America and may include [[Alaska]] in the northwest of the continent (both separated by [[Canada]]), while excluding [[Hawaii]] in the middle of the [[Pacific Ocean]].
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From the perspective of [[geology]] or [[physical geography]], a ''continent'' may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area (the [[continental shelf]]), as they are structurally part of the continent. From this perspective the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level. Coastal islands may thus be considered as part of a continent. In this sense the British Isles are part of Europe, and both Australia and the island of [[New Guinea]] together form a continent ([[Australia-New Guinea]]).
  
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From the perspective of [[geology]] or [[physical geography]], ''continent'' may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area (the [[continental shelf]])<ref>"continent [2, n] 6" (1996) ''[[Webster's Dictionary#Webster's Third New International|Webster's Third New International Dictionary, Unabridged]]''. [[ProQuest|ProQuest Information and Learning]]. "a large segment of the earth's outer shell including a terrestrial continent and the adjacent continental shelf"</ref> and the islands on the shelf ([[island#continental islands|continental island]]s), as they are structurally part of the continent.<ref>{{cite book |last=Monkhouse |first=F. J. |coauthors=John Small |title=A Dictionary of the Natural Environment |year=1978 |publisher=Edward Arnold |location=London |id= |pages= pp. 67-68 |quote=structurally it includes shallowly submerged adjacent areas (continental shelf) and neighbouring islands }}</ref> From this perspective the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level.<ref name=Ollier>Ollier, Cliff D. (1996). Planet Earth. In Ian Douglas (Ed.), ''Companion Encyclopedia of Geography : The Environment and Humankind''. London: Routledge, p. 30. "Ocean waters extend onto continental rocks at continental shelves, and the true edges of the continents are the steeper continental slopes. The actual shorelines are rather accidental, depending on the height of sea-level on the sloping shelves."</ref> In this sense the British Isles are part of Europe, and Australia and the island of [[New Guinea]] together form a continent ([[Australia-New Guinea]]).
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As a cultural construct, the concept of a continent may go beyond the continental shelf to include [[island#oceanic islands|oceanic island]]s and continental fragments. In this way, [[Iceland]] may be considered part of Europe and [[Madagascar]] part of Africa. Extrapolating the concept to its extreme, some geographers take Australia, New Zealand and all the islands of [[Oceania]] to be equivalent to a continent, allowing the entire land surface of the Earth to be divided into continents or quasi-continents.
  
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As a cultural construct, the concept of a continent may go beyond the continental shelf to include [[island#oceanic islands|oceanic island]]s and continental fragments.  In this way, [[Iceland]] may be considered part of Europe and [[Madagascar]] part of Africa. Extrapolating the concept to its extreme, some geographers take Australia, New Zealand and all the islands of [[Oceania]] (or sometimes [[Australasia]]) to be equivalent to a continent, allowing the entire land surface of the Earth to be divided into continents or quasi-continents.<ref>{{cite book |last=Lewis |first=Martin W. |authorlink= |coauthors=Kären E. Wigen |title=The Myth of Continents: a Critique of Metageography |date=1997 |publisher=University of California Press |location=Berkeley |id=ISBN 0-520-20742-4, ISBN 0-520-20743-2 |pages=p. 40 |chapter= |quote=The joining of Australia with various Pacific islands to form the quasi continent of Oceania ... }}</ref>
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===Counting the continents===
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The ideal criterion that each continent be a discrete landmass is commonly disregarded in favor of more arbitrary, historical conventions. Of the seven most commonly recognized continents, only [[Antarctica]] and [[Australia]] are actually separated from other continents.  
  
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=== Separation of continents ===
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Several continents are defined not as absolutely distinct bodies but as "''more or less'' discrete masses of land." [[Asia]] and [[Africa]] are joined by the [[Isthmus of Suez]], and North and South America by the [[Isthmus of Panama]]. Both these [[isthmus]]es are very narrow in comparison with the bulk of the landmasses they join, and both are transected by artificial [[canal]]s—the [[Suez Canal]] and [[Panama Canal]], respectively—which effectively separate these landmasses.
  
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The ideal criterion that each continent be a discrete landmass is commonly disregarded in favor of more arbitrary, historical conventions. Of the seven most commonly recognized continents, only Antarctica and Australia are separated from other continents.  
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The division of the landmass of [[Eurasia]] into the separate continents of Asia and Europe is an anomaly with no basis in physical geography. The separation is maintained for historical and cultural reasons. An alternative view is that Eurasia is a single continent, one of six continents in total. This view is held by some geographers and is preferred in [[Russia]], which spans Asia and Europe.
  
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Several continents are defined not as absolutely distinct bodies but as "''more or less'' discrete masses of land".<ref>{{cite book |last=Lewis |first=Martin W. |authorlink= |coauthors=Kären E. Wigen |title=The Myth of Continents: a Critique of Metageography |date=1997 |publisher=University of California Press |location=Berkeley |id=ISBN 0-520-20742-4, ISBN 0-520-20743-2 |pages=p. 35 |chapter= |quote= }}</ref>  Asia and Africa are joined by the [[Isthmus of Suez]], and North and South America by the [[Isthmus of Panama]]. Both these [[isthmus]]es are very narrow in comparison with the bulk of the landmasses they join, and both are transected by artificial [[canal]]s (the [[Suez Canal]] and [[Panama Canal]], respectively) which effectively separate these landmasses.
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North America and South America are treated as separate continents in much of [[Western Europe]], [[India]], [[People's Republic of China|China]], and most native [[English language|English]]-speaking countries, such as [[the United States]], [[Canada]], [[Australia]], and [[New Zealand]]. Furthermore, the concept of two American continents is prevalent in much of Asia. However, in earlier times they were viewed as a single continent known as America or, to avoid ambiguity with the [[United States of America]], as "the Americas." North and South America are viewed as a single continent—one of six in total—in [[Iberian Peninsula|Iberia]], [[Italy]], [[Israel]], some other parts of Europe, and much of [[Latin America]].
  
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The division of the landmass of [[Eurasia]] into the separate continents of Asia and Europe is an anomaly with no basis in physical geography.  The separation is maintained for historical and cultural reasons. An alternative view is that Eurasia is a single continent, one of six continents in total. This view is held by some geographers and is preferred in [[Russia]] (which spans Asia and Europe).
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When continents are defined as discrete landmasses, embracing all the contiguous land of a body, then Asia, Europe and Africa form a single continent known by various names such as [[Africa-Eurasia]]. This produces a four-continent model consisting of Africa-Eurasia, the Americas, Antarctica and Australia.
  
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North America and South America are now treated as separate continents in much of [[Western Europe]], [[India]], [[People's Republic of China|China]], and most native [[English language|English]]-speaking countries, such as [[the United States]], [[Canada]], [[Australia]], and [[New Zealand]].  Furthermore, the concept of two American continents is prevalent in much of Asia.  However in earlier times they were viewed as a single continent known as America or, to avoid ambiguity with the [[United States of America]], as the [[Americas]].  However, the plurality of this last term suggests that even in these "earlier times" some considered the New World (the Americas) as two separate continents. North and South America are viewed as a single continent, one of six in total, in [[Iberian Peninsula|Iberia]], [[Italy]], [[Israel]], some other parts of Europe, and much of [[Latin America]].
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[[Image:Beringia land bridge-noaagov.gif|thumb|350px|Animated map shows the dissipation of the Bering land bridge which once united Asia and the Americas.]]
  
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When continents ''are'' defined as discrete landmasses, embracing all the contiguous land of a body, then Asia, Europe and Africa form a single continent known by various names such as [[Africa-Eurasia]]. This produces a four-continent model consisting of Africa-Eurasia, the Americas, Antarctica and Australia.
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When [[sea level]]s were lower during the [[Pleistocene]] [[ice age]], greater areas of continental shelf were exposed as dry land, forming [[land bridge]]s. At this time [[Australia-New Guinea]] was a single, continuous continent. Likewise, North America and Asia were joined by the [[Bering land bridge]]. Other islands such as [[Great Britain]] were joined to the mainlands of their continents. At that time there were just three discrete continents: Africa-Eurasia-America, Antarctica, and Australia-New Guinea.
  
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When [[sea level]]s were lower during the [[Pleistocene]] [[ice age]], greater areas of continental shelf were exposed as dry land, forming [[land bridge]]s. At this time [[Australia-New Guinea]] was a single, continuous continent. Likewise North America and Asia were joined by the [[Bering land bridge]]. Other islands such as [[Great Britain]] were joined to the mainlands of their continents. At that time there were just three discrete continents: Africa-Eurasia-America, Antarctica and Australia-New Guinea.
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The seven-continent model is usually taught in [[Western Europe]], [[Northern Europe]], [[Central Europe]], [[People's Republic of China|China]], and most [[English language|English]]-speaking [[list of countries by English-speaking population|countries]]. The six-continent combined-Eurasia model is preferred by the geographic community, [[Russia]], [[Eastern Europe]], and [[Japan]]. The six-continent combined-America model is taught in [[Latin America]], the [[Iberian Peninsula]], [[Italy]], [[Iran]], and some other parts of Europe; this model may be taught to include only the 5 inhabited continents (excluding Antarctica).
  
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=== Number of continents ===
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[[Oceania]] or [[Australasia]] may be used in place of Australia. For example, the ''Atlas of Canada'' names Oceania.
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There are numerous ways of distinguishing the continents:
 
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<center>
 
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{| class="wikitable" align="center"
 
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! colspan="9" | Models
 
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|style="background-color:#FFFFFF" colspan="9"|[[Image:Continents vide couleurs.png|center|300px]]<center><small>Colour-coded map showing the various continents. Similar shades exhibit areas that may be consolidated or subdivided.</small>
 
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|'''7 continents'''<br/><ref name=AoCA>[http://atlas.gc.ca/site/english/maps/reference/international/world/referencemap_image_view The World - Continents], [http://atlas.nrcan.gc.ca/site/english/index.html ''Atlas of Canada'']</ref><ref name=EB>"[http://www.britannica.com/ebc/article-9361501 Continent]." ''[[Encyclopædia Britannica]]''.  2006.  Chicago: Encyclopædia Britannica, Inc.</ref><ref name=NatlGeo>[http://www.nationalgeographic.com/xpeditions/atlas/index.html?Parent=world&Mode=d&SubMode=w World], ''[[National Geographic]] - [http://www.nationalgeographic.com/xpeditions/ Xpeditions Atlas].''  2006.  Washington, DC: National Geographic Society.</ref><ref name=Oxford1>''[[Oxford English Dictionary|The New Oxford Dictionary of English]].''  2001.  New York: Oxford University Press.</ref><ref name=Encarta>"[http://encarta.msn.com/encyclopedia_761553387/Continent.html Continent]." ''[[Encarta|MSN Encarta Online Encyclopedia 2006]].''</ref><ref name=Oxford2>"Continent."  McArthur, Tom, ed.  1992.  ''The Oxford Companion to the English Language''. New York: Oxford University Press; p. 260.</ref>||<center><small><span style="background: #00cc00;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[North America]]||<center><small><span style="background: #008000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[South America]]||<center><small><span style="background: #0040ff;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[Antarctica]]||<center><small><span style="background: #fed52e;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[Africa]]||<center><small><span style="background: #c10000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[Europe]]||<center><small><span style="background: #f33e01;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[Asia]]||<center><small><span style="background: #c04080;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[Australia (continent)|Australia]]
 
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|'''6 continents'''<br/><ref name=Columbia>"[http://www.bartleby.com/65/co/continent.html Continent]."  ''[http://www.bartleby.com/65/ The Columbia Encyclopedia]''. 2001.  New York: Columbia University Press - Bartleby.</ref><ref name=EB /><ref name=McGrawHill>"[http://www.answers.com/topic/continent#Science_and_Technology_Encyclopedia Continent]."  ''McGraw-Hill Concise Encyclopedia of Earth Science'' (extracted from online ''McGraw-Hill Encyclopedia of Science and Technology'').  2005.  New York: McGraw-Hill Professional; pp. 136-7.</ref>||<center><small><span style="background: #00cc00;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;North America ||<center><small><span style="background: #008000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;South America ||<center><small><span style="background: #0040ff;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Antarctica||<center><small><span style="background: #fed52e;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Africa||colspan="2" |<center><small><span style="background: #c10000;">&nbsp;&nbsp;&nbsp;</span><span style="background: #f33e01;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[Eurasia]]||<center><small><span style="background: #c04080;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Australia
 
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|'''5 continents'''<br/>{{Fact|date=July 2007}} ||<center><small><span style="background: #00cc00;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;North America ||<center><small><span style="background: #008000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;South America ||<center><small><span style="background: #0040ff;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Antarctica||colspan="3"|<center><small><span style="background: #fed52e;">&nbsp;&nbsp;&nbsp;</span><span style="background: #c10000;">&nbsp;&nbsp;&nbsp;</span><span style="background: #f33e01;"></span></small><small><span style="background: #f33e01;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[Africa-Eurasia]]||<center><small><span style="background: #c04080;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Australia
 
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|'''6 continents'''<br/>{{Fact|date=July 2007}} ||colspan="2"|<center><small><span style="background: #00cc00;">&nbsp;&nbsp;&nbsp;</span><span style="background: #008000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;[[Americas|America]]||<center><small><span style="background: #0040ff;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Antarctica||<center><small><span style="background: #fed52e;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Africa||<center><small><span style="background: #c10000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Europe||<center><small><span style="background: #f33e01;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Asia||<center><small><span style="background: #c04080;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Australia
 
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|'''5 continents'''<br/><ref name=IOC>[http://multimedia.olympic.org/pdf/en_report_672.pdf ''The Olympic symbols.''] [[International Olympic Committee]].  2002.  Lausanne: Olympic Museum and Studies Centre.  The five rings of the [[Olympic flag#Olympic Emblem|Olympic flag]] represent the five inhabited, participating continents  ([http://www.moscow2001.olympic.org/en/pdf/members_by_continent.pdf Africa, America, Asia, Europe, and Oceania]); thus, Antarctica is excluded from the flag.  Also see [http://www.acnolympic.org Association of National Olympic Committees]: [http://www.acnoa.info] [http://www.ocasia.org] [http://www.eurolympic.org] [http://www.crwflags.com/fotw/flags/int@paso.html] [http://www.oceaniasport.com]</ref><ref name=OU>Océano Uno, Diccionario Enciclopédico y Atlas Mundial, "Continente," page 392, 1730. ISBN 84-494-0188-7</ref><ref>Los Cinco Continentes (The Five Continents), Planeta-De Agostini Editions, 1997. ISBN 84-395-6054-0</ref><!-- NOTE: Both references mention ''Oceanía'' instead of ''Australia''. —> ||colspan="2" |<center><small><span style="background: #00cc00;">&nbsp;&nbsp;&nbsp;</span><span style="background: #008000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;America|| ||<center><small><span style="background: #fed52e;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Africa||<center><small><span style="background: #c10000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Europe||<center><small><span style="background: #f33e01;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Asia||<center><small><span style="background: #c04080;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Australia
 
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|'''5 continents'''<br/>{{Fact|date=February 2007}} ||colspan="2" |<center><small><span style="background: #00cc00;">&nbsp;&nbsp;&nbsp;</span><span style="background: #008000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;America||<center><small><span style="background: #0040ff;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Antarctica||<center><small><span style="background: #fed52e;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Africa||colspan="2"|<center><small><span style="background: #c10000;">&nbsp;&nbsp;&nbsp;</span><span style="background: #f33e01;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Eurasia||<center><small><span style="background: #c04080;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Australia
 
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|'''4 continents'''<br/>{{Fact|date=February 2007}} ||colspan="2" |<center><small><span style="background: #00cc00;">&nbsp;&nbsp;&nbsp;</span><span style="background: #008000;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;America||<center><small><span style="background: #0040ff;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Antarctica||colspan="3"|<center><small><span style="background: #fed52e;">&nbsp;&nbsp;&nbsp;</span><span style="background: #c10000;">&nbsp;&nbsp;&nbsp;</span><span style="background: #f33e01;"></span></small><small><span style="background: #f33e01;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Africa-Eurasia||<center><small><span style="background: #c04080;">&nbsp;&nbsp;&nbsp;</span></small>&nbsp;Australia
 
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The 7-continent model is usually taught in [[Western Europe]], [[Northern Europe]], [[Central Europe]], [[People's Republic of China|China]] and most [[English language|English]]-speaking [[list of countries by English-speaking population|countries]]. The 6-continent combined-Eurasia model is preferred by the geographic community, [[Russia]], [[Eastern Europe]], and [[Japan]]. The 6-continent combined-America model is taught in [[Latin America]], the [[Iberian Peninsula]], [[Italy]], [[Iran]] and some other parts of Europe; this model may be taught to include only the 5 inhabited continents (excluding Antarctica).<ref name=OU />
 
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[[Oceania]] or [[Australasia]] may be used in place of Australia. For example, the ''Atlas of Canada'' names Oceania,<ref name=AoCA>[http://atlas.gc.ca/site/english/maps/reference/international/world/referencemap_image_view The World - Continents], [http://atlas.nrcan.gc.ca/site/english/index.html ''Atlas of Canada'']</ref> as does the model taught in [[Ibero-America|Latin America and Iberia]].<ref>[http://pt.wikipedia.org/wiki/Continente "Continente"] [http://pt.wikipedia.org/wiki/P%C3%A1gina_principal Portuguese Wikipedia]</ref><ref>[http://es.wikipedia.org/wiki/Continente "Continente"].  [http://es.wikipedia.org/wiki/Portada Spanish Wikipedia]</ref>
 
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== Area and population ==
 
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Continents ranked by area and by population
 
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<table>
 
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<tr><td>
 
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{| class="wikitable"
 
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! colspan="2" | Area
 
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| '''continent'''
 
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| '''(km²)'''
 
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|[[Africa-Eurasia]] ||84&nbsp;360&nbsp;000
 
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|-
 
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|[[Eurasia]] ||53&nbsp;990&nbsp;000
 
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|[[Asia]] ||43&nbsp;810&nbsp;000
 
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|-
 
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|[[Americas|America]] ||42&nbsp;330&nbsp;000
 
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|-
 
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|[[Africa]] ||30&nbsp;370&nbsp;000
 
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|[[North America]] ||24&nbsp;490&nbsp;000
 
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|[[South America]] ||17&nbsp;840&nbsp;000
 
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|[[Antarctica]] ||13&nbsp;720&nbsp;000
 
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|[[Europe]] ||10&nbsp;180&nbsp;000
 
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|[[Oceania]]||9&nbsp;010&nbsp;000
 
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|[[Australia-New Guinea]] ||8&nbsp;500&nbsp;000
 
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|[[Australia (continent)|Australia mainland]]||7&nbsp;600&nbsp;000
 
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</td><td>
 
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{| class="wikitable"
 
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! colspan="3" | Population
 
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|-
 
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| '''continent'''
 
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| '''approx. population 2002'''
 
−
| '''percent'''
 
−
|-
 
−
|Africa-Eurasia || 5&nbsp;400&nbsp;000&nbsp;000 || 86%
 
−
|-
 
−
|Eurasia || 4&nbsp;510&nbsp;000&nbsp;000 || 72%
 
−
|-
 
−
|Asia || 3&nbsp;800&nbsp;000&nbsp;000 || 60%
 
−
|-
 
−
|Africa || 890&nbsp;000&nbsp;000 || 14%
 
−
|-
 
−
|America || 886&nbsp;000&nbsp;000 || 14%
 
−
|-
 
−
|Europe ||710&nbsp;000&nbsp;000 || 11%
 
−
|-
 
−
|North America ||515&nbsp;000&nbsp;000 || 8%
 
−
|-
 
−
|South America ||371&nbsp;000&nbsp;000 || 6%
 
−
|-
 
−
|Oceania ||33,552,994 || 0.6%
 
−
|-
 
−
|Australia-New Guinea || 30&nbsp;000&nbsp;000 || 0.5%
 
−
|-
 
−
|Australia mainland || 20&nbsp;000&nbsp;000 || 0.3%
 
−
|-
 
−
|Antarctica ||1&nbsp;000 || 0.00002%
 
−
|}
 
−
</td></tr></table>
 
−
 
 
−
== Other divisions ==
 
−
 
 
−
Certain parts of continents are recognized as [[subcontinent]]s, particularly those on different [[plate tectonics|tectonic plate]]s to the rest of the continent. The most notable examples are the [[Indian subcontinent]] and the [[Arabian Peninsula]]. [[Greenland]], on the [[North American Plate]], is sometimes referred to as a subcontinent. Where America is viewed as a single continent, it is divided into two subcontinents (North America and South America)<ref>[[:en:Image:MapaAméricaJonghe.JPG|English map of 1770 by Jonghe]]</ref><ref>[http://buscon.rae.es/dpdI/ DPD]: [http://buscon.rae.es/dpdI/América América]</ref><ref>[http://www.priberam.pt/dlpo/dlpo.aspx Dicionário da língua portuguesa]: Contiente</ref> or various regions.<ref>In Ibero-America, North America usually designates a region (''subcontinente'' in Spanish) of the Americas containing Canada, the U.S., and Mexico, and often Greenland, Saint Pierre and Miquelon, and Bermuda; the land bridge of Central America is generally considered a subregion of North America.[http://mx.encarta.msn.com/encyclopedia_761562468/Norteam%C3%A9rica.html Norteamérica (Mexican version)]/[http://es.encarta.msn.com/encyclopedia_761562468/Norteam%C3%A9rica.html (Spaniard version)].  ''Encarta Online Encyclopedia.''.</ref>
 
−
 
 
−
Some areas of [[continental crust]] are largely covered by the sea and may be considered submerged continents. Notable examples are [[Zealandia (continent)|Zealandia]], emerging from the sea primarily in New Zealand and New Caledonia, and the almost completely submerged [[Kerguelen Plateau|Kerguelen continent]] in the southern [[Indian Ocean]].
 
−
 
 
−
Some islands lie on sections of continental crust that have [[rift]]ed and drifted apart from a main continental landmass. While not considered continents because of their relatively small size, they may be considered minicontinents. [[Madagascar]], the largest example, is usually considered part of Africa but has been referred to as "the eighth continent."
 
  
 
==History of the concept==
 
==History of the concept==
−
=== Early concepts of the Old World continents ===
+
=== Early concepts===
 +
[[Image:Strabo.jpg|thumb|right|The Ancient Greek geographer [[Strabo]] holding a globe showing ''Europa'' and ''Asia'']]
 +
[[Image:T and O map Guntherus Ziner 1472.jpg|thumb|200px|Medieval [[T and O map]] showing the three continents as domains of the sons of [[Noah]]—Sem ([[Shem]]), Iafeth ([[Japheth]]), and Cham ([[Ham, son of Noah|Ham]])]]
 +
[[Image:T-O Mappa mundi.jpg|thumb|200px|Mappa Mundi in La Fleur des Histoires. 1459-1463.]]
  
−
[[Image:Strabo.jpg|thumb|right|240px|The Ancient Greek geographer [[Strabo]] holding a globe showing ''Europa'' and ''Asia'']]
+
The first distinction between continents was made by [[ancient Greece|ancient Greek]] mariners who gave the names [[Europe]] and [[Asia]] to the lands on either side of the waterways of the [[Aegean Sea]], the [[Dardanelles]] strait, the [[Sea of Marmara]], the [[Bosphorus]] strait, and the [[Black Sea]]. The names were first applied just to lands near the coast and only later extended to include the hinterlands.  
−
[[Image:T and O map Guntherus Ziner 1472.jpg|thumb|200px|Medieval [[T and O map]] showing the three continents as domains of the sons of [[Noah]] - Sem ([[Shem]]), Iafeth ([[Japheth]]) and Cham ([[Ham, son of Noah|Ham]])]]
 
−
The first distinction between continents was made by [[ancient Greece|ancient Greek]] mariners who gave the names [[Europe]] and [[Asia]] to the lands on either side of the waterways of the [[Aegean Sea]], the [[Dardanelles]] strait, the [[Sea of Marmara]], the [[Bosphorus]] strait and the [[Black Sea]]. <ref name=Toynbee> [[Arnold J. Toynbee|Toynbee, Arnold J.]] (1954). ''A Study of History''. London: Oxford University Press, v. 8, pp. 711-12.</ref> The names were first applied just to lands near the coast and only later extended to include the hinterlands.<ref>{{cite book |last=Tozer |first=H. F. |title=A History of Ancient Geography |year=1897 |publisher=University Press |location=Cambridge |pages= p. 69}}</ref> But the division was only carried through to the end of navigable waterways. "... beyond that point the Hellenic geographers never succeeded in laying their finger on any inland feature in the physical landscape that could offer any convincing line for partitioning an indivisible Eurasia ...".<ref name=Toynbee/>
 
  
−
Ancient Greek thinkers subsequently debated whether [[Africa]] (then called Libya) should be considered part of Asia or a third part of the world. Division into three parts eventually came to predominate.<ref>{{cite book |last=Tozer |first=H. F. |title=A History of Ancient Geography |year=1897 |publisher=University Press |location=Cambridge |pages= p. 67}}</ref> From the Greek viewpoint, the Aegean Sea was the center of the world; Asia lay to the east, Europe to the west and north and Africa to the south.<ref>{{cite book |last=Lewis |first=Martin W. |authorlink= |coauthors=Kären E. Wigen |title=The Myth of Continents: a Critique of Metageography |date=1997 |publisher=University of California Press |location=Berkeley |id=ISBN 0-520-20742-4, ISBN 0-520-20743-2 |pages=pp. 21-22 |chapter= |quote = }}</ref> The boundaries between the continents were not fixed. Early on, the Europe-Asia boundary was taken to run from the Black Sea along the [[Rioni River]] (known then as the Phasis) in [[Georgia (country)|Georgia]]. Later it was viewed as running from the Black Sea through [[Kerch Strait]], the [[Sea of Azov]] and along the [[Don River, Russia|Don River]] (known then as the Tanais) in [[Russia]].<ref>{{cite book |last=Tozer |first=H. F. |title=A History of Ancient Geography |year=1897 |publisher=University Press |location=Cambridge |pages= p. 68}}</ref> The boundary between Asia and Africa was generally taken to be the [[Nile]] River. [[Herodotus]]<ref>[[Herodotus]]. Translated by George Rawlinson (2000). ''[[Histories (Herodotus)|The Histories of Herodotus of Halicarnassus]]'' [http://www.omphaloskepsis.com/ebooks/pdf/hrdts.pdf]. Ames, Iowa: Omphaloskepsis, book 2, p. 18.</ref> in the fifth century B.C.E., however, objected to the unity of [[Egypt]] being split into Asia and Africa ("Libya") and took the boundary to lie along the western border of Egypt, regarding Egypt as part of Asia. He also questioned the division into three of what is really a single landmass,<ref>[[Herodotus]]. Translated by George Rawlinson (2000). ''[[Histories (Herodotus)|The Histories of Herodotus of Halicarnassus]]'' [http://www.omphaloskepsis.com/ebooks/pdf/hrdts.pdf]. Ames, Iowa: Omphaloskepsis, book 4, p. 38. "I cannot conceive why three names ... should ever have been given to a tract which is in reality one"</ref> a debate that continues nearly two and a half millennia later.
+
Ancient Greek thinkers subsequently debated whether [[Africa]] (then called [[Libya]]) should be considered part of Asia or a third part of the world. A division into three parts eventually came to predominate. From the Greek viewpoint, the [[Aegean Sea]] was the center of the world; Asia lay to the east, Europe to the west and north, and Africa to the south. The boundaries between the continents were not fixed. Early on, the Europe-Asia boundary was taken to run from the [[Black Sea]] along the [[Rioni River]] (known then as the Phasis) in [[Georgia (country)|Georgia]].  
  
−
[[Eratosthenes]], in the third century B.C.E., noted that some geographers divided the continents by rivers (the Nile and the Don), thus considering them "islands." Others divided the continents by [[isthmus]]es, calling the continents "peninsulas." These latter geographers set the border between Europe and Asia at the isthmus between the Black Sea and the [[Caspian Sea]], and the border between Asia and Africa at the isthmus between the [[Red Sea]] and the mouth of [[Lake Bardawil]] on the [[Mediterranean Sea]].<ref>[[Strabo]]. Translated by Horace Leonard Jones (1917). ''[[Geographica (Strabo)|Geography]]''.[http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Strabo/] Harvard University Press, book 1, ch. 4.[http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Strabo/1D*.html]</ref>
+
Later, the boundary was viewed as running from the Black Sea through [[Kerch Strait]], the [[Sea of Azov]], and along the [[Don River, Russia|Don River]] (known then as the Tanais) in [[Russia]]. The boundary between Asia and Africa was generally taken to be the [[Nile]] River. [[Herodotus]] in the fifth century B.C.E., however, objected to the unity of [[Egypt]] being split into Asia and Africa ("Libya") and took the boundary to lie along the western border of Egypt, regarding Egypt as part of Asia. He also questioned the division into three of what is really a single landmass, a debate that continues nearly two and a half millennia later.
  
−
Through the Roman period and the [[Middle Ages]], a few writers took the [[Isthmus of Suez]] as the boundary between Asia and Africa, but most writers continued to take it to be the Nile or the western border of Egypt (Gibbon). In the Middle Ages the world was portrayed on [[T and O map]]s, with the T representing the waters dividing the three continents. By the middle of the eighteenth century, "the fashion of dividing Asia and Africa at the Nile, or at the [[Great Catabathmus]] [the boundary between Egypt and [[Libya]]] farther west, had even then scarcely passed away." <ref>Goddard, Farley Brewer (1884). "Researches in the Cyrenaica." ''The American Journal of Philology'', 5 (1) p. 38.</ref>
+
[[Eratosthenes]], in the third century B.C.E., noted that some geographers divided the continents by rivers (the Nile and the Don), thus considering the continents to be "islands." Others divided the continents by [[isthmus]]es, calling the continents "peninsulas." These latter geographers set the border between Europe and Asia at the isthmus between the Black Sea and the [[Caspian Sea]], and the border between Asia and Africa at the isthmus between the [[Red Sea]] and the mouth of [[Lake Bardawil]] on the [[Mediterranean Sea]]. Through the Roman period and the [[Middle Ages]], a few writers took the [[Isthmus of Suez]] as the boundary between Asia and Africa, but most writers continued to take it to be the Nile or the western border of Egypt (Gibbon).
  
−
=== European discovery of the Americas ===
+
In the Middle Ages, the world was portrayed on "T and O" maps, with the T representing the waters dividing the three continents, and the O representing the inhabited world. The T and O concept dates back to the seventh century scholar [[Isidore of Seville]], in his ''Etymologiae'' (chapter 14), who stated:
  
−
[[Christopher Columbus]] sailed across the [[Atlantic Ocean]] to the [[Caribbean|West Indies]] in 1492, sparking a period of European exploration of the [[Americas]]. But despite four voyages to the Americas, Columbus never believed he had reached a new continent – he always thought it was part of Asia.  
+
<blockquote>The [inhabitated] mass of solid land is called round after the roundness of a circle, because it is like a wheel… Because of this, the Ocean flowing around it is contained in a circular limit, and it is divided in three parts, one part being called Asia, the second Europe, and the third Africa.</blockquote>
  
−
In 1501, [[Amerigo Vespucci]] and [[Gonçalo Coelho]] attempted to sail around the southern end of the Asian mainland into the [[Indian Ocean]]. On reaching the coast of [[Brazil]], they sailed a long way south along the coast of [[South America]], confirming that this was a land of continental proportions and that it extended much further south than Asia was known to.<ref name=OGorman>{{cite book | last = O'Gorman | first = Edmundo | authorlink = Edmundo O'Gorman | title = The Invention of America | publisher = Indiana University Press | date = 1961 | pages = pp. 106-112}}</ref> On return to Europe, an account of the voyage, called ''Mundus Novus'' ("New World"), was published under Vespucci’s name in 1502 or 1503,<ref name=formisano1>Formisano, Luciano (Ed.) (1992). ''Letters from a New World: Amerigo Vespucci's Discovery of America''. New York: Marsilio, pp. xx-xxi. ISBN 0-941419-62-2.</ref> although it seems that it had additions or alterations by another writer.<ref name=Zerubavel1>Zerubavel, Eviatar (2003). ''Terra Cognita: The Mental Discovery of America''. New Brunswick: Transaction Publishers, pp. 77–79. ISBN 0-7658-0987-7.</ref> Regardless of who penned the words, ''Mundus Novus'' attributed Vespucci with saying, "I have discovered a continent in those southern regions that is inhabited by more numerous people and animals than our Europe, or Asia or Africa",<ref name=formisano2>Formisano, Luciano (Ed.) (1992). ''Letters from a New World: Amerigo Vespucci's Discovery of America''. New York: Marsilio, p. 45. ISBN 0-941419-62-2.</ref> the first known explicit identification of part of the Americas as a continent like the other three.
+
By the middle of the eighteenth century, "the fashion of dividing Asia and Africa at the Nile, or at the [[Great Catabathmus]] (the boundary between Egypt and [[Libya]]) farther west, had even then scarcely passed away." <ref>Farley Brewer Goddard, "Researches in the Cyrenaica." ''The American Journal of Philology'' 5 (1)(1884): 38.</ref>
  
−
[[Image:UniversalisCosmographia.jpg|thumb|360px|''Universalis Cosmographia'', Waldseemüller's 1507 world map which was the first to show the Americas separate from Asia]]
+
===European discovery of the Americas===
−
Within a few years the name "New World" began appearing as a name for South America on world maps, such as the Oliveriana (Pesaro) map of around 1504–1505. Maps of this time though still showed [[North America]] connected to Asia and showed South America as a separate land.<ref name=Zerubavel1/>
+
[[Christopher Columbus]] sailed across the [[Atlantic Ocean]] to the [[Caribbean|West Indies]] in 1492, sparking a period of European exploration of the [[Americas]]. But despite four voyages to the Americas, Columbus never believed he had reached a new continent—he always thought it was part of Asia.  
  
−
In 1507 [[Martin Waldseemüller]] published a world map, ''[[Waldseemüller map|Universalis Cosmographia]]'', which was the first to show North and South America as separate from Asia and surrounded by water. A small inset map above the main map explicitly showed for the first time the Americas being east of Asia and separated from Asia by an ocean, as opposed to just placing the Americas on the left end of the map and Asia on the right end. In the accompanying book ''[[Cosmographiae Introductio]]'', Waldseemüller noted that the earth is divided into four parts, Europe, Asia, Africa and the fourth part which he named "America" after Amerigo Vespucci's first name.<ref name=Zerubavel2>Zerubavel, Eviatar (2003). ''Terra Cognita: The Mental Discovery of America''. New Brunswick: Transaction Publishers, pp. 80–82. ISBN 0-7658-0987-7.</ref> On the map, the word "America" was placed on part of South America.
+
In 1501, [[Amerigo Vespucci]] and [[Gonçalo Coelho]] attempted to sail around the southern end of the Asian mainland into the [[Indian Ocean]]. On reaching the coast of [[Brazil]], they sailed a long way south along the coast of [[South America]], confirming that this was a land of continental proportions and that it extended much further south than was known of Asia.
 +
[[Image:UniversalisCosmographia.jpg|thumb|380px|''Universalis Cosmographia,'' Waldseemüller's 1507 world map which was the first to show the Americas separate from Asia]]
 +
Within a few years the name "New World" began appearing as a name for South America on world maps, such as the Oliveriana (Pesaro) map of around 1504–1505. However, maps of this time still showed [[North America]] connected to Asia and showed South America as a separate land.
  
−
=== The word ''continent'' ===
+
In 1507, [[Martin Waldseemüller]] published a world map, ''[[Waldseemüller map|Universalis Cosmographia]]'', which was the first to show both North and South America as separate from Asia and surrounded by water. A small inset map above the main map explicitly showed for the first time the Americas being east of Asia and separated from Asia by an ocean, as opposed to just placing the Americas on the left end of the map and Asia on the right end. In the accompanying book ''[[Cosmographiae Introductio]],'' Waldseemüller noted that the earth is divided into four parts, Europe, Asia, Africa, and the fourth part which he named "America" after Amerigo Vespucci's first name. On the map, the word "America" was placed on part of South America.
  
−
From the 1500s the English noun ''continent'' was derived from the term ''continent land'', meaning continuous or connected land<ref name=oed>"continent n." (1989) ''[[Oxford English Dictionary]]'', 2nd edition. [[Oxford University Press]].</ref> and translated from the Latin ''terra continens''.<ref>"continent<sup>1</sup> n." (2006) ''The [[Concise Oxford English Dictionary]]'', 11th edition revised. (Ed.) Catherine Soanes and Angus Stevenson. [[Oxford University Press]].</ref> The noun was used to mean "a connected or continuous tract of land" or [[mainland]].<ref name=oed/> It was not applied only to very large areas of land — in the 1600s, references were made to the ''continents'' (or mainlands) of [[Kent]], [[Ireland]] and [[Wales]] and in 1745 to [[Sumatra]].<ref name=oed/> The word ''continent'' was used in translating Greek and Latin writings about the three "parts" of the world, although in the original languages no word of exactly the same meaning as ''continent'' was used.<ref> {{cite book |last=Lewis |first=Martin W. |authorlink= |coauthors=Kären E. Wigen |title=The Myth of Continents: a Critique of Metageography |date=1997 |publisher=University of California Press |location=Berkeley |id=ISBN 0-520-20742-4, ISBN 0-520-20743-2 |pages=p. 29 |chapter= |quote= }}</ref>
+
===''"Continent,"'' the word===
 +
From the 1500s, the English noun ''continent'' was derived from the term ''continent land,'' meaning continuous or connected land. It was not applied only to very large areas of land. In the 1600s, references were made to the ''continents'' (or mainlands) of [[Kent]], [[Ireland]], and [[Wales]], and in 1745 to [[Sumatra]]. The word ''continent'' was used in translating Greek and Latin writings about the three "parts" of the world, although in the original languages no word of exactly the same meaning as ''continent'' was used.
  
−
While ''continent'' was used on the one hand for relatively small areas of continuous land, on the other hand geographers again raised Herodotus’s query about why a single large landmass should be divided into separate continents. In the mid 1600s [[Peter Heylin]] wrote in his ''Cosmographie'' that "A Continent is a great quantity of Land, not separated by any Sea from the rest of the World, as the whole Continent of Europe, Asia, Africa." In 1727 [[Ephraim Chambers]] wrote in his ''Cyclopædia,'' "The world is ordinarily divided into two grand continents: the [[Old World|old]] and the [[New World|new]]." And in his 1752 atlas, Emanuel Bowen defined a continent as "a large space of dry land comprehending many countries all joined together, without any separation by water. Thus Europe, Asia, and Africa is one great continent, as America is another."<ref>Bowen, Emanuel. (1752). ''A Complete Atlas, or Distinct View of the Known World''. London, p. 3.</ref> However, the old idea of Europe, Asia and Africa as "parts" of the world ultimately persisted with these being regarded as separate continents.
+
While ''continent'' was used on the one hand for relatively small areas of continuous land, on the other hand geographers again raised Herodotus’s query about why a single large landmass should be divided into separate continents. In the mid 1600s, [[Peter Heylin]] wrote in his ''Cosmographie'' that "A Continent is a great quantity of Land, not separated by any Sea from the rest of the World, as the whole Continent of Europe, Asia, Africa." In 1727 [[Ephraim Chambers]] wrote in his ''Cyclopædia,'' "The world is ordinarily divided into two grand continents: the [[Old World|old]] and the [[New World|new]]." [[Emanuel Bowen]], in his 1752 atlas, defined a continent as "a large space of dry land comprehending many countries all joined together, without any separation by water. Thus Europe, Asia, and Africa is ''(sic)'' one great continent, as America is another." However, the old idea of Europe, Asia, and Africa as separate "parts" of the world ultimately persisted, and these terms continued to be regarded as distinct continents.
  
−
=== Beyond four continents ===
+
===Beyond four continents===
 +
From the late-eighteenth century, some geographers started to regard North America and South America as two parts of the world, making five parts in total. Overall though the fourfold division prevailed well into the nineteenth century.
  
−
From the late 18th century some geographers started to regard North America and South America as two parts of the world, making five parts in total. Overall though the fourfold division prevailed well into the 19th century.<ref name=lewis30> {{cite book |last=Lewis |first=Martin W. |authorlink= |coauthors=Kären E. Wigen |title=The Myth of Continents: a Critique of Metageography |date=1997 |publisher=University of California Press |location=Berkeley |id=ISBN 0-520-20742-4, ISBN 0-520-20743-2 |pages=p. 30 |chapter= |quote= }}</ref>
+
Europeans discovered [[Australia (continent)|Australia]] in 1606 but, for some time, it was taken as part of Asia. By the late-eighteenth century, some geographers considered it a continent in its own right, making it the sixth (or fifth for those still taking America as a single continent).
  
−
Europeans discovered [[Australia (continent)|Australia]] in 1606 but for some time it was taken as part of Asia. By the late 18th century some geographers considered it a continent in its own right, making it the sixth (or fifth for those still taking America as a single continent).<ref name=lewis30/> In 1813 [[Samuel Butler (schoolmaster)|Samuel Butler]] wrote of Australia as "[[New Holland (Australia)|New Holland]], an immense island, which some geographers dignify with the appellation of another continent" and the [[Oxford English Dictionary]] was just as equivocal some decades later.<ref>"continent n. 5. a." (1989) ''[[Oxford English Dictionary]]'', 2nd edition. [[Oxford University Press]]. "the great island of Australia is sometimes reckoned as another [continent]"</ref>
+
[[Image:Olympic flag.svg|thumb|250px|The Olympic flag's five rings represent the five inhabited continents with the Americas counted as one.]]
  
−
[[Antarctica]] was sighted in 1820 and described as a continent by [[Charles Wilkes]] on the [[United States Exploring Expedition]] in 1838, the last continent to be identified, although a great "Antarctic" (antipodean) landmass had been anticipated for millennia. An 1849 atlas labelled Antarctica as a continent but few atlases did so until after [[World War II]].<ref> {{cite book |last=Lewis |first=Martin W. |authorlink= |coauthors=Kären E. Wigen |title=The Myth of Continents: a Critique of Metageography |date=1997 |publisher=University of California Press |location=Berkeley |id=ISBN 0-520-20742-4, ISBN 0-520-20743-2 |pages=pp. 32, 220 |chapter= |quote= }}</ref>
+
[[Antarctica]] was sighted in 1820 and described as a continent by [[Charles Wilkes]] on the [[United States Exploring Expedition]] in 1838, the last continent to be identified, although a great "Antarctic" (antipodean) landmass had been anticipated for millennia. An 1849 atlas labeled Antarctica as a continent, but few atlases did so until after [[World War II]].
  
−
From the mid-19th century, United States atlases more commonly treated North and South America as separate continents, while atlases published in Europe usually considered them one continent. However it was still not uncommon for United States atlases to treat them as one continent up till World War II.<ref name=lewis32> {{cite book |last=Lewis |first=Martin W. |authorlink= |coauthors=Kären E. Wigen |title=The Myth of Continents: a Critique of Metageography |date=1997 |publisher=University of California Press |location=Berkeley |id=ISBN 0-520-20742-4, ISBN 0-520-20743-2 |pages=p. 32 |chapter= |quote= }}</ref> The [[Olympic symbols|Olympic flag]], devised in 1913, has five rings representing the five inhabited, participating continents, with America being treated as one continent and Antarctica not included.<ref name=IOC />
+
From the mid-nineteenth century, United States atlases more commonly treated North and South America as separate continents, while atlases published in Europe usually considered them one continent. However, it was still not uncommon for United States atlases to treat them as one continent up until World War II. The [[Olympic symbols|Olympic flag]], devised in 1913, has five rings representing the five inhabited, participating continents, with the Americas being treated as one continent and [[Antarctica]] not included.
  
−
From the 1950s, most United States geographers divided America in two<ref name=lewis32/> — consistent with modern understanding of [[geology]] and [[plate tectonics]]. With the addition of Antarctica, this made the seven-continent model. However, this division of America never appealed to [[Latin America]], which saw itself spanning an America that was a single landmass, and there the conception of six continents remains, as it does in scattered other countries.
+
From the 1950s, most [[United States]] geographers divided the American continent in two, consistent with the modern understanding of [[geology]] and [[plate tectonics]]. With the addition of Antarctica, this made the seven-continent model. However, this division of America never appealed to [[Latin America]], which saw itself spanning an America that was a single landmass, and there the conception of six continents remains, as it does in scattered other countries.
  
−
However, in recent years, there has been a push for Europe and Asia—traditionally considered two continents—to be considered one single continent, dubbed "[[Eurasia]]." In this model, the world is divided into six continents (if North America and South America are considered separate continents).
+
However, in recent years, there has been a push for Europe and Asia—traditionally considered two continents—to be considered one single continent, dubbed "[[Eurasia]]." In this model, the world is divided into six continents (if North America and South America are considered separate continents).
  
 
==Geology==
 
==Geology==
−
{{further|[[Continental crust]], [[Plate tectonics]]}}
+
Geologists use the term ''continent'' in a different manner than geographers, where a continent is defined by continental [[crust (geology)|crust]]: a platform of [[metamorphic rock|metamorphic]] and [[igneous rock]], largely of [[granite|granitic]] composition. Some geologists restrict the term "continent" to portions of the crust built around a stable [[Precambrian]] "shield," typically 1.5 to 3.8 billion years old, called a [[craton]]. The craton itself is an [[accretion (geology)|accretionary]] complex of ancient mobile belts (mountain belts) from earlier cycles of [[subduction]], [[continental collision]], and break-up from [[plate tectonics|plate tectonic]] activity. An outward-thickening veneer of younger, minimally deformed [[sedimentary rock]] covers much of the craton.
−
{{unreferenced||date=June 2006}}
+
 
−
Geologists use the term ''continent'' in a different manner than geographers, where a continent is defined by continental [[crust (geology)|crust]]: a platform of [[metamorphic rock|metamorphic]] and [[igneous rock]], largely of [[granite|granitic]] composition. Some geologists restrict the term 'continent' to portions of the crust built around stable [[Precambrian]] "shield," typically 1.5 to 3.8 billion years old, called a [[craton]]. The craton itself is an [[accretion (geology)|accretionary]] complex of ancient mobile belts (mountain belts) from earlier cycles of [[subduction]], [[continental collision]] and break-up from [[plate tectonics|plate tectonic]] activity. An outward-thickening veneer of younger, minimally deformed [[sedimentary rock]] covers much of the craton. The margins of geologic continents are characterized by currently-active or relatively recently active mobile belts and deep troughs of accumulated marine or [[river delta|deltaic]] [[sediment]]s. Beyond the margin, there is either a [[continental shelf]] and drop off to the [[basalt|basaltic]] [[oceanic basin|ocean basin]] or the margin of another continent, depending on the current plate-tectonic setting of the continent. A continental boundary does not have to be a body of water. Over geologic time, continents are periodically submerged under large epicontinental seas, and continental collisions result in a continent becoming attached to another continent. The current geologic era is relatively anomalous in that so much of the continental areas are "high and dry" compared to much of geologic history.
+
The margins of geologic continents are characterized by currently active, or relatively recent active mobile belts and deep troughs of accumulated marine or [[river delta|deltaic]] [[sediment]]s. Beyond the margin, there is either a [[continental shelf]] and drop-off to the [[basalt|basaltic]] [[oceanic basin|ocean basin]], or the margin of another continent, depending on the current plate-tectonic setting of the continent. A continental boundary does not have to be a body of water. Over geologic time, continents are periodically submerged under large epicontinental seas, and continental collisions result in a continent becoming attached to another continent. The current geologic era is relatively anomalous in that so much of the continental areas are "high and dry" compared to much of geologic history.
 
[[Image:Plates tect2 en.svg|thumb|250px|The tectonic plates underlying the continents and oceans]]
 
[[Image:Plates tect2 en.svg|thumb|250px|The tectonic plates underlying the continents and oceans]]
  
 
Some argue that continents are accretionary [[continental crust|crustal]] "rafts" which, unlike the denser basaltic crust of the ocean basins, are not subjected to destruction through the plate tectonic process of subduction. This accounts for the great age of the rocks comprising the continental cratons. By this definition, Europe and Asia can be regarded as separate continental masses because they have separate, distinct ancient shield areas and a distinct younger mobile belt (the [[Ural Mountains]]) forming the mutual margin.  
 
Some argue that continents are accretionary [[continental crust|crustal]] "rafts" which, unlike the denser basaltic crust of the ocean basins, are not subjected to destruction through the plate tectonic process of subduction. This accounts for the great age of the rocks comprising the continental cratons. By this definition, Europe and Asia can be regarded as separate continental masses because they have separate, distinct ancient shield areas and a distinct younger mobile belt (the [[Ural Mountains]]) forming the mutual margin.  
  
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[[Plate tectonics]] offers yet another way of defining continents. Today, Europe and most of Asia comprise the unified [[Eurasian Plate]] which is approximately coincident with the geographic Eurasian continent excluding India, Arabia, and far eastern Russia. India contains a central shield, and the geologically recent [[Himalaya]] mobile belt forms its northern margin. North America and South America are separate continents, the connecting [[isthmus]] being largely the result of [[volcano|volcanism]] from relatively recent subduction tectonics. North American continental rocks extend to Greenland (a portion of the [[Canadian Shield]]), and in terms of plate boundaries, the North American plate includes the easternmost portion of the Asian land mass. Geologists do not use these facts to suggest that eastern Asia is part of the North American continent, even though the plate boundary extends there; the word continent is usually used in its geographic sense and additional definitions ("continental rocks," "plate boundaries") are used as appropriate.
+
[[Plate tectonics]] offers yet another way of defining continents. Today, Europe and most of Asia comprise the unified [[Eurasian Plate]] which is approximately coincident with the geographic Eurasian continent excluding India, Arabia, and far eastern Russia. India contains a central shield, and the geologically recent [[Himalaya]] mobile belt forms its northern margin. North America and South America are separate continents, the connecting [[isthmus]] being largely the result of [[volcano|volcanism]] from relatively recent subduction tectonics. North American continental rocks extend to Greenland (a portion of the [[Canadian Shield]]), and in terms of plate boundaries, the North American plate includes the easternmost portion of the Asian land mass. Geologists do not use these facts to suggest that eastern Asia is part of the North American continent, even though the plate boundary extends there; the word continent is usually used in its geographic sense and additional definitions ("continental rocks," "plate boundaries") are used as appropriate.
  
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There are many [[microcontinent]]s that are built of continental crust but do not contain a craton. Some of these are fragments of [[Gondwanaland]] or other ancient cratonic continents: [[Zealandia (continent)|Zealandia]], which includes [[Geography of New Zealand|New Zealand]] and [[Geography of New Caledonia|New Caledonia]]; [[Geography of Madagascar|Madagascar]]; the northern [[Mascarene Plateau]], which includes the [[Seychelles]]; ''etc.'' Other islands, such as several in the [[Caribbean Sea]], are composed largely of granitic rock as well, but all continents contain both granitic and basaltic crust, and there is no clear boundary as to which islands would be considered microcontinents under such a definition. The [[Kerguelen Plateau]], for example, is largely volcanic, but is associated with the breakup of Gondwanaland and is considered to be a microcontinent,<ref>[http://www.utexas.edu/opa/news/99newsreleases/nr_199905/nr_continent990528.html UT Austin scientist plays major rule in study of underwater "micro-continent".] Retrieved on 2007-07-03</ref><ref>[http://jmooneyham.com/lost-civilization-kerguelen-reference.html REFERENCE Could we eventually uncover a lost civilization on the sunken Kerguelen continent?] Retrieved on 2007-07-03</ref><ref>http://news.bbc.co.uk/1/hi/sci/tech/353277.stm Retrieved on 2007-07-03</ref> whereas volcanic [[Geography of Iceland|Iceland]] and [[Hawaiian Islands|Hawaii]] are not. The [[British Isles]], [[Sri Lanka]], [[Borneo]], and [[Newfoundland]] are margins of the Laurasian continent which are only separated by inland seas flooding its margins.
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==Notes==
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==See also==
 
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{{commons2|Continents}}
 
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*[[Continental shelf]]
 
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*[[Supercontinent]]
 
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*[[List of countries by continent]]
 
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*[[Subregion]]
 
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*[[Plate tectonics]]
 
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*[[Geology]]
 
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==References and notes==
 
 
<div class="references-small">
 
<div class="references-small">
 
<references/>
 
<references/>
 
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</div>
  
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{{Continents of the world}}
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==References==
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{{Regions of the world}}
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* Goddard, Farley Brewer. "Researches in the Cyrenaica." ''The American Journal of Philology'' 5(1) 1884.
 +
* Lewis, Martin W., & Karen E. Wigen. ''The Myth of Continents: A Critique of Metageography.'' University of California Press, 1997. ISBN 0520207424
 +
* McIlwrath, Thomas F. ''North America: The Historical Geography of a Changing Continent.'' Rowan & Littlefield Publishers, 2001. ISBN 978-0742500198
 +
* Muller, Peter, & Muller-Hames, Elizabeth. ''Geography Studyguide: Realms, Regions, & Concepts.'' Wiley, 2005. ISBN 978-0471739081
 +
* Zerubavel, Eviator. ''Terra Cognita: The Mental Discovery of America.'' Transaction Publishers, 2003. ISBN 0765809877
 +
 
  
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[[Category:nations and places]]
 
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[[Category:geography]]
 
 
{{Credit|148843311}}
 
{{Credit|148843311}}
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[[Category:Geography]]

Latest revision as of 19:07, 19 May 2020


Animated map showing the continents according to various models. Eurasia is often subdivided into Europe and Asia (red shades), while North and South America are sometimes recognized as one American continent (green shades).

A continent is one of several large landmasses on Earth. Seven areas are commonly considered as continents: Asia, Africa, North America, South America, Antarctica, Europe, and Australia. However, they are generally identified by convention rather than any strict criteria. Some geographers divide the world into six, five, or fewer continents.

The term "the Continent" (capitalized)—used predominantly in the European isles, such as the British Isles, Sardinia and Sicily—means mainland Europe, although it can also mean Asia when said in Japan.

The geological process and study of the movement, collision and division of continents, earlier known as continental drift, is known as plate tectonics. Geologists believe that the continents were once one huge landmass, an idea with conforms with the belief that the earth itself is indivisible except conceptually and that humankind will one day achieve unity in a world of peace.

Definitions and application

Continents may be defined as "large, continuous, discrete masses of land, ideally separated by expanses of water." [1] However, some of the seven most commonly recognized continents are identified by convention rather than adherence to the ideal criterion that each be a discrete landmass, separated by water from others. Likewise, the criterion that each be a continuous landmass is often disregarded by the inclusion of the continental shelf and oceanic islands.

Geologists believe that there once existed on Earth one huge landmass which separated into the areas known today as continents. Similarly, the Earth's major landmasses today are actually washed upon by a single, continuous World Ocean, which is divided into a number of principal components by the continents and various human conceptual criteria.

Extent of continents

The narrowest meaning of continent is that of a continuous area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. In this sense the term continental Europe is used to refer to mainland Europe, excluding islands such as Great Britain, Ireland, and Iceland, and the term continent of Australia may refer to the mainland of Australia, excluding Tasmania.

The Arctic continental shelves, in light blue, encompass many coastal islands.

Similarly, the continental United States refers to the 48 contiguous United States in central North America and may include Alaska in the northwest of the continent (both separated by Canada), while excluding Hawaii in the middle of the Pacific Ocean.

From the perspective of geology or physical geography, a continent may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area (the continental shelf), as they are structurally part of the continent. From this perspective the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level. Coastal islands may thus be considered as part of a continent. In this sense the British Isles are part of Europe, and both Australia and the island of New Guinea together form a continent (Australia-New Guinea).

As a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments. In this way, Iceland may be considered part of Europe and Madagascar part of Africa. Extrapolating the concept to its extreme, some geographers take Australia, New Zealand and all the islands of Oceania to be equivalent to a continent, allowing the entire land surface of the Earth to be divided into continents or quasi-continents.

Counting the continents

The ideal criterion that each continent be a discrete landmass is commonly disregarded in favor of more arbitrary, historical conventions. Of the seven most commonly recognized continents, only Antarctica and Australia are actually separated from other continents.

Several continents are defined not as absolutely distinct bodies but as "more or less discrete masses of land." Asia and Africa are joined by the Isthmus of Suez, and North and South America by the Isthmus of Panama. Both these isthmuses are very narrow in comparison with the bulk of the landmasses they join, and both are transected by artificial canals—the Suez Canal and Panama Canal, respectively—which effectively separate these landmasses.

The division of the landmass of Eurasia into the separate continents of Asia and Europe is an anomaly with no basis in physical geography. The separation is maintained for historical and cultural reasons. An alternative view is that Eurasia is a single continent, one of six continents in total. This view is held by some geographers and is preferred in Russia, which spans Asia and Europe.

North America and South America are treated as separate continents in much of Western Europe, India, China, and most native English-speaking countries, such as the United States, Canada, Australia, and New Zealand. Furthermore, the concept of two American continents is prevalent in much of Asia. However, in earlier times they were viewed as a single continent known as America or, to avoid ambiguity with the United States of America, as "the Americas." North and South America are viewed as a single continent—one of six in total—in Iberia, Italy, Israel, some other parts of Europe, and much of Latin America.

When continents are defined as discrete landmasses, embracing all the contiguous land of a body, then Asia, Europe and Africa form a single continent known by various names such as Africa-Eurasia. This produces a four-continent model consisting of Africa-Eurasia, the Americas, Antarctica and Australia.

Animated map shows the dissipation of the Bering land bridge which once united Asia and the Americas.

When sea levels were lower during the Pleistocene ice age, greater areas of continental shelf were exposed as dry land, forming land bridges. At this time Australia-New Guinea was a single, continuous continent. Likewise, North America and Asia were joined by the Bering land bridge. Other islands such as Great Britain were joined to the mainlands of their continents. At that time there were just three discrete continents: Africa-Eurasia-America, Antarctica, and Australia-New Guinea.

The seven-continent model is usually taught in Western Europe, Northern Europe, Central Europe, China, and most English-speaking countries. The six-continent combined-Eurasia model is preferred by the geographic community, Russia, Eastern Europe, and Japan. The six-continent combined-America model is taught in Latin America, the Iberian Peninsula, Italy, Iran, and some other parts of Europe; this model may be taught to include only the 5 inhabited continents (excluding Antarctica).

Oceania or Australasia may be used in place of Australia. For example, the Atlas of Canada names Oceania.

History of the concept

Early concepts

The Ancient Greek geographer Strabo holding a globe showing Europa and Asia
Medieval T and O map showing the three continents as domains of the sons of Noah—Sem (Shem), Iafeth (Japheth), and Cham (Ham)
Mappa Mundi in La Fleur des Histoires. 1459-1463.

The first distinction between continents was made by ancient Greek mariners who gave the names Europe and Asia to the lands on either side of the waterways of the Aegean Sea, the Dardanelles strait, the Sea of Marmara, the Bosphorus strait, and the Black Sea. The names were first applied just to lands near the coast and only later extended to include the hinterlands.

Ancient Greek thinkers subsequently debated whether Africa (then called Libya) should be considered part of Asia or a third part of the world. A division into three parts eventually came to predominate. From the Greek viewpoint, the Aegean Sea was the center of the world; Asia lay to the east, Europe to the west and north, and Africa to the south. The boundaries between the continents were not fixed. Early on, the Europe-Asia boundary was taken to run from the Black Sea along the Rioni River (known then as the Phasis) in Georgia.

Later, the boundary was viewed as running from the Black Sea through Kerch Strait, the Sea of Azov, and along the Don River (known then as the Tanais) in Russia. The boundary between Asia and Africa was generally taken to be the Nile River. Herodotus in the fifth century B.C.E., however, objected to the unity of Egypt being split into Asia and Africa ("Libya") and took the boundary to lie along the western border of Egypt, regarding Egypt as part of Asia. He also questioned the division into three of what is really a single landmass, a debate that continues nearly two and a half millennia later.

Eratosthenes, in the third century B.C.E., noted that some geographers divided the continents by rivers (the Nile and the Don), thus considering the continents to be "islands." Others divided the continents by isthmuses, calling the continents "peninsulas." These latter geographers set the border between Europe and Asia at the isthmus between the Black Sea and the Caspian Sea, and the border between Asia and Africa at the isthmus between the Red Sea and the mouth of Lake Bardawil on the Mediterranean Sea. Through the Roman period and the Middle Ages, a few writers took the Isthmus of Suez as the boundary between Asia and Africa, but most writers continued to take it to be the Nile or the western border of Egypt (Gibbon).

In the Middle Ages, the world was portrayed on "T and O" maps, with the T representing the waters dividing the three continents, and the O representing the inhabited world. The T and O concept dates back to the seventh century scholar Isidore of Seville, in his Etymologiae (chapter 14), who stated:

The [inhabitated] mass of solid land is called round after the roundness of a circle, because it is like a wheel… Because of this, the Ocean flowing around it is contained in a circular limit, and it is divided in three parts, one part being called Asia, the second Europe, and the third Africa.

By the middle of the eighteenth century, "the fashion of dividing Asia and Africa at the Nile, or at the Great Catabathmus (the boundary between Egypt and Libya) farther west, had even then scarcely passed away." [2]

European discovery of the Americas

Christopher Columbus sailed across the Atlantic Ocean to the West Indies in 1492, sparking a period of European exploration of the Americas. But despite four voyages to the Americas, Columbus never believed he had reached a new continent—he always thought it was part of Asia.

In 1501, Amerigo Vespucci and Gonçalo Coelho attempted to sail around the southern end of the Asian mainland into the Indian Ocean. On reaching the coast of Brazil, they sailed a long way south along the coast of South America, confirming that this was a land of continental proportions and that it extended much further south than was known of Asia.

Universalis Cosmographia, Waldseemüller's 1507 world map which was the first to show the Americas separate from Asia

Within a few years the name "New World" began appearing as a name for South America on world maps, such as the Oliveriana (Pesaro) map of around 1504–1505. However, maps of this time still showed North America connected to Asia and showed South America as a separate land.

In 1507, Martin Waldseemüller published a world map, Universalis Cosmographia, which was the first to show both North and South America as separate from Asia and surrounded by water. A small inset map above the main map explicitly showed for the first time the Americas being east of Asia and separated from Asia by an ocean, as opposed to just placing the Americas on the left end of the map and Asia on the right end. In the accompanying book Cosmographiae Introductio, Waldseemüller noted that the earth is divided into four parts, Europe, Asia, Africa, and the fourth part which he named "America" after Amerigo Vespucci's first name. On the map, the word "America" was placed on part of South America.

"Continent," the word

From the 1500s, the English noun continent was derived from the term continent land, meaning continuous or connected land. It was not applied only to very large areas of land. In the 1600s, references were made to the continents (or mainlands) of Kent, Ireland, and Wales, and in 1745 to Sumatra. The word continent was used in translating Greek and Latin writings about the three "parts" of the world, although in the original languages no word of exactly the same meaning as continent was used.

While continent was used on the one hand for relatively small areas of continuous land, on the other hand geographers again raised Herodotus’s query about why a single large landmass should be divided into separate continents. In the mid 1600s, Peter Heylin wrote in his Cosmographie that "A Continent is a great quantity of Land, not separated by any Sea from the rest of the World, as the whole Continent of Europe, Asia, Africa." In 1727 Ephraim Chambers wrote in his Cyclopædia, "The world is ordinarily divided into two grand continents: the old and the new." Emanuel Bowen, in his 1752 atlas, defined a continent as "a large space of dry land comprehending many countries all joined together, without any separation by water. Thus Europe, Asia, and Africa is (sic) one great continent, as America is another." However, the old idea of Europe, Asia, and Africa as separate "parts" of the world ultimately persisted, and these terms continued to be regarded as distinct continents.

Beyond four continents

From the late-eighteenth century, some geographers started to regard North America and South America as two parts of the world, making five parts in total. Overall though the fourfold division prevailed well into the nineteenth century.

Europeans discovered Australia in 1606 but, for some time, it was taken as part of Asia. By the late-eighteenth century, some geographers considered it a continent in its own right, making it the sixth (or fifth for those still taking America as a single continent).

The Olympic flag's five rings represent the five inhabited continents with the Americas counted as one.

Antarctica was sighted in 1820 and described as a continent by Charles Wilkes on the United States Exploring Expedition in 1838, the last continent to be identified, although a great "Antarctic" (antipodean) landmass had been anticipated for millennia. An 1849 atlas labeled Antarctica as a continent, but few atlases did so until after World War II.

From the mid-nineteenth century, United States atlases more commonly treated North and South America as separate continents, while atlases published in Europe usually considered them one continent. However, it was still not uncommon for United States atlases to treat them as one continent up until World War II. The Olympic flag, devised in 1913, has five rings representing the five inhabited, participating continents, with the Americas being treated as one continent and Antarctica not included.

From the 1950s, most United States geographers divided the American continent in two, consistent with the modern understanding of geology and plate tectonics. With the addition of Antarctica, this made the seven-continent model. However, this division of America never appealed to Latin America, which saw itself spanning an America that was a single landmass, and there the conception of six continents remains, as it does in scattered other countries.

However, in recent years, there has been a push for Europe and Asia—traditionally considered two continents—to be considered one single continent, dubbed "Eurasia." In this model, the world is divided into six continents (if North America and South America are considered separate continents).

Geology

Geologists use the term continent in a different manner than geographers, where a continent is defined by continental crust: a platform of metamorphic and igneous rock, largely of granitic composition. Some geologists restrict the term "continent" to portions of the crust built around a stable Precambrian "shield," typically 1.5 to 3.8 billion years old, called a craton. The craton itself is an accretionary complex of ancient mobile belts (mountain belts) from earlier cycles of subduction, continental collision, and break-up from plate tectonic activity. An outward-thickening veneer of younger, minimally deformed sedimentary rock covers much of the craton.

The margins of geologic continents are characterized by currently active, or relatively recent active mobile belts and deep troughs of accumulated marine or deltaic sediments. Beyond the margin, there is either a continental shelf and drop-off to the basaltic ocean basin, or the margin of another continent, depending on the current plate-tectonic setting of the continent. A continental boundary does not have to be a body of water. Over geologic time, continents are periodically submerged under large epicontinental seas, and continental collisions result in a continent becoming attached to another continent. The current geologic era is relatively anomalous in that so much of the continental areas are "high and dry" compared to much of geologic history.

The tectonic plates underlying the continents and oceans

Some argue that continents are accretionary crustal "rafts" which, unlike the denser basaltic crust of the ocean basins, are not subjected to destruction through the plate tectonic process of subduction. This accounts for the great age of the rocks comprising the continental cratons. By this definition, Europe and Asia can be regarded as separate continental masses because they have separate, distinct ancient shield areas and a distinct younger mobile belt (the Ural Mountains) forming the mutual margin.

Plate tectonics offers yet another way of defining continents. Today, Europe and most of Asia comprise the unified Eurasian Plate which is approximately coincident with the geographic Eurasian continent excluding India, Arabia, and far eastern Russia. India contains a central shield, and the geologically recent Himalaya mobile belt forms its northern margin. North America and South America are separate continents, the connecting isthmus being largely the result of volcanism from relatively recent subduction tectonics. North American continental rocks extend to Greenland (a portion of the Canadian Shield), and in terms of plate boundaries, the North American plate includes the easternmost portion of the Asian land mass. Geologists do not use these facts to suggest that eastern Asia is part of the North American continent, even though the plate boundary extends there; the word continent is usually used in its geographic sense and additional definitions ("continental rocks," "plate boundaries") are used as appropriate.

Notes

  1. ↑ Martin W. Lewis and Kären E. Wigen. The Myth of Continents: a Critique of Metageography. (Berkeley: University of California Press, 1997 ISBN 0520207424), 21
  2. ↑ Farley Brewer Goddard, "Researches in the Cyrenaica." The American Journal of Philology 5 (1)(1884): 38.

References
ISBN links support NWE through referral fees

  • Goddard, Farley Brewer. "Researches in the Cyrenaica." The American Journal of Philology 5(1) 1884.
  • Lewis, Martin W., & Karen E. Wigen. The Myth of Continents: A Critique of Metageography. University of California Press, 1997. ISBN 0520207424
  • McIlwrath, Thomas F. North America: The Historical Geography of a Changing Continent. Rowan & Littlefield Publishers, 2001. ISBN 978-0742500198
  • Muller, Peter, & Muller-Hames, Elizabeth. Geography Studyguide: Realms, Regions, & Concepts. Wiley, 2005. ISBN 978-0471739081
  • Zerubavel, Eviator. Terra Cognita: The Mental Discovery of America. Transaction Publishers, 2003. ISBN 0765809877


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