A continent is one of several large landmasses A landmass is a large continuous area of land. Although it may be most often written as one word to distinguish it from the usage "land mass"—the measure of land area—it is also used as two words on Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet,[note 6] or by its Latin name, Terra.[note 7]. They are generally identified by convention A convention is a set of agreed, stipulated or generally accepted standards, norms, social norms or criteria, often taking the form of a custom rather than any strict criteria, with seven regions commonly regarded as continents – they are (from largest in size to smallest): Asia Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.6% of the Earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population. During the 20th century Asia's population nearly quadrupled, Africa Africa is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area. With a billion people (as of 2009, see table) in 61 territories, it accounts for about 14.72% of the world's human population, North America North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific Ocean; South America lies to the southeast, South America South America is the southern continent of America, situated in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the northwest, Antarctica Antarctica (pronounced /ænˈtɑrktɪkə/ ) is Earth's southernmost continent, underlying the South Pole. It is situated in the Antarctic region of the southern hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14.0 million km2 (5.4 million sq mi), it is the fifth-largest continent in area after, Europe Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus region (Specification of borders) and the Black Sea to the southeast. Europe is bordered by the, and Australia Australia is the smallest of the geographic continents, though not of geological continents. There is no universally accepted definition of the word "continent"; the lay definition is "One of the main continuous bodies of land on the earth's surface." . By that definition, the continent of Australia includes only the Australian.[1]

Plate tectonics Plate tectonics is a scientific theory which describes the large scale motions of Earth's lithosphere. The theory builds on the older concepts of continental drift, developed during the first decades of the 20th century by Alfred Wegener, and seafloor spreading, developed in the 1960s is the geological Geology is the science and study of the physical matter and energy that constitute the Earth. The field of geology encompasses the study of the composition, structure, properties, and history of the planet's physical material, the processes by which it is formed, moved, and changed, the history of life on Earth, and human interactions with the process and study of the movement, collision and division of continents, earlier known as continental drift Continental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912. However, it was not until the development of the theory of plate tectonics in the 1960s, that a sufficient geological.

The term the Continent may also refer to mainland Europe Continental Europe, also referred to as mainland Europe or simply the Continent, is the continent of Europe, explicitly excluding European islands. Notably, in British English usage, the term means Europe excluding the United Kingdom, the Isle of Man, the Channel Islands, Ireland and Iceland, i.e., excluding the British Isles 1 These are the official languages of the eight jurisdictions within the British Isles. Other languages are spoken, including several other native languages and dialects that have regional or special status.[2]

Contents

Definitions and application

Conventionally, "Continents are understood to be large, continuous, discrete masses of land, ideally separated by expanses of water."[3] Many of the seven most commonly recognized continents identified by convention are not discrete landmasses separated by water. The criterion 'large' leads to arbitrary classification: Greenland b. ^ Greenland, the Faeroes and Iceland were formally Norwegian possessions until 1814 despite 400 years of Danish monarchy beforehand, with a surface area of 2,166,086 square kilometres (836,330 sq mi) is considered the world's largest island, while Australia, at 7,617,930 square kilometres (2,941,300 sq mi) is deemed to be a continent. Likewise, the ideal criterion that each be a continuous landmass is often disregarded by the inclusion of the continental shelf The continental shelf is the extended perimeter of each continent and associated coastal plain, and was part of the continent during the glacial periods, but is undersea during interglacial periods such as the current epoch by relatively shallow seas and gulfs and oceanic islands An island or isle (/ˈaɪl/) is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls are called islets. A key or cay is another name for a small island or islet. An island in a river or lake may be called an eyot, /ˈaɪ.ət/. A grouping of geographically or geologically related, and contradicted by classifying North and South America as one continent; and/or Asia, Europe and Africa as one continent, with no natural separation by water. This anomaly reaches its extreme if the continuous land mass of Europe and Asia is considered to constitute two continents. The Earth's major landmasses are washed upon by a single, continuous World Ocean The World Ocean, world ocean, or global ocean is the interconnected system of the earth's oceanic waters, and comprises the bulk of the hydrosphere, which is divided into a number of principal oceanic An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface (~3.61 X 1014 m2) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas components by the continents and various geographic criteria.[4][5]

Extent of continents

The narrowest meaning of continent is that of a continuous[6] 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 Continental Europe, also referred to as mainland Europe or simply the Continent, is the continent of Europe, explicitly excluding European islands. Notably, in British English usage, the term means Europe excluding the United Kingdom, the Isle of Man, the Channel Islands, Ireland and Iceland is used to refer to mainland Europe, excluding islands An island or isle (/ˈaɪl/) is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls are called islets. A key or cay is another name for a small island or islet. An island in a river or lake may be called an eyot, /ˈaɪ.ət/. A grouping of geographically or geologically related such as Great Britain Great Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island. With a population of about 61.8 million people in mid-2009, it is the third most populated island on Earth. Great Britain is surrounded by over 1,000 smaller islands and islets. The island of, Ireland Ireland (pronounced [ˈaɾlənd],; Irish: Éire, pronounced [ˈeːɾʲə] ( listen); Ulster Scots: Airlann) is the third largest island in Europe and the twentieth largest island in the world. It lies to the northwest of continental Europe and is surrounded by hundreds of islands and islets. To the east of Ireland is Great Britain, separated from, and Iceland b. ^ Iceland, the Faeroes and Greenland were formally Norwegian possessions until 1814 despite 400 years of Danish monarchy beforehand, and the term continent of Australia may refer to the mainland of Australia Australia is the smallest of the geographic continents, though not of geological continents. There is no universally accepted definition of the word "continent"; the lay definition is "One of the main continuous bodies of land on the earth's surface." . By that definition, the continent of Australia includes only the Australian, excluding Tasmania Tasmania is an Australian island and state. It is located 240 kilometres south of the continent, from which it is separated by Bass Strait. The state includes the island of Tasmania – the 26th largest island in the world – and the surrounding islands. The state has a population of 500,000 (as of December 2008[update]), of whom almost half and New Guinea New Guinea, the largest island in the Indonesian archipelago, and located in Melanesia immediately north of northeast Australia in the Southwest Pacific, is the world's second largest island with its 786,000 sq km. It has a low population density with its 7.5 million people. Its highest mount is the Puncak Jaya at an elevation of 4,884 m (16,023. Similarly, the continental United States The contiguous United States are the 48 U.S. states on the continent of North America that are south of Canada, plus the District of Columbia. The term excludes the states of Alaska and Hawaii, and all off-shore U.S. territories and possessions, such as Puerto Rico refers to the 48 contiguous United States ^ b. English is the de facto language of American government and the sole language spoken at home by 80% of Americans age five and older. Spanish is the second most commonly spoken language in central North America and may include Alaska Alaska was purchased from the Russian Empire on March 30, 1867, for $7.2 million at about two cents per acre . The land went through several administrative changes before becoming an organized territory on May 11, 1912, and the 49th state of the U.S. on January 3, 1959 in the northwest of the continent (both separated by Canada The land occupied by Canada was inhabited for millennia by various groups of Aboriginal peoples. Beginning in the late 15th century, British and French expeditions explored, and later settled, along the Atlantic coast. France ceded nearly all of its colonies in North America in 1763 after the Seven Years' War. In 1867, with the union of three), while excluding Hawaii The state encompasses nearly the entire volcanic Hawaiian Island chain, which comprises hundreds of islands spread over 1,500 miles . At the southeastern end of the archipelago, the eight "main islands" are (from the northwest to southeast) Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe, Maui, and Hawaiʻi. The last is by in the middle of the Pacific Ocean The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.

From the perspective of geology Geology is the science and study of the physical matter and energy that constitute the Earth. The field of geology encompasses the study of the composition, structure, properties, and history of the planet's physical material, the processes by which it is formed, moved, and changed, the history of life on Earth, and human interactions with the or physical geography Physical geography is one of the two major subfields of geography. Physical geography is that branch of natural science which deals with the study of processes and patterns in the natural environment like atmosphere, biosphere and geosphere, as opposed to the cultural or built environment, the domain of human geography, continent may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area (the continental shelf The continental shelf is the extended perimeter of each continent and associated coastal plain, and was part of the continent during the glacial periods, but is undersea during interglacial periods such as the current epoch by relatively shallow seas and gulfs)[7] and the islands on the shelf (continental islands An island or isle (/ˈaɪl/) is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls are called islets. A key or cay is another name for a small island or islet. An island in a river or lake may be called an eyot, /ˈaɪ.ət/. A grouping of geographically or geologically related), as they are structurally part of the continent.[8] From this perspective the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level.[9] In this sense the islands of Great Britain and Ireland are part of Europe, while Australia and the island of New Guinea New Guinea, the largest island in the Indonesian archipelago, and located in Melanesia immediately north of northeast Australia in the Southwest Pacific, is the world's second largest island with its 786,000 sq km. It has a low population density with its 7.5 million people. Its highest mount is the Puncak Jaya at an elevation of 4,884 m (16,023 together form a continent (sometimes called Sahul Australia is the smallest of the geographic continents, though not of geological continents. There is no universally accepted definition of the word "continent"; the lay definition is "One of the main continuous bodies of land on the earth's surface." . By that definition, the continent of Australia includes only the Australian or Australia-New Guinea).

As a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands An island or isle (/ˈaɪl/) is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls are called islets. A key or cay is another name for a small island or islet. An island in a river or lake may be called an eyot, /ˈaɪ.ət/. A grouping of geographically or geologically related and continental fragments. In this way, Iceland b. ^ Iceland, the Faeroes and Greenland were formally Norwegian possessions until 1814 despite 400 years of Danish monarchy beforehand is considered part of Europe and Madagascar Madagascar, or Republic of Madagascar , is an island nation in the Indian Ocean off the southeastern coast of Africa. The main island, also called Madagascar, is the fourth-largest island in the world part of Africa. Extrapolating the concept to its extreme, some geographers group the Australasian Australasia is a region of Oceania: Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes . He derived it from the Latin for "south of Asia" and differentiated the area from Polynesia (to the east) and the continental plate with other islands in the pacific The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east into one continent called Oceania Oceania is a geographical, and often geopolitical, region consisting of numerous lands—mostly islands in the Pacific Ocean and vicinity. The term "Oceania" was coined in 1831 by French explorer Dumont d'Urville.[dubious – discuss] The term is also sometimes used to denote a continent comprising Australia Continent and proximate. This allows the entire land surface of the Earth to be divided into continents or quasi-continents.[10]

Separation of continents

See also: Borders of the continents The borders of the continents are the limits of the several continents of the Earth, as defined by various geographical, cultural, and political criteria and Transcontinental country This is a list of countries spanning more than one continent, sometimes referred to as transcontinental states. The definitions of what continent a particular country covers may vary according to which criteria are used (whether purely geographical or geological or, on the other hand, political, economic or cultural criteria). An example is Russia,

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 distinctly separated from other continents.

Several continents are defined not as absolutely distinct bodies but as "more or less discrete masses of land".[11] Asia and Africa are joined by the Isthmus of Suez, and North and South America by the Isthmus of Panama The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It was formed some 3 million years ago during the Pliocene epoch. It contains the country of Panama and the Panama Canal. Like many isthmuses, it is a. Both these isthmuses An isthmus is a narrow strip of land connecting two larger land areas usually with waterforms on either side. Of note, the Isthmus of Corinth connects the peninsula of Peloponnese with the rest of the Greek peninsula, the Isthmus of Panama connects the continents of North and South America (the Americas), and the Isthmus of Suez in Egypt connects are very narrow in comparison with the bulk of the landmasses they join, and both are transected by artificial canals (the Suez and Panama canals, respectively) which effectively separate these landmasses.

The division of the landmass of Eurasia into the continents of Asia and Europe is an anomaly, as no sea separates them. An alternative view, that Eurasia is a single continent, results in a six-continent view of the world. This view is held by some geographers and is preferred in Russia (which spans Asia and Europe), East European countries and Japan. The separation of Eurasia into Europe and Asia is viewed by some as a residue of Eurocentrism: "In physical, cultural and historical diversity, China and India are comparable to the entire European landmass, not to a single European country. A better (if still imperfect) analogy would compare France, not to India as a whole, but to a single Indian state, such as Uttar Pradesh."[12][clarification needed] However, for historical and cultural reasons, the view of Europe as a separate continent continues in several categorizations.

North America and South America are now treated as separate continents in India, China, and most English-speaking countries, such as the United States, the United Kingdom, Canada, Australia, and New Zealand.[citation needed] 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, with this viewpoint remaining common in the United States until World War II.[13] This remains the more common vision in Spain, Portugal and Latin American countries, where they are taught as a single continent. This use is shown in names as the Organization of American States. From the 19th century some people used the term "Americas" to avoid ambiguity with the United States of America. The plurality of this last term suggests that even in the 19th century some considered the New World (the Americas) as two separate continents.

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 Afro-Eurasia. This produces a four-continent model consisting of Afro-Eurasia, America, Antarctica and Australia.

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 the Americas and Afro-Eurasia 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: Afro-Eurasia-America, Antarctica, and Australia-New Guinea.

Number of continents

There are numerous ways of distinguishing the continents:

Models
Color-coded map showing the various continents. Similar shades exhibit areas that may be consolidated or subdivided.
7 continents [1][14][15][16][17][18] North America South America Antarctica Africa Europe Asia Australasia
6 continents [15][19] North America South America Antarctica Africa Eurasia Australasia
6 continents [20][21] America Antarctica Africa Europe Asia Australasia
5 continents [19][20][21] America Antarctica Africa Eurasia Australasia
4 continents [19][20][21] America Antarctica Afro-Eurasia Australasia

The seven-continent model is usually taught in China and most English-speaking countries. The six-continent combined-Eurasia model is preferred by the geographic community, Russia, the former states of the USSR, and Japan. The six-continent combined-America model is taught in Latin America, and most parts of Europe including Germany[citation needed], Greece[citation needed], Italy[citation needed], Portugal and Spain. This model may be taught to include only the five inhabited continents (excluding Antarctica)[20][21] — as depicted in the Olympic logo.[22]

The names Oceania or Australasia are sometimes used in place of Australia. For example, the Atlas of Canada names Oceania,[14] as does the model taught in Latin America and Iberia.[23][24]

Area and population

Comparison of area and population

The following table summarises the area and population of each continent using the seven continent model, sorted by decreasing area.

Continent Area (km²) Area (mi²) Percent of total landmass Approx. population 2008 Percent of total population Density People per km² Density People per mi²
Asia 43,820,000 16,920,000 29.5% 3,879,000,000 60% 86.70 224.6
Africa 30,370,000 11,730,000 20.4% 922,011,000 14% 29.30 75.9
North America 24,490,000 9,460,000 16.5% 528,720,588 8% 21.0 54
South America 17,840,000 6,890,000 12.0% 382,000,000 6% 20.8 54
Antarctica 13,720,000 5,300,000 9.2% 1,000 0.00002% 0.00007 0.00018
Europe 10,180,000 3,930,000 6.8% 731,000,000 11% 69.7 181
Australia 9,008,500 3,478,200 5.9% 22,000,000 0.5% 3.6 9.3

The total land area of all continents is 148,647,000 square kilometres (57,393,000 sq mi), or 29.1% of earth's surface (510,065,600 square kilometres / 196,937,400 square miles).

Highest and lowest points

See also: Seven Summits

The following table lists the seven continents with their highest and lowest points on land, sorted in decreasing highest points.

Continent Highest point Height (m) Height (ft) Country or territory containing highest point Lowest point Height (m) Height (ft) Country or territory containing lowest point
Asia Mount Everest 8,848 29,029 Nepal, China Dead Sea -422 −1,384.5 Israel, Jordan
South America Aconcagua 6,960 22,830 Argentina Laguna del Carbón -105 −344.5 Argentina
North America Mount McKinley 6,198 20,335 United States Trough beneath Jakobshavn Isbræ † -1,512 −4,960.6[25] Greenland
Africa Mount Kilimanjaro 5,895 19,341 Tanzania Lake Assal -155 −508.5 Djibouti
Europe Mount Elbrus 5,633 18,481 Russia Caspian Sea -28 −91.9 Azerbaijan, Kazakhstan, Russia (+ Iran, Turkmenistan)
Antarctica Vinson Massif 4,892 16,050 Antarctica Bentley Subglacial Trench † -2,540 −8,333.3 Antarctica
Oceania Mount Wilhelm 4,509 14,793 Papua New Guinea Lake Eyre -15 −49.2 Australia

† The lowest non-submarine bedrock elevations are given for North America and Antarctica. These are covered by kilometers of ice. The lowest exposed points in North America and Antarctica are in Death Valley (-86 m) and on the shore of Deep Lake in the Vestfold Hills (-50 m).

Some sources list the Kuma-Manych Depression (a remnant of the Paratethys) as the geological border between Europe and Asia. This would place Caucasus outside of Europe, thus making Mont Blanc (elevation 4810 m) in the Graian Alps the highest point in Europe - the lowest point would still be the shore of the Caspian Sea.

Other divisions

Aside from the conventionally known continents, the scope and meaning of the term 'continent' may vary. Supercontinents, largely in evidence earlier in the geological record, are landmasses which comprise more than one craton or continental core. These have included Laurasia, Gondwana, Vaalbara, Kenorland, Columbia, Rodinia, and Pangaea.

Certain parts of continents are recognized as subcontinents, particularly those on different tectonic plates to the rest of the continent. The most notable examples are the Indian subcontinent and the Arabian Peninsula. Greenland, generally reckoned as the world's largest island on the northeastern periphery of the North American Plate, is sometimes referred to as a subcontinent. Where the Americas are viewed as a single continent (America), it is divided into two subcontinents (North America and South America)[26][27][28] or various regions.[29]

Some areas of continental crust are largely covered by the sea and may be considered submerged continents. Notable examples are Zealandia, emerging from the sea primarily in New Zealand and New Caledonia, and the almost completely submerged Kerguelen continent in the southern Indian Ocean.

Some islands lie on sections of continental crust that have rifted and drifted apart from a main continental landmass. While not considered continents because of their relatively small size, they may be considered microcontinents. Madagascar, the largest example, is usually considered an island of Africa but has been referred to as "the eighth continent".

In addition, a number of mythical continents exist: perhaps the most notable is Atlantis, and also Hyperborea, Thule, and Lemuria.

History of the concept

Early concepts of the Old World continents

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)

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 Bosporus strait and the Black Sea.[30] The names were first applied just to lands near the coast and only later extended to include the hinterlands.[31] But the division was only carried through to the end of navigable waterways and "... 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 ..."[30]

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.[32] 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.[33] 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 it 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.[34] The boundary between Asia and Africa was generally taken to be the Nile River. Herodotus[35] in the fifth century BC, 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,[36] a debate that continues nearly two and a half millennia later.

Eratosthenes, in the third century BC, noted that some geographers divided the continents by rivers (the Nile and the Don), thus considering them "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.[37]

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 usually portrayed on T and O maps, 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".[38]

European arrival in 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 what they considered to be the southern end of the Asian mainland into the Indian Ocean, passing through the Matsackson Islands. After reaching the coast of Brazil, they sailed a long way further south along the coast of South America, confirming that this was a land of continental proportions and that it also extended much further south than Asia was known to.[39] On return to Europe, an account of the voyage, called Mundus Novus ("New World"), was published under Vespucci’s name in 1502 or 1503,[40] although it seems that it had additions or alterations by another writer.[41] 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",[42] the first known explicit identification of part of the Americas as a continent like the other three.

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. Maps of this time though still showed North America connected to Asia and showed South America as a separate land.[41]

In 1507 Martin Waldseemüller published a world 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.[43] On the map, the word "America" was placed on part of South America.

The word continent

From the 1500s the English noun continent was derived from the term continent land, meaning continuous or connected land[44] and translated from the Latin terra continens.[45] The noun was used to mean "a connected or continuous tract of land" or mainland.[44] It was not applied only to very large areas of land — in the 1600s, references were made to the continents (or mainlands) of Isle of Man, Ireland and Wales and in 1745 to Sumatra.[44] 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.[46]

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." 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."[47] However, the old idea of Europe, Asia and Africa as "parts" of the world ultimately persisted with these being regarded as separate continents.

Beyond four continents

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.[48]

Europeans discovered 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).[48] In 1813 Samuel Butler wrote of Australia as "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.[49]

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.[50]

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 until World War II.[51] The 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.[22]

From the 1950s, most United States geographers divided America in two[51] – 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.

In recent years there has been a push for Europe and Asia together to be considered a 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

Further information: Continental crust, Plate tectonics
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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 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 recently 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, Eastern Europe, India and some other regions could be regarded as continental masses distinct from the rest of Eurasia because they have separate ancient shield areas (i.e. East European craton and Indian craton). Younger mobile belts (such as the Ural Mountains and Himalayas) mark the boundaries between these regions and the rest of Eurasia.

There are many microcontinents that are built of continental crust but do not contain a craton. Some of these are fragments of Gondwana or other ancient cratonic continents: Zealandia, which includes New Zealand and New Caledonia; 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,[52][53] whereas volcanic Iceland and 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.

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.

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References and notes

  1. ^ a b "Continents: What is a Continent?". National Geographic. http://travel.nationalgeographic.com/places/continents/. Retrieved 2009-08-22. "Most people recognize seven continents—Asia, Africa, North America, South America, Antarctica, Europe and Australasia, from largest to smallest—although sometimes Europe and Asia are considered a single continent, Eurasia."
  2. ^ "Encarta World English Dictionary". Bloomsbury Publishing Plc.. 2007. Archived from the original on 2009-10-31. http://www.webcitation.org/5kwRKDyZ6. Retrieved 2008-08-05.
  3. ^ Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. pp. 21. ISBN 0-520-20742-4, ISBN 0-520-20743-2.
  4. ^ "Ocean". The Columbia Encyclopedia (2006). New York: Columbia University Press. Retrieved 20 February 2007.
  5. ^ "Distribution of land and water on the planet." UN Atlas of the Oceans (2004). Retrieved 20 February 2007.
  6. ^ "continent n. 5. a." (1989) Oxford English Dictionary, 2nd edition. Oxford University Press ; "continent1 n." (2006) The Concise Oxford English Dictionary, 11th edition revised. (Ed.) Catherine Soanes and Angus Stevenson. Oxford University Press; "continent1 n." (2005) The New Oxford American Dictionary, 2nd edition. (Ed.) Erin McKean. Oxford University Press; "continent [2, n] 4 a" (1996) Webster's Third New International Dictionary, Unabridged. ProQuest Information and Learning ; "continent" (2007) Encyclopædia Britannica. Retrieved 14 January 2007, from Encyclopædia Britannica Online.
  7. ^ "continent [2, n] 6" (1996) Webster's Third New International Dictionary, Unabridged. ProQuest Information and Learning. "a large segment of the earth's outer shell including a terrestrial continent and the adjacent continental shelf"
  8. ^ Monkhouse, F. J.; John Small (1978). A Dictionary of the Natural Environment. London: Edward Arnold. pp. 67–68. "structurally it includes shallowly submerged adjacent areas (continental shelf) and neighbouring islands"
  9. ^ 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."
  10. ^ Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. pp. 40. ISBN 0-520-20742-4, ISBN 0-520-20743-2. "The joining of Australia with various Pacific islands to form the quasi continent of Oceania ..."
  11. ^ Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. pp. 35. ISBN 0-520-20742-4, ISBN 0-520-20743-2.
  12. ^ Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. pp. ?. ISBN 0-520-20742-4, ISBN 0-520-20743-2.
  13. ^ Lewis, Martin W.; Kären E. Wigen (1997). "1". The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. ISBN 0-520-20742-4, ISBN 0-520-20743-2. "While it might seem surprising to find North and South America still joined into a single continent in a book published in the United States in 1937, such a notion remained fairly common until World War II. [...] By the 1950s, however, virtually all American geographers had come to insist that the visually distinct landmasses of North and South America deserved separate designations."
  14. ^ a b The World - Continents, Atlas of Canada
  15. ^ a b "Continent". Encyclopædia Britannica. 2006. Chicago: Encyclopædia Britannica, Inc.
  16. ^ The New Oxford Dictionary of English. 2001. New York: Oxford University Press.
  17. ^ "Continent". MSN Encarta Online Encyclopedia 2006.. Archived 2009-10-31.
  18. ^ "Continent". McArthur, Tom, ed. 1992. The Oxford Companion to the English Language. New York: Oxford University Press; p. 260.
  19. ^ a b c "Continent". The Columbia Encyclopedia. 2001. New York: Columbia University Press - Bartleby.
  20. ^ a b c d Océano Uno, Diccionario Enciclopédico y Atlas Mundial, "Continente", page 392, 1730. ISBN 84-494-0188-7
  21. ^ a b c d Los Cinco Continentes (The Five Continents), Planeta-De Agostini Editions, 1997. ISBN 84-395-6054-0
  22. ^ a b The Olympic symbols. International Olympic Committee. 2002. Lausanne: Olympic Museum and Studies Centre. The five rings of the Olympic logo represent the five inhabited, participating continents (Africa, America, Asia, Europe, and Oceania); thus, Antarctica is excluded from the flag. Also see Association of National Olympic Committees: [1] [2] [3] [4] [5]
  23. ^ "Continente" Portuguese Wikipedia
  24. ^ "Continente". Spanish Wikipedia
  25. ^ Plummer, Joel. Jakobshavn Bed Elevation, Center for the Remote Sensing of the Ice Sheets, Dept of Geography, University of Kansas.
  26. ^ English map of 1770 by Jonghe
  27. ^ DPD: América
  28. ^ Dicionário da língua portuguesa: Contiente
  29. ^ 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.Norteamérica (Mexican version)/(Spaniard version). Encarta Online Encyclopedia.. Archived 2009-10-31.
  30. ^ a b Toynbee, Arnold J. (1954). A Study of History. London: Oxford University Press, v. 8, pp. 711-12.
  31. ^ Tozer, H. F. (1897). A History of Ancient Geography. Cambridge: University Press. pp. 69.
  32. ^ Tozer, H. F. (1897). A History of Ancient Geography. Cambridge: University Press. pp. 67.
  33. ^ Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. pp. 21–22. ISBN 0-520-20742-4, ISBN 0-520-20743-2.
  34. ^ Tozer, H. F. (1897). A History of Ancient Geography. Cambridge: University Press. pp. 68.
  35. ^ Herodotus. Translated by George Rawlinson (2000). The Histories of Herodotus of Halicarnassus [6]. Ames, Iowa: Omphaloskepsis, book 2, p. 18.
  36. ^ Herodotus. Translated by George Rawlinson (2000). The Histories of Herodotus of Halicarnassus [7]. 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"
  37. ^ Strabo. Translated by Horace Leonard Jones (1917). Geography.[8] Harvard University Press, book 1, ch. 4.[9]
  38. ^ Goddard, Farley Brewer (1884). "Researches in the Cyrenaica". The American Journal of Philology, 5 (1) p. 38.
  39. ^ O'Gorman, Edmundo (1961). The Invention of America. Indiana University Press. pp. 106–112.
  40. ^ 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.
  41. ^ a b Zerubavel, Eviatar (2003). Terra Cognita: The Mental Discovery of America. New Brunswick: Transaction Publishers, pp. 77–79. ISBN 0-7658-0987-7.
  42. ^ 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.
  43. ^ Zerubavel, Eviatar (2003). Terra Cognita: The Mental Discovery of America. New Brunswick: Transaction Publishers, pp. 80–82. ISBN 0-7658-0987-7.
  44. ^ a b c "continent n." (1989) Oxford English Dictionary, 2nd edition. Oxford University Press.
  45. ^ "continent1 n." (2006) The Concise Oxford English Dictionary, 11th edition revised. (Ed.) Catherine Soanes and Angus Stevenson. Oxford University Press.
  46. ^ Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. pp. 29. ISBN 0-520-20742-4, ISBN 0-520-20743-2.
  47. ^ Bowen, Emanuel. (1752). A Complete Atlas, or Distinct View of the Known World. London, p. 3.
  48. ^ a b Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. pp. 30. ISBN 0-520-20742-4, ISBN 0-520-20743-2.
  49. ^ "continent n. 5. a." (1989) Oxford English Dictionary, 2nd edition. Oxford University Press. "the great island of Australia is sometimes reckoned as another [continent]"
  50. ^ Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. ISBN 0-520-20742-4, ISBN 0-520-2074 220.
  51. ^ a b Lewis, Martin W.; Kären E. Wigen (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. pp. 32. ISBN 0-520-20742-4, ISBN 0-520-20743-2.
  52. ^ UT Austin scientist plays major rule in study of underwater "micro-continent". Retrieved on 2007-07-03
  53. ^ http://news.bbc.co.uk/1/hi/sci/tech/353277.stm Retrieved on 2007-07-03

External links

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Continents

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Submerged continents Kerguelen Plateau · Zealandia

Possible future supercontinents Pangaea Ultima · Amasia

Mythical and theorized continents Atlantis · Lemuria · Meropis · Mu · Terra Australis
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Q. I know that every continent other than Antarctica has a continental divide, but what is the divide on each continent?
Asked by EB m - Mon Sep 14 18:05:39 2009 - - 1 Answers - 0 Comments

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