Animated, colour-coded map showing some continents and the region of Oceania (purple), which includes the continent of Australia. Depending on the convention and model, some continents may be consolidated or subdivided.
A continent is any of several large geographical regions. Continents are generally identified by convention rather than any strict criteria. A continent could be a single landmass or a part of a very large landmass, as in the case of Asia or Europe. Due to this, the number of continents varies; up to seven or as few as four geographical regions are commonly regarded as continents. Most English-speaking countries recognize seven regions as continents. In order from largest to smallest in area, these seven regions are Asia, Africa, North America, South America, Antarctica, Europe, and Australia.[1] Different variations with fewer continents merge some of these regions; examples of this are merging North America and South America into America, Asia and Europe into Eurasia, and Africa, Asia, and Europe into Afro-Eurasia.
Oceanic islands are occasionally grouped with a nearby continent to divide all the world's land into geographical regions. Under this scheme, most of the island countries and territories in the Pacific Ocean are grouped together with the continent of Australia to form the geographical region of Oceania.[2]
The idea of continental drift gained recognition in the 20th century. It postulates that the current continents formed from the breaking up of a supercontinent (Pangaea) that formed hundreds of millions of years ago.
Etymology
From the 16th century the English noun continent was derived from the term continent land, meaning continuous or connected land[5] and translated from the Latin terra continens.[6] The noun was used to mean "a connected or continuous tract of land" or mainland.[5] It was not applied only to very large areas of land—in the 17th century, references were made to the continents (or mainlands) of the Isle of Man, Ireland and Wales and in 1745 to Sumatra.[5] 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.[7]
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-17th century, 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."[8] However, the old idea of Europe, Asia and Africa as "parts" of the world ultimately persisted with these being regarded as separate continents.
By convention, continents "are understood to be large, continuous, discrete masses of land, ideally separated by expanses of water".[9] In modern schemes with five or more recognized continents, at least one pair of continents is joined by land in some fashion. The criterion "large" leads to arbitrary classification: Greenland, with a surface area of 2,166,086 square kilometres (836,330sqmi), is only considered the world's largest island, while Australia, at 7,617,930 square kilometres (2,941,300sqmi), is deemed the smallest continent.
Earth's major landmasses all have coasts on a single, continuous World Ocean, which is divided into several principal oceanic components by the continents and various geographic criteria.[10][11]
The geological definition of a continent has four criteria: high elevation relative to the ocean floor; a wide range of igneous, metamorphic and sedimentary rocks rich in silica; a crust thicker than the surrounding oceanic crust; and well-defined limits around a large enough area.[12]
Extent
The most restricted meaning of continent is that of a continuous[13][non-tertiary source needed] 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 (sometimes referred to in Britain as "the Continent") is used to refer to mainland Europe, excluding islands such as Great Britain, Iceland, Ireland, and Malta, while the term continent of Australia may refer to the mainland of Australia, excluding New Guinea, Tasmania, and other nearby islands. Similarly, the continental United States refers to "the 49 States (including Alaska but excluding Hawaii) located on the continent of North America, and the District of Columbia."[14]
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)[15] and the islands on the shelf (continental islands), as they are structurally part of the continent.[16]
From this perspective, the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level.[17] In this sense the islands of Great Britain and Ireland are part of Europe, while Australia and the island of New Guinea together form a continent. Taken to its limit, this view could support the view that there are only three continents: Antarctica, Australia-New Guinea, and a single mega-continent which joins Afro-Eurasia and America via the contiguous continental shelf in and around the Bering Sea. The vast size of the latter compared to the first two might even lead some to say it is the only continent, the others being more comparable to Greenland or New Zealand.[18]
Map of island nations depicting sovereign states and a de facto state (Taiwan) (tw). Those with land borders are shaded green, and those without shaded blue. Along with dependent or disputed island territories, which do not appear on the map, these states are often grouped geographically with a neighboring continental landmass.
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 is considered a part of Europe, and Madagascar a part of Africa. Extrapolating the concept to its extreme, some geographers group the Australian continental landmass with other islands in the Pacific Ocean into Oceania, which is usually considered a region rather than a continent. This divides the entire land surface of Earth into continents, regions, or quasi-continents.[19]
The criterion that each continent is a discrete landmass is commonly relaxed due to historical conventions and practical use. Of the seven most globally recognized continents, only Antarctica and Australia are completely separated from other continents by the ocean. Several continents are defined not as absolutely distinct bodies but as "more or less discrete masses of land".[20] Africa and Asia are joined by the Isthmus of Suez, and North America and South America by the Isthmus of Panama. In both cases, there is no complete separation of these landmasses by water (disregarding the Suez Canal and the Panama Canal, which are both narrow and shallow, as well as human-made). Both of these isthmuses are very narrow compared to the bulk of the landmasses they unite.
North America and South America are treated as separate continents in the seven-continent model. However, they may also be viewed as a single continent known as America. This viewpoint was common in the United States until World War II, and remains prevalent in some Asian six-continent models.[21] The single American continent model remains a common view in European countries like France, Greece, Hungary, Italy, Malta, Portugal, Spain, Latin American countries and some Asian countries.
The criterion of a discrete landmass is completely disregarded if the continuous landmass of Eurasia is classified as two separate continents (Asia and Europe). Physiographically, Europe and the Indian subcontinent are large peninsulas of the Eurasian landmass. However, Europe is considered a continent with its comparatively large land area of 10,180,000 square kilometres (3,930,000sqmi), while the Indian subcontinent, with less than half that area, is considered a subcontinent. The alternative view—in geology and geography—that Eurasia is a single continent results in a six-continent view of the world. Some view the separation of Eurasia into Asia and Europe 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. [...]."[22] However, for historical and cultural reasons, the view of Europe as a separate continent continues in almost all categorizations.
If continents are defined strictly as discrete landmasses, embracing all the contiguous land of a body, then Africa, Asia, and Europe form a single continent which may be referred to as Afro-Eurasia.[23] Combined with the consolidation of the Americas, this would produce a four-continent model consisting of Afro-Eurasia, America, Antarctica, and Australia.
The following table provides areas given by Encyclopædia Britannica for each continent in accordance with the seven-continent model, including Australasia along with Melanesia, Micronesia, and Polynesia as parts of Oceania. It also provides populations of continents according to 2021 estimates by the United Nations Statistics Division based on the United Nations geoscheme, which includes all of Egypt (including the Isthmus of Suez and the Sinai Peninsula) as a part of Africa, all of Armenia, Azerbaijan, Cyprus, Georgia, Indonesia, Kazakhstan, and Turkey (including East Thrace) as parts of Asia, all of Russia (including Siberia) as a part of Europe, all of Panama and the United States (including Hawaii) as parts of North America, and all of Chile (including Easter Island) as a part of South America.
Reconstruction of the supercontinent Pangaea approximately 200 million years ago
Apart from the current continents, the scope and meaning of the term continent includes past geological ones. Supercontinents, largely in evidence earlier in the geological record, are landmasses that comprise most of the world's cratons or continental cores.[61] These have included Vaalbara, Kenorland, Columbia, Rodinia, Pannotia, and Pangaea. Over time, these supercontinents broke apart into large landmasses which formed the present continents.
Certain parts of continents are recognized as subcontinents, especially the large peninsulas separated from the main continental landmass by geographical features. The most widely recognized example is the Indian subcontinent.[62] The Arabian Peninsula, Southern Africa, the Southern Cone of South America, and Alaska in North America might be considered further examples.[62][63]
In many of these cases, the "subcontinents" concerned are on different tectonic plates from the rest of the continent, providing a geological justification for the terminology.[64]Greenland, generally considered the world's largest island on the northeastern periphery of the North American Plate, is sometimes referred to as a subcontinent.[65][66] This is a significant departure from the more conventional view of a subcontinent as comprising a very large peninsula on the fringe of a continent.[62]
Where the Americas are viewed as a single continent (America), it is divided into two subcontinents (North America and South America)[67][68][69] or three (Central America being the third).[70][71] When Eurasia is regarded as a single continent, Asia and Europe are treated as subcontinents.[62]
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 its divergent evolution has caused it to be referred to as "the eighth continent" from a biological perspective.[74]
Due to a seeming lack of Precambrian cratonic rocks, Zealandia's status as a geological continent has been disputed by some geologists.[77] However, a study conducted in 2021 found that part of the submerged continent is indeed Precambrian, twice as old as geologists had previously thought, which is further evidence that supports the idea of Zealandia being a geological continent.[78][79]
All seven geological continents are spatially isolated by geologic features.[80]
History of the concept
Early concepts of the Old World continents
The Ancient Greek geographer Strabo holding a globe showing Europa and Asia
The term "continent" translates the Greek word ἤπειρος, meaning "landmass, terra firma", the proper name of Epirus and later especially used for Asia (i.e. Asia Minor).[81]
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.[82] The names were first applied just to lands near the coast and only later extended to include the hinterlands.[83][84] 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 ..."[82]
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.[85] From the Greek viewpoint, the Aegean Sea was the center of the world; Asia lay to the east, Europe to the north and west, and Africa to the south.[86] 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.[87] The boundary between Asia and Africa was generally taken to be the Nile River. Herodotus[88] in the 5th century BCE objected to the whole of Egypt being split between Asia and Africa ("Libya") and took the boundary to lie along the western border of Egypt, regarding Egypt as part of Asia.[89][90][91][92] He also questioned the division into three of what is really a single landmass,[93] a debate that continues nearly two and a half millennia later. Herodotus believed Europe to be larger (at least in width) than the other two continents:
I wonder, then, at those who have mapped out and divided the world into Libya, Asia, and Europe; for the difference between them is great, seeing that in length Europe stretches along both the others together, and it appears to me to be wider beyond all comparison.[94]
Eratosthenes, in the 3rd century BCE, 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.[95]
The Roman author Pliny the Elder, writing in the 1st century CE, stated that "The whole globe is divided into three parts, Europe, Asia, and Africa", adding:
I shall first then speak of Europe, the foster-mother of that people which has conquered all other nations, and itself by far the most beauteous portion of the earth. Indeed, many persons have, not without reason, considered it, not as a third part only of the earth, but as equal to all the rest, looking upon the whole of our globe as divided into two parts only, by a line drawn from the river Tanais to the Straits of Gades.[96]
Medieval T and O map showing the three continents as domains of the sons of Noah—Asia to Sem (Shem), Europe to Iafeth (Japheth), and Africa to Cham (Ham).
Following the fall of the Western Roman Empire, the culture that developed in its place, linked to Latin and the Catholic church, began to associate itself with the concept of Europe.[84] 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 consider it the Nile or the western border of Egypt (Gibbon).[citation needed] 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 18th 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".[97]
European arrival in the Americas
Christopher Columbus sailed across the Atlantic Ocean to the Caribbean 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 the southern end of the Asian mainland into the Indian Ocean, passing through Fernando de Noronha. After reaching the coast of Brazil, they sailed along the coast of South America much farther south than Asia was known to extend, confirming that this was a land of continental proportions.[98] On return to Europe, an account of the voyage, called Mundus Novus ("New World"), was published under Vespucci's name in 1502 or 1503,[99] although it seems that it had additions or alterations by another writer.[100] Regardless of who penned the words, Mundus Novus credited 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",[101] the first known explicit identification of part of the Americas as a continent like the other three.
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.[100]
Universalis Cosmographia, Waldseemüller's 1507 world map—the first to show the Americas separate from Asia
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.[102] On the map, the word "America" was placed on part of South America.
Beyond four continents
The Sanskrit text Rig Veda often dated 1500 BCE [note 1] has the earliest mention of seven continents in the Earth, the text claims that the Earth has seven continents and Lord Vishnu Measured the entire universe from his first foot from the land of Earth which has 7 continents.[109]
ato devā avantu no yato viṣṇurvicakrame | pṛthivyāḥ saptadhāmabhiḥ ||
In regard to the above-quoted verses, it is commonly accepted that there are Seven Continents or 'regions of the earth'. A. Glucklich adds that 'In the Matsya Purana, for instance, there is a seven-part map of the world ... [it has] one centre, where an immense mountain – Mount Meru (or Maha Meru, Great Meru) – stands ... The continents encircle the mountain in seven concentric circles ... It seems clear that the Himalayas were the approximate location of Mt. Meru and the text is clear that the earth has seven continents.[109]
Hollandia Nova, 1659 map prepared by Joan Blaeu based on voyages by Abel Tasman and Willem Jansz, this image shows a French edition of 1663
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.[112]
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).[112] 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.[113] It was in the 1950s that the concept of Oceania as a "great division" of the world was replaced by the concept of Australia as a continent.[114]
Over time, the western concept of dividing the world into continents spread globally, replacing conceptions in other areas of the world. The idea of continents continued to become imbued with cultural and political meaning. In the 19th century during the Meiji period, Japanese leaders began to self-identify with the concept of being Asian, and renew relations with other "Asian" countries while conceiving of the idea of Asian solidarity against western countries. This conception of an Asian identity, as well as the idea of Asian solidarity, was later taken up by others in the region, such as Republican China and Vietnam.[116]
From the mid-19th century, atlases published in the United States 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 American atlases to treat them as one continent up until World War II.[117] From the 1950s, most U.S. geographers divided the Americas into two continents.[117] With the addition of Antarctica, this made the seven-continent model. However, this division of the Americas never appealed to Latin Americans, who saw their region spanning an América as a single landmass, and there the conception of six continents remains dominant, as it does in scattered other countries.[citation needed]
Some geographers regard Europe and Asia together as a single continent, dubbed Eurasia.[118] In this model, the world is divided into six continents, with North America and South America considered separate continents.
Geologists use the term continent in a different manner from geographers. In geology, a continent is defined by continental crust, which is a platform of metamorphic and igneous rocks, largely of granitic composition. Continental crust is less dense and much thicker than oceanic crust, which causes it to "float" higher than oceanic crust on the dense underlying mantle. This explains why the continents form high platforms surrounded by deep ocean basins.[119][3]
Some geologists restrict the term continent to portions of the crust built around stable regions called cratons. Cratons have largely been unaffected by mountain-building events (orogenies) since the Precambrian. A craton typically consists of a continental shield surrounded by a continental platform. The shield is a region where ancient crystalline basement rock (typically 1.5 to 3.8 billion years old) is widely exposed at the surface. The platform surrounding the shield is also composed of ancient basement rock, but with a cover of younger sedimentary rock.[120] The continents are accretionary crustal "rafts" that, 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.[121]
The margins of geologic continents are either active or passive. An active margin is characterised by mountain building, either through a continent-on continent collision or a subduction zone. Continents grow by accreting lighter volcanic island chains and microcontinents along these active margins, forming orogens. At a passive margin, the continental crust is stretched thin by extension to form a continental shelf, which tapers off with a gradual slope covered in sediment, connecting it directly to the oceanic crust beyond. Most passive margins eventually transition into active margins: where the oceanic plate becomes too heavy due to cooling, it disconnects from the continental crust, and starts subducting below it, forming a new subduction zone.[122]
Sixteen principal tectonic plates of the continents and the floor of the oceans
There are many microcontinents, or continental fragments, 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,[75] which includes New Zealand and New Caledonia; Madagascar; the northern Mascarene Plateau, which includes the Seychelles. 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 a microcontinent,[123][124] whereas volcanic Iceland and Hawaii are not. The British Isles, Sri Lanka, Borneo, and Newfoundland were on the margins of the Laurasian continent—only separated from the main continental landmass by inland seas flooding its margins.
The movement of plates has caused the continual formation and breakup of continents, and occasionally supercontinents, in a process called the Wilson Cycle. The supercontinent Columbia or Nuna formed during a period of 2.0–1.8 billion years ago and broke up about 1.5–1.3 billion years ago.[125][126] The supercontinent Rodinia is thought to have formed about 1 billion years ago and to have embodied most or all of Earth's continents, and broken up into eight continents around 600 million years ago. The eight continents later reassembled into another supercontinent called Pangaea; Pangaea broke up into Laurasia (which became North America and Eurasia) and Gondwana (which became the remaining continents).[127]
Criticism
Some academics, such as the historical geographer Martin W. Lewis argue that the systems we understand today are more rooted in social, political, and cultural history than in geological fact, a view particularly outlined in his book The Myth of Continents: A Critique of Metageography.[128]
↑ It is certain that the hymns of the Rig Veda post-date Indo-Iranian separation of c.2000BCE and probably that of the relevant Mitanni documents of c. 1400BCE. Philological estimates tend to date the bulk of the text to the second half of the second millennium:
Max Müller: "the hymns of the Rig-Veda are said to date from 1500 B.C."[103]
Thomas Oberlies (Die Religion des Rgveda, 1998, p. 158) based on 'cumulative evidence' sets a wide range of 1700–1100BCE.[107]Oberlies 1998, p.155 gives an estimate of 1100BCE for the youngest hymns in book 10.[108]
Witzel 1995, p.4 mentions c. 1500–1200BCE. According to Witzel 1997, p.263, the whole Rig Vedic period may have lasted from c. 1900BCE to c. 1200BCE: "the bulk of the RV represents only 5 or 6 generations of kings (and of the contemporary poets) of the Pūru and Bharata tribes. It contains little else before and after this "snapshot" view of contemporary Rgvedic history, as reported by these contemporary "tape recordings." On the other hand, the whole Rgvedic period may have lasted even up to 700 years, from the infiltration of the Indo-Aryans into the subcontinent, c. 1900B.C. (at the utmost, the time of collapse of the Indus civilization), up to c. 1200B.C., the time of the introduction of iron which is first mentioned in the clearly post-gvedic hymns of the Atharvaveda."
↑ In accordance with these attributes, Eurasia and North America are connected by a bridge of continental crust at least 2 thousand kilometers wide. And with Africa, Eurasia is connected by such a bridge (interrupted by internal sections of the oceanic crust) with a width of at least 5 thousand kilometers.
Related Research Articles
In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leaves room for interpretation and is easier to apply to Precambrian times. To separate supercontinents from other groupings, a limit has been proposed in which a continent must include at least about 75% of the continental crust then in existence in order to qualify as a supercontinent.
A landmass, or land mass, is a large region or area of land that is in one piece and not noticeably broken up by oceans. The term is often used to refer to lands surrounded by an ocean or sea, such as a continent or a large island. In the field of geology, a landmass is a defined section of continental crust extending above sea level.
Lemuria, or Limuria, was a continent proposed in 1864 by zoologist Philip Sclater, theorized to have sunk beneath the Indian Ocean, later appropriated by occultists in supposed accounts of human origins. The theory was discredited with the discovery of plate tectonics and continental drift in the 20th century.
Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial because its bulk composition is richer in aluminium silicates (Al-Si) and has a lower density compared to the oceanic crust, called sima which is richer in magnesium silicate (Mg-Si) minerals. Changes in seismic wave velocities have shown that at a certain depth, there is a reasonably sharp contrast between the more felsic upper continental crust and the lower continental crust, which is more mafic in character.
A subregion is a part of a larger geographical region or continent. Cardinal directions are commonly used to define subregions. There are many criteria for creating systems of subregions; this article is focusing on the United Nations geoscheme, which is a changing, constantly updated, UN tool based on specific political geography and demography considerations relevant in UN statistics.
Pangaea Proxima is a possible future supercontinent configuration. Consistent with the supercontinent cycle, Pangaea Proxima could form within the next 250 million years. This potential configuration, hypothesized by Christopher Scotese in November 1982, earned its name from its similarity to the previous Pangaea supercontinent. Scotese later changed Pangaea Ultima to Pangaea Proxima to alleviate confusion about the name Pangaea Ultima which could imply that it would be the last supercontinent. The concept was suggested by extrapolating past cycles of formation and breakup of supercontinents, not on theoretical understanding of the mechanisms of tectonic change, which are too imprecise to project that far into the future. "It's all pretty much fantasy to start with," Scotese has said. "But it's a fun exercise to think about what might happen. And you can only do it if you have a really clear idea of why things happen in the first place."
Siberia, also known as Siberian Craton, Angaraland and Angarida, is an ancient craton in the heart of Siberia. Today forming the Central Siberian Plateau, it formed an independent landmass prior to its fusion into Pangea during the Late Carboniferous-Permian. The Verkhoyansk Sea, a passive continental margin, was fringing the Siberian Craton to the east in what is now the East Siberian Lowland.
The geological history of the Earth follows the major geological events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.
Determining the boundaries between the continents is generally a matter of geographical convention. Several slightly different conventions are in use. The number of continents is most commonly considered seven but may range as low as four when Afro-Eurasia and the Americas are both considered as single continents. An island can be considered to be associated with a given continent by either lying on the continent's adjacent continental shelf or being a part of a microcontinent on the same principal tectonic plate. An island can also be entirely oceanic while still being associated with a continent by geology or by common geopolitical convention. Another example is the grouping into Oceania of the Pacific Islands with Australia and Zealandia.
Zealandia, also known as Te Riu-a-Māui (Māori) or Tasmantis, is an almost entirely submerged mass of continental crust in Oceania that subsided after breaking away from Gondwana 83–79 million years ago. It has been described variously as a submerged continent, continental fragment, and microcontinent. The name and concept for Zealandia was proposed by Bruce Luyendyk in 1995, and satellite imagery shows it to be almost the size of Australia. A 2021 study suggests Zealandia is over a billion years old, about twice as old as geologists previously thought.
Afro-Eurasia is a landmass comprising the continents of Africa, Europe, and Asia. The terms are compound words of the names of its constituent parts. Afro-Eurasia has also been called the "Old World", in contrast to the "New World" referring to the Americas.
Pangaea or Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic and beginning of the Jurassic. Pangaea was C-shaped, with the bulk of its mass stretching between Earth's northern and southern polar regions and surrounded by the superocean Panthalassa and the Paleo-Tethys and subsequent Tethys Oceans. Pangaea is the most recent supercontinent to have existed and the first to be reconstructed by geologists.
Eurasia is the largest continental area on Earth, comprising all of Europe and Asia. According to some geographers, physiographically, Eurasia is a single supercontinent. The concepts of Europe and Asia as distinct continents date back to antiquity, but their borders have historically been subject to change. For example, to the ancient Greeks, Asia originally included Africa but they classified Europe as separate land. Eurasia is connected to Africa at the Suez Canal, and the two are sometimes combined to describe the largest contiguous landmass on Earth, Afro-Eurasia.
The continent of Australia, sometimes known in technical contexts by the names Sahul, Australia-New Guinea, Australinea, or Meganesia to distinguish it from the country of Australia, is located within the Southern and Eastern hemispheres. The continent includes mainland Australia, Tasmania, the island of New Guinea, the Aru Islands, the Ashmore and Cartier Islands, most of the Coral Sea Islands, and some other nearby islands. Situated in the geographical region of Oceania, Australia is the smallest of the seven traditional continents.
This is a list of articles related to plate tectonics and tectonic plates.
A paleocontinent or palaeocontinent is a distinct area of continental crust that existed as a major landmass in the geological past. There have been many different landmasses throughout Earth's time. They range in sizes; some are just a collection of small microcontinents while others are large conglomerates of crust. As time progresses and sea levels rise and fall more crust can be exposed making way for larger landmasses. The continents of the past shaped the evolution of organisms on Earth and contributed to the climate of the globe as well. As landmasses break apart, species are separated and those that were once the same now have evolved to their new climate. The constant movement of these landmasses greatly determines the distribution of organisms on Earth's surface. This is evident with how similar fossils are found on completely separate continents. Also, as continents move, mountain building events (orogenies) occur, causing a shift in the global climate as new rock is exposed and then there is more exposed rock at higher elevations. This causes glacial ice expansion and an overall cooler global climate. The movement of the continents greatly affects the overall dispersal of organisms throughout the world and the trend in climate throughout Earth's history. Examples include Laurentia, Baltica and Avalonia, which collided together during the Caledonian orogeny to form the Old Red Sandstone paleocontinent of Laurussia. Another example includes a collision that occurred during the late Pennsylvanian and early Permian time when there was a collision between the two continents of Tarimsky and Kirghiz-Kazakh. This collision was caused because of their askew convergence when the paleoceanic basin closed.
References
↑ "Continents: What is a Continent?". National Geographic. 20 September 2011. Archived from the original on 16 July 2019. Retrieved 6 December 2020. "Most people recognize seven continents—Asia, Africa, North America, South America, Antarctica, Europe, and Australia, from largest to smallest—although sometimes Asia and Europe are considered a single continent, Eurasia."
↑ Monkhouse, F. J.; Small, John (1978). A Dictionary of the Natural Environment. London: Edward Arnold. pp.67–68. structurally it includes shallowly submerged adjacent areas (continental shelf) and neighboring islands
↑ 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."
↑ Lewis & Wigen, The Myth of Continents (1997), Chapter 1: "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."
↑ McColl, R.W., ed. (2005). "continents". Encyclopedia of World Geography. Vol.1. Facts on File, Inc. p.215. ISBN978-0-8160-7229-3. Archived from the original on 21 February 2023. Retrieved 26 June 2012– via Google Books. And since Africa and Asia are connected at the Suez Peninsula, Europe, Africa, and Asia are sometimes combined as Afro-Eurasia or Eurafrasia. The International Olympic Committee's official flag, containing [...] the single continent of America (North and South America being connected as the Isthmus of Panama).
↑ "How many continents are there?". Wonderopolis. Archived from the original on 29 May 2023. Retrieved 26 April 2020. If you count Europe and Asia as one continent (called Eurasia), then there are six continents. Some people also count North America and South America as one continent (called America), since the two land masses are separated only by the human-made Panama Canal. This would allow for a model with only five continents.wonderopolis
↑ Archived 26 March 2023 at the Wayback Machine "In some textbooks, North and South America are combined into 'America' and/or Europe and Asia are combined into 'Eurasia', for a grand total of 6 or even 5."scienceline
↑ Martin W. Lewis and Kären E. Wigen, The Myth of Continents: A Critique of Metageography (Berkeley and Los Angeles: University of California Press, 1997)Wigen
↑ Archived 16 May 2023 at the Wayback Machine "There are even geographical views that prefer the presence of both a Eurasian as well as one American continent. These geographers therefore contend that there should only be 5 continents."universetoday
↑ "kontynent". encyklopedia pwn. WN PWN SA. Archived from the original on 7 November 2023. 7 November 2023
↑ "Preamble"(PDF). Olympic Charter. International Olympic Committee. 17 July 2020. p.10. Archived(PDF) from the original on 19 November 2021. Retrieved 3 August 2021. the five interlaced rings, which represent the union of the five continents
p. 98: Thus, we can calculate past positions of the Indian Plate, with the Indian Subcontinent as its passenger, with respect to the Eurasian Plate.
p. 116: The Arabian Subcontinent later, approximately 35 million years ago, collided with southern Eurasia to form the Zagros Mountains of southwestern Iran.
↑ In Ibero-America, North America usually designates a region (subcontinente in Spanish) of the Americas containing Canada, the United States, 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)Archived 30 January 2009 at the Wayback Machine /(Spaniard version)Archived 29 January 2009 at the Wayback Machine . Encarta Online Encyclopedia. 2009.
↑ Henry George Liddell, Robert Scott, Henry Stuart Jones, A Greek-English Lexicon (1940), s.v. ἤπειρος. The English noun was introduced in the mid-16th century, shortened from continent land (15th century), adapted from Latin terra continens "continuous landmass".
1 2 Toynbee, Arnold J. (1954). A Study of History. London: Oxford University Press, v. 8, pp. 711–712.
↑ "Herodotus, Histories, Book IV, Chapters 40-41". penelope.uchicago.edu. As far as India, Asia is an inhabited land; but thereafter all to the east is desert, nor can any man say what kind of land is there. Such is Asia, and such its extent. But Libya is on this second promontory; for Libya comes next after Egypt.
↑ Herodotus. Translated by George Rawlinson (2000). The Histories of Herodotus of Halicarnassus"Archived copy"(PDF). Archived from the original(PDF) on 19 August 2006. Retrieved 8 February 2016.{{cite web}}: CS1 maint: archived copy as title (link). 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,"
↑ Goddard, Farley Brewer (1884). "Researches in the Cyrenaica". The American Journal of Philology, 5 (1) p. 38.
↑ O'Gorman, Edmundo (1961). The Invention of America. Indiana University Press. pp.106–112.
↑ Formisano, Luciano (Ed.) (1992). Letters from a New World: Amerigo Vespucci's Discovery of America. New York: Marsilio, pp. xx–xxi. ISBN0-941419-62-2.
1 2 Zerubavel, Eviatar (2003). Terra Cognita: The Mental Discovery of America. New Brunswick: Transaction Publishers, pp. 77–79. ISBN0-7658-0987-7.
↑ Formisano, Luciano (Ed.) (1992). Letters from a New World: Amerigo Vespucci's Discovery of America. New York: Marsilio, p. 45. ISBN0-941419-62-2.
↑ Zerubavel, Eviatar (2003). Terra Cognita: The Mental Discovery of America. New Brunswick: Transaction Publishers, pp. 80–82. ISBN0-7658-0987-7.
↑ Müller, F. Max (1883). India: What Can It Teach Us?. London: Longmans, Green & Co. p.202. Archived from the original on 7 July 2023. Retrieved 7 September 2023.
↑ Lewis & Wigen, The Myth of Continents (1997), p.32: "...the 1950s... was also the period when... Oceania as a "great division" was replaced by Australia as a continent along with a series of isolated and continentally attached islands. [Footnote 78: When Southeast Asia was conceptualized as a world region during World War II..., Indonesia and the Philippines were perforce added to Asia, which reduced the extent of Oceania, leading to a reconceptualization of Australia as a continent in its own right. This maneuver is apparent in postwar atlases]"
↑ Lewis, Martin W.; Wigen, Kären E. (1997). The Myth of Continents: a Critique of Metageography. Berkeley: University of California Press. ISBN978-0-520-20743-1.
Anthony, David W. (2007), The Horse The Wheel And Language. How Bronze-Age Riders From the Eurasian Steppes Shaped The Modern World, Princeton University Press
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