Everything about Continent totally explained
A
continent is one of several large
landmasses on
Earth. They are generally identified by
convention rather than any strict criteria, but seven areas are commonly regarded as continents – they're (from largest in size to smallest):
Asia,
Africa,
North America,
South America,
Antarctica,
Europe, and
Australia.
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Plate tectonics is the
geological process and study of the movement, collision and division of continents, earlier known as
continental drift.
The term "the Continent" (capitalized), used predominantly in the European isles and peninsulas, such as the
British Isles,
Sardinia,
Sicily and the
Scandinavian Peninsula, means
mainland Europe, although it can also mean Asia when said in
Japan.
Definitions and application
"Continents are understood to be large, continuous, discrete masses of land, ideally separated by expanses of water." However, many of the seven most commonly recognized continents are identified by convention rather than adherence to the ideal criterion that each be a discrete landmass, separated by water from others. Likewise, the criterion that each be a continuous landmass is often disregarded by the inclusion of the
continental shelf and
oceanic islands. The Earth's major landmasses are washed upon by a single, continuous
World Ocean, which is divided into a number of principal
oceanic components by the continents and various geographic criteria.
Extent of continents
The narrowest meaning of
continent is that of a continuous area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. In this sense the term
continental Europe is used to refer to mainland Europe, excluding
islands such as
Great Britain,
Ireland, and
Iceland, and the term
continent of Australia may refer to the
mainland of Australia, excluding
Tasmania. Similarly, the
continental United States refers to the 48 contiguous
United States in central North America and may include
Alaska in the northwest of the continent (both separated by
Canada), while excluding
Hawaii in the middle of the
Pacific Ocean.
From the perspective of
geology or
physical geography,
continent may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area (the
continental shelf) and the islands on the shelf (
continental islands), as they're structurally part of the continent. From this perspective the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level. In this sense the islands of Great Britain and Ireland are part of Europe, and Australia and the island of
New Guinea together form a continent (
Australia-New Guinea).
As a cultural construct, the concept of a continent may go beyond the continental shelf to include
oceanic islands and continental fragments. In this way,
Iceland is considered part of Europe and
Madagascar part of Africa. Extrapolating the concept to its extreme, some geographers take Australia, New Zealand and all the islands of
Oceania (or sometimes
Australasia) to be equivalent to a continent, allowing the entire land surface of the Earth to be divided into continents or quasi-continents.
Separation of continents
» See also Borders of the continents and Transcontinental country
The ideal criterion that each continent be a discrete landmass is commonly disregarded in favor of more arbitrary, historical conventions. Of the seven most commonly recognized continents, only Antarctica and Australia are separated from other continents.
Several continents are defined not as absolutely distinct bodies but as "
more or less discrete masses of land". Asia and Africa are joined by the
Isthmus of Suez, and North and South America by the
Isthmus of Panama. Both these
isthmuses are very narrow in comparison with the bulk of the landmasses they join, and both are transected by artificial
canals (the
Suez Canal and
Panama Canal, respectively) which effectively separate these landmasses.
The division of the landmass of
Eurasia into the continents of Asia and Europe is an anomaly, as no sea separates them. The distinction is maintained for historical and cultural reasons. An alternative view is that Eurasia is a single continent, one of six continents in total. This view is held by some geographers and is preferred in
Russia (which spans Asia and Europe).
North America and South America are now treated as separate continents in much of
Western Europe,
India,
China, and most native
English-speaking countries, such as
the United States,
Canada,
Australia, and
New Zealand. Furthermore, the concept of two American continents is prevalent in much of Asia. However, in earlier times they were viewed as a single continent known as America or, to avoid ambiguity with the
United States of America, as the
Americas. However, the plurality of this last term suggests that even in these "earlier times" some considered the New World (the Americas) as two separate continents. North and South America are viewed as a single continent, one of six in total, in some parts of Europe, and much of
Latin America.
When continents
are defined as discrete landmasses, embracing all the contiguous land of a body, then Asia, Europe and Africa form a single continent known by various names such as
Afro-Eurasia. This produces a four-continent model consisting of Afro-Eurasia, the Americas, 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 North America and Asia were joined by the
Bering land bridge. Other islands such as
Great Britain were joined to the mainlands of their continents. At that time there were just three discrete continents: Afro-Eurasia-America, Antarctica, and Australia-New Guinea.
Number of continents
There are numerous ways of distinguishing the continents;
The seven-continent model is usually taught in
Western Europe,
Northern Europe,
Central Europe,
Southeastern Europe,
China and most
English-speaking
countries. The six-continent combined-Eurasia model is preferred by the
geographic community,
Russia,
Eastern Europe, and
Japan. The six-continent combined-America model is taught in
Latin America, the
Iberian Peninsula,
Iran,
Greece and some other parts of Europe. This model may be taught to include only the five inhabited continents (excluding Antarctica).
The names
Oceania or
Australasia are sometimes used in place of
Australia. For example, the
Atlas of Canada names Oceania, as does the model taught in
Latin America and Iberia.
Area and population
| Continent |
Area (km²) |
Approx. population
2002 |
Percent of
total population |
Density
People per
square kilometre |
| Asia | 43,810,000 |
3,800,000,000 |
60% |
86.7
|
| Africa | 30,370,000 |
922,011,000 |
14% |
29.3
|
| Americas | 42,330,000 |
890,000,000 |
14% |
20.9
|
| North America | 24,490,000 |
515,000,000 |
8% |
21.0
|
| South America | 17,840,000 |
371,000,000 |
6% |
20.8
|
| Antarctica | 13,720,000 |
1,000 |
0.00002% |
0.00007
|
| Europe | 10,180,000 |
710,000,000 |
11% |
69.7
|
| Oceania | 9,010,000 |
33,552,994 |
0.6% |
3.7
|
| Australia-New Guinea | 8,500,000 |
30,000,000 |
0.5% |
3.5
|
| Australia mainland | 7,600,000 |
21,000,000 |
0.3% |
2.8
|
The total land area of all continents is 148,647,000 km², or approximately 29.1% of earth's surface (510,065,600 km
2).
Other divisions
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, on the
North American Plate, is sometimes referred to as a subcontinent. Where America is viewed as a single continent, it's divided into two subcontinents (North America and South America) or various regions.
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 part of Africa but has been referred to as "the eighth continent".
History of the concept
Early concepts of the Old World continents
The first distinction between continents was made by
ancient Greek mariners who gave the names
Europe and
Asia to the lands on either side of the waterways of the
Aegean Sea, the
Dardanelles strait, the
Sea of Marmara, the
Bosphorus strait and the
Black Sea. The names were first applied just to lands near the coast and only later extended to include the hinterlands. 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 ..." From the Greek viewpoint, the Aegean Sea was the center of the world; Asia lay to the east, Europe to the west and north and Africa to the south. The boundaries between the continents were not fixed. Early on, the Europe-Asia boundary was taken to run from the Black Sea along the
Rioni River (known then as the Phasis) in
Georgia. Later 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. The boundary between Asia and Africa was generally taken to be the
Nile River.
Herodotus 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, 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.
Through the Roman period and the
Middle Ages, a few writers took the
Isthmus of Suez as the boundary between Asia and Africa, but most writers continued to take it to be the Nile or the western border of Egypt (Gibbon). In the Middle Ages the world was portrayed on
T and O maps, with the T representing the waters dividing the three continents. By the middle of the eighteenth century, "the fashion of dividing Asia and Africa at the Nile, or at the
Great Catabathmus [theboundary between Egypt and
Libya] farther west, had even then scarcely passed away".
European discovery of the Americas
Christopher Columbus sailed across the
Atlantic Ocean to the
West Indies in 1492, sparking a period of European exploration of the
Americas. But despite four voyages to the Americas, Columbus never believed he'd reached a new continent – he always thought it was part of Asia.
In 1501,
Amerigo Vespucci and
Gonçalo Coelho attempted to sail around the southern end of the Asian mainland into the
Indian Ocean. On reaching the coast of
Brazil, they sailed a long way south along the coast of
South America, confirming that this was a land of continental proportions and that it extended much further south than Asia was known to. On return to Europe, an account of the voyage, called
Mundus Novus ("New World"), was published under Vespucci’s name in 1502 or 1503, although it seems that it had additions or alterations by another writer. Regardless of who penned the words,
Mundus Novus attributed Vespucci with saying, "I have discovered a continent in those southern regions that's inhabited by more numerous people and animals than our Europe, or Asia or Africa", 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. 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 and translated from the Latin
terra continens. The noun was used to mean "a connected or continuous tract of land" or
mainland.
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." 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.
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).
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.
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. 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. 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 don't 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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