CONTINENT

Continent

From Wikipedia, the free encyclopedia

Animated, color-coded map showing the various continents. Depending on the 

convention and model, some continents may be consolidated or subdivided: for example, Eurasia is often subdivided into Europe and Asia (red shades), while North and South America are sometimes recognized as one American continent (green shades).

Dymaxion map by Buckminster Fuller shows land masses with minimal distortion as nearly one continuous continent

A continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents – they are (from largest in size to smallest): Asia, Africa, North America, South America, Antarctica, Europe, and Australia.[1]

Plate tectonics is the geological process and study of the movement, collision and 

division of continents, earlier known as continental drift.

Theoretically, if other planets largely, but not completely covered by water or another liquid substance were discovered; the word "continent" could be used for any large 

landmasses on those planets.

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.[2]

Definitions and application

"Continents are understood to be large, continuous, discrete masses of land, ideally separated by expanses of water."[3] 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.^[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 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)^[7] and the islands on the shelf (continental islands), 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, 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.^[10]

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".[11] 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. 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] 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 much of Western Europe, India, China, and most native English-speaking countries, such as the United States, 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. 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. 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^{[citation needed]}.

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 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;

Models
Color-coded map showing the various continents. Similar shades exhibit areas that may be consolidated or subdivided.
7 continents [13][14][15][16][17][18]	North America	South America	Antarctica	Africa	Europe	Asia	Australia
6 continents [19][14]	North America	South America	Antarctica	Africa	Eurasia		Australia
6 continents [20][21]	America		Antarctica	Africa	Europe	Asia	Australia
5 continents [19][20][21]	America		Antarctica	Africa	Eurasia		Australia
4 continents [19][20][21]	America		Antarctica	Afro-Eurasia			Australia

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, Iran and some parts of Europe including Iberian Peninsula and Greece. 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,^[13] as does the model taught in Latin America and Iberia.^[23][24]

Area and population

Comparison of area and population

Continent	Area (km²)	Approx. population 2002	Percent of total population	Density People per square kilometre
Afro-Eurasia	84,360,000	5,710,000,000	85%	56.4
Eurasia	53,990,000	4,510,000,000	71%	83.5
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	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% of earth's surface (510,065,600 km2).

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 is divided into two subcontinents (North America and South America)^[25][26][27] or various regions.^[28]

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". From Wikipedia, the free encyclopedia

Penulis : Drs.Simon Arnold Julian Jacob