What is a mainland? Continent and mainland - two big differences

Today, with your permission, I will take a walk into the past and try to look a little into the future. What will be the object of my curiosity, who or what will become the hero of my today's story? And it will be, literally, the land on which we live. No, reader, this is not about the planet - today I will lead my story about the continents.

What is a mainland

Mainland- he is continent(synonyms absolutely are equivalent, just geologists prefer the first term, and politicians, for some reason, the second) - is a large part of the earth's land, the edges of which, like a crust on a pie, are bent, lowered down and are below sea level. Why, you ask, Greenland not considered a mainland, but Australia, for example, consider? Everything is simple. Greenland is composed of rocks of the oceanic crust, which is typical for islands, moreover, he has no continental shelf. same - this "piece" of continental crust, which, in addition to itself, includes the adjacent islands. So the maximum that "shines" Greenland is an encouraging "mainland island", although this title is somewhat unscientific.

History of the continents

What is a mainland- sort of figured it out. Now it will unwind the film a little, just for several billion years ago, and look at landforms planet Earth. I remind you - I deliberately do not dwell on modern continental models, I am more attracted to their history! So, how, according to the numerous hypotheses of scientists, land and ocean were earlier more clearly separated than they are now, and all modern continents consisted of one- the so-called supercontinent:

• Kenorland, 2.75 billion years ago. The supercontinent was located in the southern latitudes.
• Nuna, 1.8 billion years ago. Consisted of the ancient "progenitors" of the Ukrainian shield, Amazonia, Australia, Siberia, the Kalaharian platform and others.
• Lavrussia(euroamerica, Caledonia, "Red Continent"). It was formed as a result of the collision of the North American (Laurentian continent) and East European (Baltic continent) platforms, then merged with Pangea, becoming part of Laurasia.
• gondwana, 700 million years ago located around the South Pole. About 360 million years ago, it merged with the Scandinavian mainland to form Pangea. About 80 million years ago, it split into modern continents.
• Pangea, Paleozoic. At the end of the Triassic period, it split into Laurasia and Gondwana.
• Laurasia, Mesozoic. Contained modern northern continents.

The future of the continents

Some scientists are in solidarity in their prediction that through 100-200 Ma continents again converge in a big pile with the prefix "super". Assume three options kind of future supercontinent:

• Pangea Ultima, a giant desert supercontinent dotted with towering mountain ranges;
• Amazia, a supercontinent with a center at the North Pole, which is formed as a result of a kind of compression, “shrinking” of all modern continents together (as if they squeezed a giant sponge;
• Novopangea, with the Pacific Ocean closed inside the Australian-Asian chain and the extremely warmer Antarctica.

MAINLAND
or continent, a large landmass (as opposed to a smaller massif - islands), surrounded by water. There are seven parts of the world (Europe, Asia, Africa, North America, South America, Australia and Antarctica) and six continents: Eurasia, Africa, North America, South America, Australia and Antarctica. Some large islands are close in size to the mainland and are sometimes referred to as "mainland islands". Among them, the most famous are Greenland, New Guinea, Kalimantan and Madagascar. The continents are surrounded by shallow zones of the oceans - shelves, with depths usually not exceeding 150 m.

CONTAINERS AND THEIR SIZES

The names of parts of the world and continents have different origins. The ancient Greeks called all the lands to the west of the Bosphorus Europe, and to the east of it - Asia. The Romans divided their eastern (Asian) provinces into Asia and Asia Minor (Anatolia). The name "Africa", also of ancient origin, referred only to the northwestern part of the mainland and did not include Egypt, Libya and Ethiopia. Ancient geographers assumed that there must be a large mainland in the south (Terra Australis - southern land), which would balance the vast land masses in the north, but it was discovered only in the 17th century. Its original name "New Holland" was later changed to "Australia". By the 18th century include the first guesses about the existence of Antarctica (which means "the antipode of the Arctic"), but the discovery and study of this continent refers only to the 19-20 centuries. Unlike Australia, the existence of America was not predicted by anyone, and when it was discovered, it was mistaken for part of China or India. The term "America" ​​first appeared on the map of Martin Waldseemüller (1507), who named the New World in honor of the geographer and explorer Amerigo Vespucci. Vespucci was probably the first to realize that a new continent had been discovered. The term "mainland" in its modern meaning appeared in England in the 17th century. The continents account for 94% of the land area and 29% of the planet's surface area. However, not the entire area of ​​the continents is land, as there are large inland seas (for example, the Caspian Sea), lakes and areas covered with ice (especially in Antarctica and Greenland). The boundaries of the continents were often the subject of controversy. Residents of Great Britain, for example, traditionally separated their island state from the mainland of Europe, which, in their opinion, began from Calais. The boundaries of parts of the world and continents have always caused a "headache" to geographers. Europe and Asia are demarcated along the watershed of the Ural Mountains, but to the south, the border becomes less clear and is again defined only in the Greater Caucasus. Further, the border runs along the Bosphorus, dividing Turkey into the European part (Thrace) and the Asian part (Anatolia, or Asia Minor). A similar problem arises in Egypt: the Sinai Peninsula is often referred to as Asia. From a geographical point of view, all of Central America, including Panama, is usually annexed to North America, but politically, it is often practiced to refer all territories located south of the United States to Latin America.
STRUCTURAL GEOLOGY
The word "continent" comes from the Latin continens (continere - to stick together), which implies a structural unity, although not necessarily in relation to land. With the development of the theory of lithospheric plate tectonics in geology, a geophysical definition of continental plates, in contrast to oceanic ones, arose. These structural units have a completely different structure, power and history of development. Continental crust composed of predominantly silicon (Si) and aluminum (Al) rocks is lighter and much older (some parts over 4 billion years old) than oceanic crust composed primarily of silicon (Si) and magnesium (Mg) and having an age of no more than 200 million years. The boundary between the continental and oceanic crust runs along the foot of the continental slope or along the outer boundary of the shallow shelf that borders each continent. The shelf adds 18% to the area of ​​the continents. This geophysical definition emphasizes the well-known differences between such "continental islands" as the British, Newfoundland and Madagascar, from the oceanic ones - Bermuda, Hawaii and Guam.
History of the Continents. During the long evolution of the earth's crust, the continents gradually grew due to the accumulation of lava and ash from volcanic eruptions, the intrusion of molten magma from rocks such as granite, and the accumulation of sediments that were originally deposited in the ocean. The constant fragmentation of the ancient land masses - the "procontinents" - predetermined the drift of the continents, as a result of which their collision periodically occurred. Ancient continental plates were firmly connected along these contact lines, or "seams", forming a complex mosaic ("patchwork quilt") of structural units that make up modern continents. In the east of North America, such a suture zone can be traced from Newfoundland to Alabama. Fossils found in the rocks to the east of it are of African origin, which is evidence of the detachment of this site from the African mainland that occurred (about 300 million years ago). Another suture zone, marking the collision of Europe with Africa about 100 million years ago, can be traced in the Alps. Another seam runs along the southern border of Tibet, where the Indian subcontinent collided with the Asian one and in geologically recent times (about 50 million years ago) the Himalaya mountain system was formed.

The theory of lithospheric plate tectonics is today as generally accepted in geology as, for example, the law of universal gravitation is in physics. Rocks and fossils of the "African type" have been found in many places in the east of America. The suture zones are clearly visible on satellite images. It is possible to measure the speed of upward movements where the mountains that arose as a result of the collision of the continents are still continuing to rise. These speeds do not exceed 1 mm per year in the Alps, and in some parts of the Himalayas they are more than 10 mm per year. The logical consequence of the considered mechanism of mountain building is continental rifting and spreading of the ocean floor. Fragmentation of the earth's crust is a widespread phenomenon, clearly visible on satellite images. The main fault lines, called lineaments, can be traced both in space - for thousands of kilometers, and in time - to the most ancient stages of geological history. When both sides of the lineament are strongly displaced, a fault is formed. The origin of the largest faults has not yet been fully established. A computer model of the fault network suggests that their formation is associated with changes in the shape of the globe in the past, which, in turn, was predetermined by fluctuations in the speed of the Earth's rotation and a change in the position of its poles. These changes were due to a number of processes, among which the most significant influence was exerted by ancient glaciations and the bombardment of the Earth by meteorites. Ice ages recurred approximately every 250 million years and were accompanied by the accumulation of significant masses of glacial ice near the poles. This accumulation of ice caused an increase in the speed of the Earth's rotation, leading to a flattening of its shape. At the same time, the equatorial belt expanded in diameter, and the spheroid seemed to shrink at the poles (i.e., the Earth became less and less like a ball). Due to the fragility of the earth's crust, a network of intersecting faults has formed. The speed of the Earth's rotation changed dozens of times during one ice age. In the early stages of the Earth's history, there was an intense bombardment of the planet by asteroids and smaller objects - meteorites. It was uneven and, apparently, led to a deviation of the axis of rotation and a change in its speed. The scars from these impacts and the craters left by the "heavenly guests" are visible everywhere on the lower planets (Mercury and Venus), although on the earth's surface they are partially masked by precipitation, water and ice. These bombings also contributed to the chemical composition of the continental crust. Since falling objects tended to concentrate near the equator, they increased the mass of the outer edge of the globe, noticeably slowing down the speed of its rotation. In addition, throughout geological history, any powerful outpouring of volcanic lavas in one of the hemispheres or any movement of masses contributed to a change in the inclination of the axis of rotation and the speed of rotation of the Earth. It has been established that the lineaments are weakened zones of the continental crust. The earth's crust is able to bend like window glass under the onslaught of gusts of wind. All of it is actually dissected by faults. Along these zones, slight movements occur all the time, due to the tide-forming forces of the Moon. As the plate moves toward the equator, it is subjected to more and more stress, both due to tidal forces and changes in the Earth's rotational speed. These stresses are most pronounced in the central parts of the continents, where rifting occurs. Zones of young rifting run in North America from the Snake River to the Rio Grande River, in Africa and the Middle East - from the Jordan River Valley to Lakes Tanganyika and Nyasa (Malawi). In the central regions of Asia, there is also a rift system passing through Lake Baikal. As a result of long-term processes of rifting, continental drift and their collisions, the continental crust was formed in the form of a "patchwork quilt" consisting of fragments of different ages. It is curious to note that rocks of all geological epochs are apparently present on every continent at the present time. The basis of the continents is the so-called. shields composed of ancient strong crystalline rocks (mainly of granite and metamorphic series), which belong to different epochs of the Precambrian (i.e., their age exceeds 560 million years). In North America, the Canadian Shield is such an ancient core. At least 75% of the continental crust was already formed 2.5 billion years ago. Areas of shields covered by sedimentary rocks are called platforms. They are characterized by a flat plain relief or gently undulating vaulted hills and basins. When drilling for oil under sedimentary rocks, a crystalline foundation is sometimes opened. Platforms are always extensions of ancient shields. In general, this core of the mainland - a shield together with a platform - is called a craton (from the Greek krtos - strength, fortress). Attached to the edges of the craton are fragments of young folded mountain belts, usually including small cores ("fragments") of other continents. So, in North America in the eastern Appalachians there are "fragments" of African origin. These young components of each continent provide clues to the ancient shield's history and appear to evolve in much the same way as it does. In the past, the shield also consisted of mountain belts, which are now leveled almost to a flat relief or only moderately dissected by erosion. Such a leveled surface, called peneplain, is the result of erosion-denudation processes that took place more than half a billion years ago. Basically, these processes of leveling proceeded under conditions of tropical crust formation. Since chemical weathering is the main agent of such processes, a sculptural plain is formed as a result. In the modern era, only bedrocks are represented on the shields, which remained after the rivers and glaciers destroyed and demolished the ancient loose deposits. In younger mountain belts, uplifts often repeated along the edges of the cratons, but there was not enough time for the formation of peneplain, so a series of stepped erosional surfaces formed instead.
Continental rifting. The most impressive result of young rifting is the Red Sea rift between the Arabian Peninsula and Northeast Africa. The formation of this rift began c. 30 million years ago and is still happening. The opening of the Red Sea basin continues to the south in the East African Rift Zone and to the north - in the zone of the Dead Sea and the Jordan Valley. The biblical story of the collapsed walls of Jericho is likely based on fact, as this ancient city lies within the main drop zone. The Red Sea is a "young ocean". Although its width is only 100-160 km, the depths in some areas are comparable to those of the ocean, but what is most remarkable is that there are no remains of the continental crust. Previously, it was believed that the rift is like a destroyed arch with a fallen upper ("castle") stone. Numerous studies have not confirmed this assumption. It has been established that the two edges of the rift are, as it were, moved apart, and the bottom consists of hardened "oceanic" lava, which is currently largely covered by young sediments. This is the beginning of seafloor spreading, the geological process that forms oceanic-type crust. underlain by the continental crust. At the beginning of the formation of the theory of plate tectonics, the question was often asked: if the continental rifts and the ocean floor expand during spreading, should not the globe itself expand accordingly? The mystery was solved when subduction zones were discovered - planes inclined at about 45° along which oceanic crust is being pushed under the edge of the continental plate. At a depth of approx. 500-800 km from the surface of the Earth, the crust melts and rises again, forming magma chambers - reservoirs with lava, which then erupts from volcanoes.
Volcanoes. The locations of volcanoes are closely related to the movement of lithospheric plates, while three types of volcanic zones are distinguished. The volcanoes of the subduction zones form the Pacific Ring of Fire, the Indonesian Arc, and the Antilles Arc in the West Indies. Such volcanoes of subduction zones are known as Fujiyama in Japan, St. Helens and others in the Cascade Mountains of the USA, Montagne Pele in the West Indies. Inland volcanoes are often confined to fault or rift zones. They are found in the Rocky Mountains from the Yellowstone National Park and the Snake River to the Rio Grande, as well as in East Africa (for example, Mount Kenya and Mount Kilimanjaro). Volcanoes of the mid-ocean fault zones are found on the oceanic islands of Hawaii, Tahiti, Iceland, etc. Both inland and mid-ocean volcanoes (at least the largest of them) are associated with deep-seated "hot spots" (ascending convective jets) in the mantle. As the overlying plate shifts, a chain of volcanic centers appears, arranged in chronological order. These three types of volcanoes differ in the nature of volcanic activity, the chemical composition of the lava, and the history of development. Only the lava of volcanoes in subduction zones contains large volumes of dissolved gases, which can lead to catastrophic explosions. Other types of volcanoes can hardly be called "friendly", but they are much less dangerous. Note that only the most general classification of eruptions is possible, since the activity of the same volcano proceeds in its own way each time, and even individual phases of one eruption may differ.
Continental surface. The relief features of the continents are studied by the science of geomorphology (geo is derived from the name of the Greek goddess of the Earth Gaia, morphology is the science of forms). Landforms can be of any size: from large, including mountain systems (such as the Himalayas), giant river basins (Amazon), deserts (Sahara); to small ones - sea beaches, cliffs, hills, streams, etc. Each form of relief can be analyzed from the point of view of structural features, material composition and development. It is also possible to consider dynamic processes, which mean the physical mechanisms that caused the change in landforms over time, i.e. predetermined the modern shape of the relief. Almost all geomorphological processes depend on the following factors: the nature of the source material (substrate), structural position and tectonic activity, as well as climate. The largest landforms include mountain systems, plateaus, depressions and plains. The mountain systems have undergone crushing and compression in the process of plate movement; at present, erosion-denudation processes prevail there. The land surface is gradually destroyed under the influence of frost, ice, rivers, landslides and wind, and the destruction products accumulate in depressions and on plains. Structurally, mountains and plateaus are characterized by continuing uplifts (from the point of view of the theory of plate tectonics, this means warming up of deep layers), while depressions and plains are characterized by weak subsidence (due to cooling of deep layers).

There is a compensation process, the so-called. isostasy, one of the results of which is that, as mountains are eroded, they experience uplift, and the plains and depressions where precipitation accumulates tend to sink. Under the earth's crust is the asthenosphere, consisting of molten rocks, on the surface of which lithospheric plates "float". If any section of the earth's crust is overloaded, then it will "sink" (plunge into the molten rock), while the rest of it will "float" (rise). The main reason for the uplift of mountains and plateaus is plate tectonics, however, erosion-denudation processes in combination with isostasy contribute to the periodic rejuvenation of ancient mountain systems. Plateaus are similar to mountains, but they are not crushed as a result of a collision (collision of plates), but are raised as a single block and are usually characterized by horizontal sedimentary rocks (which, for example, is clearly visible in the Grand Canyon outcrops in Colorado). Another geological process that plays a very important role in the long history of the continents - eustasia - reflects global fluctuations in sea level. There are three types of eustasia. Tectonic eustasia is caused by changes in the shape of the seafloor. During rapid subduction, the width of the ocean basin shrinks and sea levels rise. The ocean basin is also becoming shallower due to the thermal expansion of the oceanic crust as seafloor spreading suddenly accelerates. Sedimentary eustasia is due to the filling of the ocean basin with sediments and lava. Glacioeustasia is associated with the removal of water from the oceans during continental glaciations and its return during the subsequent global melting of glaciers. During periods of maximum glaciation, the area of ​​the continents increased by almost 18%. Of the three types considered, glacioeustasia has played the most important role in human history. On the other hand, the effect of tectonic eustasia was the most prolonged. Periodically, the level of the World Ocean rose, and as a result, significant parts of the continents were flooded. Mountains were an exception. These global floods are called "thalassocratic" (from the Greek thlassa sea and krtos - strength, power) phases of the Earth's development. The last such flood occurred ca. 100 million years ago, in the era of dinosaurs (some living organisms of that time preferred an aquatic lifestyle). The marine sediments of that time found in the inland regions, with their characteristic fossils, testify that North America from the Gulf of Mexico to the Arctic was flooded by the sea. Africa was divided into two parts by a shallow strait that crossed the Sahara. Thus, each continent was reduced to the size of a large archipelago. Quite different conditions existed in the eras when the ocean floor was sinking. The sea receded from the shelves, and the land expanded everywhere. Such epochs are called "epeirocratic" (from the Greek peiros - mainland, dry land). The alternation of epeirocratic and thalassocratic phases determined the main course of geological history and left traces in the main features of the relief of each continent. These phenomena also had a great impact on the animal and plant world. The course of evolution of both the physical and biological world was also determined by changes in the area of ​​the oceans. During the thalassocratic phases, an oceanic climate was formed with moisture-saturated air masses penetrating the land. As a result, the average temperature on Earth was at least 5.5°C warmer than today. Glaciers existed only in very high mountains. Conditions on all continents were more or less uniform, the land was covered with lush vegetation, which contributed to the development of soils. However, land animals have experienced severe stress due to overpopulation and disunity, unlike their marine counterparts, who thrived on the vast expanses of the shelves that have significantly increased in area. During the epeirocratic phases, the opposite situation developed. The area of ​​the continents increased, and the new habitats were ideally suited for the existence of large animals such as dinosaurs. The largest land area covered approx. 200 million years ago, which favored the evolution of these creatures. In the climatic conditions of that time with a high "continental index", deserts and red-colored deposits were widespread and mechanical erosion prevailed. The modern relief is closely dependent on the geological history. The appearance of the Alps or the Himalayas testifies to a young uplift: these mountains are typical collisional structures. The Great Interior Plains of North America and northern Eurasia are overlain by predominantly subhorizontally occurring sedimentary formations that were formed during repeated global marine transgressions throughout geological history. In turn, they are covered by a thin moraine cover (deposits of ice ages) and loess (products of the activity of especially strong winds, usually blowing in the direction from large ice sheets to their periphery). It is interesting to note that the plains of the northern and southern hemispheres look completely different. In Brazil, South Africa and Australia, exotic landforms invariably amaze. The modern era is an epeirocratic phase in the history of the Earth, with increasing differentiation of individual continents and increasing climatic contrasts. But why is there a difference between the northern and southern continents? The answer to this question lies in plate tectonics. All the northern continents were moved apart for considerable distances and over the past almost 200 million years have been slowly moving northward. As a result of this drift, they moved from tropical and subtropical latitudes to temperate and arctic latitudes. From those distant times, red-colored soils were inherited, typical of hot dry climate conditions, and many existing landforms could not have formed in modern climatic conditions. In the recent geological past, vast areas of these continents were covered with glaciers. The history of the development of the southern continents was completely different. They experienced the last glaciation 250 million years ago, being part of the pre-existing fore-continent of Gondwana. Since then, they have gradually moved northward (i.e., towards the modern equator), so that many modern landforms in these regions are inherited from colder climatic conditions. The Northern Hemisphere has 48% more land area than the Southern Hemisphere. This distribution has a profound effect on the climate, causing more continentality in the north and more oceanicity in the south.
Rates of erosion-denudation processes. Studies have shown that in many regions of the world there are ancient land areas - cratons, which are remnants composed of ancient sedimentary formations, which are often cemented with silica bedrock and form covers as strong as quartz. This cementation took place during the formation of sculptural plains in tropical and subtropical environments. Once formed, such a shell, armoring the relief, could then exist without change for millions of years. In mountainous areas, rivers cut through this solid cover, but fragments of it often remain. The subhorizontal watersheds in the Appalachians, the Ardennes, and the Urals are remnants of pre-existing sculptural plains. Based on the age of such ancient residual formations, the average denudation rate over a long time interval is calculated, which is approx. 10 cm in a million years. The surfaces of the ancient cratons of the Earth have absolute heights of 250-300 m, therefore, in order to cut them to the modern sea level, it would take approx. 3 billion years.
LITERATURE
Le Pichon K., Franchteau J., Bonnin J. Plate tectonics. M., 1977 Leontiev O. K., Rychagov G. I. General geomorphology. M., 1979 Ushakov S. A., Yasamanov N. A. Continental drift and climates of the Earth. M., 1984 Khain V. E., Mikhailov A. E. General geotectonics. M., 1985

Collier Encyclopedia. - Open Society. 2000 .

However, depending on where you live, there may be five, seven or even four continents. This is due to the fact that there are no generally accepted international criteria for defining the term "continent". Although the position of the main land masses on the earth's crust can be described as continents, geopolitical factors also affect their demarcation.

Below is the most popular classification system, which identifies the six continents of the world in descending order of their area.

Eurasia

• Area: 54,759,000 km²;
• Population: 5,262,489,285 (2017);
• Number of sovereign states: more than 90.

Eurasia on the world map/Wikipedia

Eurasia is the largest continent on Earth both in terms of area and population. Almost all of its territory is located on the Eurasian Plate, one of several lithospheric plates that cover our planet. There is no geological difference between and, therefore, these parts of the world are united into the Eurasia continent.

The Ural Mountains are considered the dividing line between Europe and Asia. Eurasia extends from the Atlantic Ocean in the west to the easternmost, in the Bering Strait between the Arctic Ocean and the Pacific Ocean.

The mainland has different climatic conditions since it is located in all climatic zones, from the arctic to. In this regard, the continent has a significantly diverse flora and fauna. However, this does not apply to the European part of the world, where a temperate climate prevails, which does not contribute to significant.

Asia is the eastern part of Eurasia, which occupies about 30% of the entire land mass of our planet. About 60% of the world's population lives in this part of the world. It is home to endemic animals including the Asiatic, Indian cobra, and Japanese macaque. More than four billion people live in Asia. China is the world's most populous country, although India's population is predicted to overtake China in 2022. Asia is home to some of the world's most important economic centers, including Hong Kong, Tokyo, Shanghai and Seoul.

Europe is located in the western part of the continent. Despite being physically connected to Asia, Europe has historically been considered a separate continent due to cultural and linguistic differences. More than 10% of the world's population lives in Europe. Europe has the second highest population density in the world after Asia. Monaco is the most populous country in this part of the world. There are several countries in Europe that are considered transcontinental, that is, they are located in both Europe and Asia. These countries include Turkey, Armenia, Georgia and Russia.

Africa

• Area: 30,370,000 km²
• Population: 1,225,080,510 (2016)
• Number of sovereign states: 54

Africa on the world map/Wikipedia

Africa is the second largest continent in the world both in terms of land area and population. passes through the middle of the continent, dividing it into two parts. About one third of Africa is located in. The continent occupies about 20% of the total land area of ​​the planet. The Indian Ocean, Atlantic Ocean, Mediterranean Sea and Red Sea border Africa to the east, west and north respectively.

The climate of Africa is characterized by hot in the north, jungles in both the central and southern parts. Africa has a lot of biological diversity and is home to the largest (elephants, hippos, rhinos and giraffes).

Africa has the youngest population of any continent, with an average age of just 19.5 years. This is the result of high population growth over the past 40 years. Africa is extremely linguistically diverse, with over two thousand languages ​​on the continent. The largest city in Africa is Lagos, Nigeria.

North America

• Area: 24,709,000 km²;
• Population: 579,024,000;
• Number of sovereign states: 23.

North America on the world map/Wikipedia

North America is the 3rd largest continent and the 4th most populous continent on Earth. North America lies entirely in and is washed by the Arctic Ocean to the north, the Atlantic Ocean to the east, the Pacific Ocean to the west, and the Caribbean Sea to the south. The continent has a coastline about 60 thousand km long.

The climate of North America is warmer in the south of the continent and colder in the north. While climatic conditions near the coast tend to be mild, temperatures inland can reach extremes. Although the southern part of the continent (including the south of the USA and Central America) is, and its northern part consists mainly of the arctic.

North America has an abundance of deposits, vast fresh water resources, and some of the most fertile soils on the planet. Thanks to this, the continent has become economically developed, and its population has a high standard of living.

The US is the most populated country in North America, followed by Mexico. The inhabitants of the mainland are characterized by ethnic diversity. English, Spanish and French are the most widely spoken languages ​​on the continent.

South America

• Site area: 17,840,000 km²;
• Population: 420,458,044
• Number of sovereign states: 12.

South America on the world map/Wikipedia

South America is the 4th largest continent in the world. It is mainly located in the Southern Hemisphere (with the exception of a small area of ​​the northernmost part), and is also located entirely in the Western Hemisphere. South America is bordered by the Atlantic Ocean to the east, the Pacific Ocean to the west, the Southern Ocean to the south, and the Caribbean Sea to the north.

South America's climate ranges from the driest Atacama Desert to the lush Amazon. South America is home to amazing species and species, including unique tropical birds and monkeys. Some of the most famous animals endemic to South America include the world's largest rodent, the world's largest flying bird, the Andean condor, and one of the world's largest butterflies, the morpho menelaus.

The importance of South America in terms of strategic natural resources is primarily determined by the abundance of minerals, biodiversity, forests, as well. After the Middle East, South America contains the largest oil reserves.

Brazil is the most populous country on the mainland, followed by Colombia and Argentina. Spanish is the most popular language in South America. English serves as the official language in Guyana and Dutch in Suriname.

Antarctica

• Area: 14,000,000 km²;
• Population: about 1,000 people;
• Number of sovereign states: 0.

Antarctica on the world map/Wikipedia

Antarctica is located on and does not have a permanent population and countries. The mainland is used as a scientific base. Antarctica is the fifth largest continent and the least populated. It is completely surrounded by the Southern Ocean.

Strong winds, extremely cold temperatures, almost no weather, and a very cold desert make Antarctica's climate quite inhospitable. Despite this, a number of species have adapted to these difficult weather conditions. This includes seals, penguins, as well as some plants and.

Antarctica is completely surrounded by ocean, causing the sea ice to expand significantly in winter. It typically covers about 47 million km² during the September maximum (winter) and decreases to 8 million km² during the February minimum (summer).

The only human presence in Antarctica is the scientists who live on the mainland on a temporary basis. You can also visit Antarctica as a tourist.

Antarctica is the geographic opposite of the Arctic, which is an ocean half-covered by land masses. These surrounding lands impede the movement of ice, causing it to accumulate on high and thick ridges during the winter. During the warmer months, the Arctic retains about 47% ice (7-15 million km²).

Antarctic sea ice volume has increased by about one percent in the decade since 1979 and reached record levels in 2012-2014. However, these benefits do not compensate for the decrease in sea ice in the Arctic, and global sea ice continues to disappear at a rate of 35,000 km² (more than the area of ​​Moldova) per year.

Australia

• Area: 7,659,861 km²;
• Population: 23,130,931;
• Number of sovereign states: 1.

Australia on the world map/Wikipedia

Australia is the smallest continent in the world and the second least populated. It is located between the Indian and Pacific oceans. Although it is a large country, its topography is not very varied and most of it is desert. There are, however, fertile plains in the southeast.

Australia's climate ranges from tropical, arid and hot in the north to cooler in the south. Due to its isolation and remoteness from the rest of the world, the mainland exhibits a surprising number of endemic species. Some animals unique to Australia are the koala, platypus, wombat, kangaroo and echidna.

Although most of the continent is an arid desert, it supports a wide range of diversity, making it incredibly diverse. Due to the geographical isolation from the rest of the world, alpine forests, rainforests and a wide variety of plants and animals thrive. Thus, 85% of plants, 84% of mammals and 45% of birds are endemic to Australia. The mainland also has the largest number of reptile species in the world, as well as some of the most venomous snakes and other dangerous creatures such as crocodiles. Australia is best known for its cats, which include the kangaroo, koala, and wombat.

About 89% of Australia's fish species are endemic. In addition, endangered coral reefs are located near the coast of the continent. The most famous of them is the Great Barrier Reef. It is the world's largest coral reef system and covers an area of ​​344,400 km². It is made up of over 2,900 individual reefs and supports a variety of species, many of which are endangered.

Australia is considered a developed nation with a strong economy due to its vast natural resources, well-developed industry and tourism. Agriculture also plays an important role in the economy of the country and the mainland as a whole.

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Consists of body of water and land. The share of the World Ocean accounts for 70.8% of the Earth's surface, which is 361.06 million km 2, and the share of land - 29.2%, or 149.02 million km 2.

It is customary to conditionally divide all the land of the Earth into parts of the world and continents.

Continents of the Earth

continents, or continents are very large areas of land surrounded by water (Table 1). There are six of them on Earth: Eurasia, Africa, North America, South America, Antarctica and Australia. All continents are quite well isolated from each other.

The total area of ​​all continents is 139 million km2.

A piece of land that extends into an ocean or sea and is surrounded on three sides by water is called peninsula. The largest peninsula on Earth is the Arabian Peninsula (its area is 2732 thousand km 2).

A small piece of land compared to the mainland, surrounded on all sides by water, is island. There are single islands (the largest is Greenland, its area is 2176 thousand km 2) and clusters of islands - archipelagos(for example, the Canadian Arctic Archipelago). By origin, the islands are divided into:

• continental - large islands that have separated from the continents and are located on the underwater margin of the continents (for example, the island of Great Britain);
• oceanic, among which there are volcanic and coral.

Perhaps the largest number of volcanic islands can be observed in the Pacific Ocean. Coral (organogenic) islands are characteristic of the hot zone. Coral structures - atolls have the shape of a ring or a horseshoe with a diameter of up to several tens of kilometers. Sometimes atolls form truly gigantic clusters along the coast - barrier reefs(for example, the Great Barrier Reef along the east coast of Australia has a length of 2000 km).

Parts of the world

In addition to the division of land into continents, in the course of cultural and historical development, there was another allocation parts of the world of which there are also six: Europe, Asia, America, Africa, Antarctica and Australia. Part of the world includes not only the mainland, but also the islands adjacent to it. Far from the mainland, the islands of the Pacific Ocean form a special group called Oceania. The largest of them - about. New Guinea (area - 792.5 thousand km 2).

Geography of the continents

The location of the continents, as well as differences in the properties of waters, the system of currents and tides, allows us to divide, called oceans.

Currently, five oceans are distinguished: the Pacific, Atlantic, Indian, Arctic, and since 1996, by decision of the Commission on Geographical Names, the South. More information about the oceans will be given in the next section.

Table 1. General information about the continents

Characteristics			North America	South America	Australia	Antarctica
Area, mln km2 without islands with islands
Coastline, thousand km
Length, km: from North to South from west to east
extreme points
northern	Cape Chelyuskin 77°43" N	m Ben Secca 37°20" N	Cape Murchison 71°50" N	Cape Gapinas 12°25" N	m York 10°41"S	Sifre 63° S
	m. Piai 1° 16" media.	Cape Igolny 34°52" Yu.Sh.	m. Maryato 7° 12" N	Cape Froward 53°54" Jul.	m. Yugo-Vostochny 39°11" S
western	Cape Roca 9°34"W	Cape Almadi 17°32"W	m Prince of Wales 168°00"W	Cape Parinhas 81°20"W	m. Steep Point 113°05"E
eastern	Dezhnev metro station 169°40"W	Cape Ras Hafun 51°23"E	m. St. Charles 55°40" PLN	Cape Cabo Branco 34°46"W	Cape Byron 153°39"E