In geography, continents are called large areas of land that dominate the background of neighboring islands and archipelagos. In the scientific sense, the continental part of the land also includes the sea shelf, which disappeared under water due to flooding, but is one with the surface part.
Solid land - the earth's crust - is only a thin layer of solid matter resting on a huge ocean of hot magma. In many places on the Earth, for example, under the ocean, the depth of the earth's crust is only 13 kilometers (and up to 350 km), while the liquid part - magma - reaches 5,000 kilometers.
The reason for the liquid state of the planet's interior is the high temperature generated by the fusion reaction at the core. Magma heated to enormous temperatures moves from the very center of the Earth to the earth's crust, where cooling processes take place. Thus, a constant convection is observed in the liquid layer, which is recorded by satellite magnetometers.
Convection is chaotic, often more active in some areas than in others. The rise of magma, which is under enormous pressure, occurs very slowly, but with great kinetic energy, which affects the surface of the planet.
Magma, making cyclic movements, pushes individual fragments of the surface in the direction in which the impulse is directed, thus, the surface movement of the continents is associated with deep processes, up to the very core.
Continents move at a very slow speed - a few centimeters per year, but the energy released during their movement is much more powerful than all power plants or atomic weapons of people.
The presence of a glacier gives unique properties to the movement. The enormous weight of the ice shell of Antarctica pushes the once surface areas up to 2.5 kilometers deep. It also turns out to be a slowing motion, so once "stuck" at the South Pole, the previously hot and tropical Antarctica will not soon lose its ice burden.
Have continents always moved?
Since the planet was originally a molten liquid ball, the movement of the continents did not begin immediately. First, the planet cooled and covered with a hard crust, then the continents appeared.
Their origin began only 500 million years after the formation of the planet. when solid surface layer cracked under the pressure of magma. Having split, the giant plates formed the future elements of the surface. Those that were higher became land, and those that, under the influence of weight, went deeper - oceanic plates.
From the moment of the split of the earth's crust, it is customary to count geological eras, the first of which was the Archean. For 3.5 billion years, the plates moved under the influence of magma, repeatedly colliding, pushing or rising, forming existing on this moment continents, seas and oceans.
How is the movement of the continents reflected on the Earth's surface?
The most obvious example of the movement of continents is an earthquake. Earthquakes form when two plates touch each other at fault points. The prerequisites for this are always long periods of uplift of magmatic matter, so today most earthquakes can be predicted by studying satellite magnetograms.
Less obvious is volcanism, probably the first manifestation of geological activity on the planet. The once solid earth's crust received its first impulse precisely thanks to the explosions of supervolcanoes (today they no longer exist on the planet in the active phase). The volcano is a point outlet of the very rising magma in the place of the greatest increase in pressure.
The third manifestation is mountains - all of them were formed in the process of collisions of two plates, as a result of which one of them crawled onto the other, forming a sharp uplift of the rock. Depressions manifest themselves similarly - the main difference is that one of the plates does not crawl, but, on the contrary, falls under the other.
All existing large mountain systems, including the Himalayas, are formed precisely in the places where two plates interact. The height of these mountains is explained precisely by the high speed of movement of the Indian continental plate.
Continents and oceans do not always occupy the same position on Earth. Although we do not notice it, they are constantly moving at a speed of only a few centimeters per year. Surface movements served as the basis for the creation of the theory of plate tectonics. The solid outer layer of the Earth, called , varies in thickness from a few to 240 km and is divided into six main plates. The heat of the deep inner layers of the Earth allows the plates to move on top of the hot molten inner layer (asthenosphere). The outer part of the lithosphere is called the earth's crust.
The oceanic crust that forms the bottom of the oceans is made up of basalt. The continental crust consists of granite, which has a lower density than basalt, and therefore it remains at the top. Oceans form, grow, shrink or disappear as the plates move. For example, the Atlantic Ocean has expanded by about 15 meters in the last 500 years.
Modern continents are similar to those that existed 400 million years ago, when, after a series of collisions, individual continents merged into the only huge supercontinent Pangea. About 160 million years ago, huge thermal vertical flows from the inner layers of the mantle stretched the earth's crust, and Pangea split into two large parts: Gondwana in the south and Lauraeia in the north. Gondwana consisted of present-day South America, Africa, India, Australia, and possibly Antarctica. Lauraeia consisted of present-day North America, Europe and Asia. They were separated by the Tethys Ocean. About 100 million years ago, when the African and South American plates began to diverge and Laurasia split in two, the Atlantic Ocean began to form. About 80 million years ago, India separated and moved north, closing the Tethys Ocean. The Gondwana rasol ended about 40 million years ago, when Australia separated from Antarctica. Even today, the coastlines of the continents, formed in the places of faults, surprisingly exactly coincide. The plates are still moving. North America is moving away from Europe at a rate of about 8 centimeters per year.
Ocean floor formation
Where two plates moved apart, hot matter from the deep layers of the mantle rose, filling the space and forming a new ocean floor. Ocean ridges have formed along the fault lines. The Pacific and Nazca plates, which make up the bottom, were moving apart faster than all the others, at a rate of about 14 cm per year. Where two plates collided, one went under the other and plunged into the mantle. Such a place is called a fault zone, where ocean trenches arose. Usually in these places there is increased seismic activity, the probability of earthquakes is high. Earthquakes are also common where two plates have pressed into each other, as happened at the San Andreas Trench off the west coast of North America.
The birth of the ocean
Someday the Red Sea may become an ocean. The African and Arabian plates began to move apart 70 million years ago and continue to move apart at a rate of 0.5 cm per year. It is likely that this shift created the East African Rift Zone, a fissure in the earth's continental crust that stretches from the Jordan Valley and the Dead Sea in the north through East Africa to the south. When the fault reaches the coastline, it will connect the Red Sea to the Mediterranean. This connection was broken and restored several times. Once the Red Sea was naturally connected to the Mediterranean Sea and the Indian Ocean.
death of the ocean
The Tethys Ocean was squeezed by two plates when the Indian plate collided with the Eurasian plate and shifted under it. When the mainland crust of India collided with the crust of Asia, it warped and the Himalayas formed. Part of the shallow continental shelf of the Tethys Ocean was uplifted in this process, so that sea shells are now found in the Himalayas, at an altitude of several thousand meters.
How are islands formed?
Some islands are formed from fragments of the granitic earth's crust, torn off the continents and remaining in the same place. So, for example, the Seychelles were part of or in "hot spots". "Hot spots" are places where magma flows rise to the surface from the earth's mantle. The "hot spots" are stationary, and the chain forms as the plate moves over them. There are 16 "hot spots" known, including the Hawaiian archipelago and the Partnership Islands. Midway is the oldest of the Hawaiian Islands and the furthest from the hotspot.
Volcanic oceanic islands often turn into atolls if they are located in areas of warm climate. At first, the island is surrounded by a coral reef, and as the island sinks, the reef continues to grow. In the end, the central island may disappear, and in its place remains a lagoon surrounded by a coral reef.
Tidal waves are almost unrelated to tides. Usually they are caused by underwater volcanic eruptions, or earthquakes, which create the movement of water masses and high waves. Pillow-shaped lava is formed when a volcanic eruption occurs beneath. As the water cools the lava rapidly, it takes on a strange rounded shape. Islands often have unique plant and animal species. On islands of mainland origin, there are species that may be descendants of those that existed on the mainland thousands of years ago, such as the sea coconut in the Seychelles. Other species of animals and plants reach ocean islands by wind, ocean currents and floating objects such as logs, or they are transported by people.
Simple questions. A book similar to an encyclopedia Antonets Vladimir Alexandrovich
Is it true that continents move?
As soon as relatively accurate maps of North and South America were created in the 17th century, many immediately noticed the similarity of the coastlines of the New and Old Worlds. The thought involuntarily crept in: weren't these continents once a single whole? But it was only in the middle of the 19th century that scientists began to look for evidence of this, studying the traces of prehistoric life.
At the beginning of the 20th century, the German meteorologist, geologist and astronomer Alfred Wegener, who studied changes in global climate, tried to find logic in the fact that fossil remains of tropical plants were found in ice-covered Greenland, and geological samples clearly confirm that in ancient times the African Sahara and South America were covered with a thick layer of ice.
In 1915, Wegener published a book in which he argued that when tropical plants grew in Greenland, it was located near the equator, and when Africa and South America were covered with ice, their place was near the South Pole of the Earth. Thus, Wegener concluded that the continents were slowly drifting, but could not explain why.
It took the scientific community about 40 years to accept this theory. By the 60s of the 20th century, the bottom of the ocean was studied in great detail. It turned out that the transitional shallow zone between the land and the deep ocean - the coastal shelf - abruptly breaks off with an almost vertical wall going down, and this wall reaches several kilometers in depth. If we draw the border of the continents exactly along the line of the shelf cliff, then America and Africa join almost perfectly. But most importantly, mid-ocean underwater ridges 1.5-2 km high were discovered, which are formed as a result of the backwater of the ocean floor by the ascending flows of the Earth's mantle - a hot liquid substance that occupies a layer from 30 to 2800 km below the surface. The convection movement of the mantle, similar to the convection movement of water in a boiling pot, becomes the engine that moves huge tectonic plates with continents located on them. Thus, a new science about the structure of the earth's crust was born - tectonics, which justifies the movement of continents at a speed of 1–10 cm per year. For tens of millions of years, this amounts to thousands of kilometers separating the once united continents.
The life of the mantle is complex, and periodically, as has happened more than once in the history of the Earth, the continents approach and collide, forming mountains, for example, the Urals, the Himalayas, and the Alps. If there are no sudden changes in the future, then as a result of the convergence of the continents in 200-300 million years, a single continent Pangea Ultima (the last Pangea) will arise, almost entirely located in the Northern Hemisphere. Scientists are already predicting what animals will be like then. For example, based on the analysis of the change of species at previous stages of history, there is an assumption that in 150-200 million years octopuses and squids will come to land and flying fish will appear.
We live on an amazing planet, but one cannot help but be amazed at the inquisitiveness of the human mind, which, starting with the obvious coincidence of the contours of the shores, managed to achieve a deep understanding of the structure of the entire planet.
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Continents are large areas of land that dominate the background of nearby archipelagos and islands. Of course, this is a general definition. If we consider the continents from the point of view of science, then these are not only land areas, but also the sea shelf, which is one with the mainland, but has long been hidden under water as a result of flooding. Often, children have questions, for example, why do continents move? Let's see if this is actually the case.
Liquid magma and solid land
To understand why the continents move, you should study the structure of the planet. So what is solid land? First of all, it is part of the earth's crust. Solid land is only a thin layer of various rocks that hide hot magma underneath. The thickness of the earth's crust can vary greatly. For example, under the ocean, the depth of solid rocks can be from 13 to 350 kilometers, and the depth of liquid magma can be almost 5,000 kilometers. The difference is, of course, significant.
Why is magma liquid? The main reason is the high temperature, which is released as a result of thermonuclear reactions occurring in the core of the planet. The substance gets very hot. In this case, the movement of magma from the center to the earth's crust is observed, where the processes of its cooling take place. Convections are constantly observed in the liquid layer, which are recorded by satellite magnetometers. This phenomenon allows us to answer the question of why the continents move. A brief description of such processes allows us to fully imagine the picture of what is happening. 
The main reason for the movement of the continents
So why do continents move? The answer to this question is quite simple. The convections occurring inside the magma are chaotic. Very often there is less activity in certain areas than in others. It is worth noting that the rise of magma proceeds under high pressure and very slowly. However, when such phenomena occur, a large amount of kinetic energy is released. All this has a certain effect on solid land.
Magma carries out cyclic movements. It pushes the surface fragments exactly in the direction where the momentum is present. That's why continents move. In other words, the surface displacement of solid land is associated with the processes that take place inside our planet right up to its very core.
How continents move
The reason why the continents move was established long ago. Experts note that the displacement of solid land is insignificant. In a year, the continents can move only one centimeter. However, the energy that is released during the course of such processes is much more than the network of power plants is able to generate. 
It has been established that glaciers also influence the movement of continents. In some places, the ice shell of Antarctica is able to push the surface of the earth's crust up to two and a half kilometers deep. As a result, the displacement of the continents is significantly slowed down.
Have continents always moved?
The movement of the earth's crust did not begin immediately, because at first our planet was a liquid molten ball. Gradually, the Earth cooled down, its surface was covered with a hard crust, and only after 500 million years the continents were formed. The resulting land cracked under the pressure of hot magma. This is how the future surface elements were formed. Those that were located higher began to form land. Part of the plates, due to the rather large weight, plunged deep into the planet and became oceanic. Under the influence of magma, the earth's crust moved. These processes lasted about 3 and a half billion years. Plates collided, rose and pressed through. As a result, the oceans, seas and continents that exist today were formed.
Continents are large areas of land that dominate the background of nearby archipelagos and islands. Of course, this is a general definition. If we consider the continents from the point of view of science, then these are not only land areas, but also the sea shelf, which is one with the mainland, but has long been hidden under water as a result of flooding. Often, children have questions, for example, why do continents move? Let's see if this is actually the case.
Liquid magma and solid land
To understand why the continents move, you should study the structure of the planet. So what is solid land? First of all, it is part of the earth's crust. Solid land is only a thin layer of various rocks that hide hot magma underneath. The thickness of the earth's crust can vary greatly. For example, under the ocean, the depth of solid rocks can be from 13 to 350 kilometers, and the depth of liquid magma can be almost 5,000 kilometers. The difference is, of course, significant.
Why is magma liquid? The main reason is the high temperature that is released as a result of flows in the core of the planet. The substance gets very hot. In this case, the movement of magma from the center to the earth's crust is observed, where the processes of its cooling take place. Convections are constantly observed in the liquid layer, which are recorded by satellite magnetometers. This phenomenon allows us to answer the question of why the continents move. A brief description of such processes allows us to fully imagine the picture of what is happening.
The main reason for the movement of the continents
So why do continents move? The answer to this question is quite simple. The convections occurring inside the magma are chaotic. Very often there is less activity in certain areas than in others. It is worth noting that the rise of magma proceeds under high pressure and very slowly. However, when such phenomena occur, a large amount of kinetic energy is released. All this has a certain effect on solid land.
Magma carries out cyclic movements. It pushes the surface fragments exactly in the direction where the momentum is present. That's why continents move. In other words, the surface displacement of solid land is associated with the processes that take place inside our planet right up to its very core.
How continents move
The reason why the continents move was established long ago. Experts note that the displacement of solid land is insignificant. In a year, the continents can move only one centimeter. However, the energy that is released during the course of such processes is much more than the network of power plants is able to generate.
It has been established that glaciers also influence the movement of continents. In some places, the ice shell of Antarctica is able to push the surface of the earth's crust up to two and a half kilometers deep. As a result, the displacement of the continents is significantly slowed down.
Have continents always moved?
It did not start right away, because at first our planet was a liquid molten ball. Gradually, the Earth cooled down, its surface was covered with a hard crust, and only after 500 million years the continents were formed. The resulting land cracked under the pressure of hot magma. This is how the future surface elements were formed. Those that were located higher began to form land. Part of the plates, due to the rather large weight, plunged deep into the planet and became oceanic. Under the influence of magma, the earth's crust moved. These processes lasted about 3 and a half billion years. Plates collided, rose and pressed through. As a result, the oceans, seas and continents that exist today were formed.