Together with part of the upper mantle, it consists of several very large blocks, which are called lithospheric plates. Their thickness is different - from 60 to 100 km. Most plates include both continental and oceanic crust. There are 13 main plates, of which 7 are the largest: American, African, Indo-, Amur.

The plates lie on the plastic layer of the upper mantle (asthenosphere) and slowly move relative to each other at a speed of 1-6 cm per year. This fact was established by comparing photographs taken with artificial satellites Earth. They suggest that the configuration in the future may be completely different from the current one, since it is known that the American lithospheric plate is moving towards the Pacific, and the Eurasian one is approaching the African, Indo-Australian, and also the Pacific. The American and African lithospheric plates are slowly moving apart.

The forces that cause the separation of lithospheric plates arise when the mantle substance moves. Powerful ascending flows of this substance push apart the plates, break the earth's crust, forming deep faults in it. Due to underwater outpourings of lavas, strata are formed along the faults. Freezing, they seem to heal wounds - cracks. However, the stretch increases again, and breaks occur again. So, gradually increasing lithospheric plates diverge in different directions.

There are fault zones on land, but most of them are in ocean ridges on where the earth's crust is thinner. The largest fault on land is located in the east. It stretched for 4000 km. The width of this fault is 80-120 km. Its outskirts are dotted with extinct and active ones.

Collision is observed along other plate boundaries. It happens in different ways. If the plates, one of which has an oceanic crust and the other a continental one, approach each other, then the lithospheric plate, covered by the sea, sinks under the continental one. In this case, arcs () or mountain ranges(). If two plates that have a continental crust collide, then there is a collapse into folds. rocks the edges of these plates, and the formation of mountainous regions. So they arose, for example, on the border of the Eurasian and Indo-Australian plates. The presence of mountainous areas in internal parts the lithospheric plate suggests that once there was a boundary between two plates, firmly soldered to each other and turned into a single, larger lithospheric plate. Thus, we can draw a general conclusion: the boundaries of lithospheric plates are mobile areas to which volcanoes are confined , zones, mountainous areas, mid-ocean ridges, deep-sea depressions and trenches. It is at the boundary of lithospheric plates that are formed, the origin of which is associated with magmatism.

Lithospheric plates are large blocks earth's crust and parts of the upper mantle that make up the lithosphere.

What is the composition of the lithosphere.

At this time, on the boundary opposite from the fault, collision of lithospheric plates. This collision can proceed in different ways depending on the types of colliding plates.

• If the oceanic and continental plates collide, the first sinks under the second. In this case, deep-sea trenches, island arcs (Japanese islands) or mountain ranges (Andes) arise.
• If two continental lithospheric plates collide, then at this point the edges of the plates are crumpled into folds, which leads to the formation of volcanoes and mountain ranges. Thus, the Himalayas arose on the border of the Eurasian and Indo-Australian plates. In general, if there are mountains in the center of the mainland, this means that once it was a place of collision of two lithospheric plates welded into one.

Thus, the earth's crust is in constant motion. In her irreversible development mobile areas - geosynclines- are transformed through long-term transformations into relatively calm areas - platforms.

Lithospheric plates of Russia.

Russia is located on four lithospheric plates.

• Eurasian plate- most of the western and northern parts of the country,
• North American Plate- northeastern part of Russia,
• Amur lithospheric plate- south of Siberia,
• Sea of ​​Okhotsk plate The Sea of ​​Okhotsk and its coast.

Fig 2. Map of the lithospheric plates of Russia.

In the structure of lithospheric plates, relatively even ancient platforms and mobile folded belts stand out. Plains are located on stable areas of the platforms, and mountain ranges are located in the region of folded belts.

Fig 3. Tectonic structure of Russia.

Russia is located on two ancient platforms (East European and Siberian). Within the platforms stand out plates and shields. A plate is a section of the earth's crust, the folded base of which is covered with a layer of sedimentary rocks. Shields, in contrast to slabs, have very little sedimentary deposits and only a thin layer of soil.

In Russia, the Baltic Shield is distinguished on the East European Platform and the Aldan and Anabar Shields on the Siberian Platform.

Figure 4. Platforms, slabs and shields in Russia.

Plate tectonics- modern geological theory about the movement and interaction of lithospheric plates.
The word "tectonics" comes from the Greek "tecton" - "builder" or "a carpenter", In tectonics, giant blocks of the lithosphere are called plates.
According to this theory, the entire lithosphere is divided into parts - lithospheric plates, which are separated by deep tectonic faults and move along the viscous layer of the asthenosphere relative to each other at a speed of 2-16 cm per year.
There are 7 large lithospheric plates and about 10 smaller plates (the number of plates in different sources is different).

When lithospheric plates collide, the earth's crust is destroyed, and when they diverge, a new one is formed. At the edges of the plates, where the tension inside the Earth is the strongest, various processes occur: strong earthquakes, volcanic eruptions and the formation of mountains. It is at the edges of the lithospheric plates that the largest landforms are formed - mountain ranges and deep-sea trenches.

Why do lithospheric plates move?
The direction and movement of lithospheric plates is influenced by internal processes occurring in the upper mantle - the movement of matter in the mantle.
When lithospheric plates diverge in one place, then in another place their opposite edges collide with other lithospheric plates.

Convergence (convergence) of oceanic and continental lithospheric plates

A thinner oceanic lithospheric plate “dives” under a powerful continental lithospheric plate, creating a deep depression or trench on the surface.
The area where this happens is called subductive. Plunging into the mantle, the plate begins to melt. The crust of the upper plate is compressed and mountains grow on it. Some of them are volcanoes formed by magma.

Lithospheric plates

Then surely you would like to know what are lithospheric plates.

So, lithospheric plates are huge blocks into which the solid surface layer of the earth is divided. Given the fact that the rocks beneath them are melted, the plates move slowly, at a speed of 1 to 10 centimeters per year.

To date, there are 13 largest lithospheric plates that cover 90% of the earth's surface.

The largest lithospheric plates:

• australian plate- 47,000,000 km²
• Antarctic Plate- 60,900,000 km²
• Arabian subcontinent- 5,000,000 km²
• African plate- 61,300,000 km²
• Eurasian plate- 67,800,000 km²
• Hindustan plate- 11,900,000 km²
• Coconut Plate - 2,900,000 km²
• Nazca Plate - 15,600,000 km²
• Pacific Plate- 103,300,000 km²
• North American Plate- 75,900,000 km²
• Somali plate- 16,700,000 km²
• South American Plate- 43,600,000 km²
• Philippine plate- 5,500,000 km²

Here it must be said that there is a continental and oceanic crust. Some plates are composed entirely of one type of crust (such as the Pacific Plate), and some are mixed types when the plate starts in the ocean and smoothly transitions to the continent. The thickness of these layers is 70-100 kilometers.

Map of lithospheric plates

The largest lithospheric plates (13 pcs.)

At the beginning of the 20th century, the American F.B. Taylor and the German Alfred Wegener simultaneously came to the conclusion that the location of the continents is slowly changing. By the way, this is exactly what, to a large extent, is. But scientists could not explain how this happens until the 60s of the twentieth century, when the doctrine of geological processes on the seabed was developed.

Map of the location of lithospheric plates

It was the fossils that played the main role here. On different continents, fossilized remains of animals were found that clearly could not swim across the ocean. This led to the assumption that once all the continents were connected and animals calmly passed between them.

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What do we know about the lithosphere?

Tectonic plates are large stable areas of the Earth's crust that are constituent parts lithosphere. If we turn to tectonics, the science that studies lithospheric platforms, we learn that large areas of the earth's crust are limited on all sides by specific zones: volcanic, tectonic and seismic activities. It is at the junctions of neighboring plates that phenomena occur, which, as a rule, have catastrophic consequences. These include both volcanic eruptions and strong earthquakes on the scale of seismic activity. In the process of studying the planet, platform tectonics played a very important role. Its significance can be compared to the discovery of DNA or the heliocentric concept in astronomy.

If we recall the geometry, then we can imagine that one point can be the point of contact of the boundaries of three or more plates. The study of the tectonic structure of the earth's crust shows that the most dangerous and rapidly collapsing are the junctions of four or more platforms. This formation is the most unstable.

The lithosphere is divided into two types of plates, different in their characteristics: continental and oceanic. It is worth highlighting the Pacific platform, composed of oceanic crust. Most of the others consist of the so-called block, when the continental plate is soldered into the oceanic one.

The location of the platforms shows that about 90% of the surface of our planet consists of 13 large, stable areas of the earth's crust. The remaining 10% fall on small formations.

Scientists have compiled a map of the largest tectonic plates:

• Australian;
• Arabian subcontinent;
• Antarctic;
• African;
• Hindustan;
• Eurasian;
• Nazca plate;
• Cooker Coconut;
• Pacific;
• North and South American platforms;
• Scotia plate;
• Philippine plate.

From theory, we know that the solid shell of the earth (lithosphere) consists not only of the plates that form the relief of the surface of the planet, but also of the deep part - the mantle. Continental platforms have a thickness of 35 km (in the flat areas) to 70 km (in the zone of mountain ranges). Scientists have proven that the plate in the Himalayas has the greatest thickness. Here the thickness of the platform reaches 90 km. The thinnest lithosphere is found in the ocean zone. Its thickness does not exceed 10 km, and in some areas this figure is 5 km. Based on information about the depth at which the epicenter of the earthquake is located and what is the speed of propagation of seismic waves, calculations are made of the thickness of the sections of the earth's crust.

The process of formation of lithospheric plates

The lithosphere is composed primarily of crystalline substances, formed as a result of cooling of magma at the exit to the surface. The description of the structure of the platforms speaks of their heterogeneity. The process of formation of the earth's crust took place over a long period, and continues to this day. Through microcracks in the rock, molten liquid magma came to the surface, creating new bizarre forms. Its properties changed depending on the change in temperature, and new substances were formed. For this reason, minerals that are at different depths differ in their characteristics.

The surface of the earth's crust depends on the influence of the hydrosphere and atmosphere. There is constant weathering. Under the influence of this process, the forms change, and the minerals are crushed, changing their characteristics with the same chemical composition. As a result of weathering, the surface became looser, cracks and microdepressions appeared. In these places deposits appeared, which we know as soil.

Map of tectonic plates

At first glance it seems that the lithosphere is stable. Its upper part is such, but the lower part, which is distinguished by viscosity and fluidity, is mobile. The lithosphere is divided into a certain number of parts, the so-called tectonic plates. Scientists cannot say how many parts the earth's crust consists of, since in addition to large platforms, there are also smaller formations. The names of the largest plates were given above. The process of formation of the earth's crust is ongoing. We do not notice this, since these actions occur very slowly, but by comparing the results of observations for different periods, you can see how many centimeters per year the boundaries of formations are shifting. For this reason, the tectonic map of the world is constantly updated.

Tectonic Plate Cocos

The Cocos platform is a typical representative of the oceanic parts of the earth's crust. It is located in the Pacific region. In the west, its boundary runs along the ridge of the East Pacific Rise, and in the east its boundary can be determined by a conditional line along the coast. North America from California to the Isthmus of Panama. This plate is subducting under the neighboring Caribbean plate. This zone is characterized by high seismic activity.

Mexico suffers the most from earthquakes in this region. Among all the countries of America, it is on its territory that the most extinct and active volcanoes are located. The country has suffered a large number of earthquakes with a magnitude greater than 8 points. The region is quite densely populated, therefore, in addition to destruction, seismic activity also leads to a large number victims. Unlike Cocos, located in another part of the planet, the Australian and West Siberian platforms are stable.

Movement of tectonic plates

For a long time, scientists have been trying to figure out why one region of the planet has mountainous terrain, while another is flat, and why earthquakes and volcanic eruptions occur. Various hypotheses were built mainly on the knowledge that was available. Only after the 50s of the twentieth century was it possible to study the earth's crust in more detail. Mountains formed at the sites of plate faults were studied, chemical composition these plates, and also created maps of regions with tectonic activity.

In the study of tectonics, a special place was occupied by the hypothesis of the displacement of lithospheric plates. Back in the early twentieth century, the German geophysicist A. Wegener put forward a bold theory about why they move. He carefully studied the outline of the west coast of Africa and the east coast South America. The starting point in his research was precisely the similarity of the outlines of these continents. He suggested that, perhaps, these continents used to be a single whole, and then a break occurred and the shift of parts of the Earth's crust began.

His research touched upon the processes of volcanism, the stretching of the surface of the ocean floor, the viscous-liquid structure the globe. It was the works of A. Wegener that formed the basis of the research conducted in the 60s of the last century. They became the foundation for the emergence of the theory of "lithospheric plate tectonics".

This hypothesis described the model of the Earth as follows: tectonic platforms with a rigid structure and different masses were placed on the plastic substance of the asthenosphere. They were in a very unstable state and were constantly moving. For a simpler understanding, we can draw an analogy with icebergs that are constantly drifting in ocean waters. Similarly, tectonic structures, being on a plastic substance, are constantly moving. During displacements, the plates constantly collided, came one on top of the other, joints and zones of separation of the plates arose. This process was due to the difference in mass. Areas of increased tectonic activity were formed at the collision sites, mountains arose, earthquakes and volcanic eruptions occurred.

The displacement rate was no more than 18 cm per year. Faults formed, into which magma entered from the deep layers of the lithosphere. For this reason, the rocks that make up the oceanic platforms are of different ages. But scientists have put forward an even more incredible theory. According to some representatives scientific world, magma came to the surface and gradually cooled, creating a new bottom structure, while the "excess" of the earth's crust, under the influence of plate drift, sank into the earth's interior and again turned into liquid magma. Be that as it may, the movements of the continents occur in our time, and for this reason new maps are being created to further study the process of drifting tectonic structures.