Volcanic mountains are all around us. Formation of mountains and their types. Modern mountain formation

Mountains are the most picturesque regions of the globe. Majestic and beautiful are the peaks of the Tien Shan, Caucasus, Alps, sparkling with eternal snow, and the inaccessible snow-white mountains of the Himalayas; The harsh ridges of the Urals are also beautiful, crowned with intricately weathered rocks rising like watchtowers, over the chaos of stone blocks; The green slopes and valleys of the Carpathians with fast-flowing rivers are beautiful.

Mountains attract people not only with their beauty. In their depths are hidden ore wealth, the extraction and use of which is associated with the cultural development of mankind. Fast mountain ones are a powerful source of energy. Clean mountain air and a variety of vegetables, which young mountains are especially rich in, restore the strength and health of sick and tired people.

You can get to know the structure of mountains quite well without laying boreholes or digging deep mines: the structure of mountains is revealed in gorges and on exposed slopes in river valleys.

Let's take a mental journey through the river valleys of the Northern Urals and get acquainted with the structure of this ridge. To cross the Northern Urals, you need to take a boat up one of the tributaries of the Pechora running from it, cross the mountain watershed on foot and go down on a raft along one of the rivers on the eastern slope belonging to the river basin. Obi. Along the banks of the Ural rivers there are picturesque rocks and exposed cliffs, or outcrops. You will see that they consist of sedimentary rocks: limestones, sandstones, conglomerates, clayey and siliceous shales. These rocks contain imprints and fossilized remains of extinct organisms; There are especially many of them in limestones.

Limestone deposits indicate that millions of years ago there was an open, shallow warm water, at the bottom of which marine animals with calcareous skeletons existed.

Sandstones with remains of marine organisms and with imprints of plants that are visible here were deposited in the area sea ​​coast or sea ​​islands, and sandstones and clays with remains of plants and freshwater - river or lake sediments. In the coastal outcrops of rivers on the western slope of the Urals, mainly layers of marine sediments appear.

The remains of organisms found in rocks make it possible not only to determine the conditions in which these rocks were formed, but also make it possible to determine which layers were deposited earlier and which later.

Geologists divide the history of the Earth into five major periods of time, or eras: Archaeozoic (era of ancient life), Proterozoic (era of primitive life), Paleozoic (era of ancient life), Mesozoic (era of middle life) and Cenozoic (era of new life). The duration of eras is measured in hundreds of millions of years. They, in turn, are divided into periods whose duration is measured in tens of millions of years.

The study of fossil remains of animals and plants found in the strata that make up the Ural ridge shows that they were deposited during the Paleozoic era of Earth's history. As you move east, layers of more and more ancient sediments from the Paleozoic era will appear in the coastal rocks of the Ural rivers.

Along the westernmost edge of the Urals, a strip of sediments formed in the last, Permian period of this era stretches from north to south. The rocks deposited at the beginning of the Permian period consist of sandstones, conglomerates and shales with marine fauna, and the sediments of the second half of the Permian period were formed not in the sea, but in rivers and lakes; they contain remains of plants, freshwater mollusks and fish, and in one outcrop on the shore of the Upper Pechora the bones of large extinct reptiles were found.

On Polar Urals, in the basin of the Pechora river tributary. Mustache, among the Permian deposits there are numerous layers of coal. Here in 1926 prof. A. A. Chernov discovered the richest Pechora coal basin. Within the Upper Pechora, Permian deposits do not contain coal at all. But deposits of rock salt and valuable potassium salts were discovered here.

The thickness of Permian deposits on the western slope of the Northern Urals is very large; it reaches several kilometers.

Further east of the strip of Permian rocks in the foothills of the western slope of the Urals stretches a strip of deposits of the Carboniferous period that preceded the Permian. This is mainly with the remains of marine animals. In these regions of the Urals, the places are especially picturesque. Looking closely at the water-smoothed surface of limestone, you can kind of look at the bottom of the Carboniferous, where you can see a variety of shells, large colonies of corals or entire layers of rocks consisting of segments of the stems of sea lilies and needles sea ​​urchins. Looking through a magnifying glass, you can see that it often consists entirely of tiny shells of rhizomes - foraminifera.

Among the sediments formed at the beginning of the Carboniferous period, in addition to limestone, there are layers of sandstone with plant remains, and in some places with layers of coal. This means that at that time there was a shallowing of the sea and in some places land appeared, covered with rich vegetation, which provided material for the formation of coal.

Behind the strip of Carboniferous limestone, an area of ​​more ancient deposits appears - the Devonian and then the Silurian periods. They also consist partly of limestone, partly of sandstone. Among them there are siliceous and - monuments from deeper areas of the sea.

Examining the Paleozoic rocks protruding along the banks of rivers, you will notice that the layers do not lie horizontally. Limestone layers in coastal cliffs usually tilt, or “dip,” in one direction or another at a smaller or larger angle to the horizon. Sometimes the layers stand vertically. These. inclined and vertical layers are parts of large, dilapidated folds. The sizes of the folds are very diverse: from the smallest, measured in centimeters, to the huge ones, tens of kilometers long, hundreds and thousands of meters wide. Such large folds can form high mountain ranges.

The most ancient and most altered sediments make up the main Ural ridge. Looking at the exposed rocks and scree on the peaks Ural mountains, you can see crystalline schists formed as a result of changes in sedimentary rocks, mica schists, and less often marbles. You can often see how these rocks are interbedded with greenschists of a different origin, formed due to the metamorphism of basaltic lavas.

It is believed that the ancient crystalline shales of the Urals belong to sediments of the Cambrian period and partly even of the Proterozoic era.

A number of peaks of the Ural Mountains consist of deep-seated igneous rocks: granites, gabbros, etc.

In the area of ​​​​the ancient shales of the mountain strip, especially where granites and gabbro are common, there are various ore deposits for which the Urals are so famous. There are lead and zinc ores, and a number of other metals.

On the eastern slope of the Urals, an area of ​​Paleozoic deposits opens up again. They will differ in abundance from sediments corresponding to their age on the western slope.

At the very edge of the eastern foothills of the Urals, on their border with the vast West Siberian Lowland, younger sediments formed during the Mesozoic and Cenozoic eras appear. These marine and continental sediments are covered by Quaternary rocks from the Ice Age. Unlike Paleozoic sediments, they lie horizontally.

What can be said about the origin of the Ural ridge based on what we saw while crossing it?

In what direction did the forces act that caused the folding? Oblique, overturned and recumbent folds in the mountains directly indicate in which direction the forces that crushed the layers acted. Such folds were undoubtedly formed under the influence of lateral, horizontal pressure. This pressure was most often one-sided, since in each mountainous region the folds usually overturn and lie in one predominant direction. On the western slope of the Urals, the folds are inclined and overturned to the west under the influence of pressure that came from the east. A straight fold can arise as a result of pressure both from the bottom up and acting from the sides, in the horizontal direction. This can be easily verified by simple experiment. If you put a stack of sheets of paper on the table, place a stick under it and lift it, the paper will bend; and forms a straight line anticlinal fold. The same fold can be obtained by carefully squeezing sheets of paper lying on the table from both sides with your hands. As you can see, folds are formed as a result of disruption of the original occurrence of layers. Such disturbances in the occurrence of earth layers are called dislocations.

As you can see, the Ural ridge is composed of a thick layer of sedimentary rocks of Paleozoic age and almost exclusively of marine origin. Among the latter, in the mountain strip and on the eastern slope there are many erupted volcanic rocks. This indicates that in the place of the Urals in the Paleozoic there was a sea, at the bottom of which underwater eruptions and powerful outpourings of lavas occurred.

The thickness of Paleozoic deposits in the Urals is great; it reaches 10-12 km. How could a sediment layer of such enormous thickness be formed? This can only be explained by the fact that in the area of ​​the sea basin located on the site of the present Urals, as sediment accumulated, the seabed sank.

At the end of the Paleozoic era, layers that had been deposited over many millions of years were folded and powerful rocks rose from the bottom of the Ural Sea. mountain ranges. Particularly significant uplifts occurred in the area of ​​the current mountain strip.

The folds, which can be found in many outcrops of the Urals, have a rather complex structure. Geologists have long been interested in the conditions under which they form. For bending of thick layers of sandstones and limestones to occur, the rocks had to be in a particularly pliable, plastic state. On the surface of the earth, these rocks under the conditions familiar to us are rigid: they are not capable of giving smooth bends and must crack under the pressure of the internal forces of the Earth. Rocks acquire plasticity in the depths of the earth’s crust, so geologists concluded that folds, forming mountains, arise in the deep bowels of the Earth.

The formation of the Ural Mountains was accompanied by the introduction of molten water, which formed slowly cooling underground chambers. From these cooling centers, hot vapors and hot solutions rose and penetrated into the cracks of the surrounding rocks. The formation of those ore deposits and precious stones, for which the Urals are famous. The destruction of the Ural ridge, which has continued for many millions of years, has revealed batholiths frozen in the depths, which are now protruding to the surface.

Getting acquainted with the history of the formation of the Urals, one can be convinced that in its place during the Paleozoic era there was an area of ​​​​long-term subsidence, flooded. At the bottom of this sea, thick layers of sediment accumulated, capable of being crushed into folds. Such areas are called geosynclines. At the end of the Paleozoic (in the Permian period) and at the beginning of the Mesozoic (in the Triassic), large mountain-building processes took place in the Ural geosyncline and high mountain ranges arose.

The emergence of mountains in place of geosynclines is the basic law of mountain formation, which is confirmed by the study of any mountainous country.

After the processes of folding, intrusion of molten magma and mountain uplift are completed, the geosyncline changes its properties. It turns into a more stable, rigid region of the earth's crust, where folds can no longer appear, and under the pressure of mountain-building forces, the rocks split, cracks appear, along which the movement of layers is observed. This is how faults, grabens and horsts are formed. Regions of the Earth that are not capable of collapse are called platforms. They show slow uplifts of vast spaces, followed by slow downturns. The advances and retreats of the sea are associated with these fluctuations.

Fractures on platforms, leading to the formation of faults, occur under the influence of pressure coming from geosynclines. In some cases, the movement of faults reaches a large scale: horsts arise, raised to a height of 3-4 km. Fault ruptures still occur in many mountains on Earth. In the mountains Central Asia, for example, are often associated with ruptures of earth layers and the formation of faults.

Horst uplifts lead to the formation of mountain ranges in place of platforms. These mountains are called blocky(reborn), unlike folded(Urals, Caucasus, Alps), where folding processes play a major role.

The height of mountains is measured from sea surface level. So the height of Mount K-2 (8616 m) is equal to the distance from its peak to this level.

The Earth's crust is made up of 17 separate parts called tectonic plates. They fit together like pieces of a mosaic. These plates “float” on the surface of the magma, move apart or move towards each other. When plates collide, earthquakes occur and mountain ranges are formed. Moving plates compress rocks, they bend into folds and form folded mountains. Sometimes cracks appear in the crust, and huge blocks of rock - horsts - come to the surface. This is how horst mountains are formed.

Cones and domes

Pouring out from the vent, the magma hardens and forms a cone-shaped mountain. Sometimes, rising from the bowels of the earth, it only swells plastic rocks above itself, like a bubble, and forms dome-shaped mountains.

fold mountains

The Himalaya mountain range was formed as a result of the collision of India, which at that time was an island, with the plate on which Asia is located. The collision of the African plate with the Eurasian plate gave rise to mountain systems such as the Alps, Apennines, Pyrenees and Atlas Mountains.

Gorst Mountains

The Sierra Nevada mountain range in North America is made up of horst mountains

What is a valley

A valley is a trough-shaped depression located between the slopes of the mountains. It is formed by and sliding down. The shape of a valley depends on its origin.

Glacial valleys, formed by slow-moving glaciers, are U-shaped, with steep sides and flat bottoms.

River valleys formed by rivers and water streams are shaped like the Latin letter “V”: their slopes are flatter and their bottoms are narrow.

1. Legends about the formation of mountains
The question of how mountains were formed occupied people already in ancient times, but they could not answer it, since they knew too little about the composition and structure of the earth’s crust. Therefore, they thought that the masses supporting the clouds were created by gods or spirits. People believed that the gods built mountains in order to support the firmament. We have already talked about Mount Olympus, on which, according to legend, the gods lived ancient Greece. People also thought that mountains were not fixed to one place and that the gods could take them and throw them at each other during their battles.
The inhabitants of Kamchatka have the following legend about Mount Shiveluch. This mountain is a volcano; it stands completely apart from other volcanoes of Kamchatka. Local Kamchadal residents believe that once this volcano was located among other volcanoes on the site of the current Kronotsky Lake. But the marmots, which were found in abundance in this area, so disturbed the volcano by digging their holes on its slopes that he finally decided to leave them. The volcano broke away from the ground, leaving behind a large depression in which water later accumulated and a lake was formed. The volcano flew north, but during its flight it caught on the top of a neighboring mountain and broke it off, and as it descended to the ground, it squeezed out depressions for two more lakes before settling on a place 220 kilometers from the old one. In this new place the volcano strengthened forever.
Many peoples have similar legends about the formation of mountains. They, of course, have nothing to do with the actual formation of mountains.

2. Mountains - wrinkles of the cooling Earth
Many people compare the mountains on Earth to the wrinkles that form on the peel of a drying apple or potato. Sometimes they say that the mountains on Earth arose in exactly the same way as these wrinkles.
This is not entirely true. The earth does not dry out, but decreases in volume, because it is constantly cooling and cooling down. This cooling began even when the substance that makes up the Earth began to condense into a ball of hot gases, and then into a fiery liquid ball; it continued, although more slowly, after the formation of the solid earth's crust and is also happening at the present time. Volcanoes, which emit hot gases and fiery liquid lava, and also form numerous hot springs, constantly carry a lot of heat from the bowels of the earth to the surface, and this heat is lost irretrievably to the Earth; The heat that the sun's rays give to the Earth penetrates deep into the earth's crust only a few meters. Thus, the Earth loses more heat than it receives, and therefore slowly cools.
Volcanic eruptions, hot springs, and observations in boreholes and deep mines show that the temperature of rocks increases noticeably as one goes deeper into the earth's crust. This proves that there is still a lot of heat preserved in the bowels of the Earth, and this heat continues to be consumed. But, as you know, every body decreases in volume when it cools; The earth's core (the inner part of the globe) is also shrinking. Therefore, the earth's crust, adapting to the shrinking core, must wrinkle, its layers form folds-wrinkles, which represent mountain ranges. If we remember that the diameter of the globe is approximately 13 thousand kilometers, and the most high mountains reach only 7–8 kilometers, then compared to the Earth they are completely insignificant wrinkles, much smaller than the wrinkles of the peel of a shriveled apple compared to its size.
This explanation for the formation of mountains is still very common among scientists; it is, in general, correct, but not enough. The formation of mountains is more complex than just described. It will become clear to us if we become more familiar with the structure of these “wrinkles” or, as scientists call them, folds of the earth’s crust.

3. What do the mountain folds tell you?
Folds can be very clearly seen and studied on the slopes of mountains and hills, in gorges, on steep cliffs of the banks of rivers, lakes and seas - in general, almost everywhere where layers of sedimentary rocks protrude. It is precisely such rocks, consisting of separate regular layers lying on top of each other like the pages of a book, that clearly show the folding of mountains. The layers were originally formed in water at the bottom of some reservoir and, when formed, lay flat - horizontally or with a very gentle slope in one direction or another. But in the mountains we see that these layers are inclined steeply or even stand vertically - “put on their heads.” This means that some terrible force lifted them up and moved them from their place.
Let's follow the same rock layer in a fold (Fig. 10). We will see that it rises up, gradually bends, forming an arch, then falls down, then rises up again. And all the other layers lying under and above it repeat the same movement. Sometimes such a fold is completely isolated, lonely, but usually one fold is followed by others. The shapes of the folds are different - sometimes flat (Fig. 11, a), sometimes steep (Fig. 11, b), sometimes with smooth bends, sometimes with fractures at an angle (Fig. 11, c). There are folds in which the bend is turned not up or down, but to the side; such folds are called recumbent (Fig. 11, d). Sometimes very complex folding results, which can also often be seen in the mountains (Fig. 11, e); it shows that in this place the earth's crust was compressed, wrinkled very much, and the folds bent, forming mountains.

Various fold shapes:
a - flat; b - steep; c - with a sharp fracture; g - recumbent; d - complex

The reader, who has never been to the mountains and has not seen these folds with his own eyes, will say with disbelief: this cannot be! Layers of such hard rocks as sandstones, limestones, shales are not paper, not cloth, not leather, which can be bent in any way you like. Scientists used to think so and therefore believed that the folds were formed at a time when the rocks were still soft and consisted of sand, clay, and silt. But the study of mountains showed that rocks actually bent in a solid state. This is evident from the fact that the layers suffered greatly during bending - they are torn by small cracks, in some places even crushed, and parts of the broken layers are often moved away from each other (Fig. 12). Such torn folds can be seen in the mountains; shifts sometimes reach enormous magnitude.

The bends of solid rocks are explained as follows. The layers now raised high in the mountains previously lay at shallow depths and were under the pressure of all the layers lying above. And under strong pressure, even solid bodies can change their shape. For example, lead under strong pressure can flow through a narrow hole in a stream, like water, and thick sheets of iron, steel, and copper bend like a sheet of paper. Glass and ice are very fragile bodies, but they can also be bent without breaking if you press on them very slowly and gradually. Deep in the earth's crust, rocks could bend very strongly, rupturing only slightly; Of course, these bends happened very slowly. But when the pressure force was already too great, the fold broke in one place or another and parts of it moved towards each other, as we saw in Fig. 12.

4. Crustal faults
Fractures of rock layers occurred not only from the pressure of the upper layers on the lower ones. In addition to these pressure forces that crushed layered rocks and folds, other forces acted that lifted molten masses from the depths of the earth from the bottom up to the surface of the Earth. They tore the earth's crust with large cracks, along which one side rose up or the other went down. Such ruptures and movements of the earth's crust are called faults (Fig. 13); they can often be seen in the mountains and in mines, both next to folds and in areas where there are no folds. Faults are well known to both the miner and the coal miner from bitter experience. When he encounters a crack along which a displacement has occurred, he sees that a seam of coal or a vein with ore behind the crack suddenly disappears, as if cut off, and the face rests on waste rock. The missing continuation of a layer or vein has to be looked for at the top, bottom or side.

During faults, sometimes entire sections, huge blocks of the earth's crust move; they also form mountains, but these mountains are of a different type than those resulting from the formation of folds.
Breaks in the earth's crust deep cracks created convenient ways for molten masses located at depth to rise upward; An easier road was prepared for them along the cracks of the gaps. The molten masses used this road and penetrated the surface of the Earth, creating volcanoes, or stopped at a certain depth, where they solidified, forming massifs of deep rocks. That is why along large cracks that cut through the earth’s crust, we especially often see extinct and active volcanoes. We see areas where the earth's crust is heavily cracked and where there are many volcanoes along the coast. Pacific Ocean, - there, from New Zealand to Kamchatka and from Alaska to Tierra del Fuego, a long chain of fire-breathing mountains stretches.

5. What forces formed the mountains?
Now we know how the mountains were formed, how they rose to the top. It remains to answer the question - what forces created these irregularities on the surface of the continents?
There are several scientific assumptions (or, as scientists call them, hypotheses) about the reasons for the formation of mountains. We will not consider all these hypotheses here - that would take a lot of time. We will limit ourselves to presenting one hypothesis proposed by the Soviet scientist Usov and the American geologist Becher. This hypothesis is called “pulsating” from the word “pulsate”, i.e. act in jerks. It is as follows.
It is well known that all bodies expand when heated and contract when cooled. This also applies to the particles of substances that make up the Earth.
Since the globe is cooling all the time, its particles are compressed and attracted to each other. This compression causes the particles to move faster; Scientists have found that such an increase in movement leads to an increase in temperature, to heating of bodies. And this heating causes the expansion of bodies and the repulsion of particles from each other. Thus, in the bowels of the Earth, from the beginning of its formation to the present day, there has been a struggle between the forces of attraction and repulsion of particles. As a result of this struggle, the solid earth's crust vibrates, and all those irregularities that we talked about are created on its surface. According to the Usov-Becher theory, compression and expansion do not occur simultaneously, but alternately, in the form of shocks - the earth’s interior “pulsates”. A sharp contraction is usually followed by a more or less sharp expansion. The folding of rocks is caused by compression, and faults and the penetration of molten masses into them are a consequence of expansion.
In the earth's crust, periods (times) of compression are expressed in different ways in different parts of it: in geosynclines, where thick layers of sedimentary rocks have accumulated, compression creates strong and complex folding.
On stable platforms, individual blocks move forward along fault cracks, as well as weaker folding of less thick strata of sedimentary rocks formed on land in lakes and shallow internal and coastal seas, and a gentle upward arching of individual more or less large areas.
Periods of stretching of the earth's crust during the expansion of the Earth's core also cause various consequences: platforms are cut by new rupture cracks, old cracks widen, and through both of them volcanic rocks pour out onto the surface; individual blocks and areas rise. In geosynclines, strata of sedimentary rocks, strongly compressed during the period of compression, bulge upward and form mountain chains, and through cracks, molten masses penetrate into these strata from the depths and form massifs and veins of deep rocks, partly also reaching the surface and creating volcanoes.
Next to the old geosynclines, extended in the form of mountain systems, on the outskirts of the platforms, trough-shaped depressions are often formed in the stretched crust, which then often turn into new geosynclines.
Studying the structure of mountains in different countries showed that periods of strong compression and folding occur almost simultaneously everywhere on Earth and consist of several separate shocks, separated from each other by times of comparative rest. A lot of time passes from one shock to the next.
But even in these intervals between shocks, the earth’s crust does not remain completely at rest, since compression shocks are replaced by expansion shocks, and each shock begins and ends with weaker movements of the earth’s crust, indicating the ongoing struggle of forces of attraction and repulsion in the bowels of the Earth.
The last strong movements on Earth occurred, as scientists have established, more than a million years ago.
Currently, the Earth is experiencing a quieter period, but accurate observations have shown that weak movements of the earth's crust are still continuing. By measuring the level of the oceans, scientists have found that in some places the coastlines are rising, in others they are lowering.
On the slopes of river valleys, so-called terraces are formed, i.e. steps that are caused by the elevation of the terrain. Strong earthquakes that occur in different countries from time to time are undoubtedly caused by a sudden displacement of strata deep in the crust, and from time to time repeated eruptions of the same volcano prove that weak movements of the earth's crust are still occurring.
At the site of internal and coastal geosynclines, mountains appear, which join the continents and increase their size; this is repeated at each period of expansion, so that during such past periods the continents gradually grew larger.
On the other hand, large areas of the earth's crust may sink below ocean level and be flooded by the sea; near the mountain range that has risen from the geosyncline, a new depression is formed, which can also be flooded with water. The sea advances on land and retreats when the earth's crust rises and geosynclines transform into mountain structures. So there is a constant struggle between land and water.
Research has shown that in total area continents has increased significantly compared to the original.

Once upon a time, mountains were considered a dangerous and forbidden place, but they have always attracted people with their mystery and mystery. In recent times, almost all the secrets and mysteries have been revealed and humanity can safely answer the question: “How were the mountains formed?” This became possible thanks to the study of lithospheric plate tectonics. Let's look at two methods of formation and origin of mountains (volcanic and folded), as well as the processes of their destruction and deformation.

Volcanic mountains

The origin of the volcanic mountains speaks for itself. Volcanic magma, seeking to fill areas of divergence of tectonic plates, breaks out and forms new rocks. These rocks accumulate around the chasm over time and become cone-shaped, with craters at the top. Sometimes several located close to each other unite, thereby forming volcanic ridges.

fold mountains

Mountains occupy 24% of the land surface. They are also found at the bottom of the World Ocean. 10% of the human race who live in mountainous area, are slightly puzzled by the reasons for the appearance of such “giants”. Moreover, when the next earthquake occurs. Naturally, if the mountains are young, they are prone to tectonism, volcanism and seismism.

How mountains are formed - all versions

Each people living in the mountains created their own legend about mountain formation. The popular version is that these are giant people, frozen or punished for what they have done by higher powers. From time to time they come to life, demonstrating their bad character

Fortunately, today we have full list reasons for the formation of mountains, so the fear of this form of relief can be left only to those who violate safety regulations during trekking, mountain hiking, and mountaineering. Let's explore together the question of how mountains are actually “born.” Please note that genesis mountain system became the key classifier of this landform.

Types of mountain building

fold mountains

The first option, folded mountains, were the result of the work of the internal forces of the Earth. The discussed relief form is obtained in the event of a convergence (collision) of two lithospheric plates. The most striking example is the “cutting” of the Indo-Australian plate into the Eurasian plate, as a result of which the earth’s crust folded into folds, forming the Himalayas.

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Interesting facts about mountains

As a bonus, we can recall the Alps, which resulted from the interaction of the African-Arabian platform with the same Eurasian one.

Or the Cordillera, resulting from the “collision” of the North American plate onto a plate lying under the water masses of the Pacific Ocean. The “design” of fold mountains is several rows of mountain ranges running parallel to one another. With a developed imagination or while flying on an airplane, you can “see” how the earth’s crust folded into folds, forming modern mountain systems.

Block-fold mountains

Another option for the formation of mountains is two-phase tectonism. In the first phase we get typical folded mountains. The process is familiar - described above. But! A mountain range can be long. And the earth's crust is everywhere divided into blocks. Which can move up and down, regardless of the general movement of the platform. Therefore, in the second phase of this type of mountain building, the long, long mountain range is broken into fragments. One begins to slowly move up, the other - down, the third - also down, but at a different speed.