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.

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 of ancient Greece lived. 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 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, emitting hot gases and fiery liquid lava, and also forming numerous hot springs, constantly carry a lot of heat from the bowels of the earth to the surface, and this heat is lost irrevocably 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 highest mountains reach only 7–8 kilometers, then compared to the Earth they are insignificant wrinkles, much smaller than the wrinkles of the peel of a shriveled apple.

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 FOLDINGS TELL?

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 leaves of a book, that clearly show the folding formation 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 powerful force lifted them up and moved them from their place.

Rice. 8. Mountain folds.

Let's follow the same rock layer in a fold (Fig. 8). 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 - some are flat (Fig. 9, A), then steep (Fig. 9, b), sometimes with smooth bends, sometimes with fractures at an angle (Fig. 9, V). There are folds in which the bend is turned not up or down, but to the side; such folds are called recumbent (Fig. 9, G). Sometimes very complex folding results, which can also often be seen in the mountains (Fig. 9, d); it shows that in this place the earth's crust was compressed, wrinkled very much, and the folds bent, forming mountains.

Rice. 9. Various forms of folds: 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. 10). Such torn folds can be seen in the mountains; shifts sometimes reach enormous magnitude.

Rice. 10. Formation of shear due to fold rupture. The black straight line shows in which direction the shift occurred.

The bends of solid rocks are explained as follows. The layers now raised high in the mountains previously lay at great 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 Figure 10.

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, which crushed layered rocks into folds, other forces acted, raising molten masses from the depths of the earth from bottom to top, 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 breaks and movements of the earth's crust are called faults (Fig. 11); 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.

Rice. 11. Reset. The layers that make up one whole before the break are shaded equally.

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 with deep cracks created convenient paths for the 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 such areas where the earth's crust is strongly cut by cracks and where there are many volcanoes along the coast of the Pacific Ocean - there are long chains of fire-breathing mountains.

5. WHAT FORCES DID THE MOUNTAINS FORM?

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 Vecher. 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 tremors - 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 their compression in geosynclines, and the uplifting of folded strata from geosynclines and their transformation into mountain chains occurs during expansion that replaced compression.

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; in stable places, individual blocks move forward along the cracks of the ruptures. Periods of stretching of the earth's crust during the expansion of the Earth's core also cause various consequences: stable places are cut by new cracks, old cracks expand, 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.

A study of the structure of mountains in different countries has shown that periods of strong compression and folding occur on Earth almost simultaneously everywhere 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.

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 coasts are rising, in others they are lowering.

On the slopes of river valleys, so-called terraces are formed, i.e., steps that are formed due to the uplift of the terrain, which caused an increase in the slope of the river bed and therefore an increase in the erosive force of water and a new incision of the bed into the old sediments of the same river or into the bedrock of the valley. Finally, 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.

Studies have shown that, in general, the area of ​​the continents has increased significantly compared to the original.

Mountains differ not only in their height, variety of landscape, size, but also in origin. There are three main types of mountains: block, fold and dome mountains.

How block mountains are formed

The earth's crust does not stand still, but is in constant motion. When cracks or faults of tectonic plates appear in it, huge masses of rock begin to move not in the longitudinal, but in the vertical direction. Part of the rock may fall, while the other part adjacent to the fault may rise. An example of the formation of block mountains is the Teton mountain range. This ridge is located in the state of Wyoming. On the eastern side of the ridge you can see sheer rocks that rose when the earth's crust fractured. On the other side of the Teton Range is a valley that has dropped down.

How fold mountains form

The parallel movement of the earth's crust leads to the appearance of folded mountains. The appearance of folded mountains can best be seen using the example of the famous Alps. The Alps arose as a result of the collision of the lithospheric plate of the continent of Africa and the lithospheric plate of the continent of Eurasia. For several million years, these plates were in contact with each other under enormous pressure. As a result, the edges of the lithospheric plates were crushed, forming giant folds, which over time were covered with faults. This is how one of the most majestic mountain ranges in the world was formed.

How domed mountains are formed

Inside the earth's crust there is hot magma. Magma, breaking upward under enormous pressure, lifts the rocks that lie above. This results in a dome-shaped bend of the earth's crust. Over time, wind erosion exposes the igneous rock. An example of dome-shaped mountains is the Drakensberg Mountains, located in South Africa. More than a thousand meters high, weathered igneous rock is clearly visible in it.

Mountain systems are perhaps one of the most monumental and impressive creations of nature. When you look at the snow-covered peaks, lined up one after another for hundreds of kilometers, you can’t help but wonder: what kind of immense force created them?

Mountains always seem to people like something immutable, ancient, like eternity itself. But the data of modern geology perfectly demonstrate how changeable the relief is. Mountains can be located where the sea once splashed. And who knows which point on Earth will be the highest in a million years, and what will happen to the majestic Everest...

Mechanisms of mountain range formation

To understand how mountains are formed, you need to have a good understanding of what the lithosphere is. This term refers to the outer shell of the Earth, which has a very heterogeneous structure. On it you can find peaks thousands of meters high, the deepest canyons, and vast plains.

The earth's crust is formed by giant rocks that are in continuous motion and from time to time collide with their edges. This leads to the fact that certain parts of them crack, rise and change the structure in every possible way. As a result, mountains are formed. Of course, the change in the position of the plates occurs very slowly - only a few centimeters per year. However, it was precisely due to these gradual shifts that dozens of mountain systems were formed on Earth over millions of years.

The land has both sedentary areas (mostly large plains are formed in their place, such as the Caspian plain), and rather “restless” areas. Basically, ancient seas were once located on their territory. At a certain moment, a period of intense pressure and pressure of approaching magma began. As a result, the seabed, with all its diversity of sedimentary rocks, rose to the surface. So, for example, there arose

As soon as the sea finally “retreats”, the rock mass that appears on the surface begins to be actively affected by precipitation, winds and temperature changes. It is thanks to them that each mountain system has its own special, unique relief.

How are tectonic mountains formed?

Scientists believe the movement of tectonic plates is the most accurate explanation of how folded and block mountains are formed. When the platforms shift, the earth's crust in certain areas can be compressed, and sometimes even break, rising from one edge. In the first case, they are formed (some of their areas can be found in the Himalayas); another mechanism describes the emergence of blocky ones (for example, Altai).

Some systems feature massive, steep, but not too separated slopes. This is a characteristic feature of block mountains.

How are volcanic mountains formed?

The process by which volcanic peaks form is quite different from how fold mountains form. The name speaks quite clearly about their origin. Volcanic mountains arise where magma - molten rock - erupts to the surface. It can come out through one of the cracks in the earth's crust and accumulate around it.

In some parts of the planet, entire ridges of this type can be observed - the result of the eruption of several nearby volcanoes. Regarding how mountains are formed, there is also the following assumption: molten rocks, not finding a way out, simply press on the surface of the earth’s crust from the inside, as a result of which huge “bulges” appear on it.

A separate case is underwater volcanoes located at the bottom of the oceans. The magma that comes out of them can harden, forming entire islands. Countries such as Japan and Indonesia are located precisely on land areas of volcanic origin.

Young and ancient mountains

The age of the mountain system is clearly indicated by its relief. The sharper and higher the peaks, the later it was formed. Mountains that were formed no more than 60 million years ago are considered young. This group includes, for example, the Alps and the Himalayas. Research has shown that they arose about 10 million years ago. And although there was still a huge amount of time left before the appearance of man, in comparison with the age of the planet this is a very short period of time. The Caucasus, Pamir and Carpathians are also considered young.

An example of ancient mountains is the Ural ridge (its age is more than 4 billion years). This group also includes the North and South American Cordilleras and the Andes. According to some reports, the most ancient mountains on the planet are located in Canada.

Modern mountain formation

In the 20th century, geologists came to an unequivocal conclusion: enormous forces lie in the bowels of the Earth, and the formation of its relief never stops. Young mountains “grow” all the time, increasing in height by about 8 cm per year, ancient ones are constantly destroyed by wind and water, slowly but surely turning into plains.

A striking example of the fact that the process of changing the natural landscape never stops is the constantly occurring earthquakes and volcanic eruptions. Another factor influencing the process of how mountains are formed is the movement of rivers. When a certain area of ​​land rises, their channels become deeper and cut into the rocks more strongly, sometimes creating entire gorges. Traces of rivers can be found on the slopes of peaks, along with the remains of valleys. It is worth noting that the same natural forces that once formed their relief are involved in the destruction of mountain ranges: temperatures, precipitation and winds, glaciers and underground springs.

Scientific versions

Modern versions of orogeny (the origin of mountains) are represented by several hypotheses. Scientists put forward the following probable reasons:

• subsidence of oceanic trenches;
• drift (sliding) of continents;
• subcrustal currents;
• swelling;
• reduction of the earth's crust.

One version of how mountains are formed is associated with the action. Since the Earth is spherical, all particles of matter tend to be located symmetrically relative to the center. In addition, all rocks differ in mass, and the lighter ones over time are “pushed out” to the surface by the heavier ones. Together, these reasons lead to the appearance of irregularities in the earth's crust.

Modern science is trying to determine the underlying mechanism of tectonic change based on which mountains were formed as a result of which process. There are still many questions associated with orogenesis that still remain unanswered.

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.

Magma can also create entire islands, some of which are now states (for example, Japan, Indonesia, the Philippines). This was made possible by underwater volcanoes, which push magma to the surface of the water, where it solidifies. Cooled magma turns into granite, and the latter, in turn, is the main component in the formation of mountains. To be more precise, many mountains are made of this acidic igneous rock.
Such majestic mountains as the Alps, Himalayas, and Andes were formed in ancient times. They are folds of rock that have undergone a long process of mountain building from the bottom of ancient oceans until today. Now the above mountains are considered the great creation of “Mother Nature”.

fold mountains

According to scientists, the reason for the formation of folded mountains is the pressure that occurs when tectonic plates move.

Fold mountains are formed by gradually rising rocks that are located between the plates. That is, the plates move at a very low speed (about 2-3 cm per year), but their convergence causes the rocks (located on the outskirts of the plates) to rise upward. During this process, mountain ranges are formed.
When tectonic plates collide, heat is generated, which melts more fragile rocks and destroys (crushes) stronger ones. Next, such a mixture is pushed to the surface with the help of magma, which with enormous force tries to escape to the surface. The released consistency hardens and forms a granite core, which serves as the basis of folded mountains. Further, more and more new masses of rocks and magma are “superimposed” (stored) on this core.

The simplest mountain folds are anticlines (they are also called “domes”) and synclines (deflections). Some folds tip over (take a lying position), while others, on the contrary, move horizontally in relation to their base.

Examples of folded mountains include the mountains located in northern Greenland, Sweden and Scotland, Norway and Ireland, as well as the mountains of North America. All of them were formed at a time when North America and Europe were a single continent, and with the advent of the Atlantic Ocean this common mountain range was destroyed.