What causes mountains to form. How mountains are formed, methods of mountain formation. Young and ancient mountains
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 time before the advent of man great amount time, compared to 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 - 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 clear example of the process of change natural landscape never stops - 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 in destruction mountain ranges The same natural forces that once shaped their relief are involved: 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 how the Alps, Himalayas, 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. This process produces mountain ranges.
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 Atlantic Ocean this common mountain range was destroyed.
Instructions
Scientists have long established that mountains appear in places where intense movements of the earth's plates occur. Many millions of years ago, tectonic plates crawled on top of each other and were compressed under enormous pressure into giant folds, breaking into cracks and faults. Thus, folded mountains, an example of which are the Appalachians, which have already lost their original height, and most of Alps
Vaulted or dome-shaped mountains arose in a slightly different way. These layers of rocks were bent upward by molten lava, which, under great pressure, rushed to the surface of the Earth. On these today you can see intruded masses of igneous rocks. An example of this is the Black Hills, located in the US state of Dakota.
Solid, or, as they are also called, block mountains, appeared as a result of failures or faults in the earth’s crust. Giant blocks began to move along the fault, falling inward or rising upward. This is how the Teton Range and the Sierra Nevada chain in America appeared.
Some single mountains, having a beautiful conical and symmetrical shape, were formed at the site of the volcano. During its eruption, magma, ash, and dirt settled on the surface. Over time, the lava solidified, forming a small hill, which became higher with each volcanic eruption. In a similar way it was formed beautiful mountain Fuji in Japan or Vesuvius in Italy. They are easily recognized by their cut off top, where the volcano's mouth is located.
Despite the apparent solidity and inviolability of the mountains, they tend to change and even change. Their soil is often washed away by streams of water and rain, and their slopes are destroyed by frozen water. Over time, even the peaks can turn into small hills and even, although this will take many millions of years.
The most beautiful Mountain peaks, which thousands of tourists come to see, seem unique. Formed a thousand years ago, they still change their appearance to this day.
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. WITH east side The ridge shows 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 dome-shaped 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.
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 such mountain systems like the Alps, Apennines, Pyrenees and Atlas Mountains.
Gorst Mountains
The Sierra Nevada mountain range North America make up the horst mountains
What is a valley
A valley is a trough-shaped depression located between the slopes of the mountains. It is formed by sliding down and. 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 gentler and their bottoms are narrow.
Mountains are not eternal, they are “born” and “age”, gradually turning into hills. But how are mountains formed, how do these majestic accumulations of stone giants appear?
As scientists have found out, mountains are formed, or were formed millions of years ago, in four different ways and, according to the method of formation, are folded, vaulted, solid or volcanic.
How fold mountains form
Fold mountains were formed as a result of pressure and compression of the earth's surface during tectonic movement of the earth's crust. They look like giant folds of rock layers. Example fold mountains are the Alps.
How vaulted mountains are formed
Vaulted mountains are rocks that were raised above the surface of the Earth by molten lava as it moved outward from the bowels of the earth. Such mountains are characterized by the shape of the arch, which is why they are called that.
How are solid mountains formed?
Solid mountains were formed when entire sections of the earth's surface rose or fell during tectonic movement. Continuous mountain ranges (for example, the Sierra Nevada) are the result of faults or, conversely, failures in the earth's crust.
How are volcanic mountains formed?
Volcanic mountains are extinct or (for example, Vesuvius or Fuji). They consist of lava ejected from ash from volcanic eruptions and have a conical shape.
These are the main ways mountains are formed, but many mountains are the result of their combination during tectonic movement of layers of the earth's crust.