Mountain systems are perhaps one of the most monumental and impressive creations of nature. When looking at the snow-capped peaks, lined up one after another for hundreds of kilometers, one involuntarily wonders: what immense force created them?
Mountains always seem to people something unshakable, ancient, like eternity itself. But the data of modern geology perfectly demonstrate how variable the terrain is. Mountains can be located where the sea once splashed. And who knows what point of the Earth will be the highest in a million years, and what will become of the majestic Everest ...
Mountain range formation mechanisms
To understand how mountains are formed, it is necessary to have a good idea 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, and the deepest canyons, and vast plains.
The earth's crust is formed by giant lithospheric plates, which are in continuous motion and from time to time collide with the edges. This leads to the fact that certain of their sections crack, rise and in every way change the structure. As a result, mountains form. Of course, the change in the position of the plates is very slow - only a few centimeters per year. However, thanks to these gradual shifts over millions of years, dozens of mountain systems have formed on Earth.
The land has both inactive sections (mainly large plains form in their place, such as the Caspian region), and quite “restless” areas. Mostly, ancient seas were once located on their territory. At a certain moment, a period of intensive movement of lithospheric plates and pressure of incoming magma began. As a result, the seabed, with all its variety of sedimentary rocks, rose to the surface. So, for example, the Ural Mountains arose .
As soon as the sea finally “recedes”, precipitation, wind and temperature changes begin to actively influence the rock mass on the surface. It is thanks to them that each mountain system has its own special, unique relief.
How tectonic mountains are formed
Scientists consider the movement of tectonic plates the most accurate explanation of how folded and block mountains are formed. When the platforms are displaced, the crust in certain areas can be squeezed, and sometimes even broken, rising from one edge. In the first case, folded mountains are formed (some of their areas can be found in the Himalayas); another mechanism describes the occurrence of block ones (for example, Altai).
Some systems have massive, steep, but not too separated slopes. This is a characteristic feature of block mountains.
How volcanic mountains form
The process of formation of volcanic peaks is quite different from how folded mountains are formed. Their origin is quite clearly indicated by the name. Volcanic mountains arise in the place where magma erupts to the surface - molten rock. It can exit through one of the cracks in the earth's crust and accumulate around it.
At some points on the planet you can observe entire ridges of this type - the result of the eruption of several nearby volcanoes. Regarding how the mountains are formed, there is such an assumption: molten rocks, without 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 submarine volcanoes located at the bottom of the oceans. The magma that emerges from them is able to solidify, forming entire islands. States 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 peak, the later it formed. Mountains are considered to be young, formed no more than 60 million years ago. This group includes, for example, the Alps and the Himalayas. Studies have shown that they arose about 10 million years ago. And although there was still a huge amount of time before the appearance of man, in comparison with the age of the planet this is a very short time. The Caucasus, the Pamirs and the Carpathians are also considered young.
An example of ancient mountains is the Ural Range (its age is more than 4 billion years). This group also includes North and South American Cordillera and Andes. According to some, the oldest mountains on the planet are in Canada.
The modern formation of mountains
In the XX century, geologists came to an unambiguous conclusion: huge forces are contained 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, the ancient ones are constantly being destroyed by wind and water, slowly but surely turning into plains.
A vivid example of the fact that the process of changing the natural landscape never stops - constantly occurring earthquakes and volcanic eruptions. Another factor affecting the process of how mountains are formed is the movement of rivers. When a certain land area is raised, their channels become deeper and stronger cut into the rocks, sometimes laying entire gorges. Traces of rivers can be found on the slopes of the peaks, along with the remnants of the valleys. It is worth noting that the destruction of mountain ranges involves the same natural forces that once formed their topography: temperature, precipitation and wind, glaciers and underground sources.
Scientific Versions
Modern versions of orogenesis (the origin of mountains) are presented by several hypotheses. Scientists put forward the following probable causes:
- sinking of ocean troughs;
- the drift (slip) of the continents;
- subcrustal currents;
- swelling;
- contraction of the earth's crust.
One version of how mountains form is related to the action of gravity. Since the Earth has the shape of a ball, all particles of matter tend to be located symmetrically relative to the center. In addition, all rocks vary in mass, and the lighter of them over time are "crowded out" to the surface heavy. Together, these causes lead to the appearance of irregularities on the earth's crust.
Modern science is trying to determine the basic mechanism of tectonic changes on the basis of which mountains were formed as a result of a process. Many questions are still connected with orogenesis, which still remain unanswered.