Mountain systems - perhaps one of the mostmonumental and impressive creations of nature. When looking at snow-capped peaks lined up one after another for hundreds of kilometers, one can not help asking: what great power has created them?
The mountains always seem to people as something unshakable,ancient as eternity itself. But the data of modern geology perfectly show how volatile the relief of the earth's surface is. Mountains can be located where the sea once splashed. And who knows which point of the earth will be the highest in a million years, and what will become of the majestic Everest ...
To understand how mountains are formed, it is necessaryit is good to imagine what a lithosphere is. This term designates the outer shell of the Earth, which has a very heterogeneous structure. It can be found and the tops of a height of thousands of meters, and the deepest canyons, and vast plains.
The earth's crust is formed by giant lithosphericPlates that are in continuous motion and occasionally face the edges. This leads to the fact that some of their areas are cracking, rising and changing the structure in every way. As a result, mountains are formed. Of course, the change in the position of the plates is very slow - only a few centimeters per year. However, it is due to these gradual shifts that dozens of mountain systems have been formed on Earth for millions of years.
The land has both inactive parts (mostlyin their place large plains are formed, as, for example, the Caspian Sea), and enough "restless" areas. Basically in their territory once were the ancient seas. At a certain moment, there was a period of intensive movement of lithospheric plates and the pressure of the approaching magma. As a result, the seabed, with all its variety of sedimentary rocks, rose to the surface. So, for example, the Ural Mountains arose.
Once the sea finally "retreats", theThe precipitations, winds and temperature changes that have appeared on the surface of the rock mass are actively affected. It is thanks to them that each mountain system has its own unique, unique relief.
Scientists consider the motion of tectonic plates the mosta correct explanation of how folded and blocky mountains are formed. When the platforms move, the crust in certain areas can be squeezed, and sometimes even cracked, 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 blocky (for example, Altai).
Some systems are distinguished by massive, steep, but not too separated slopes. This is a characteristic feature of blocky mountains.
The process of formation of volcanic peaksquite different from the way folded mountains are formed. The name speaks quite clearly of their origin. Volcanic mountains occur in the place where magma - molten rock - breaks to the surface. It can exit through one of the cracks in the earth's crust and accumulate around it.
In some points of the planet you can observe wholeridges of this type - the result of the eruption of several nearby volcanoes. Concerning the way mountains are formed, there is also such an assumption: molten rocks, without finding an outlet, just press on the surface of the earth's crust from the inside, as a result of which huge "bulges" arise on it.
A separate case is underwater volcanoes,located at the bottom of the oceans. Magma, released from them, can harden, forming entire islands. States such as Japan and Indonesia are located precisely on land of volcanic origin.
The age of the mountain system is clearly indicated by its relief.The sharper and higher the peak, the later it was formed. Young mountains are considered to have 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 before the appearance of man there was still a huge amount of time, 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 (ageit 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 in Canada.
In the XX century, geologists came to an unambiguous conclusion:In the bowels of the earth huge forces are enclosed, and the formation of its relief never ceases. Young mountain all the time "grow", increasing in height by about 8 cm a year old - is constantly destroyed by wind and water, is slowly but surely turning into a plain.
A vivid example of the fact that the process of changeThe natural landscape never stops - constantly occurring earthquakes and volcanic eruptions. Another factor affecting the process of how the mountains are formed is the movement of rivers. When a certain part of the land is raised, their channels become deeper and harder to cut into the rocks, sometimes laying 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 destruction of mountain chains involved the same natural forces that once formed their relief: temperature, precipitation and wind, glaciers and underground sources.
Modern versions of orogenesis (origin of mountains) are represented by several hypotheses. The scientists put forward the following probable causes:
One of the versions of how the mountains are formed is connectedwith the action of gravitational force. Since the Earth has the shape of a sphere, all particles of matter tend to be located symmetrically about the center. In addition, all rocks differ in mass, and the lighter of them with time are "forced out" to the surface by heavy ones. Together, these causes lead to the appearance of irregularities on the earth's crust.
Modern science is trying to determine the mainThe mechanism of tectonic changes on the basis of what mountains were formed as a result of this or that process. Many problems still remain connected with orogenesis, which are still unanswered.