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Formation of mountains

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There was time when mountains were considered as a place dangerous and mysterious. However last two decades many secrets with which occurrence of mountains communicated, it was possible to solve thanks to the revolutionary theory - tectonics litosfernyh plates.

Some mountains are obliged by the origin of volcanic activity, others - to pressure because of which earlier flat layers of rock are deformed and displaced, and meet on those sites where earth crust is unstable - along edges of rigid plates forming it.

Volcanic mountains

There, where near to median-oceanic ridges litosfernye plates disperse in the parties (spreding), magma (the fused breed), aspiring to fill a crevice, rises upwards, in due course forming new crystal breed. Sometimes it is heated up on a sea-bottom - so there are the underwater volcanoes, which tops islands rise over a surface of waves.

In deep-water trenches one plate moves under another (subduktsija), is absorbed by a cloak and rasplavljaetsja to the magma condition which part is pushed out on a surface, creating chains of islands of a volcanic origin: so, for example, there was Japan, Philippines, Indonesia.

Rising magma not always streams on a surface through a volcano muzzle, it can vspuchivat blocking breeds, forming dome-shaped mountains - for example, Blek-Hills in Dakota (USA). Cooling down, magma turns to a granite. The most extended and majestic mountain chains on a land, including the Himalayas, the Andes, Rocky mountains and the Alpes, represent the folds of the rocky breed mainly formed by strongly deformed layers of a material, besieged at the bottom of ancient oceans. Some sedimentary breeds were formed at the bottom of sea shoal of a dirt, sand and the silt brought by a current of the rivers. On bolshej to depth calcareous breeds were formed of the hardened remains of organisms.

Folded mountains

Folded mountains the majority of experts believe Today that the reason skladchatosti is the pressure arising at drift of tectonic plates. Only on some centimetres a year plates upon which continents are based move, but their convergence forces breeds on suburbs of these plates, and also layers of adjournment at the bottom of the oceans dividing continents, gradually to rise upwards crests of mountain chains.

At movement of plates it is formed warmly and pressure under which influence one layers of breed are deformed, lose durability and as if plastic, others are bent in huge folds, and, not so razogretye or stronger, break and quite often come off the basis. Warm during mountain building also leads to occurrence of magma near to a layer spreading continental sites of earth crust. Huge weights of magma rise and, hardening, form a granite core of folded mountains.

The Certificate of former collisions of continents are old, for a long time already stopped to grow, but not in time yet to collapse folded mountains. For example, in the northeast of the North America, the east of Greenland, the West of Ireland and Scotland, and also in Norway and Sweden they have appeared still when the North America and Europe, having converged, became one huge continent. Later, somewhere 100 million years ago, this enormous mountain chain was broke off because of formation of Atlantic ocean. Folds are often accessible to a sight at the bared rocks in a hilly terrain, but not only there. Elementary of folds are anticlines (dome) and sinklinali (deflections). Some folds happen overturned (lying). Others are displaced in relation to the basis so that the top parts of folds are put forward - sometimes on some kilometres, and them name covers.

Movement of plates leads razlamyvaniju mountains at edges of a plate with formation in breed of long shifts (crevices). Land blocks sometimes are put forward up along a plane of dumps, creating inclined mountains - as Sierra-Nevada in California. And happens that the block is put out upwards between two almost parallel lines of breaks. Ranges of such mountains abruptly tower over surrounding relief.


Erosion Already when mountains grow, process of their destruction begins. Erosion in mountains is especially strong because of the big steepness of slopes.

Thereof, blocks collapsing from a frost roll down downwards and are carried away away by glaciers or rough waters of mountain streams. These forces of the nature, together with tectonics of plates, also form impressing mountain landscape.