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Graben is ... What are grabens, and how are they formed?

In this article, we will discuss the issue of natural phenomena. What are grabens and how are they formed? Also, running ahead, we pay attention to the opposite of graben - it's a handful.

What is graben

Graben - this is the part of the earth's crust which has subsided, which was formed as a result of a tectonic fault and stands out clearly among elevated areas.

Grabs usually appear as a result of the appearance of tensile forces near elevated areas of the earth. Under the effect of this, soil subsidence occurs and a formation rock failure occurs.

On the edges of the graben appear towering parts, which are formed as a result of the accumulation of new rocks, they are called "wings of graben."

In length can reach several tens and hundreds of kilometers - in width. The most pronounced and widely known grabens are in East Africa. They are located along the lakes of Tanganyika, Victoria, Nyanza. In Russia, the largest graben is the Barguzin Basin, the basin of Lake Baikal.

In the solar system, the largest graben is the Mariner Valley, located on Mars. The reason for the formation is volcanic activity.

What is a horst

Horst is a block of the earth's crust, elevated along faults, formed as a result of tectonic movements.

Three types of horsts are distinguished with respect to the surface:

  1. Inclined - the surface over the whole area is inclined in one direction.
  2. Wedge-shaped - there is a gradual narrowing down.
  3. One-sided - ups and downs occur only on one side.

Often a set of horsts create mountains with flat tops. The length usually reaches hundreds, and the width is tens of kilometers, and the height is several thousand meters. Striking examples of the horsts are the mountain range in Spain Siera-Nevada, the mountain massif in the southwest of Germany, the Black Forest.

For the first time the term "horst" was introduced in the science of geology in 1873 by the Austrian Edward Suess. In their own words, the graben is a hollow, the horst is an eminence.

Rift zones

Rift is a linear-horizontal coarse depression in the earth's crust. Usually this is a collection of depressions that occupy a huge area.

There are two types of rift zones - oceanic and continental.

The first arise as a result of the action of magmatic melt, coming from the depths of the Earth to the ocean floor. Magma under pressure pushes hard lithospheric plates, as a result of this process, a young oceanic crust forms.

Continental rift zones are formed as a result of a rise to the surface of plumes (hot mantle), with active volcanism, thinning and stretching of the continental crust occurs. Such rifts can lead to the formation of a new ocean. In the East African rift system, namely in the Afar region, in some places an oceanic young crust was formed.

Rifts, which stopped in development and did not turn into oceans, are called avlakogeny. Usually in such places deposits of natural resources are formed. For example, Devonian Donetsk trough is a large coal deposit.

Usually the combination of horst-graben is an aulacogen.

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