Characterization and classification of exogenous processes. Results of exogenous processes. Interrelation of exogenous and endogenous geological processes

Throughout the entire existence of the Earth, its surface has continuously changed. This process continues today. It flows very slowly and unnoticed for a person and even for many generations. However, it is these transformations that ultimately fundamentally change the external appearance of the Earth. Such processes are divided into exogenous (external) and endogenous (internal).

Classification

Exogenous processes are the result of interaction of the planet's shell with the hydrosphere, atmosphere and biosphere. They are studied in order to accurately determine the dynamics of the geological evolution of the Earth. Without the exogenous processes there would be no regularities in the development of the planet. They are explored by science with dynamic geology (or geomorphology).

Specialists accepted a general classification of exogenous processes, which are divided into three groups. The first is weathering, which is a change in the properties of rocks and minerals under the influence not only of wind, but also of carbon dioxide, oxygen, life activity of organisms and water. The next type of exogenous processes is denudation. This is the destruction of rocks (and not the change in properties as in the case of weathering), their fragmentation by flowing waters and winds. The last type is accumulation. This formation of new sedimentary rocks due to precipitation, accumulated in depressions of the earth's relief as a result of weathering and denudation. On the example of accumulation, one can note the evident interrelation of all exogenous processes.

Mechanical weathering

Physical weathering is also called mechanical. As a result of such exogenous processes rocks are converted into blocks, sand and gravel, and also break up into fragments. The most important factor of physical weathering is insolation. Due to heating by the sun's rays and subsequent cooling, the rock volume changes periodically. It causes cracking and disruption of the bond between the minerals. The results of exogenous processes are obvious - the breed splits into pieces. The larger the temperature amplitude, the faster this happens.

The rate of formation of cracks depends on the properties of the rock, its schistosity, stratification, cleavage of minerals. Mechanical destruction can take several forms. From a material with a massive structure, chunks resembling scales are broken off, which is why this process is also called scaling. And granite breaks up into blocks with the shape of a parallelepiped.

Chemical destruction

Among other things, the chemical action of water and air contributes to the dissolution of rocks. Oxygen and carbon dioxide are the most active agents, which are dangerous for the integrity of surfaces. Water carries in itself solutions of salts, and therefore its role in the process of chemical weathering is particularly great. Such destruction can be expressed in a variety of forms: carbonatization, oxidation and dissolution. In addition, chemical weathering leads to the formation of new minerals.

Water masses for millennia every day flow down the surfaces and seep through the pores formed in the decaying rocks. The liquid takes out a large number of elements, thereby leading to the decomposition of minerals. Therefore, we can say that in nature there are absolutely insoluble substances. The whole question is only how long they retain their structure in spite of exogenous processes.

Oxidation

Oxidation affects mainly minerals, which include sulfur, iron, manganese, cobalt, nickel and some other elements. This chemical process is particularly active in a medium saturated with air, oxygen and water. For example, in contact with moisture, the constituents of the metal oxide become oxides, sulfides - sulfates, etc. All these processes directly affect the relief of the Earth.

As a result of oxidation, precipitation of the rough iron ore (ortzanda) accumulates in the lower layers of the soil. There are other examples of its influence on the relief. Thus, weathered rocks containing iron are covered with brown limonite crusts.

Organic weathering

Organisms also participate in the destruction of rocks. For example, lichens (protozoa) can settle almost on any surface. They support life by extracting nutrients from the organic acids. After the simplest plants, woody vegetation settles on rocks. In this case, the cracks become a home for the roots.

Characterization of exogenous processes can not do without the mention of worms, ants and termites. They make long and numerous underground passages and thereby contribute to getting under the soil of atmospheric air, which includes destructive carbon dioxide and moisture.

Effect of ice

Ice is an important geological factor. It plays a significant role in the formation of the earth's relief. In the mountain areas, ice, moving along river valleys, change the shape of the drains and smooth out the surfaces. Such a destruction geologists called an exhalation (plowing). Moving ice performs one more function. It carries clastic material that has broken away from the rocks. The weathering products are showered from the slopes of the valleys and settle on the surface of the ice. Such a destroyed geological material is called moraine.

No less important is ground ice, which forms in the soil and fills soil pores in the territories of perennial and permafrost. As a contributing factor here is also the climate. The lower the average temperature, the greater the depth of freezing. Wherever the ice melts in the summer, pressurized waters break out onto the surface of the earth. They destroy the terrain and change its shape. Such processes from year to year are cyclically repeated, for example, in the north of Russia.

Sea factor

The sea occupies about 70% of the surface of our planet and, undoubtedly, has always been an important geological exogenous factor. Ocean water moves under the influence of wind, tidal and tide currents. This process is associated with a significant destruction of the earth's crust. Waves that splash, even with the slightest excitement of the sea off the coast, without a break, the surrounding rocks undermine. During a storm, surf power can be several tons per square meter.

The process of demolition and physical destruction of coastal rocks by sea water is called abrasion. It proceeds unevenly. On the shore, there may appear a fuzzy bay, a cape or some rocks. In addition, surf waves form cliffs and ledges. The nature of the damage depends on the structure and composition of the coastal rocks.

At the bottom of the oceans and seas there are continuous processes of denudation. This is promoted by intensive currents. During a storm and other cataclysms, powerful deep waves are formed, which on their way run across underwater slopes. In the event of a collision, a hydraulic shock occurs , which dilutes the silt and destroys the rock.

Wind Operation

The wind changes the earth's surface as nothing else. It destroys rocks, transfers clastic material of small size and deposits it evenly. At a speed of 3 meters per second, the wind moves leaves, at 10 meters - swings thick branches, raises dust and sand, at 40 meters, tears out trees and demolishes houses. Particularly destructive work is done by dust vortices and tornadoes.

The process of wind blowing rock particles is called deflation. In semi-deserts and deserts, it forms significant depressions on the surface, composed of solonchaks. The wind acts more intensively if the earth is not protected by vegetation. Therefore, it deforms mountain hollows especially strongly.

Interaction

In the formation of the Earth's relief, an enormous role is played by the interrelation between exogenous and endogenous geological processes. Nature is arranged in such a way that some breed others. For example, external exogenous processes eventually lead to the appearance of cracks in the earth's crust. Through these holes from the bowels of the planet comes magma. It spreads in the form of integuments and forms new breeds.

Magmatism is not the only example of how the interaction of exogenous and endogenous processes is arranged. Glaciers contribute to the alignment of the terrain. This is an external exogenous process. As a result of it, a peneplain is formed (a plain with small hills). Then, as a result of endogenous processes (tectonic movement of plates), this surface rises. Thus, internal and external factors may contradict each other. The interconnection of endogenous and exogenous processes is complex and multifaceted. Today, it is studied in detail within the framework of geomorphology.