Throughout the existence of the Earth itsthe surface is constantly changing. This process continues today. It proceeds extremely slowly and imperceptibly for a person and even for many generations. However, it is these transformations that ultimately radically change the appearance of the Earth. Similar processes are divided into exogenous (external) and endogenous (internal).
Exogenous processes - the result of interactionshell of the planet with hydrosphere, atmosphere and biosphere. They are studied in order to accurately determine the dynamics of the geological evolution of the Earth. Without exogenous processes, there would be no pattern of development of the planet. They are explored by the science of dynamic geology (or geomorphology).
Experts adopted a universal classification.exogenous processes, dividing 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, the vital activity of organisms and water. The next type of exogenous process is denudation. It is the destruction of rocks (and not the change of properties as in the case of weathering), their fragmentation by flowing waters and winds. The last type is accumulation. This is the formation of new sedimentary rocks due to precipitation accumulated in depressions of the terrestrial relief as a result of weathering and denudation. On the example of accumulation, we can note the visual interrelation of all exogenous processes.
Physical weathering is also calledmechanical. As a result of such exogenous processes, rocks turn into blocks, sand and grind, and also break up into fragments. The most important factor of physical weathering is insolation. Due to the heating of the sun and the subsequent cooling, there is a periodic change in the volume of the rock. It causes cracking and loss of bond between minerals. The results of exogenous processes are obvious - the rock splits into pieces. The greater the temperature amplitude, the faster this happens.
The rate of cracking depends on the propertiesrock, its shale, stratification, cleavage of minerals. Mechanical failure can take several forms. Chunks that look like scales are chipped off from a material with a massive structure, which is also called scaling. A granite splits into blocks with the shape of a parallelepiped.
In addition, the dissolution of rockspromotes chemical exposure to water and air. Oxygen and carbon dioxide are the most active agents that are dangerous to the integrity of surfaces. Water carries salt solutions, and therefore its role in the process of chemical weathering is especially great. Such destruction can be expressed in various forms: carbonation, oxidation and dissolution. In addition, chemical weathering leads to the formation of new minerals.
Водные массы на протяжении тысячелетий каждый day flow on the surface and seep through the pores formed in the decaying rocks. Liquid carries a large number of elements, thereby leading to the decomposition of minerals. Therefore, it can be said that in nature there are no absolutely insoluble substances. The only question is how long they retain their structure in spite of exogenous processes.
Oxidation mainly affects minerals, incomposition of which includes sulfur, iron, manganese, cobalt, nickel and some other elements. This chemical process is particularly active in an environment saturated with air, oxygen and water. For example, when they come into contact with moisture, the metal oxides that make up the rocks become oxides, sulfides — sulfates, etc. All these processes directly affect the relief of the Earth.
As a result of oxidation in the lower layers of the soilprecipitates of rough iron ore (ortsandy) accumulate. There are other examples of its effect on relief. So, weathered rocks containing iron are covered with brown crusts of limonite.
Организмы также участвуют в разрушении горных rocks. For example, lichens (protozoa) can settle on almost any surface. They support life by extracting nutrients through the secretion of organic acids. After the simplest of plants on the rocks settles woody vegetation. In this case, the cracks become home to the roots.
Characteristics of exogenous processes cannotdo without mentioning worms, ants and termites. They make long and numerous underground passages and thus contribute to the release of atmospheric air under the soil, which contains destructive carbon dioxide and moisture.
Ice is an important geological factor.He plays a significant role in shaping the terrestrial relief. In mountainous areas, ice, moving along river valleys, changes the shape of drains and smooths the surface. Geologists called such destruction an excretion. Moving ice performs another function. He carries clastic material, a breakaway from rocks. Weathering products fall off the slopes of the valleys and settle on the surface of the ice. Such a destroyed geological material is called a moraine.
No less important is the ground ice that formsin the soil and fills the soil pores in the territories of perennial and permafrost. Climate is also a contributing factor here. The lower the average temperature, the greater the depth of frost penetration. Where the ice melts in summer, pressurized water rushes to the surface of the earth. They destroy the relief and change its shape. Similar processes are repeated cyclically from year to year, for example, in the north of Russia.
The sea occupies about 70% of the surface of our planet.and, no doubt, it has always been an important exogenous geological factor. Ocean water moves under the influence of wind, tidal currents. This process is associated with significant destruction of the earth's crust. Waves that splash even at the weakest waves of the sea off the coast, without stopping, undermine the surrounding rocks. During a storm, the power of the surf can be several tons per square meter.
The process of demolition and physical destruction of coastalrocks sea water is called abrasion. It is uneven. A blurred bay, a cape or individual rocks may appear on the shore. In addition, the surf waves form precipices 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 flow uninterrupteddenudation processes. This is facilitated by intense currents. During a storm and other cataclysms powerful deep waves are formed, which in their path stumble upon the underwater slopes. In the event of a collision a hydraulic shock occurs, which dilutes the sludge and destroys the rock.
Ветер как ничто больше меняет земную поверхность.It destroys rocks, carries clastic material of small size and deposits it in an even layer. At a speed of 3 meters per second, the wind moves leaves, 10 meters - pumps thick branches, picks up dust and sand, 40 meters, pulls out trees and blows down houses. Particularly destructive work is done by dust eddies and tornadoes.
The process of blowing wind particles of rockscalled deflation. In semi-deserts and deserts, it forms significant depressions on the surface, composed of salt marshes. Wind is more intense if the land is not protected by vegetation. Therefore, it is especially strongly deformed mountain basins.
In the formation of the relief of the Earth plays a huge rolethe relationship of exogenous and endogenous geological processes. Nature is such that some spawn others. For example, exogenous external processes eventually lead to cracks in the crust. Through these holes from the bowels of the planet magma enters. It spreads in the form of covers and forms new breeds.
Magmatism is not the only example of howarranged interaction of exogenous and endogenous processes. Glaciers contribute to leveling the terrain. This is an external exogenous process. As a result, it forms a peneplain (a plain with small hills). Then, as a result of endogenous processes (plate tectonic movement), this surface rises. Thus, internal and external factors can contradict each other. The relationship between endogenous and exogenous processes is complex and multifaceted. Today it is studied in detail in the framework of geomorphology.
