All life on Earth, the life of all living organisms from simple unicellular bacteria to complex biological species, the life of plants, animals and humans occurs in 3 important components: on the geographic surface of the Earth; in the aquatic environment of the planet's hydrosphere; and under the blue and white dome - the atmosphere of the Earth.
The main part of the earth's surface is occupied by the world ocean, where the continental and waterless parts account for less than 1/3 of the entire surface of the Earth. The Earth's surface consists of the earth's crust, its underwater part and the continental, watery part, as well as the atmosphere, which creates a blue dome that envelops the globe.
Interestingly, the Earth's atmosphere is an important component of the origin and maintenance of life on the planet, and is also the protective shell of the planet. In the atmosphere, weather is formed on the Earth, it regulates the water cycle in nature, the atmosphere protects the Earth from cosmic rays and raises the temperature of the Earth's surface, forming a "greenhouse effect".
The concepts of the internal heterogeneity of the Earth's structure and its concentric-zonal structure are based on the results of complex geophysical studies. Direct evidence of the deep structure of the earth's interior refers to shallow depths. They were obtained in the process of studying natural sections ( outcrops) rocks, open pits, mines and boreholes. The deepest well in the world on the Kola Peninsula went 12 kilometers into the bowels. This is only 0.2% of the Earth's radius (the Earth's radius is about 6 thousand km.) (Fig. 3.5.). The products of volcanic eruptions make it possible to judge the temperatures and composition of matter at depths of 50-100 km.
Figure: 3.5. Inner shells of the earth
Seismic waves. The main method for studying the subsoil is the seismic method. It is based on measuring the speed of passage of mechanical vibrations of various types through the substance of the Earth. This process is accompanied by the release of a large amount of energy and the occurrence of mechanical vibrations, which propagate in the form of seismic waves in all directions from the place of origin. The propagation speed of seismic waves is very high and in dense bodies, for example, in a stone (in rocks) it reaches several kilometers per second. There are two groups of seismic waves - volumetric and superficial(fig. 3.6. and 3.7.). The rocks that make up the Earth are resilient and therefore can deform and vibrate when pressure (loads) is applied abruptly. Body waves propagate inside the volume of rocks. They are of two types: longitudinal (P) and transverse (S) ... Longitudinal waves in the body of the Earth (as in any other physical bodies) arise as a reaction to a change in volume. Like sound waves in air, they alternately compress and stretch rock material in the direction of their motion. Waves of another type - transverse ones arise as a reaction to a change in the shape of the body. They vibrate the medium through which they pass, across their path of motion.
At the boundary of two media with different physical properties, seismic waves experience refraction or reflection (P, S, PcP, PkP, etc.). Geophysical studies were supplemented by thermodynamic calculations and the results of physical modeling and data from the study of meteorites.
The data obtained indicate the presence of numerous subhorizontal interfaces in the Earth's interior. At these boundaries, there is a change in the velocities and directions of propagation of physical waves (seismic, electromagnetic, etc.) when they propagate deep into the planet.
Figure: 3.6. Propagation of seismic waves (O - earthquake source).
These boundaries are separated from each other by separate shells - "geospheres", which differ from each other in chemical composition and in the state of aggregation of matter in them. These boundaries, by no means, represent the usual geometrically correct infinitely thin planes. Any of these boundaries is a certain volume of subsoil, relatively small compared to the volume of the separated geospheres. Within each such volume, there is a rapid, but gradual change in the chemical composition and state of aggregation of matter.
Bowels of the earth. According to existing concepts, the globe is divided into a number of concentric shells (geospheres), as if nested into each other (Fig. 3.7., Table 3.5.). "Outer" shells and "inner" shells (sometimes the latter are simply called "bowels") are separated from each other by the surface of the earth. The inner shells are represented, respectively, by the core, the mantle and the earth's crust. Each of these geospheres, in turn, has a complex structure. The Gutenberg-Bullen model uses geosphere indexing, which is still popular today. The authors highlight: earth crust(layer A) - granites, metamorphic rocks, gabbro; top mantle(layer B); transition zone(layer C); bottom mantle(layer D), composed of oxygen, silica, magnesium and iron. At a depth of 2900 km, the boundary is drawn between the mantle and the core. Below is outer core(layer E), and from a depth of 5120 m - inner core(layer G) folded with iron:
-
earth's crust
- the thin outer stone shell of the Earth. It extends from the surface of the Earth down to 35-75 km, layer A: Cf. 6-7 km thick - under the oceans; 35-49 km - under the flat platform territories of the continents; 50-75 km - under the young mountain structures. It is the uppermost of the Earth's inner shells.
mantle - intermediate shell (35-75 km. to 2900 km) (layers B, C, D) (Greek “mantion” - cover): layers B (75-400 km) and C (400-1000 km) correspond to the upper mantle ; transitional layer D (1000-2900 km) - the lower mantle.
-core - (2900 km. - 6371 km.) Layers E, F, G where: E (2900-4980 km) - outer core; F (4980-5120 km) - transitional shell; G (5120-6371 km) - inner core.
Core of the earth ... The core is 16.2% of its volume and 1/3 of its mass. It is apparently compressed at the poles by 10 km. At the boundary of the mantle and the core (2900 km), there is an abrupt decrease in the velocity of longitudinal waves from 13.6 to 8.1 km / s. Shear waves do not penetrate below this interface. The kernel does not let them pass through itself. This gave rise to the conclusion that in the outer part of the core, the substance is in a liquid (molten) state. Below the boundary of the mantle and the core, the velocity of longitudinal waves increases again - up to 10.4 km / s. On the border of the outer and inner core (5120 km), the velocity of longitudinal waves reaches 11.1 km / s. And then to the center of the Earth almost does not change. On this basis, it is assumed that from a depth of 5080 km, the core material again acquires the properties of a very dense body, and a solid internal is released " nucleolus"with a radius of 1290 km. According to some scientists, the earth's core consists of nickel iron. Others argue that iron, in addition to nickel, contains an admixture of light elements - silicon, oxygen, possibly sulfur, etc. In any case, iron as a good conductor of electricity can serve as a source of dynamo effect and formation of the Earth's magnetic field.
Indeed, from the point of view of physics, the Earth in some approximation is a magnetic dipole, i.e. a kind of magnet with two poles: south and north.
Japanese scientists argue that the Earth's core is gradually increasing due to the differentiation of mantle matter 12. makes up 82.3% of the Earth's volume. Only hypothetical assumptions can be made about its structure and material composition. They are based on seismological data and materials of experimental modeling of physical and chemical processes occurring in the bowels at high pressures and temperatures. The velocity of longitudinal seismic waves in the mantle increases to 13.6 km / s, transverse - up to 7.2-7.3 km / s.
Mantle of the Earth (upper and bottom). Below the Mohorovichich section between the earth's crust and the Earth's core is mantle (to a depth of about 2900 km). It is the most massive of the Earth's shells - it makes up 83% of the Earth's volume and about 67% of its mass. Three layers are distinguished in the Earth's mantle in terms of structure, composition and properties: gutenberg layer - Bto a depth of 200-400 km, galicin layer - C up to 700-900 km and layer D up to 2900 km. As a first approximation, layers B and C are usually combined into the upper mantle, and layer D considered as the lower mantle. On the whole, within the mantle, the density of matter and the speed of seismic waves increase rapidly.
Upper mantle. It is believed that the upper mantle is composed of igneous rocks, highly depleted in silica, but enriched in iron and magnesium (the so-called ultrabasic rocks), mainly peridotite. Peridotite is 80% composed of the mineral olivine (Mg, Fe) 2 and 20% pyroxene (Mg, Fe) 2.
Earth's crustdiffers from the underlying shells in its structure and chemical composition. The base of the earth's crust is outlined by the seismic boundary of Mohorovichich, at which the velocities of propagation of seismic waves sharply increase and reach 8 - 8.2 km / s.
Table 3.5. The prevalence of rocks in the earth's crust
(after A. B. Ronov, A. A. Yaroshevsky, 1976. and V. V. Dobrovolsky, 2001)
|
Breed groups |
Prevalence,% of the volume of the earth's crust |
Weight, 10 18 t |
|
|
Sands and sandy rocks | |||
|
Clays, shales, siliceous rocks | |||
|
Carbonates | |||
|
Salt deposits (sulfate and halogen rocks) | |||
|
Granitoids, granite gneisses, felsic effusive rocks and their metamorphic equivalents | |||
|
Gabbros, basalts and their metamorphic equivalents | |||
|
Dunites, peridotites, serpentinites | |||
|
Metasandstones | |||
|
Paragneisses and crystalline schists | |||
|
Metamorphosed carbonate rocks | |||
|
Ferruginous rocks | |||
The earth's surface and about 25 kilometers of the earth's crust are formed under the influence of:
1)endogenous processes (tectonic or mechanical and magmatic processes), due to which the relief of the earth's surface is created and strata of magmatic and metamorphic rocks are formed;
2) exogenous processescausing denudation (destruction) and leveling of the relief, weathering and transfer of rock debris and their redeposition in lower parts of the relief. As a result of a wide variety of exogenous processes, sedimentary rocks are formed, which make up the uppermost layer of the earth's crust.
There are two main types of the earth's crust: continental(granite-gneiss) and ocean(basaltic) with discontinuous sedimentary layer. The transition from the continental-type crust to the oceanic-type crust is shown in Fig. 3.8.
Three layers are distinguished in the continental crust: upper - sedimentary and two lower, composed of crystalline rocks. The thickness of the upper sedimentary layer varies widely: from almost complete absence on ancient shields to 10-15 km on the shelves of passive continental margins and in the marginal troughs of platforms. The average thickness of sediments on stable platforms is about 3 km.
Under the sedimentary layer are strata with a predominance of magmatic and metamorphic rocks of the granitoid series, relatively rich in silica. In some places in the areas where ancient shields are located, they come out on the earth's surface (Canadian, Baltic, Aldan, Brazilian, African, etc.). The rocks of the "granite" layer are usually transformed by the processes of regional metamorphism and have a very ancient age (80% of the continental crust is older than 2.5 billion years).
P 
below the “granite” layer is the “basalt” layer. Its material composition has not been studied, but judging by the data of geophysical studies, it is assumed that it is close to the rocks of the oceanic crust.
Both continental and oceanic crust are underlain by rocks of the upper mantle, from which they are separated by the Mohorovichich boundary (Moho boundary).
In general, the Earth's crust consists mainly of silicates and aluminosilicates. It is dominated by oxygen (43.13%), silicon (26%) and aluminum (7.45%), mainly in the form of oxides, silicates and aluminosilicates. The average chemical composition of the earth's crust is given in table. 3.6.
In the earth's crust of the continental type, there is a relatively high content of long-lived radioactive isotopes of uranium 238 U, thorium 232 Th and potassium 40 K. Their highest concentration is characteristic of the "granite" layer.
|
Table 3.6. Average chemical composition of continental and oceanic crust |
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|
Oxides and dioxides | ||
|
continental |
ocean |
|
The uppermost layer - sedimentary - is represented by sandy-clayey and carbonate sediments deposited at shallow depths. At great depths, siliceous silts and deep-sea red clays are deposited.
The average thickness of oceanic sediments does not exceed 500 m, and only at the foot of the continental slopes, especially in the regions of large river deltas, it increases to 12-15 km. This is caused by a kind of fast-flowing "avalanche" sedimentation, when almost all the terrigenous material carried by river systems from the continent is deposited in the coastal parts of the oceans, on the continental slope and at its foot.
The second layer of the oceanic crust in the upper part is composed of pillow basalt lavas. Dolerite dikes of the same composition are located below. The total thickness of the second layer of the oceanic crust is 1.5 km and rarely reaches 2 km. Under the dyke complex there are gabbro and serpentenites, which are the upper part of the third layer. The thickness of the gabbro-serpentinite layer reaches 5 km. Thus, the total thickness of the oceanic crust without sedimentary cover is 6.5 - 7 km. Under the axial part of the mid-ocean ridges, the thickness of the oceanic crust is reduced to 3-4, and sometimes to 2-2.5 km.
Under the crests of the mid-ocean ridges, the oceanic crust lies over the centers of basaltic melts released from the material of the asthenosphere. The average density of the oceanic crust without sedimentary layer is 2.9 g / cm 3. Based on this, the total mass of the oceanic crust is 6.4 10 24 g. The oceanic crust is formed in the rift regions of the mid-ocean ridges due to the influx of basaltic melts from the asthenospheric layer of the Earth and the outpouring of tholeiitic basalts on the ocean floor.
Lithosphere. The solid dense shell (including the earth's crust) overlying the asthenosphere is called the lithosphere (Greek "lithos" - stone). A characteristic feature of the lithosphere is its rigidity and fragility. It is the fragility that explains the observed block structure of the lithosphere. It is broken by large cracks - deep faults into large blocks - lithospheric plates.
Due to the global system of mechanical stresses, whose occurrence is associated with the rotation of the Earth, the lithosphere is split into fragments - blocks by faults of submeridial, sublatitudinal and diagonal directions. These faults ensure the relative independence of the movement of blocks of the lithosphere relative to each other, which explains the difference in the structure and geological history of individual lithospheric blocks and their associations. The faults separating the blocks are weakened zones along which magmatic melts and flows of vapors and gases rise.
In contrast to the lithosphere, the substance of the asthenosphere does not have a tensile strength and can deform (flow) under the action of even very small loads.
The chemical composition of the earth's crust ... The abundance of elements in the earth's crust is characterized by a large contrast, reaching 10 10. The most common chemical elements (Fig. 3.10) throughout the Earth are:
oxygen (О 2) - makes up 47 mass% of the earth's crust. It is part of about 2 thousand minerals;
silicon (Si) - is 29.5% and is included in more than a thousand minerals;
aluminum (Al) - 8.05%;
iron (Fe), calcium (Ca), potassium (TO), sodium (Na), titanium (Ti), magnesium (Mg) - make up the first% of the mass of the earth's crust;
The rest of the elements account for about 1%.
A.E. Fersman suggested expressing the clarke numbers not in weight percent, but in atomic percentages, which better reflects the ratio of the numbers of atoms, rather than their masses, and formulated three main regularities:
1. The abundance of elements in the earth's crust is characterized by a large contrast, reaching 10 10.
2. Only nine elements O, Si, Al, Fe, Ca, Na, K, Mg, H, are the main builders of the lithosphere, accounting for 99.18% of its weight. Of these, the first three account for 84.55%. The remaining 83 account for less than 1% (Figure 3.9.).
3. The leading element is oxygen. Its mass clarke is estimated in the range of 44.6 - 49%, atomic - 53.3 (according to A.E. Fersman), and volumetric (according to V.M.Goldschmidt) - 92%.
Thus, the earth's crust, both in volume and in mass, consists mainly of oxygen.
If the average content of elements in the crust in a first approximation can be considered unchanged throughout its history, then in some of its parts there are periodic changes. Although the Earth's crust is not a closed system, its exchange of matter masses with space and deeper zones of the planet cannot yet be accounted for quantitatively, go beyond the accuracy of our measurements, and obviously will not affect the clarke numbers.
TO 
lark
... In 1889, the American geochemist Frank Clark was the first to determine the average contents of chemical elements in the earth's crust. In honor of him, the Russian academician A.E. Fersman suggested calling " clarke"- the average content of chemical elements in any natural system - in the earth's crust, in a rock, in a mineral 13. The higher the natural clarke of a chemical element, the more minerals that contain this element. So, oxygen is found in almost half of all known minerals Any area that contains more than a clarke of a given substance is potentially interesting, as there may be industrial reserves of this substance. Such areas are explored by geologists in order to identify deposits of minerals.
Some chemical elements (for example, radioactive) change over time. So, uranium and thorium, decaying, turn into stable elements - lead and helium. This suggests that in the past geological epochs the clarkes of uranium and thorium were obviously much higher, and the clarkes of lead were lower than they are now. Apparently, this also applies to all other elements subject to radioactive transformations. The isotopic composition of some chemical elements changes over time (for example, the isotope of uranium 238 U). It is believed that two billion years ago, there were almost six times more atoms of the 235 U isotope on Earth than they are now.
Earth is the 3rd planet from the Sun, located between Venus and Mars. It is the densest planet in the solar system, the largest of the four, and the only astronomical object known to contain life. According to radiometric dating and other research methods, our planet was formed about 4.54 billion years ago. The Earth interacts gravitationally with other objects in space, especially the Sun and Moon.
The Earth consists of four main spheres or shells, which depend on each other and are the biological and physical components of our planet. They are scientifically called biophysical elements, namely the hydrosphere ("hydro" for water), the biosphere ("bio" for living things), the lithosphere ("litho" for land or the earth's surface), and the atmosphere ("atmosphere" for air). These major spheres of our planet are further divided into different sub-spheres.
Let's consider all four shells of the Earth in more detail in order to understand their functions and significance.
The lithosphere is the solid shell of the Earth
Scientists estimate that there are more than 1386 million km³ of water on our planet.
The oceans contain more than 97% of the Earth's water reserves. The rest is fresh water, two-thirds of which is frozen in the polar regions of the planet and on the snow-capped mountains. It is interesting to note that although water covers most of the planet's surface, it only accounts for 0.023% of the total mass of the Earth.
Biosphere - the living shell of the Earth
The biosphere is sometimes considered one big - a complex community of living and nonliving components that function as a whole. However, most often the biosphere is described as a collection of many ecological systems.
Atmosphere - Earth's air shell
The atmosphere is a collection of gases that surround our planet, held in place by Earth's gravity. Most of our atmosphere is near the earth's surface, where it is most dense. The air of the Earth is 79% nitrogen and just under 21% oxygen, as well as argon, carbon dioxide and other gases. Water vapor and dust are also part of the Earth's atmosphere. Other planets and the Moon have very different atmospheres, and some do not have one at all. There is no atmosphere in space.
The atmosphere is so widespread that it is almost invisible, but its weight is equal to a layer of water more than 10 meters deep that covers our entire planet. The lower 30 kilometers of the atmosphere contains about 98% of its total mass.
Scientists claim that many of the gases in our atmosphere were thrown into the air by early volcanoes. At that time, there was little or no free oxygen around the Earth. Free oxygen consists of oxygen molecules that are not bonded to another element, such as carbon (to form carbon dioxide) or hydrogen (to form water).
Free oxygen may have been added to the atmosphere by primitive organisms, probably bacteria, at the time. Later, more complex forms added more oxygen to the atmosphere. Oxygen in today's atmosphere has probably taken millions of years to build up.
The atmosphere acts like a giant filter, absorbing most of the ultraviolet radiation and allowing the sun's rays to penetrate. Ultraviolet radiation is harmful to living things and can cause burns. Nevertheless, solar energy is essential for all life on earth.
Earth's atmosphere has. The following layers go from the surface of the planet to the sky: the troposphere, stratosphere, mesosphere, thermosphere and exosphere. Another layer, called the ionosphere, extends from the mesosphere to the exosphere. Outside the exosphere is space. The boundaries between the atmospheric layers are not clearly defined and vary with latitude and season.
Interrelation of the Earth's shells
All four spheres can be present in one place. For example, a piece of soil will contain minerals from the lithosphere. In addition, there will be elements of the hydrosphere, which is moisture in the soil, the biosphere like insects and plants, and even the atmosphere in the form of soil air.
All spheres are interconnected and depend on each other, as a single organism. Changes in one area will lead to changes in another. Therefore, everything that we do on our planet affects other processes within it (even if we cannot see it with our own eyes).
For people dealing with problems, it is very important to understand the interconnection of all the shells of the Earth.
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The central part of the planet, like the core of an apple, is occupied by a heavy coreconsisting mainly of iron and other metals in solid state. Due to the incredibly high pressure created by the weight of the overlying layers, it is squeezed from all sides so much that it cannot melt, despite the very high temperature prevailing in the depths. Therefore, only the outer part of the core is liquid. It is the movements of the liquid and solid parts of the core relative to each other that generate the Earth's magnetic field - the same to which the compass needle reacts.
The core is divided into two parts: external and internal. The earth's core is believed to be made up of molten iron, inside of which is a solid inner core.
Mantle
Mantle (in Greek - "veil") covers the core. The mantle makes up the bulk of our planet, like the pulp of an apple. It stretches from the earth's crust to the earth's core for almost 3000 km. Scientists assume that the mantle is solid and at the same time plastic, red-hot. The upper mantle, the asthenosphere, and the lower one, the mesosphere, are distinguished.
The substance of the mantle differs from the core in composition: if we consider the core to be metallic, then the mantle can be called stony. It is composed of heavy rocks, such as basalt and ores of various metals. Although they are heavy, they are lighter than the metals themselves, therefore they did not "sink" deeper. The temperature and pressure here are almost as high as in the core, and this leads to the same result: most of the material in the mantle is held in a solid state, more precisely, reminiscent of thick glue. Only closer to the surface, where the pressure "releases" a little, the material of the mantle becomes liquid and can even pour out through the craters of volcanoes in the form of lava. In the depths of the mantle matter, an extremely slow thermal stirring, similar to what can be observed in a saucepan with steaming thick jelly. We feel the echoes of such mixing in the form of earthquakes: the centers of earthquakes are just found in the upper layers of the mantle.
Through the "fire-breathing mountains" - volcanoes - the mantle substance enters the Earth's surface. Volcanic eruptions give people a lot of trouble, but it is the volcanoes that our planet owes its water and air envelopes.
Lithosphere
Lithosphere (stone shell) - this is the very upper shell of the Earth. It covers the outside of the globe. The upper layer of the lithosphere is called the earth's crust (Fig. 42). We walk along this crust, cities and villages have been built on it, rivers flow along it, the waters of the seas and oceans splash in its depressions.
The surface of the globe is diverse. In some places, flat areas stretch for many tens of kilometers, in others - mountains, the tops of which are covered with snow and ice.
The thickness of the lithosphere is not the same everywhere. Under the oceans, its lower boundary goes to a depth of 5-10 km, under the plains - by 30-40 km, and under the mountain ranges - by 50-70 km.
In the composition of the lithosphere, geologists include the entire earth's crust and the uppermost parts of the mantle, frozen under the crust.
Earth's crust
The thin outer "skin" of the planet (its average thickness is only 33 km) is called crust... If we compare the Earth with an apple, then the crust will be even thinner than an apple peel. It can also be compared to the frozen foam on jelly: it is just as thin and heterogeneous. The rocks of the earth's crust are in a solid, frozen state. The lower, deep layer consists mainly of a heavier basalt... On top of it is covered with a layer composed mainly of lighter granite... Both of these rocks are well-known to every person: they can be constantly seen in nature and on the streets of the city. In nature, they do not often come to the surface of the Earth, because they are usually hidden by the third layer - the layer sedimentary rocks, which was formed from the products of destruction of the granite layer throughout the history of the Earth. There is a granite layer only on the continents. Due to it, the earth's crust is thicker here, but fragile. At the bottom of the oceans, there is no granite layer - only basalt. So under the oceans, the earth's crust is thinner and more plastic.
- The soil ... Soil is the outermost layer of the earth's crust.
- Rocks ... The rocks that make up the earth's crust, according to the method of their formation, are magmatic, sedimentary and metamorphic... The lowest layer of the earth's crust consists of basalts; a granite layer rests on it, but only under the continents. There is no granite layer under the oceans. In a number of places around the world, granites come to the surface.
Drilling of the wells
People are digging mines to extract coal and ore. The depth of some mines reaches 3 kilometers. Of course, this value in itself is not so great - compared to 6.5 thousand kilometers separating the planet's surface from its center - and, nevertheless, it is known that when you go down into the mine, the temperature rises by about 3 ° for every 100 m depth. The deeper, the faster this temperature rise. It is not difficult to calculate that already at a depth of 40 km the temperature will exceed a thousand degrees. And at this temperature, many rocks melt into liquid.
Seismic method
The sound from impacts on the ground travels differently than through the air - faster and further. In the same way, there are differences in the transmission of sound through solid and molten to a liquid rocks. Studying the "echo" spreading in the depths of the planet after special impacts (small directed explosions), scientists have found that at depths from 60 to 250 kilometers, rocks do become partially molten.
Geography is the science of the internal and external structure of the Earth, which studies the nature of all continents and oceans. The main objects of study are various geospheres and geosystems.
Introduction
The geographic shell or GO is one of the basic concepts of geography as a science, introduced into circulation at the beginning of the 20th century. It denotes the shell of the entire Earth, a special natural system. The geographic shell of the Earth is an integral and continuous shell, consisting of several parts that interact with each other, penetrate each other, constantly exchange substances and energy with each other.
Fig 1. Geographic shell of the Earth
There are similar terms, with narrow meanings, used in the writings of European scholars. But they do not denote a natural system, only a set of natural and social phenomena.
Stages of development
The geographic envelope of the earth has gone through a number of specific stages in its development and formation:
- geological (prebiogenic) - the first stage of formation, which began about 4.5 billion years ago (lasted about 3 billion years);
- biological - the second stage, which began about 600 million years ago;
- anthropogenic (modern) - a stage that continues to this day, which began about 40 thousand years ago, when humanity began to exert a noticeable influence on nature.
The composition of the geographic shell of the Earth
Geographic envelope - this is a system of the planet, which, as you know, has the shape of a ball, flattened on both sides by the caps of the poles, with a long equator of more than 40 t km. GO has a certain structure. It consists of media interconnected with each other.
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Some experts divide HE into four areas (which in turn are also divided):
- atmosphere;
- lithosphere;
- hydrosphere;
- biosphere.
In any case, the structure of the geographic envelope is not arbitrary. It has clear boundaries.
Upper and lower bounds
In the entire structure of the geographic envelope and geographic environments, there is a clear zoning.
The law of geographic zoning provides not only for the division of the entire shell into spheres and environments, but also for the division into natural zones of land and oceans. Interestingly, this division is regularly repeated in both hemispheres.
Zoning is due to the nature of the spread of the Sun's energy across latitudes and the intensity of moisture (different in different hemispheres, continents).
Naturally, you can define the upper boundary of the geographic envelope and the lower one. Upper bound located at an altitude of 25 km, and bottom line the geographic envelope runs at a level of 6 km under the oceans and at a level of 30-50 km on the continents. Although, it should be noted that the lower limit is conditional and there are still disputes over its setting.
Even if we take the upper boundary in the region of 25 km, and the lower one in the region of 50 km, then, in comparison with the overall dimensions of the Earth, we get something like a very thin film that covers the planet and protects it.
Basic laws and properties of the geographic envelope
Within these boundaries of the geographic envelope, the basic laws and properties operate that characterize and determine it.
- Interpenetration of components or intra-component movement - the main property (there are two types of intra-component movement of substances - horizontal and vertical; they do not contradict and do not interfere with each other, although the speed of movement of components is different in different structural parts of the HE).
- Geographic zoning - the basic Law.
- Rhythm - the frequency of occurrence of all natural phenomena (daily, annual).
- The unity of all parts of the geographic envelopedue to their close relationship.
Characteristics of the Earth's shells included in GO
Atmosphere
The atmosphere is important for keeping warm and thus for life on the planet. It also protects all living things from ultraviolet radiation, affects soil formation and climate.
The size of this shell is from 8 km to 1 ton km (or more) in height. It includes:
- gases (nitrogen, oxygen, argon, carbon dioxide, ozone, helium, hydrogen, inert gases);
- dust;
- water vapor.
The atmosphere, in turn, is divided into several interconnected layers. Their characteristics are presented in the table.
All shells of the earth are similar. For example, they contain all types of aggregate states of substances: solid, liquid, gaseous.
Fig 2. The structure of the atmosphere
Lithosphere
The hard shell of the earth, the earth's crust. It has several layers, which are characterized by different thickness, thickness, density, composition:
- upper lithospheric layer;
- sigmatic membrane;
- semi-metallic or ore shell.
The limiting depth of the lithosphere is 2900 km.
What does the lithosphere consist of? From solids: basalt, magnesium, cobalt, iron and others.
Hydrosphere
The hydrosphere is made up of all the waters of the Earth (oceans, seas, rivers, lakes, swamps, glaciers and even underground waters). It is located on the surface of the Earth and occupies more than 70% of the space. It is interesting that there is a theory according to which the earth's crust contains large reserves of water.
There are two types of water: salt and fresh. As a result of interaction with the atmosphere, during condensation, the salt evaporates, thereby providing the land with fresh water.
Fig 3. Earth's hydrosphere (view of the oceans from space)
Biosphere
The biosphere is the most "living" shell of the earth. It includes the entire hydrosphere, lower atmosphere, land surface and upper lithospheric layer. It is interesting that living organisms that populate the biosphere are responsible for the accumulation and distribution of the sun's energy, for the migration processes of chemicals in the soil, for gas exchange, for redox reactions. We can say that the atmosphere exists only thanks to living organisms.
Fig 4. Components of the Earth's biosphere
Examples of interaction of environments (shells) of the Earth
There are a lot of examples of interaction between environments.
- When water evaporates from the surface of rivers, lakes, seas and oceans, water enters the atmosphere.
- Air and water, penetrating through the soil into the depths of the lithosphere, makes it possible for vegetation to rise.
- Vegetation provides photosynthesis by enriching the atmosphere with oxygen and absorbing carbon dioxide.
- From the surface of the earth and oceans, the upper layers of the atmosphere are heated, creating a climate for life.
- Living organisms, when they die, form the soil. Assessment of the report
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