External and internal shells of the earth. Characteristics of the shells of the earth

Stages of the evolutionary development of the Earth

The Earth arose by thickening a predominantly high-temperature fraction with a significant amount of metallic iron, and the remaining near-Earth material, in which iron was oxidized and turned into silicates, probably went to build the Moon.

The early stages of the development of the Earth are not fixed in the stone geological record, according to which the geological sciences successfully restore its history. Even the most ancient rocks (their age is marked by a huge figure - 3.9 billion years) are the product of much later events that occurred after the formation of the planet itself.

The early stages of the existence of our planet were marked by the process of its planetary integration (accumulation) and subsequent differentiation, which led to the formation of the central core and the primary silicate mantle enveloping it. The formation of an aluminosilicate crust of oceanic and continental types refers to later events associated with physicochemical processes in the mantle itself.

The Earth as a primary planet was formed at temperatures below the melting point of its material 5-4.6 billion years ago. The earth arose by accumulation as a chemically relatively homogeneous sphere. It was a relatively homogeneous mixture of iron particles, silicates, and less sulfides, distributed fairly evenly throughout the volume.

Most of its mass was formed at a temperature below the condensation temperature of the high-temperature fraction (metal, silicate), i.e., below 800° K. In general, the completion of the formation of the Earth could not occur below 320° K, which was dictated by the distance from the Sun. Particle impacts during the accumulation process could raise the temperature of the nascent Earth, but a quantitative estimate of the energy of this process cannot be made reliably enough.

From the beginning of the formation of the young Earth, its radioactive heating was noted, caused by the decay of rapidly dying out radioactive nuclei, including a certain number of transuranic ones that have survived from the era of nuclear fusion, and the decay of now preserved radioisotopes and.

In the total radiogenic atomic energy in the early epochs of the Earth's existence, there was enough for its material to begin to melt in places, followed by degassing and the rise of light components to the upper horizons.

With a relatively homogeneous distribution of radioactive elements with a uniform distribution of radiogenic heat over the entire volume of the Earth, the maximum temperature increase occurred in its center, followed by equalization along the periphery. However, in the central regions of the Earth, the pressure was too high for melting. Melting as a result of radioactive heating began at some critical depths, where the temperature exceeded the melting point of some part of the Earth's primary material. In this case, the iron material with an admixture of sulfur began to melt faster than pure iron or silicate.

All this happened geologically rather quickly, since the huge masses of molten iron could not remain in an unstable state for a long time in the upper parts of the Earth. In the end, all liquid iron glassed into the central regions of the Earth, forming a metallic core. The inner part of it passed into a solid dense phase under the influence of high pressure, forming a small core deeper than 5000 km.

The asymmetric process of differentiation of the planet's material began 4.5 billion years ago, which led to the appearance of continental and oceanic hemispheres (segments). It is possible that the hemisphere of the modern Pacific Ocean was the segment into which the masses of iron sank towards the center, and in the opposite hemisphere they rose with the rise of silicate material and the subsequent melting of lighter aluminosilicate masses and volatile components. The fusible fractions of the mantle material concentrated the most typical lithophile elements, which arrived along with gases and water vapor on the surface of the primary Earth. At the end of planetary differentiation, most of the silicates formed a thick mantle of the planet, and the products of its melting gave rise to the development of an aluminosilicate crust, a primary ocean, and a primary atmosphere saturated with CO 2 .

A.P. Vinogradov (1971), on the basis of an analysis of the metal phases of meteorite matter, believes that a solid iron-nickel alloy arose independently and directly from the vapor phase of a protoplanetary cloud and condensed at 1500 ° C. The iron-nickel alloy of meteorites, according to the scientist, has a primary character and correspondingly characterizes the metallic phase of the terrestrial planets. Iron-nickel alloys of rather high density, as Vinogradov believes, arose in a protoplanetary cloud, sintered due to high thermal conductivity into separate pieces that fell to the center of the gas-dust cloud, continuing continuous condensation growth. Only a mass of iron-nickel alloy, independently condensed from a protoplanetary cloud, could form the cores of terrestrial-type planets.

The high activity of the primary Sun created a magnetic field in the surrounding space, which contributed to the magnetization of ferromagnetic substances. These include metallic iron, cobalt, nickel, and partly iron sulfide. The Curie point - the temperature below which substances acquire magnetic properties - for iron is 1043 ° K, for cobalt - 1393 ° K, for nickel - 630 ° K and for iron sulfide (pyrrhotite, close to troilite) - 598 ° K. Since magnetic forces for small particles are many orders of magnitude greater than the gravitational forces of attraction, which depend on masses, then the accumulation of iron particles from the cooling solar nebula could begin at temperatures below 1000 ° K in the form of large concentrations and was many times more efficient than the accumulation of silicate particles at other equal conditions. Iron sulfide below 580°K could also accumulate under the influence of magnetic forces after iron, cobalt and nickel.

The main motif of the zonal structure of our planet was associated with the course of the successive accumulation of particles of different compositions – first, strongly ferromagnetic, then weakly ferromagnetic, and, finally, silicate and other particles, the accumulation of which was already dictated mainly by the gravitational forces of the grown massive metal masses.

Thus, the main reason for the zonal structure and composition of the earth's crust was rapid radiogenic heating, which determined the increase in its temperature and further contributed to the local melting of the material, the development of chemical differentiation and ferromagnetic properties under the influence of solar energy.

The stage of the gas-dust cloud and the formation of the Earth as a condensation in this cloud. The atmosphere contained H and Not, dissipation of these gases occurred.

In the process of gradual heating of the protoplanet, iron oxides and silicates were reduced, and the inner parts of the protoplanet were enriched with metallic iron. Various gases were released into the atmosphere. The formation of gases occurred due to radioactive, radiochemical and chemical processes. Initially, mainly inert gases were released into the atmosphere: Ne(neon), Ns(nilsborium), CO 2(carbon monoxide), H 2(hydrogen), Not(helium), Ag(argon), Kg(krypton), Heh(xenon). A restorative atmosphere was created in the atmosphere. Perhaps there was some education NH3(ammonia) through synthesis. Then, in addition to those indicated, sour smoke began to enter the atmosphere - CO 2, H 2 S, HF, SO2. Dissociation of hydrogen and helium took place. The release of water vapor and the formation of the hydrosphere caused a decrease in the concentrations of highly soluble and reactive gases ( CO2, H 2 S, NH3). The composition of the atmosphere changed accordingly.

Through volcanoes and in other ways, the release of water vapor from magma and igneous rocks continued, CO 2, SO, NH3, NO 2, SO2. There was also a selection H 2, About 2, Not, Ag, Ne, kr, Xe due to radiochemical processes and transformations of radioactive elements. gradually accumulated in the atmosphere CO 2 and N 2. There was a slight concentration About 2 in the atmosphere, but were also present in it CH 4 , H 2 and SO(from volcanoes). Oxygen oxidized these gases. As the Earth cooled, hydrogen and inert gases were absorbed by the atmosphere, retained by gravity and the geomagnetic field, like other gases of the primary atmosphere. The secondary atmosphere contained some residual hydrogen, water, ammonia, hydrogen sulfide and was of a sharply reducing character.

During the formation of the proto-Earth, all water was in various forms associated with the substance of the protoplanet. As the Earth formed from a cold protoplanet and its temperature gradually increased, water was increasingly included in the composition of the silicate magmatic solution. Part of it evaporated from the magma into the atmosphere, and then dissipated. As the Earth cooled, the dissipation of water vapor weakened, and then practically stopped altogether. The atmosphere of the Earth began to be enriched with the content of water vapor. However, atmospheric precipitation and the formation of water bodies on the Earth's surface became possible only much later, when the temperature on the Earth's surface became below 100°C. The drop in temperature on the Earth's surface to less than 100°C was undoubtedly a leap in the history of the Earth's hydrosphere. Until that moment, water in the earth's crust was only in a chemically and physically bound state, constituting, together with rocks, a single indivisible whole. Water was in the form of gas or hot vapor in the atmosphere. As the temperature of the Earth's surface fell below 100°C, rather extensive shallow reservoirs began to form on its surface, as a result of heavy rainfall. Since that time, seas began to form on the surface, and then the primary ocean. In the rocks of the Earth, along with water-bound solidifying magma and emerging igneous rocks, free drip-liquid water appears.

The cooling of the Earth contributed to the emergence of groundwater, which differed significantly in chemical composition between themselves and the surface waters of the primary seas. The terrestrial atmosphere, which arose during the cooling of the initial hot matter from volatile materials, vapors and gases, became the basis for the formation of the atmosphere and water in the oceans. The emergence of water on the earth's surface contributed to the process of atmospheric circulation of air masses between the sea and land. The uneven distribution of solar energy over the earth's surface has caused atmospheric circulation between the poles and the equator.

All existing elements were formed in the earth's crust. Eight of them—oxygen, silicon, aluminium, iron, calcium, sodium, potassium, and magnesium—made up more than 99% of the earth's crust by weight and number of atoms, while all the rest accounted for less than 1%. The main mass of elements is dispersed in the earth's crust and only a small part of them formed accumulations in the form of mineral deposits. In deposits, elements are usually not found in pure form. They form natural chemical compounds - minerals. Only a few - sulfur, gold and platinum - can accumulate in a pure native form.

A rock is a material from which sections of the earth's crust are built with a more or less constant composition and structure, consisting of an accumulation of several minerals. The main rock-forming process in the lithosphere is volcanism (Fig. 6.1.2). At great depths, magma is under conditions of high pressure and temperature. Magma (Greek: "thick mud") consists of a number of chemical elements or simple compounds.

Rice. 6.1.2. Eruption

With a drop in pressure and temperature, the chemical elements and their compounds are gradually "ordered", forming the prototypes of future minerals. As soon as the temperature drops enough to begin solidification, minerals begin to exude from the magma. This isolation is accompanied by a crystallization process. As an example of crystallization, we give the formation of a salt crystal NaCl(Fig. 6.1.3).

Fig.6.1.3. The structure of a crystal of table salt (sodium chloride). (Small balls are sodium atoms, large balls are chlorine atoms.)

The chemical formula indicates that the substance is built from the same number of sodium and chlorine atoms. There are no atoms of sodium chloride in nature. The substance sodium chloride is built from sodium chloride molecules. Rock salt crystals consist of sodium and chlorine atoms alternating along the axes of the cube. During crystallization, due to electromagnetic forces, each of the atoms in the crystal structure tends to take its place.

Crystallization of magma occurred in the past and occurs now during volcanic eruptions in various natural conditions. When magma solidifies at a depth, then the process of its cooling is slow, granular well-crystallized rocks appear, which are called deep. These include granites, diarites, gabbro, syanites and peridotites. Often, under the influence of the active internal forces of the Earth, magma pours out to the surface. At the surface, lava cools much faster than at depth, so the conditions for crystal formation are less favorable. Crystals are less durable and quickly turn into metamorphic, loose and sedimentary rocks.

In nature, there are no minerals and rocks that exist forever. Any rock once arose and someday its existence comes to an end. It does not disappear without a trace, but turns into another rock. So, when granite is destroyed, its particles give rise to layers of sand and clay. Sand, when submerged, can turn into sandstone and quartzite, and at higher pressure and temperature give rise to granite.

The world of minerals and rocks has its own special "life". There are twin minerals. For example, if a “lead sheen” mineral is found, then the “zinc blende” mineral will always be next to it. The same twins are gold and quartz, cinnabar and antimonite.

There are minerals "enemies" - quartz and nepheline. Quartz in composition corresponds to silica, nepheline - to sodium aluminosilicate. And although quartz is very widespread in nature and is part of many rocks, it does not “tolerate” nepheline and never occurs with it in a place. The secret of antagonism is related to the fact that nepheline is undersaturated with silica.

In the world of minerals, there are cases when one mineral turns out to be aggressive and develops at the expense of another, when environmental conditions change.

A mineral, falling into other conditions, sometimes turns out to be unstable, and is replaced by another mineral while maintaining its original form. Such transformations often occur with pyrite, which is similar in composition to iron disulfide. It usually forms golden-colored cubic crystals with a strong metallic sheen. Under the influence of atmospheric oxygen, pyrite decomposes into brown iron ore. Brown iron ore does not form crystals, but, arising in place of pyrite, retains the shape of its crystal.

Such minerals are jokingly called "deceivers". Their scientific name is pseudomorphoses, or false crystals; their shape is not characteristic of the constituent mineral.

Pseudomorphoses testify to complex relationships between different minerals. Relationships between crystals of one mineral are not always simple either. In geological museums, you have probably admired beautiful intergrowths of crystals more than once. Such intergrowths are called druze, or mountain brushes. In mineral deposits, they are the objects of reckless "hunting" of stone lovers - both beginners and experienced mineralogists (Fig. 6.1.4).

Druzes are very beautiful, so such interest in them is quite understandable. But it's not just about looks. Let's see how these brushes of crystals are formed, find out why the crystals, by their elongation, are always located more or less perpendicular to the growth surface, why there are no or almost no crystals in druze that would lie flat or grow obliquely. It would seem that during the formation of a “nucleus” of a crystal, it should lie on the growth surface, and not stand vertically on it.

Rice. 6.1.4. Scheme of geometric selection of growing crystals during the formation of druse (according to D. P. Grigoriev).

All these questions are well explained by the theory of geometric selection of crystals by the famous mineralogist - professor of the Leningrad Mining Institute D. P. Grigoriev. He proved that a number of reasons influence the formation of crystal druses, but in any case, growing crystals interact with each other. Some of them turn out to be "weaker", so their growth soon stops. The more “strong” ones continue to grow, and in order not to be “constrained” by their neighbors, they stretch upwards.

What is the mechanism of formation of mountain brushes? How do numerous differently oriented "nuclei" turn into a small number of large crystals located more or less perpendicular to the growth surface? The answer to this question can be obtained if we carefully consider the structure of a druse, consisting of zone-colored crystals, that is, those in which color changes give out traces of growth.

Let's take a closer look at the longitudinal section of the Druse. A number of crystal nuclei are visible on the uneven growing surface. Naturally, their elongations correspond to the direction of greatest growth. Initially, all nuclei, regardless of orientation, grew at the same rate in the direction of crystal elongation. But then the crystals began to touch. The leaning ones quickly found themselves squeezed by their vertically growing neighbors, leaving no free space for them. Therefore, from the mass of differently oriented small crystals, only those that were located perpendicular or almost perpendicular to the growth surface "survived". Behind the sparkling cold brilliance of crystal druze, stored in the showcases of museums, lies a long life full of collisions...

Another remarkable mineralogical phenomenon is a rock crystal with bundles of rutile mineral inclusions. A great stone connoisseur A. A. Malakhov said that “when you turn this stone in your hands, it seems that you look at the seabed through the depths pierced by solar filaments.” In the Urals, such a stone is called “hairy”, and in the mineralogical literature it is known under the magnificent name “Hair of Venus”.

The process of crystal formation begins at some distance from the source of fiery magma, when hot aqueous solutions with silicon and titanium enter the cracks in the rocks. In the case of a decrease in temperature, the solution turns out to be supersaturated, silica crystals (rock crystal) and titanium oxide (rutile) simultaneously precipitate from it. This explains the penetration of rock crystal with rutile needles. Minerals crystallize in a certain sequence. Sometimes they stand out simultaneously, as in the formation of "Hair of Venus".

Colossal destructive and creative work is still going on in the bowels of the Earth. In chains of endless reactions, new substances are born - elements, minerals, rocks. The magma of the mantle rushes from unknown depths into the thin shell of the earth's crust, breaks through it, trying to find a way out to the surface of the planet. Waves of electromagnetic oscillations, streams of neurons, radioactive radiation stream from the bowels of the earth. It was they who became one of the main ones in the origin and development of life on Earth.

Anthropogenic impact on nature is currently penetrating into all areas, so it is necessary to briefly consider the characteristics of the individual shells of the Earth.

The earth consists of the core, mantle, crust, lithosphere, hydrosphere and. Due to the impact of living matter and human activity, two more shells arose - the biosphere and the noosphere, including the technosphere. Human activity extends to the hydrosphere, lithosphere, biosphere and noosphere. Let us briefly consider these shells and the nature of the impact of human activity on them.

General characteristics of the atmosphere

The outer gaseous shell of the Earth. The lower part is in contact with the lithosphere or, and the upper part is in contact with interplanetary space. consists of three parts:

1. Troposphere (lower part) and its height above the surface is 15 km. The troposphere consists of , the density of which decreases with height. The upper part of the troposphere is in contact with the ozone screen - an ozone layer 7-8 km thick.

The ozone shield prevents hard ultraviolet radiation or high-energy cosmic radiation from reaching the Earth's surface (lithosphere, hydrosphere), which are detrimental to all living things. The lower layers of the troposphere - up to 5 km from sea level - are an air habitat, while the lowest layers are most densely populated - up to 100 m from the land surface or. The greatest impact from human activity, which has the greatest ecological significance, is experienced by the troposphere and especially its lower layers.

2. Stratosphere - the middle layer, the limit of which is a height of 100 km above sea level. The stratosphere is filled with rarefied gas (nitrogen, hydrogen, helium, etc.). It goes into the ionosphere.

3. Ionosphere - the upper layer, passing into interplanetary space. The ionosphere is filled with particles arising from the decay of molecules - ions, electrons, etc. In the lower part of the ionosphere, the "northern lights" appear, which is observed in areas beyond the Arctic Circle.

In ecological terms, the troposphere is of the greatest importance.

Brief description of the lithosphere and hydrosphere

The surface of the Earth, located under the troposphere, is heterogeneous - part of it is occupied by water, which forms the hydrosphere, and part is land, which forms the lithosphere.

Lithosphere - the outer hard shell of the globe, formed by rocks (hence the name - "cast" - stone). It consists of two layers - the upper, formed by sedimentary rocks with granite, and the lower, formed by solid basalt rocks. Part of the lithosphere is occupied by water (), and part is land, making up about 30% of the earth's surface. The topmost layer of land (for the most part) is covered with a thin layer of fertile surface - soil. The soil is one of the environments of life, and the lithosphere is the substrate on which various organisms live.

Hydrosphere - the water shell of the earth's surface, formed by the totality of all water bodies on Earth. The thickness of the hydrosphere is different in different areas, but the average depth of the ocean is 3.8 km, and in some depressions - up to 11 km. The hydrosphere is a source of water for all organisms living on Earth, it is a powerful geological force that cycles water and other substances, the "cradle of life" and the habitat of aquatic organisms. The anthropogenic impact on the hydrosphere is also great and will be discussed below.

General characteristics of the biosphere and noosphere

Since the appearance of life on Earth, a new, specific shell has arisen - the biosphere. The term "biosphere" was introduced by E. Suess (1875).

The biosphere (sphere of life) is that part of the shells of the Earth in which various organisms live. The biosphere occupies a part (the lower part of the troposphere), the lithosphere (the upper part, including soil) and permeates the entire hydrosphere and the upper part of the bottom surface.

The biosphere can also be defined as a geological shell inhabited by living organisms.

The boundaries of the biosphere are determined by the presence of conditions necessary for the normal functioning of organisms. The upper part of the biosphere is limited by the intensity of ultraviolet radiation, and the lower part by high temperature (up to 100°C). Bacterial spores are found at an altitude of 20 km above sea level, and anaerobic bacteria are found at a depth of up to 3 km from the earth's surface.

It is known that they are formed by living matter. The density of the biosphere is characterized by the concentration of living matter. It has been established that the highest density of the biosphere is characteristic of the land and ocean surfaces at the interface between the lithosphere and hydrosphere and the atmosphere. The density of life in the soil is very high.

The mass of living matter in comparison with the mass of the earth's crust and hydrosphere is small, but plays a huge role in the processes of change in the earth's crust.

The biosphere is the totality of all biogeocenoses on Earth, therefore it is considered the highest ecosystem of the Earth. Everything in the biosphere is interconnected and interdependent. The gene pool of all organisms on the Earth ensures the relative stability and renewability of the biological resources of the planet, if there is no sharp interference in natural ecological processes by various forces of a geological or interplanetary nature. At present, as mentioned above, anthropogenic factors affecting the biosphere have taken on the character of a geological force, which must be taken into account by humanity if it wants to survive on Earth.

Since the appearance of man on Earth, anthropogenic factors have arisen in nature, the effect of which is intensifying with the development of civilization, and a new specific shell of the Earth has arisen - the noosphere (the sphere of intelligent life). The term "noosphere" was first introduced by E. Leroy and T. Ya. de Chardin (1927), and in Russia for the first time in his works was used by V. I. Vernadsky (30-40s of the XX century). In the interpretation of the term "noosphere" there are two approaches:

1. "The noosphere is that part of the biosphere where human economic activity is carried out." The author of this concept was LN Gumilyov (son of the poetess A. Akhmatova and the poet N. Gumilyov). This point of view is correct if it is necessary to single out human activity in the biosphere, to show its difference from the activity of other organisms. Such a concept characterizes the "narrow sense" of the essence of the noosphere as the shell of the Earth.

2. "The noosphere is the biosphere, the development of which is directed by the human mind." This concept is widely represented in and is a concept in a broad understanding of the essence of the noosphere, since the influence of the human mind on the biosphere can be both positive and negative, the latter very often prevailing. The composition of the noosphere includes the technosphere - a part of the noosphere associated with the production activity of man.

At the present stage of the development of civilization and population, it is necessary to “reasonably” influence Nature, optimally influence it in order to bring minimal harm to natural ecological processes, restore destroyed or disturbed biogeocenoses, and even on human life as an integral part of the biosphere. Human activity inevitably makes changes to the world around, but, given the possible consequences, anticipating possible negative impacts, it is necessary to make sure that these consequences are the least destructive.

Brief description of emergency situations that occur on the surface of the Earth, and their classification

An important role in natural ecological processes is played by emergencies that constantly arise on the surface of the Earth. They destroy local biogeocenoses, and, if repeated cyclically, in some cases they are environmental factors that contribute to the evolutionary processes.

Situations in which the normal functioning of a large number of people or the biogeocenosis as a whole becomes difficult or impossible are called emergency.

The concept of "emergency situations" is more applicable to human activities, but it also applies to natural communities.

By origin, emergencies are divided into natural and anthropogenic (technogenic).

Natural emergencies arise as a result of natural phenomena. These include floods, earthquakes, landslides, mudflows, hurricanes, eruptions, etc. Consider some of the phenomena that cause natural emergencies.

This is a sudden release of the potential energy of the earth's interior, which takes the form of shock waves and elastic vibrations (seismic waves).

Earthquakes occur mainly due to underground volcanic phenomena, displacement of layers relative to each other, but they can also be man-made in nature and occur due to the collapse of mineral excavations. During earthquakes, displacements, vibrations and vibrations of rocks from seismic waves and tectonic movements of the earth's crust occur, which leads to the destruction of the surface - the appearance of cracks, faults, etc., as well as to the occurrence of fires, the destruction of buildings.

Landslides - sliding displacement of rocks downslope from inclined surfaces (mountains, hills, sea terraces, etc.) under the influence of gravity.

During landslides, the surface is disturbed, biocenoses die, settlements are destroyed, etc. The greatest damage is caused by very deep landslides, the depth of which exceeds 20 meters.

Volcanism (volcanic eruptions) is a set of phenomena associated with the movement of magma (molten rock mass), hot gases and water vapor rising through channels or cracks in the earth's crust.

Volcanism is a typical natural phenomenon that causes great destruction of natural biogeocenoses, causing enormous damage to human economic activity, and heavily polluting the region adjacent to volcanoes. Volcanic eruptions are accompanied by other catastrophic natural phenomena - fires, landslides, floods, etc.

Mudflows are short-term stormy floods that carry a large amount of sand, pebbles, large rubble and stones, which have the character of mud-stone flows.

Mudflows are characteristic of mountainous regions and can cause significant damage to human activities, cause the death of various animals and cause the destruction of local plant communities.

Snow avalanches are called avalanches of snow, carrying with them more and more masses of snow and other bulk materials. Avalanches are of both natural and anthropogenic origin. They cause great damage to human economic activity, destroying roads, power lines, causing death of people, animals and plant communities.

The above phenomena, which are the cause of emergency situations, are closely related to the lithosphere. Natural phenomena that create emergency situations are also possible in the hydrosphere. These include floods and tsunamis.

Floods are the flooding of areas with water within river valleys, lake coasts, seas and oceans.

If floods are strictly periodic in nature (tides, ebbs), then in this case natural biogeocenoses are adapted to them as to a habitat under certain conditions. But often floods are unexpected and associated with individual non-periodic phenomena (excessive snowfall in winter creates conditions for the occurrence of extensive floods that cause flooding of a large area, etc.). During floods, soil covers are disturbed, the area may be contaminated with various wastes due to the erosion of their storage facilities, the death of animals, plants and people, the destruction of settlements, etc.

Gravitational waves of great strength arising on the surface of the seas and oceans.

Tsunamis have natural and man-made causes. Earthquakes, seaquakes and underwater volcanic eruptions are classified as natural causes, underwater nuclear explosions as man-made causes.

Tsunamis cause the death of ships and accidents on them, which in turn leads to pollution of the natural environment, for example, the destruction of an oil tanker will lead to pollution of a huge water surface with an oil film that is poisonous to plankton and pelargic forms of animals (plankton are suspended small organisms, living in the surface layer of the water of the ocean or other body of water; pelargic forms of animals - animals that freely move in the water column due to active movement, for example, sharks, whales, cephalopods; benthic forms of organisms - organisms leading a benthic lifestyle, for example, flounder, hermit crabs , echinoderms, algae attached to the bottom, etc.). Tsunamis cause strong mixing of waters, the transfer of organisms to an unusual habitat and death.

There are also phenomena that cause emergencies. These include hurricanes, tornadoes, various types of storms.

Hurricanes - tropical and extratropical cyclones, which have a greatly reduced pressure in the center, are accompanied by the occurrence of winds with high speed and destructive power.

There are weak, strong and extreme hurricanes that cause showers, sea waves and the destruction of land objects, the death of various organisms.

Vortex storms (squalls) are atmospheric phenomena associated with the occurrence of strong winds with great destructive power and a large area of distribution. There are snow, dust and dustless storms. Flurries cause the transfer of the upper layers of the soil, their destruction, the death of plants, animals, and the destruction of structures.

Tornadoes (tornadoes) are a vortex-like form of movement of air masses, accompanied by the appearance of air funnels.

The power of tornadoes is great, in the area of their movement there is a complete destruction of the soil, animals die, buildings are destroyed, objects are transferred from one place to another, causing damage to objects located there.

In addition to the natural phenomena described above, leading to the emergence of emergency situations, there are other phenomena that cause them, the cause of which is human activity. Man-made emergencies include:

1. Transport accidents. When traffic rules are violated on various highways (roads, railways, rivers, seas), vehicles, people, animals, etc. die. Various substances enter the natural environment, including those that lead to the death of organisms of all kingdoms ( such as pesticides, etc.). As a result of accidents in transport, fires and ingress into gases (hydrogen chloride, ammonia, flammable and explosive substances) are possible.

2. Accidents at large enterprises. Violation of technological processes, non-compliance with the rules of operation of equipment, imperfection of technology can cause the release of harmful compounds into the environment, causing various diseases in humans and animals, contributing to the appearance of mutations in plant and animal organisms, as well as lead to destruction of buildings and fires. The most dangerous accidents at enterprises using. Accidents at nuclear power plants (NPPs) cause great harm, since in addition to the usual damaging factors (mechanical damage, single-acting release of harmful substances, fires), accidents at NPPs are characterized by damage to the area by radionuclides, penetrating radiation, and the damage radius in this case significantly exceeds the probability of occurrence accidents at other enterprises.

3. Fires covering large areas of forests or peatlands. As a rule, such fires are anthropogenic in nature due to violation of the rules for handling fire, but they can also be natural in nature, for example, due to lightning discharges (lightning). Such fires can also be caused by faults in power lines. Fires destroy natural communities of organisms over large areas, causing great economic damage to human economic activity.

All the described phenomena that violate natural biogeocenoses, causing great damage to human economic activity, require the development and adoption of measures to reduce their negative impact, which is implemented in the implementation of environmental actions and dealing with the consequences of emergency situations.

It is called the crust and enters the lithosphere, which in Greek literally means "stony" or "hard ball". It also includes part of the upper mantle. All this is located directly above the asthenosphere ("powerless ball") - above a more viscous or plastic layer, as if underlying the lithosphere.

Earth's internal structure

Our planet has the shape of an ellipsoid, or more precisely, a geoid, which is a three-dimensional geometric body of a closed shape. This most important geodesic concept is literally translated as "similar to the Earth." This is what our planet looks like from the outside. Internally, it is arranged as follows - the Earth consists of layers separated by boundaries that have their own specific names (the clearest of them is the Mohorovichic boundary, or Moho, separates the crust and mantle). The core, which is the center of our planet, the shell (or mantle) and the crust - the upper solid shell of the Earth - these are the main layers, two of which - the core and the mantle, in turn, are divided into 2 sublayers - inner and outer, or lower and upper. Thus, the core, whose sphere radius is 3.5 thousand kilometers, consists of a solid inner core (radius 1.3) and a liquid outer one. And the mantle, or silicate shell, is divided into lower and upper parts, which together account for 67% of the total mass of our planet.

The thinnest layer of the planet

The soils themselves arose simultaneously with life on Earth and are the product of the influence of the environment - water, air, living organisms and plants. Depending on various conditions (geological, geographical and climatic), this most important natural resource has a thickness of 15 cm to 3 m. The value of some types of soil is very high. For example, during the occupation, the Germans exported Ukrainian black earth in rolls to Germany. Speaking of the earth's crust, one cannot help but mention large solid areas that slide over more liquid layers of the mantle and move relative to each other. Their rapprochement and "arrivals" threaten tectonic shifts, which can be the cause of disasters on Earth.

About 40,000 kilometers. The geographic shells of the Earth are systems of the planet, where all the components inside are interconnected and determined relative to each other. There are four types of shells - atmosphere, lithosphere, hydrosphere and biosphere. Aggregate states of substances in them are of all types - liquid, solid and gaseous.

Shells of the Earth: the atmosphere

The atmosphere is the outer shell. It consists of various gases:

nitrogen - 78.08%;
oxygen - 20.95%;
argon - 0.93%;
carbon dioxide - 0.03%.

In addition to them, there are ozone, helium, hydrogen, inert gases, but their share in the total volume is no more than 0.01%. This shell of the Earth also includes dust and water vapor.

The atmosphere, in turn, is divided into 5 layers:

troposphere - height from 8 to 12 km, the presence of water vapor, the formation of precipitation, the movement of air masses are characteristic;
stratosphere - 8-55 km, contains an ozone layer that absorbs UV radiation;
mesosphere - 55-80 km, low air density compared to the lower troposphere;
ionosphere - 80-1000 km, composed of ionized oxygen atoms, free electrons and other charged gas molecules;
upper atmosphere (scattering sphere) - more than 1000 km, molecules move at great speeds and can penetrate into space.

The atmosphere supports life on the planet because it helps keep the earth warm. It also prevents direct sunlight from entering. And its precipitation influenced the soil-forming process and climate formation.

Shells of the Earth: lithosphere

It is a hard shell that makes up the earth's crust. The composition of the globe includes several concentric layers with different thicknesses and densities. They also have a heterogeneous composition. The average density of the Earth is 5.52 g/cm 3 , and in the upper layers - 2.7. This indicates that there are heavier substances inside the planet than on the surface.

The upper lithospheric layers are 60-120 km thick. They are dominated by igneous rocks - granite, gneiss, basalt. Most of them have been subjected to destruction processes, pressure, temperatures for millions of years and turned into loose rocks - sand, clay, loess, etc.

Up to 1200 km is the so-called sigmatic shell. Its main constituents are magnesium and silicon.

At depths of 1200-2900 km there is a shell, called the average semi-metallic or ore. It mainly contains metals, in particular iron.

Below 2900 km is the central part of the Earth.

Hydrosphere

The composition of this shell of the Earth is represented by all the waters of the planet, whether it be oceans, seas, rivers, lakes, swamps, groundwater. The hydrosphere is located on the surface of the Earth and occupies 70% of the total area - 361 million km 2.

1375 million km 3 of water are concentrated in the ocean, 25 on the land surface and in glaciers, and 0.25 in lakes. According to Academician Vernadsky, large reserves of water are located in the thickness of the earth's crust.

On the surface of the land, water is involved in continuous water exchange. Evaporation occurs mainly from the surface of the ocean, where the water is salty. Due to the process of condensation in the atmosphere, land is provided with fresh water.

Biosphere

The structure, composition and energy of this shell of the Earth are determined by the processes of activity of living organisms. Biospheric boundaries - the land surface, the soil layer, the lower atmosphere and the entire hydrosphere.

Plants distribute and store solar energy in the form of various organic substances. Living organisms carry out the migration process of chemicals in the soil, atmosphere, hydrosphere, sedimentary rocks. Thanks to animals, gas exchange and redox reactions take place in these shells. The atmosphere is also the result of the activity of living organisms.

The shell is represented by biogeocenoses, which are genetically homogeneous areas of the Earth with one type of vegetation cover and inhabiting animals. Biogeocenoses have their own soils, topography and microclimate.

All shells of the Earth are in close continuous interaction, which is expressed as an exchange of matter and energy. Research in the field of this interaction and the identification of general principles is important for understanding the soil-forming process. The geographic shells of the Earth are unique systems that are characteristic only for our planet.

Introduction

1. Basic shells of the earth

3. Geothermal regime of the earth

Conclusion

List of sources used

Introduction

Geology is the science of the structure and history of the development of the Earth. The main objects of research are rocks, in which the geological record of the Earth is imprinted, as well as modern physical processes and mechanisms acting both on its surface and in the bowels, the study of which allows us to understand how our planet developed in the past.

The earth is constantly changing. Some changes occur suddenly and very rapidly (for example, volcanic eruptions, earthquakes or large floods), but most often they occur slowly (a layer of precipitation no more than 30 cm thick is demolished or accumulated over a century). Such changes are not noticeable during the life of one person, but some information has been accumulated about changes over a long period of time, and with the help of regular accurate measurements, even insignificant movements of the earth's crust are recorded.

The history of the Earth began simultaneously with the development of the solar system about 4.6 billion years ago. However, the geological record is characterized by fragmentation and incompleteness, since many ancient rocks have been destroyed or overlain by younger sediments. Gaps need to be filled by correlation with events that have occurred elsewhere and for which more data are available, as well as by analogy and hypotheses. The relative age of rocks is determined on the basis of the complexes of fossil remains contained in them, and the deposits in which such remains are absent, on the basis of the relative position of both. In addition, the absolute age of almost all rocks can be determined by geochemical methods.

In this paper, the main shells of the earth, its composition and physical structure are considered.

1. Basic shells of the earth

The Earth has 6 shells: atmosphere, hydrosphere, biosphere, lithosphere, pyrosphere and centrosphere.

The atmosphere is the outer gaseous shell of the Earth. Its lower boundary passes through the lithosphere and hydrosphere, and the upper one - at an altitude of 1000 km. The atmosphere is divided into the troposphere (the moving layer), the stratosphere (the layer above the troposphere) and the ionosphere (the upper layer).

The average height of the troposphere is 10 km. Its mass is 75% of the total mass of the atmosphere. Air in the troposphere moves both horizontally and vertically.

The stratosphere rises 80 km above the troposphere. Its air, moving only in a horizontal direction, forms layers.

Even higher extends the ionosphere, which got its name due to the fact that its air is constantly ionized under the influence of ultraviolet and cosmic rays.

The hydrosphere covers 71% of the Earth's surface. Its average salinity is 35 g/l. The temperature of the ocean surface is from 3 to 32 ° C, the density is about 1. Sunlight penetrates to a depth of 200 m, and ultraviolet rays to a depth of 800 m.

The biosphere, or sphere of life, merges with the atmosphere, hydrosphere and lithosphere. Its upper boundary reaches the upper layers of the troposphere, while the lower one runs along the bottom of the ocean basins. The biosphere is subdivided into the sphere of plants (over 500,000 species) and the sphere of animals (over 1,000,000 species).

The lithosphere - the stone shell of the Earth - is 40 to 100 km thick. It includes continents, islands and the bottom of the oceans. The average height of the continents above ocean level: Antarctica - 2200 m, Asia - 960 m, Africa - 750 m, North America - 720 m, South America - 590 m, Europe - 340 m, Australia - 340 m.

Under the lithosphere is the pyrosphere - the fiery shell of the Earth. Its temperature rises by about 1°C for every 33 m of depth. Rocks at considerable depths are probably in a molten state due to high temperatures and high pressure.

The centrosphere, or the core of the Earth, is located at a depth of 1800 km. According to most scientists, it consists of iron and nickel. The pressure here reaches 300000000000 Pa (3000000 atmospheres), the temperature is several thousand degrees. The state of the core is still unknown.

The fiery sphere of the Earth continues to cool. The hard shell thickens, the fiery shell thickens. At one time, this led to the formation of solid boulders - continents. However, the influence of the fiery sphere on the life of planet Earth is still very great. The contours of the continents and oceans, the climate, and the composition of the atmosphere have repeatedly changed.

Exogenous and endogenous processes continuously change the solid surface of our planet, which, in turn, actively affects the Earth's biosphere.

2. Composition and physical structure of the earth

Geophysical data and the results of studying deep inclusions indicate that our planet consists of several shells with different physical properties, the change in which reflects both the change in the chemical composition of matter with depth and the change in its state of aggregation as a function of pressure.

The uppermost shell of the Earth - the earth's crust - under the continents has an average thickness of about 40 km (25-70 km), and under the oceans - only 5-10 km (without a layer of water, averaging 4.5 km). The surface of Mohorovichich is taken as the lower edge of the earth's crust - a seismic section, on which the propagation velocity of longitudinal elastic waves increases abruptly with a depth of 6.5-7.5 to 8-9 km / s, which corresponds to an increase in the density of matter from 2.8-3 .0 to 3.3 g/cm3.

From the surface of Mohorovichich to a depth of 2900 km, the Earth's mantle extends; the upper least dense zone 400 km thick stands out as the upper mantle. The interval from 2900 to 5150 km is occupied by the outer core, and from this level to the center of the Earth, i.e. from 5150 to 6371 km, is the inner core.

The Earth's core has been of interest to scientists since its discovery in 1936. It was extremely difficult to image it because of the relatively small number of seismic waves reaching it and returning to the surface. In addition, the extreme temperatures and pressures of the core have long been difficult to reproduce in the laboratory. New research could provide a more detailed picture of our planet's center. The Earth's core is divided into 2 separate regions: liquid (outer core) and solid (inner), the transition between which lies at a depth of 5,156 km.

Iron is the only element that closely matches the seismic properties of the earth's core and is abundant enough in the universe to represent approximately 35% of the planet's mass in the core of the planet. According to modern data, the outer core is a rotating stream of molten iron and nickel, a good conductor of electricity. It is with him that the origin of the earth's magnetic field is associated, considering that, like a giant generator, electric currents flowing in the liquid core create a global magnetic field. The mantle layer, which is in direct contact with the outer core, is affected by it, since the temperatures in the core are higher than in the mantle. In some places, this layer generates huge heat and mass flows directed to the Earth's surface - plumes.

The inner solid core is not connected to the mantle. It is believed that its solid state, despite the high temperature, is provided by the gigantic pressure in the center of the Earth. It is suggested that, in addition to iron-nickel alloys, lighter elements, such as silicon and sulfur, and possibly silicon and oxygen, should also be present in the core. The question of the state of the Earth's core is still debatable. As the distance from the surface increases, the compression to which the substance is subjected increases. Calculations show that the pressure in the earth's core can reach 3 million atm. At the same time, many substances seem to be metallized - they pass into a metallic state. There was even a hypothesis that the core of the Earth consists of metallic hydrogen.

The outer core is also metallic (essentially iron), but unlike the inner core, the metal is here in a liquid state and does not transmit transverse elastic waves. Convective currents in the metallic outer core are the cause of the formation of the Earth's magnetic field.

The Earth's mantle consists of silicates: compounds of silicon and oxygen with Mg, Fe, Ca. The upper mantle is dominated by peridotites - rocks consisting mainly of two minerals: olivine (Fe, Mg) 2SiO4 and pyroxene (Ca, Na) (Fe, Mg, Al) (Si, Al) 2O6. These rocks contain relatively little (< 45 мас. %) кремнезема (SiO2) и обогащены магнием и железом. Поэтому их называют ультраосновными и ультрамафическими. Выше поверхности Мохоровичича в пределах континентальной земной коры преобладают силикатные магматические породы основного и кислого составов. Основные породы содержат 45-53 мас. % SiO2. Кроме оливина и пироксена в состав основных пород входит Ca-Na полевой шпат - плагиоклаз CaAl2Si2O8 - NaAlSi3O8. Кислые магматические породы предельно обогащены кремнеземом, содержание которого возрастает до 65-75 мас. %. Они состоят из кварца SiO2, плагиоклаза и K-Na полевого шпата (K,Na) AlSi3O8. Наиболее распространенной интрузивной породой основного состава является габбро, а вулканической породой - базальт. Среди кислых интрузивных пород чаще всего встречается гранит, a вулканическим аналогом гранита является риолит.

Thus, the upper mantle consists of ultramafic and ultramafic rocks, while the Earth's crust is formed mainly by basic and felsic igneous rocks: gabbro, granites, and their volcanic analogs, which, compared to the peridotites of the upper mantle, contain less magnesium and iron and, at the same time, are enriched in silica. , aluminum and alkali metals.

Under the continents, the main rocks are concentrated in the lower part of the crust, and the acidic rocks are in its upper part. Beneath the oceans, the thin crust is composed almost entirely of gabbro and basalts. It is firmly established that the basic rocks, which, according to various estimates, make up from 75 to 25% of the mass of the continental crust and almost the entire oceanic crust, were smelted from the upper mantle in the process of magmatic activity. Acid rocks are usually considered as the product of repeated partial melting of mafic rocks within the continental crust. Peridotites from the uppermost part of the mantle are depleted in fusible components displaced in the course of magmatic processes into the earth's crust. Especially "depleted" is the upper mantle under the continents, where the thickest earth's crust arose.

earth shell atmosphere biosphere

3. Geothermal regime of the earth

The geothermal regime of frozen strata is determined by the conditions of heat transfer at the boundaries of the frozen massif. The main forms of the geothermal regime are periodic temperature fluctuations (annual, long-term, secular, etc.), the nature of which is due to changes in surface temperatures and the flow of heat from the bowels of the Earth. When temperature fluctuations propagate from the surface deep into the rocks, their period remains unchanged, and the amplitude decreases exponentially with depth. In proportion to the increase in depth, extreme temperatures lag behind by a period of time called the phase shift. With equal amplitudes of temperature fluctuations, the ratio of the depths of their attenuation is proportional to the square root of the ratios of the periods.

The specificity of the geothermal regime of frozen strata is determined by the presence of "water-ice" phase transitions, accompanied by the release or absorption of heat and a change in the thermophysical properties of rocks. Heat consumption for phase transitions slows down the advancement of the 0°С isotherm and causes the thermal inertia of the frozen strata. In the upper part of the permafrost section, a layer of annual temperature fluctuations is distinguished. At the bottom of this layer, the temperature corresponds to the average annual temperature for a long-term (5-10 years) period. The thickness of the layer of annual temperature fluctuations varies on average from 3-5 to 20-25 m, depending on the average annual temperature and the thermophysical properties of the rocks.

The temperature field of rocks below the layer of annual fluctuations is formed under the influence of a heat flow from the bowels of the Earth and temperature fluctuations on the surface with a period of more than 1 year. It is influenced by the geological structure, thermophysical characteristics of rocks, and heat transfer by groundwater in contact with permafrost.

During the degradation of permafrost, the lowest temperature is observed deeper than the base of the layer of annual fluctuations, this is caused by an increase in the average annual temperature. During aggradational development, the temperature field reflects the cooling of the frozen strata from the surface, which is expressed in an increase in the temperature gradient.

The dynamics of the lower boundary of the frozen strata depends on the ratio of heat flows in the frozen and thawed zone. Their inequality is due to long-term temperature fluctuations on the surface, which penetrate to a depth exceeding the thickness of the permafrost. Geotechnical and hydrogeological conditions of field development significantly depend on the features of the geothermal regime and its changes under the influence of mine workings and other engineering structures. The study of the geothermal regime and the forecast of its change is carried out in the course of geocryological survey.

Conclusion

The individual face of the planet, like the appearance of a living being, is largely determined by internal factors that arise in its deep depths. It is very difficult to study these interiors, since the materials that make up the Earth are opaque and dense, so the volume of direct data on the substance of the deep zones is very limited.

There are many ingenious and interesting methods of studying our planet, but the main information about its internal structure is obtained as a result of studies of seismic waves that occur during earthquakes and powerful explosions. Every hour, about 10 oscillations of the earth's surface are recorded at various points on the Earth. In this case, seismic waves of two types arise: longitudinal and transverse. Both types of waves can propagate in a solid, but only longitudinal waves can propagate in liquids.

Displacements of the earth's surface are recorded by seismographs installed around the globe. Observations of the speed at which waves travel through the Earth allow geophysicists to determine the density and hardness of rocks at depths that are inaccessible to direct research. A comparison of the densities known from seismic data and those obtained in the course of laboratory experiments with rocks (where temperature and pressure corresponding to a certain depth of the Earth are modeled) allows us to draw a conclusion about the material composition of the earth's interior. The latest data of geophysics and experiments related to the study of structural transformations of minerals made it possible to model many features of the structure, composition and processes occurring in the depths of the Earth.

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