In educational literature, the “stone shell of the Earth” refers to one of its shells - the lithosphere. It extends from the earth's surface to a depth of 100-250 km under the continents and up to 50-300 km under the oceans to the asthenosphere layer, a layer of “softened” plastic rocks. The lithosphere includes two components: the earth's crust and the upper solid layer of the mantle. Thus, the earth's crust is the solid upper shell of the Earth, and it relates to the lithosphere as a part and a whole.

The term “earth’s crust” was introduced into geographical science by the Austrian geologist E. Suess in 1881. (8) In addition to this term, this layer has another name - sial, composed of the first letters of the most common elements here - silicon (silicium, 26%) and aluminum (aluminum, 7.45%). The thickness of the earth's crust ranges from 5-20 km under the oceans to 30-40 km under the continents, in mountainous areas - up to 75 km. (10)

The structure of the earth's crust is heterogeneous. There are three layers in it: sedimentary, “granite” and “basalt”. Since the “granite” layer is approximately half composed of granites, and 40% of it is occupied by granite gneisses and orthogneisses, it is more correct to call it a granite gneiss layer. Also the “basalt” layer, since its composition is quite diverse, and metamorphic rocks of basic composition (granulites, eclogites) predominate in it, it is more correct to call it a granulite-mafic layer. The boundary between granite-gneiss and granulite-mafic layers is the Conrad section. The lower boundary of the earth's crust stands out quite clearly, which is associated with an increase in the speed of longitudinal seismic waves in the underlying layer of the mantle. This boundary is called the Mohorovicic boundary in honor of the Yugoslav seismologist A. Mohorovicic, who first established it.

In different regions of the planet, the structure of the earth's crust is also different. In general, it can be divided into two types: continental and oceanic.

Continental type - its thickness ranges from 35-45 km on platforms to 55-75 km in mountainous areas. It is composed of three layers: sedimentary - from 0 km on shields to 15-20 km in marginal foothill troughs and platform depressions; granite gneiss layer - 20-30 km thick; granulite-mafic layer, the thickness of which reaches 15-35 km.

The oceanic crust is much thinner than the continental crust. Its structure also includes three layers: sedimentary with a maximum thickness of up to 1 km, composed of various sedimentary formations, most of which are in a loose state and saturated with water; basalt layer with interlayers of carbonate and siliceous rocks, 1-3 km thick; gabbro-basalt layer with the presence of ultrabasic rocks (pyroxenites, serpentinites), the thickness of which ranges from 3 to 5 km. Previously, it was believed that the oceanic crust was composed of only two layers, without granite, but after underwater drilling and seismic research, more accurate results were obtained.

In addition to the main ones, there are two transitional types: suboceanic and subcontinental.

The subcontinental type is similar in structure to the continental type and is distributed along the margins of continents and in areas of island arcs. The upper layer is sedimentary-volcanogenic with a thickness of 0.5-5 km; the second layer is composed of granite-metamorphic strata and has a thickness of up to 10 km; the third layer is basalt, the thickness of which ranges from 15 to 40 km.

Suboceanic type - similar in structure to the oceanic crust, located in the basins of marginal and inland seas (Sea of ​​Okhotsk, Black Sea). This type differs from the oceanic crust by a much thicker layer of sedimentary rocks, reaching 10 km.

The question of the origin of the earth's crust remains unresolved to this day, as evidenced by the presence of various hypotheses for its formation. One of the most substantiated views is the principle of “zone” melting by A.P. Vinogradova. Its essence is as follows: the substance of the mantle is in a solid equilibrium state, but when external conditions (pressure, temperature) change, the mass of the substance transforms into a liquid mobile form and begins to mix in the radial direction towards the Earth’s surface. As it progresses, differentiation of the substance occurs: low-melting compounds are brought to the surface, refractory compounds remain at depth. This process, which was repeated many times in the past and has not ceased its activity in the present, determined not only the formation of the earth’s crust, but also its chemical composition. As a result of the radial removal of elements, layers of the earth's crust were also formed: the basaltic layer was formed during the melting of mantle material, the formation of the granite layer is associated with the melting of metamorphic rocks and their enrichment with chemical elements due to the degassing process. This process was more active in geosynclinal belts, on continents, as evidenced by the greater thickness of the granite layer here. In the oceans, degassing was less efficient, as evidenced by the absence of a granite layer and the poverty of oceanic basalts in chemical elements. The sedimentary layer has a slightly different origin. The rocks of the granite layer that appeared on the surface were exposed to external conditions, the most important of which was and remains the geochemical effect of the vital activity of organisms, as evidenced by the high content of oxidized forms of sulfur, organic carbon, nitrogen, etc. in the sedimentary layer. This effect manifests itself both directly and indirectly through influencing the conditions that determine the transformation of rocks (acidity / alkalinity, the amount of oxygen and carbon dioxide, the presence of organic compounds, etc.) (9)

That. the earth's crust is the upper solid shell of the Earth; in its structure three layers are distinguished: sedimentary, granite-gneiss and granulite-mafic; According to the type of structure, continental and oceanic crust are distinguished, differing in thickness and composition of layers, as well as transitional - suboceanic and subcontinental, which have similarities with the main types, but at the same time have some isolation.

§ 13. The Earth's crust and lithosphere - the rocky shells of the Earth

Remember

• What inner shells of the Earth stand out? Which shell is the thinnest? Which shell is the largest? How are granite and basalt formed? What is their appearance?

The earth's crust and its structure. The Earth's crust is the outermost rocky shell of the Earth. It consists of igneous, metamorphic and sedimentary rocks. On continents and under oceans it is structured differently. Therefore, a distinction is made between the continental crust and the oceanic crust (Fig. 42).

They differ from each other in thickness and structure. The continental crust is thicker - 35-40 km, under high mountains - up to 75 km. It consists of three layers. The top layer is sedimentary. It is composed of sedimentary rocks. The second and third layers consist of a variety of igneous and metamorphic rocks. The second, middle layer is conventionally called “granite”, and the third, lower layer is called “basalt”.

Rice. 42. Structure of the continental and oceanic crust

The oceanic crust is much thinner - from 0.5 to 12 km - and consists of two layers. The upper, sedimentary layer is composed of sediments covering the bottom of modern seas and oceans. The bottom layer consists of solidified basaltic lavas and is called basaltic.

Continental and oceanic crust on the surface of the Earth form giant steps of different heights. The higher levels are the continents rising above sea level, the lower ones are the bottom of the World Ocean.

Lithosphere. As you already know, under the earth's crust is the mantle. The rocks that make it up differ from the rocks of the earth's crust: they are denser and heavier. The earth's crust is firmly attached to the upper mantle, forming a single whole with it - the lithosphere (from the Greek "cast" - stone) (Fig. 43).

Rice. 43. Relationship between the lithosphere and the earth's crust

Consider the relationship between the earth's crust and lithosphere. Compare their thickness.

Remember why there is a layer of plastic material in the mantle. Determine from the drawing the depth at which it lies.

Find in the figure the boundaries of separation and the boundaries of collision of lithospheric plates.

Lithosphere is the solid shell of the Earth, consisting of the earth's crust and the upper part of the mantle.

Under the lithosphere there is a heated plastic layer of the mantle. The lithosphere seems to float on it. At the same time, it moves in different directions: it rises, falls and slides horizontally. Together with the lithosphere, the earth's crust - the outer part of the lithosphere - also moves.

Rice. 44. Main lithospheric plates

The lithosphere is not monolithic. It is divided by faults into separate blocks - lithospheric plates (Fig. 44). In total, there are seven very large lithospheric plates and several smaller ones on Earth. Lithospheric plates interact with each other in different ways. Moving along the plastic layer of the mantle, they move apart in some places and collide with each other in others.

Questions and tasks

1. What two types of earth's crust do you know?
2. How is the lithosphere different from the earth's crust?
3. What lithospheric plate do you live on?

Atmosphere Hydrosphere Lithosphere The atmosphere closest to the Earth is the air space around the Earth. The atmosphere consists of nitrogen, oxygen, water vapor and small amounts of other gases. Thanks to the atmosphere, life arose on our planet. Plants, animals and humans need oxygen to breathe, which they receive from the atmosphere. Seas, oceans, rivers, lakes, reservoirs, and glaciers form the hydrosphere, the intermittent water shell of the Earth. Without the hydrosphere, life on our planet would be impossible (the human body is 65% water!). The lithosphere is the hard shell of the Earth, the land and the bottom of the oceans, it is formed by rocks, and geologists call it the earth's crust.

In nature, minerals are found in pure form, but much more often they form compounds with other minerals. Such natural compounds of minerals are called rocks. If you carefully examine a pebble found by the sea or in the mountains, you will notice that it is often multi-colored or striped due to piercing veins, or spotted, or with irregularly shaped stains. This happens because the found pebble consists of different minerals on which natural processes have left their traces. Minerals differ in color, hardness, weight and composition. The inanimate world around us consists of them, like bricks.

The agate mineral is a beautiful ornamental stone; it is considered semi-precious. Agate can be bluish-gray, dark gray, white. Coal, as it turns out, is the sibling of the shiny precious diamond. Diamond is the hardest substance in the world. Red crystals of the garnet mineral. Transparent garnet crystals are gemstones. They have high hardness, so they are often used as abrasives (grinding materials). People have learned to synthesize this mineral.

The mineral sapphire is a gemstone that has long been used as jewelry. Synthetic colorless sapphire is also obtained, the crystals of which are used in microelectronics, infrared technology, and other fields. Salt is not only dissolved in sea water. It is also found in the mountains in the form of crystals. This rock salt is called halite. This is the only mineral that can be eaten. The name comes from the Greek “gallos”, sea salt. In color it is predominantly white, sometimes colorless. Sometimes, due to impurities of other minerals, it acquires an intense blue or red color. When combined with oxygen, silicon forms quartz, the most common mineral on Earth. Varieties of quartz include everyone's favorite semi-precious stones: rock crystal, amethyst, smoky topaz (rauchtopaz), morion, chalcedony, aventurine, jasper, and agate.

Groups according to the conditions of their formation When molten rocks erupt from the depths of the Earth, igneous rocks are formed. These are granite, andesite, basalt, gabbro, peridotite. The red-hot mass rises along natural cracks, gradually cools and hardens. Sometimes molten rocks flow onto the surface of the Earth in the form of lava (during volcanic eruptions) and also solidify. 1. Igneous granite massif. The rock granite is composed of quartz, mica and feldspar. A sheer mountain wall composed of igneous rock basalt. Black basalt. Basalts also occupy vast areas of the ocean floor. This is a valuable building and facing material.

2. Sedimentary From fragments of ancient rocks, destroyed by wind and sudden temperature changes, sedimentary rocks arise. Such debris and grains of sand often accumulate along with the remains of plants and animals on the bottom of oceans and seas. This process is very long and continuous, so the following layers are gradually applied to the already settled debris and particles, under the weight of which the lower layers are compacted. Limestone, sandstone, gypsum, clay, gravel, peat, coal, and oil are formed. Small fragments of quartz turn into sand, a building material and raw material for glass. The amount of sand in the world is enormous. And its application is widespread. Coal is an important mineral resource. Used as fuel.

3. Metamorphic If sedimentary or igneous rocks fall to great depths, then under the influence of high temperatures and pressure they change greatly and turn into new metamorphic rocks. In this way, hard marble, iron ore, and slates are formed from soft and loose limestone. marble Iron ore slates

1. Construction of roads, houses (gravel, sand, clay, limestone) 2. Decoration of buildings, metro stations, making monuments (marble, granite, labradorite) 3. Medicine (diamond dust, talc) 4. Decorative items and jewelry 5. Art (natural dyes - ocher, cinnabar, graphite) 6. Making dishes (clay, quartz sand) 7. Food (halite - table salt) 8. Agriculture (mineral fertilizers)

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 that contain the geological record of the Earth, as well as modern physical processes and mechanisms operating both on its surface and in the depths, 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 violently (for example, volcanic eruptions, earthquakes or large floods), but more often - slowly (a layer of sediment no more than 30 cm thick is removed or accumulated over a century). Such changes are not noticeable throughout 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 minor movements of the earth’s crust are recorded.

The history of the Earth began simultaneously with the development of the solar system approximately 4.6 billion years ago. However, the geological record is characterized by fragmentation and incompleteness, because many ancient rocks were destroyed or covered by younger sediments. Gaps must 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 they contain, and sediments in which such remains are absent are determined by the relative positions of both. In addition, the absolute age of almost all rocks can be determined by geochemical methods.

This work examines the main shells of the earth, its composition and physical structure.

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 runs along the lithosphere and hydrosphere, and its upper boundary is at an altitude of 1000 km. The atmosphere is divided into the troposphere (moving layer), stratosphere (layer above the troposphere) and ionosphere (upper layer).

The average height of the troposphere is 10 km. Its mass makes up 75% of the total mass of the atmosphere. The air in the troposphere moves in both horizontal and vertical directions.

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 occupies 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, density is about 1. Sunlight penetrates to a depth of 200 m, and ultraviolet rays penetrate 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, the lower boundary runs along the bottom of the ocean basins. The biosphere is divided into the sphere of plants (over 500,000 species) and the sphere of animals (over 1,000,000 species).

The lithosphere - the rocky shell of the Earth - is from 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 increases by about 1°C for every 33 m of depth. Due to high temperatures and high pressure, rocks at significant depths are likely to be in a molten state.

The centosphere, or 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 stone blocks - continents. However, the influence of the fiery sphere on the life of planet Earth is still very great. The outlines of continents and oceans, the climate, and the composition of the atmosphere changed repeatedly.

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 the substance 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 the layer of water, which averages 4.5 km). The lower edge of the earth's crust is taken to be the Mohorovicic surface - a seismic section on which the speed of propagation of longitudinal elastic waves with a depth of 6.5-7.5 to 8-9 km/s increases abruptly, which corresponds to an increase in the density of matter from 2.8-3 .0 to 3.3 g/cm3.

From the surface of Mohorovicic to a depth of 2900 km, the Earth's mantle extends; the upper least dense zone, 400 km thick, is distinguished 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, the inner core is located.

The Earth's core has interested scientists since its discovery in 1936. It was extremely difficult to image because of the relatively small number of seismic waves that reached it and returned to the surface. Additionally, the core's extreme temperatures and pressures have long been difficult to reproduce in the laboratory. New research may provide a more detailed picture of the center of our planet. 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. According to modern data, the outer core is a rotating stream of molten iron and nickel that conducts electricity well. It is with this that the origin of the earth's magnetic field is associated, believing that, like a giant generator, electric currents flowing in the liquid core create a global magnetic field. The layer of the mantle that is in direct contact with the outer core is influenced by it, since temperatures in the core are higher than in the mantle. In some places, this layer generates huge heat and mass flows directed towards 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 ensured by the gigantic pressure in the center of the Earth. It has been suggested that in addition to iron-nickel alloys, the core should also contain lighter elements, such as silicon and sulfur, and possibly silicon and oxygen. The question of the state of the Earth's core is still controversial. As you move away from the surface, the compression to which the substance is subjected increases. Calculations show that in the earth's core the pressure can reach 3 million atm. At the same time, many substances seem to be metallized - they pass into the metallic state. There was even a hypothesis that the Earth's core 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 cause 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 ultrabasic and ultramafic rocks, and the earth’s crust is formed mainly by basic and acidic igneous rocks: gabbro, granites and their volcanic analogues, 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.

Beneath the continents, mafic rocks are concentrated in the lower part of the crust, and felsic rocks are concentrated in the upper part. Beneath the oceans, the thin crust of the earth consists almost entirely of gabbro and basalt. It is firmly established that the basic rocks, which according to various estimates constitute from 75 to 25% of the mass of the continental crust and almost all of the oceanic crust, were smelted from the upper mantle during the process of magmatic activity. Felsic rocks are usually considered to be 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 transported into the earth's crust during magmatic processes. The upper mantle beneath the continents, where the thickest crust arose, is especially “depleted.”

How often, in search of answers to our questions about how the world works, we look up at the sky, the sun, the stars, we look far, far away hundreds of light years in search of new galaxies. But, if you look under your feet, then under your feet there is a whole underground world that makes up our planet - the Earth!

Bowels of the earth this is the same mysterious world under our feet, the underground organism of our Earth on which we live, build houses, lay roads, bridges and for many thousands of years we have been developing the territories of our native planet.

This world is the secret depths of the bowels of the Earth!

Structure of the Earth

Our planet belongs to the terrestrial planets, and, like other planets, consists of layers. The surface of the Earth consists of a hard shell of the earth's crust, deeper there is an extremely viscous mantle, and in the center there is a metal core, which consists of two parts, the outer is liquid, the inner is solid.

Interestingly, many objects of the Universe are so well studied that every schoolchild knows about them, spacecraft are sent into space to distant hundreds of thousands of kilometers, but getting into the deepest depths of our planet still remains an impossible task, so what is under the surface of the Earth is still remains a big mystery.