Earth's crust and lithosphere. Stone shell of the Earth. Earth's crust Stone shell

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 host life. According to radiometric dating and other research methods, our planet formed about 4.54 billion years ago. The Earth gravitationally interacts 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 earth's surface), and the atmosphere ("atmo" for air). These main spheres of our planet are further divided into various sub-spheres.

Let's look at all four shells of the Earth in more detail to understand their functions and meaning.

Lithosphere - the hard shell of the Earth

According to scientists, there are more than 1386 million km³ of water on our planet.

The oceans contain more than 97% of the Earth's water. The rest is fresh water, two-thirds of which is frozen in the planet's polar regions and on snowy mountain peaks. It is interesting to note that although water covers most of the planet's surface, it makes up only 0.023% of the Earth's total mass.

The biosphere is the living shell of the Earth

The biosphere is sometimes considered one big one - a complex community of living and nonliving components functioning as a single whole. However, most often the biosphere is described as a collection of many ecological systems.

Atmosphere - the air envelope of the Earth

The atmosphere is the collection of gases surrounding our planet, held in place by the Earth's gravity. Most of our atmosphere is located near the earth's surface, where it is densest. The Earth's air 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 have no atmosphere at all. There is no atmosphere in space.

The atmosphere is so widespread that it is almost invisible, but its weight is equal to the layer of water more than 10 meters deep that covers our entire planet. The lower 30 kilometers of the atmosphere contain about 98% of its total mass.

Scientists say many of the gases in our atmosphere were released 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 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, during . Later, more complex forms added more oxygen to the atmosphere. The oxygen in today's atmosphere likely took millions of years to accumulate.

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. However, solar energy is essential for all life on Earth.

The Earth's atmosphere has. The following layers extend from the surface of the planet to the sky: 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 atmospheric layers are not clearly defined and vary depending on latitude and time of year.

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, which is insects and plants, and even the atmosphere, which is soil air.

All spheres are interconnected and depend on each other, like a single organism. Changes in one area will lead to changes in another. Therefore, everything we do on our planet affects other processes within its boundaries (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 layers of the Earth.

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 produced, 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.”

The rocky shell of the Earth - the earth's crust - is firmly attached to the upper mantle and forms a single whole with it -. The study of the earth's crust and lithosphere allows scientists to explain the processes occurring on the Earth's surface and anticipate changes in the appearance of our planet in the future.

Structure of the earth's crust

The earth's crust, consisting of igneous, metamorphic and sedimentary rocks, on continents and under oceans has different thickness and structure.

It is customary to distinguish three layers in the continental crust. The upper layer is sedimentary, in which sedimentary rocks predominate. The two lower layers are conventionally called granite and basalt. The granite layer consists primarily of granite and metamorphic rocks. The basalt layer is made of denser rocks, comparable in density to basalts. Oceanic crust has two layers. In it, the upper layer - sedimentary - has a small thickness, the lower layer - basalt - consists of basalt rocks, and there is no granite layer.

The thickness of the continental crust under the plains is 30-50 kilometers, under the mountains - up to 75 kilometers. The oceanic crust is much thinner, its thickness is from 5 to 10 kilometers.

There is a crust on other terrestrial planets, on the Moon and on many satellites of the giant planets. But only the Earth has two types of crust: continental and oceanic. On other planets, in most cases it consists of basalts.

Lithosphere

The rocky shell of the Earth, including the crust and the upper part of the mantle, is called the lithosphere. Beneath it there is a heated plastic layer of the mantle. The lithosphere seems to float on this layer. The thickness of the lithosphere in different regions of the Earth varies from 20 to 200 kilometers or more. In general, it is thicker under continents than under oceans.

Scientists have found that the lithosphere is not monolithic, but consists of. They are separated from each other by deep faults. There are seven very large and several smaller lithospheric plates, which constantly but slowly move along the plastic layer of the mantle. The average speed of their movement is about 5 centimeters per year. Some plates are entirely oceanic, but most have different types of crust.

Lithospheric plates move relative to each other in different directions: either they move away, or, conversely, they come closer and collide. As part of the lithospheric plates, their upper “floor” - the earth’s crust - also moves. Due to the movement of lithospheric plates, the location of continents and oceans on the Earth's surface changes. The continents either collide with each other or move thousands of kilometers away from each other.

Lesson summary 5th grade

Topic: Lithosphere - the “stone” shell of the Earth. Internal structure of the Earth. Earth's crust. The structure of the earth's crust.

The purpose of the lesson : to form an idea of ​​the inner layers of the Earth and their distinctive features, of the movement of lithospheric plates.

Tasks:

To familiarize students with the internal layers: the earth's crust, mantle, core and their distinctive features. Give the concept of lithosphere.

Demonstrate the result of the movement of lithospheric plates.

To develop students’ skills in analyzing information, reading a diagram, highlighting the main points, using additional information, and working with a geographical map.

Train students to work with electronic textbooks.

To promote the formation of geographical thinking of schoolchildren and geographical culture.

During the classes:

Organizing time

Emotional mood.

Hello guys. I hope that our mutual work in the lesson will be fruitful, and that you are active. Sit down. Today we are starting to study a new topic. For successful work in the lesson, we have prepared everything you need: a textbook, a notebook, a pencil, a pen.

Updating knowledge

Astronauts who have flown in outer space say that it has a superb blue color when viewed from a spaceship. Looks like a precious blue pearl.

This color is due to the properties of the atmosphere and the fact that the World Ocean covers 71% of its area.

What or who are we talking about?(About planet Earth)

Guys, I’ll read the text to you now. You will listen to the text carefully and then answer a series of questions.

“Initially the planet was cold, then it began to warm up, and then it began to cool again. At the same time, the “light” elements rose, and the “heavy” ones fell. This is how the original earth's crust was formed. Heavy elements formed the planet’s interior—the core and mantle.”

What do these lines say? (On the hypothesis of the origin of the Earth. The Schmidt-Fesenkov hypothesis has fewer contradictions and answers more questions.)

What cloud did our planet form from?(From a cold gas and dust cloud.)

What is the shape of the Earth?(The shape of the Earth is spherical.)

Remember from the material of natural history, which outer shells of the Earth are known to you?(The Earth has the following external shells: atmosphere, hydrosphere, biosphere, lithosphere.)

Do the shells interact with each other?(Yes)

Motivation for learning activities.

Once - a circle,

Two - a circle,

Three - a circle,

Circle again...

How many different shells!

Not the Earth, but just an onion!

The earth is cleverly designed

More complex than any toy:

Inside is the CORE,

But not a cannonball!

Then, imagine, THE MANTLE

Lies inside the Earth.

But not such a robe,

What do kings wear?

Then - LITHOSPHERE

(Earth's crust).

We got to the surface

Hooray!

And in the middle of this LITO -

HYDROSPHERE is spilled.

HYDRO is not HYDRA.

Still sometimes

People call her -

WATER!

Well, beyond this sphere

We meet with ATMOSPHERE.

(This is both air and clouds...)

What's behind it? - Unknown yet!

(A. Usachev)

Task "Encryption".

Decipher the topic of the lesson

S O R L A I F T E

Answer: LITHOSPHERE

Preparing students to master a new topic.

Guys, do you like fairy tales? Now I want to tell you a fairy tale. Are you ready to listen?

In a certain kingdom, in a certain state, there lived a king, Zakir. He had a son - a daring, good fellow, Ivan - Tsarevich. It became difficult for King Zakir to rule; he grew old.

King Zakir decided to test his son. He sends him on a long journey, and he himself gives the order: “Go, Ivan the Tsarevich, see the world and show yourself. Find me the key of the Earth, and then you will be king.”

Ivan Zakirov's son set off on a journey - a journey. Whether it was a long walk or a short one, he reached a foreign kingdom - a state. He sees: in front of him there are 4 white palaces with golden roofs, and above them there is an inscription - “Atmosphere”, “Hydrosphere”, “Biosphere”, “Lithosphere”. Ivan read the inscriptions and wondered what it was.

Guys, let's tell Ivan what these words mean.

Ivan stands at the gate, and the old man passes by and asks: “What, dear man, did he hang his head? »

“Well, I need to find the key of the Earth, but I just can’t determine where to go. Help me, good man.

The elder explained that Ivan needed to go to the palace called “Lithosphere”.

“Is there a key to the Earth in this country?” asks the prince. “There is, that is, but it’s not easy to find. It is kept deep underground, and is guarded by a beautiful princess.”

“How can I get there?” asks Ivan.

“We need to dig a deep well,” the old man answers him.”

Ivan Zakirov’s son took a shovel in his hands and began to dig a well. At first it was easy for the prince to dig; the rocks he came across were light and loose: sand, clay, chalk, rock salt. Ivan digs deeper, the rocks become harder. He comes across iron ores - brown, magnetic, ores of useful metals.

Tsarevich Ivan got carried away with his work, struck once, struck again, and a huge block fell off. Ivan found himself in a large cave. Its walls shine and shimmer with precious stones. And in the center of the hall, a beautiful princess sits on a throne. Ivan bowed to her and said: “People say that you are hiding the key of the Earth, but I need it, I promised my father to get it!”

“Well, if you guess my tasks, I’ll give you the treasured key!” the princess answered and handed Ivan an envelope with the tasks.

“Riddle,” said Ivan the Tsarevich, “I’ll try to guess!”

What is the internal structure of the Earth?

The internal structure of the Earth is complex. At its center is the core. Then follows the mantle, and the earth's crust. The structure of the Earth can be compared to an egg.

It consists of shell, white and yolk. The shell is like a breathing earth's crust. She is very thin. Protein is the mantle. The yolk is the core.

In diagrammatic form, this can be depicted as follows:

The internal structure of the Earth = core + mantle + crust.

What is the core?

The core is divided into two layers: the inner core is solid, the outer core is liquid. Consists of iron and nickel.

It was previously believed that the Earth's core was smooth, almost like a cannonball.

It is assumed that the surface of the core consists of a substance with the properties of a liquid. The boundary of the outer core is located at a depth of 2900 km.

But the inner region, starting from a depth of 5100 km, behaves like a solid body. This is due to very high blood pressure. Even at the upper boundary of the core, the theoretically calculated pressure is about 1.3 million atmospheres. And in the center it reaches 3 million atmospheres. The temperature here can exceed 10,000 C°.

It is possible that the material in the outer core includes a relatively light element, most likely sulfur.

Core composition = iron + nickel

What properties does the mantle material have?

Mantle translated from Latin. language means "blanket". It occupies up to 83% of the planet's volume and is divided into the upper and lower mantle. The substance of the mantle is in a solid state due to high pressure, although the temperature of the mantle is 2000 C°. The middle layer of the mantle is slightly softened, while the inner and outer layers are in a solid state.

The first lies to a depth of 670 km. The rapid drop in pressure in the upper part of the mantle and high temperature lead to the melting of the substance.

At a depth of 400 km under the continents and 10 - 150 km under the oceans, that is, in the upper mantle, a layer was discovered where seismic waves propagate relatively slowly. This layer was called the asthenosphere (from the Greek “asthenes” - weak). The asthenosphere, which is more plastic than the rest of the mantle, serves as a “lubricant” along which rigid lithospheric plates move.

What does it consist of? Mainly from rocks rich in magnesium and iron. Mantle rocks are highly dense.

What the lower mantle consists of remains a mystery.

What is the earth's crust?

The Earth's crust is the hard outer shell of the Earth. On the scale of the entire Earth, it represents the thinnest film and is insignificant compared to the radius of the Earth. It reaches a maximum thickness of 75 km over the Pamir, Tibet, and Himalaya mountain ranges. Despite its small thickness, the earth's crust has a complex structure.

Earth's crust

oceanic continental

5-10km 30-80 km

The upper boundaries of the earth's crust have been well studied using well drilling(deep drilling method).

The deepest well is only 15 km deep. Compared to the size of the Earth, this value is very small. But, despite the fact that man has penetrated only a few kilometers deep into the Earth, scientists have obtained some information about its internal structure using geophysical methods. Geophysicists produce explosions on the surface or at some depth from the surface. Special, very sensitive instruments record how fast vibrations propagate inside the Earth. Thus, geophysicists have established that to a depth of an average of 30 km, the globe consists of sand, limestone, granite and other rocks.

Temperature changes with depth in the earth's crust. The temperature of the upper layer of the lithosphere varies with the seasons of the year. Below this layer to a depth of about 1000 m, a pattern is observed: for every 100 m of depth, the temperature of the earth’s crust increases by an average of 3 degrees.

How did the earth's crust form?

The formation of the earth's crust occurred billions of years ago from the viscous-liquid substance of the mantle - magma. The most common and light chemical substances that were part of it - silicon and aluminum - solidified in the upper layers. Having hardened, they no longer sank and remained afloat in the form of peculiar islands. But these islands were not stable; they were at the mercy of internal mantle currents, which carried them down, and often simply sank in the hot magma. Magma (from the Greek tagma - thick mud) is a molten mass formed in the Earth's mantle. But time passed, and the first small solid massifs gradually connected with each other, forming territories of a significant area. Like ice floes in the open ocean, they moved around the planet at the will of internal mantle currents.

How did people manage to get an idea of ​​the internal structure of the Earth?

Humanity receives valuable information about the structure of the Earth as a result of drilling ultra-deep wells, as well as using special seismic research methods (from the Greek “seismos” - vibration). This is how geophysicists study our Earth. This method is based on studying the speed of propagation of vibrations in the Earth that occur during earthquakes, volcanic eruptions or explosions. For this purpose, a special device is used - a seismograph. Seismologists obtain unique information about the interior of the Earth from observations of volcanic eruptions. The science of seismology is the science of earthquakes. Based on seismic data, 3 main shells are distinguished in the structure of the Earth, differing in chemical composition, state of aggregation and physical properties.

Lithosphere

The rocky shell of the Earth, including the crust and the upper part of the mantle, is called the lithosphere. Beneath it there is a heated plastic layer of the mantle. The lithosphere seems to float on this layer. The thickness of the lithosphere in different regions of the Earth varies from 20 to 200 kilometers or more. In general, it is thicker under continents than under oceans. Scientists have found that the lithosphere is not monolithic, but consists of lithospheric plates. They are separated from each other by deep faults. There are seven very large and several smaller lithospheric plates, which constantly but slowly move along the plastic layer of the mantle. The average speed of their movement is about 5 centimeters per year. Some plates are entirely oceanic, but most have different types of crust.

Lithospheric plates move relative to each other in different directions: either they move away, or, conversely, they come closer and collide. As part of the lithospheric plates, their upper “floor”, the earth’s crust, also moves. Due to the movement of lithospheric plates, the location of continents and oceans on the Earth's surface changes. The continents either collide with each other or move thousands of kilometers away from each other.

Now guys, let's get back to our fairy tale.

“Well done, Ivan the Tsarevich, he correctly guessed my tasks with the guys, here is the key of the Earth and remember: only knowledge, like a key, opens any locks and doors,” the princess told him.

Ivan bowed and went home, and so that he doesn’t get lost, let’s help him remember the way back.

Practical work

Fill out the table using the textbook

Test tasks. Choose the correct answer.

1. The earth consists of:

a) Core and mantle

b) Mantle and crust

V)Core, mantle and crust

d) Core and crust.

2. The Earth's core consists of:

a) One layer

b)Two layers

c) Three layers

Summarizing. Student assessment. Reflection.

Guys, today in class we set tasks: to study the internal structure of the Earth, methods of study and the lithosphere.

Do you think we have met these challenges?

So the goal of the lesson has been achieved?

Each of you has emoticons printed on your desk that show your mood.

Note what mood you had in class today.

The lesson is over. Thanks to all. Well done!