The shape of the Earth (geoid) is close to an oblate ellipsoid. The average diameter of the planet is approximately 12,742 km.
The earth has a layered internal structure. It consists of hard silicate shells (crust, extremely viscous mantle), and a metal core. The outer part of the core is liquid (much less viscous than the mantle), and the inner part is solid.
The earth's crust is top part solid ground... It is separated from the mantle by a boundary with a sharp increase in seismic wave velocities - the Mohorovichich boundary. There are two types of crust - continental and oceanic. The thickness of the crust ranges from 6 km under the ocean, to 30-50 km on the continents. Three geological layers are distinguished in the structure of the continental crust: sedimentary cover, granite and basalt. The oceanic crust is composed mainly of basic rocks, plus a sedimentary cover. The earth's crust is divided into various sizes lithospheric plates moving relative to each other.
The mantle is a silicate shell of the Earth, composed mainly of peridotites - rocks consisting of silicates of magnesium, iron, calcium, etc. Partial melting of mantle rocks gives rise to basaltic and similar melts, which form the earth's crust when rising to the surface.
The mantle makes up 67% of the entire mass of the Earth and about 83% of the total volume of the Earth. It stretches from depths of 5-70 kilometers below the border with the earth's crust, to the border with the core at a depth of 2900 km. The mantle is located in a huge range of depths, and with an increase in pressure in the substance, phase transitions occur, during which minerals acquire an increasingly dense structure. The most significant transformation occurs at a depth of 660 kilometers. The thermodynamics of this phase transition is such that mantle matter below this boundary cannot penetrate through it, and vice versa. Above the border of 660 kilometers is the upper mantle, and below, respectively, the lower one. These two parts of the mantle are of different composition and physical properties... Although information on the composition of the lower mantle is limited, and the number of direct data is very small, it can be confidently asserted that its composition since the formation of the Earth has changed significantly less than the upper mantle that gave birth to the earth's crust.
The core is the central, deepest part of the Earth, the geosphere, located under the mantle and, presumably, consisting of an iron-nickel alloy with an admixture of other siderophilic elements. The depth of occurrence is 2900 km. The average radius of the sphere is 3.5 thousand km. It is divided into a solid inner core with a radius of about 1300 km and a liquid outer core with a radius of about 2200 km, between which a transition zone is sometimes distinguished. The temperature in the center of the Earth's core reaches 5000 C, the density is about 12.5 t / m³, the pressure is up to 361 GPa. The mass of the core is 1.932X1024 kg.
Earth's crust is the outer hard shell of the Earth (geosphere). The Moho boundary separates the crust and mantle. WITH outside most of the crust is covered by the hydrosphere, and less is influenced by the atmosphere. The earth has two types of crust: continental and oceanic.
Weight crust is estimated at 2.8x1019 tons (of which 21% is oceanic crust and 79% is continental). The crust makes up only 0.473% of the total mass of the Earth.
The oceanic crust is mainly composed of basalts. the oceanic crust is relatively young, and the oldest parts of it date back to the late Jurassic. The thickness of the oceanic crust practically does not change over time, since it is mainly determined by the amount of melt released from the mantle material in the zones of mid-ocean ridges. The thickness of the sedimentary layer at the bottom of the oceans is to some extent influenced. In different geographic areas, the thickness of the oceanic crust ranges from 5-7 kilometers.
The standard oceanic crust is 7 km thick and has a strictly regular structure. From top to bottom, it is folded by the following complexes:
sedimentary rocks, represented by deep ocean sediments.
basalt covers poured out under water.
dike complex, consists of nested basalt dikes.
bed of main layered intrusions
mantle, represented by dunites and peridotites.
Dunites and peridotites are usually found at the bottom of the oceanic crust.
The continental crust has a three-layered structure. The upper layer is represented by a discontinuous sedimentary cover, which is widely developed, but rarely has a large thickness. Most of crust is folded under the upper crust - a layer consisting mainly of granites and gneisses, which has a low density and ancient history... Below is the lower crust, consisting of metamorphic rocks - granulites and the like.
Composition of the upper continental crust
The earth's crust is composed of a relatively small number of elements. About half of the mass of the earth's crust is oxygen, more than 25% is silicon. A total of 18 elements: O, Si, Al, Fe, Ca, Na, K, Mg, H, Ti, C, Cl, P, S, N, Mn, F, Ba - make up 99.8% of the mass of the earth's crust. the earth's crust consists of many rocks of various compositions.In different regions, completely different types rocks.
Earth, with an average distance of 149,597,890 km from the Sun, is the third and one of the most unique planets in Solar system... It formed about 4.5-4.6 billion years ago and is the only planet known to support life. This is due to a number of factors, for example, atmospheric composition and physical properties such as the presence of water, which covers about 70.8% of the planet's surface, allow life to flourish.
The Earth is also unique in that it is the largest of the terrestrial planets (Mercury, Venus, Earth and Mars), consisting of a thin layer rocks, in comparison with gas giants (Jupiter, Saturn, Neptune and Uranus). In terms of mass, density and diameter, Earth is the fifth largest planet in the entire solar system.
Size of the earth: mass, volume, circumference and diameter
Terrestrial planets (Mercury, Venus, Earth and Mars)
As the largest of the terrestrial planets, Earth has an estimated mass of 5.9722 ± 0.0006 × 10 24 kg. Its volume is also the largest of these planets and is 1.08321 × 10¹² km³.
In addition, our planet is the most dense of the terrestrial planets, as it consists of a crust, mantle and core. The Earth's crust is the thinnest of these layers, while the mantle makes up 84% of the Earth's volume and extends 2,900 km below the surface. The core is the component that makes the Earth the most dense. It is the only terrestrial planet with a liquid outer core surrounding a solid, dense inner core.
The average density of the Earth is 5.514 × 10 g / cm³. Mars, the smallest of the Earth-like planets in the solar system, has only about 70% of the Earth's density.
The Earth is also classified as the largest of the terrestrial planets in terms of circumference and diameter. The equatorial circumference of the Earth is 40,075.16 km. It is slightly smaller between the North and South poles- 40 008 km. The diameter of the Earth at the poles is 12,713.5 km, and at the equator - 12,756.1 km. By comparison, the largest planet in the solar system, Jupiter, has a diameter of 142,984 km.
Shape of the earth
Hammer-Aitov projection
The circumference and diameter of the Earth is different because its shape represents a flattened spheroid or ellipsoid instead of a true sphere. The planet's poles flatten slightly, resulting in a bulge at the equator and therefore a larger circumference and diameter.
The Earth's equatorial bulge is 42.72 km and is caused by the planet's rotation and gravity. Gravity itself causes planets and other celestial bodies to contract and form a sphere. This is due to the fact that it pulls the entire mass of the object as close to the center of gravity as possible (the earth's core in this case).
As the planet rotates, the sphere is distorted by centrifugal force. It is the force that causes objects to move outward from the center of gravity. When the Earth rotates, the greatest centrifugal force is at the equator, so it causes a slight outward bulge, giving this area a larger circumference and diameter.
Local topography also plays a role in the shape of the Earth, but globally it is negligible. The greatest differences in local topography around the world are Mount Everest, the highest point above sea level at 8,848 m and the Mariana Trench, the lowest point below sea level at 10,994 ± 40 m. This difference is only about 19 km, which is very insignificantly on a planetary scale. If we consider the equatorial bulge, then the highest point in the world and the place farthest from the center of the Earth is the summit of the Chimborazo volcano in Ecuador, which is the highest peak near the equator. Its height is 6,267 m.
Geodesy
Geodesy, the branch of science responsible for measuring the size and shape of the Earth through surveys and mathematical calculations, is used to properly study the size and shape of the Earth.
Throughout history, surveying has been an important branch of science, as early scientists and philosophers tried to determine the shape of the earth. Aristotle is the first person credited with trying to calculate the size of the Earth and therefore an early surveyor. Then followed Greek philosopher Eratosthenes, who estimated the circumference of the Earth at 40,233 km, which is only slightly larger than the measurement accepted today.
To explore the Earth and use geodesy, researchers often refer to the ellipsoid, geoid, and reference ellipsoid. An ellipsoid is a theoretical mathematical model that shows a smooth, simplified view of the earth's surface. It is used to measure distances on a surface without considering factors such as changes in elevation and landform. Taking into account reality earth surface Surveyors use a geoid - a model of the planet that is built using global mean sea level and therefore takes elevation changes into account.
The basis of geodesy today is data, which act as reference points for global geodetic work. Today, technologies such as satellites and global positioning systems (GPS) enable surveyors and other scientists to make extremely accurate measurements of the Earth's surface. In fact, they are so accurate that they provide centimeter-accurate data about the Earth's surface, providing the most accurate measurements of the size and shape of the Earth.
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Earth crust is called the outer hard shell of the Earth, bounded from below by the surface of Mohorovichich, or Moho, which is distinguished by a sharp increase in the speed of elastic waves as they pass from the surface of the Earth into its depths.
Below the surface of Mohorovichich is the following solid shell - upper mantle ... The uppermost part of the mantle, together with the earth's crust, is a tough and fragile solid shell of the Earth. - lithosphere (stone). It is underlain by more plastic and malleable, less viscous layers of the mantle - asthenosphere (weak). In it, the temperature is close to the melting point of the mantle material, but due to the high pressure, the material does not melt, but is in an amorphous state and can flow, remaining solid, like a glacier in the mountains. It is the asthenosphere that is the plastic layer on which individual blocks of the lithosphere float.
The thickness of the earth's crust on the continents is about 30-40 km, under mountain ranges it increases to 80 km (continental type of the earth's crust). Under the deep-sea part of the oceans, the thickness of the earth's crust is 5-15 km (oceanic type of the earth's crust). On average, the base of the earth's crust (the surface of Mohorovichich) lies under the continents at a depth of 35 km, and under the oceans at a depth of 7 km, i.e., the oceanic crust is about five times thinner than the mainland.
In addition to differences in thickness, there are differences in the structure of the earth's crust of the continental and oceanic types.
Continental crust consists of three layers: upper - sedimentary, extending on average to a depth of 5 km; medium granite (the name is due to the fact that the speed of seismic waves in it is the same as in granite) with an average thickness of 10-15 km; the lower one is basalt, about 15 km thick.
Oceanic crust also consists of three layers: upper - sedimentary to a depth of 1 km; medium with little-known composition, occurring at depths from 1 to 2.5 km; lower - basalt with a thickness of about 5 km.
A clear idea of the nature of the distribution of land heights and depths of the ocean floor gives hypsographic curve (fig. 1). It reflects the ratio of the areas of the Earth's solid shell with different heights on land and with different depths in the sea. The curve was used to calculate the average values of the land height (840 m) and the average sea depth (-3880 m). If we do not take into account mountainous areas and deep-sea depressions, which occupy a relatively small area, then two prevailing levels are clearly distinguished on the gypsographic curve: the level of the continental platform with a height of about 1000 m and the level of the oceanic bed with marks from -2000 to -6000 m. the zone is a relatively sharp ledge and is called the continental slope. Thus, the natural boundary separating the ocean and continents is not the visible coastline, but the outer edge of the slope.
Rice. 1. Hypsographic curve (A) and generalized profile of the ocean floor (B). (I - submarine margin of continents, II - transition zone, III - ocean floor, IV - mid-ocean ridges).
Within the oceanic part of the gypsographic (bathygraphic) The curve distinguishes four main stages of the bottom topography: continental shelf or shelf (0-200 m), continental slope (200-2000 m), ocean floor (2000-6000 m) and deep-water depressions (6000-11000 m).
Shelf (continental shelf)- an underwater continuation of the continent. This is an area of the continental crust, which is generally characterized by a flat relief with traces of flooded river valleys, Quaternary glaciation, and ancient coastlines.
The outer boundary of the shelf is brow - a sharp bend of the bottom, beyond which the continental slope begins. The average depth of the shelf edge is 130 m, but in specific cases its depth may vary.
The shelf width varies in a very wide range: from zero (in some areas of the African coast) to thousands of kilometers (near north coast Asia). In general, the shelf occupies about 7% of the area of the World Ocean.
Continental slope- the area from the edge of the shelf to the continental foot, that is, before the transition of the slope to a flatter ocean floor. The average angle of inclination of the continental slope is about 6о, but often the steepness of the slope can increase to 20-30 0, and in some cases almost steep ledges are possible. Due to the steep fall, the width of the continental slope is usually small - about 100 km.
The relief of the continental slope is characterized by great difficulty and variety, but its most characteristic form is underwater canyons ... These are narrow troughs with a large dip angle along the longitudinal profile and steep slopes. The tops of underwater canyons often cut into the edge of the shelf, and their mouths reach the continental foot, where, in such cases, cones of outflow of loose sedimentary material are observed.
Continental foot- the third element of the ocean floor relief, located within the continental crust. The continental foot is a vast sloping plain formed by sedimentary rocks thickness up to 3.5 km. The width of this slightly hilly plain can reach hundreds of kilometers, and the area is close to the areas of the shelf and continental slope.
Ocean bed- the deepest part of the ocean floor, occupying more than 2/3 of the entire area of the World Ocean. The prevailing depths of the ocean floor range from 4 to 6 km, and the bottom topography is the most calm. The main elements of the ocean floor relief are ocean basins, mid-ocean ridges and oceanic uplifts.
Ocean basins- extensive depressions in the bottom of the World Ocean with depths of about 5 km. The leveled surface of the bottom of the hollows is called abyssal (bottomless) plains, and it is due to the accumulation of sedimentary material brought from land. The abyssal plains in the oceans occupy about 8% of the ocean floor.
Mid ocean ridges- tectonically active zones in the ocean, in which a new formation of the earth's crust occurs. They are composed of basaltic rocks formed as a result of the inflow of the material of the upper mantle from the Earth's interior. This determined the originality of the earth's crust of the mid-oceanic ridges and its differentiation into a riftogenic type.
Oceanic uplifts- large positive landforms of the ocean floor, not associated with mid-ocean ridges. They are located within the oceanic type of the earth's crust and are distinguished by large horizontal and vertical dimensions.
Separate volcanic seamounts have been discovered in the deep ocean. Seamounts with flat peaks located at a depth of more than 200 m are called guyots.
Deep sea depressions (troughs)- zones of the most great depths Of the World Ocean exceeding 6,000 m.
The deepest depression is the Mariana Trench, discovered in 1954 by the research vessel Vityaz. Its depth is 11022 m.
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The internal structure of the Earth
There are three main shells in the structure of the Earth: the earth's crust, mantle and core.
Diagram of the internal structure of the Earth
The surface of the Earth is covered with a stone shell - Earth's crust... Its thickness under the oceans is only 3-15 km, and on the continents it reaches 75 km. It turns out that in relation to the entire planet, the earth's crust is thinner than the peel of a peach. The upper layer of the crust is formed by sedimentary rocks, under which there are "granite" and "basalt" layers, which are named so conventionally.
Under the earth's crust is located mantle... The mantle is the inner shell that covers the core of the Earth. WITH Greek"Mantle" is translated as "veil". Scientists suggest that the upper part of the mantle is composed of dense rocks, that is, it is solid. However, at a depth of 50-250 km from the Earth's surface, there is a partially molten layer called magma.
Earth's crust
It is comparatively soft and pliable, capable of flowing slowly and thus moving. The speed of magma movement is low - a few centimeters per year. However, this plays a decisive role in the movements of the earth's crust. The temperature of the upper magma layer is about +2000 ° С, and in the lower layers the heat can reach +5000 ° С. The earth's crust, together with the upper layer of the incandescent mantle, is called the lithosphere.
Under the mantle, at a depth of about 2900 km from the surface, is hidden core of the earth... It has the shape of a sphere with a radius of almost 3500 km. In the core, the outer and inner parts are distinguished, which differ in composition, temperature and density. The inner core is the hottest and densest part of our planet, which scientists believe is composed mainly of iron and nickel. The pressure in the inner core is so great that, despite the enormous temperature (+ 6000 ... + 10,000 ° C), it is solid... The outer core is in a liquid state, its temperature is 4300 ° C.
The structure of the earth's crust
Most of the crust is covered by the hydrosphere on the outside, and the smaller part is bordered by the atmosphere. In accordance with this, the earth's crust is distinguished oceanic and mainland types, and they have a different structure.
The continental (continental) crust occupies a smaller area (about 40% of the entire surface of the Earth), but has more complex structure... Under high mountains its thickness reaches 60-70 km. The continental crust consists of 3 layers - basalt, granite and sedimentary... The oceanic crust is thinner - only 5-7 km. It consists of two layers: lower - basalt and upper - sedimentary.
The Earth's crust has been most studied to a depth of 20 km. Based on the results of the analysis of numerous samples of rocks and minerals emerging on the earth's surface during mountain-building processes, as well as taken from mine workings and deep boreholes, the average composition of the chemical elements of the earth's crust was calculated.
The boundary layer separating the mantle and crust of the Earth is called the Mohorovicic boundary, or the Moho surface, in honor of the Croatian scientist A. Mohorovicic. He was the first in 1909 to point out the characteristic command of seismic waves when crossing the border, which can be traced throughout the globe at a depth of 5 to 70 km.
How is the mantle studied?
The mantle is deep underground, and even the deepest boreholes do not reach it. But sometimes, when gases break through the earth's crust, so-called kimberlite pipes are formed. Through them, mantle rocks and minerals come to the surface. The most famous of these is the diamond, the deepest fragment of our planet that we can study. Thanks to such pipes, we can judge the structure of the mantle.
The kimberlite pipe in Yakutia, where diamonds are mined, has been developed for a long time. Huge quarries have been set up in place of such pipes. Their very name comes from the city of Kimberley in South Africa.
Until recently, ideas about the thickness of the earth's crust under the ocean floor were based on rather rare profiles of seismic studies of deep structure.
Some data on the possible thickness of the crust under the bottom of the oceans were obtained by V.F.Bonchkovsky based on the study of surface waves of earthquakes.
R. M. Demenitskaya, having developed new method determining the thickness of the earth's crust, based on its known connections with gravity anomalies (in the Bouguer reduction) and with the relief of the earth's surface, she built schematic maps of the distribution of the thickness of the earth's crust of continents and oceans. Judging by these maps, the thickness of the earth's crust in the oceans is as follows.
V Atlantic Ocean, within the continental shelf, the crust thickness varies from 35 to 25 km. It does not differ from that in the adjacent parts of the continent, since the continental structures directly continue on the shelf. In the area of the continental slope, with increasing depth, the thickness of the crust decreases from 25-15 km in the upper part of the slope to 15-10 and even less than 10 km in its lower part. The bottom of the Atlantic Ocean basins is characterized by a small crust - from 2 to 7 km, but where it forms submarine ridges or plateaus, its thickness increases to 15-25 km (Bermuda submarine plateau, Telegraph plateau).
We see a similar picture in the Arctic basin of the Northern Arctic Ocean with a crust thickness of 15 to 25 km; only in its central parts it is less than 10-5 km. In the Scandic Basin, the crustal thickness (15 to 25 km) differs from that typical for oceanic basins. On the continental slope, the crustal thickness changes in the same way as in the Atlantic Ocean. We see the same analogy in the crust of the continental shelf of the Arctic Ocean with a crust thickness of 25 to 35 km; it thickens in the Laptev Sea, as well as in the adjacent parts of the Kara and East Siberian Seas and further on the Lomonosov Ridge.
The internal structure of the Earth
It is possible that the increase in the thickness of the crust here is associated with the spread of young - Mesozoic folded structures.
The Indian Ocean has a relatively thick crust (more than 25 km) in the Mozambique Strait and partly east of Madagascar up to the Seychelles ridge inclusive. Middle ridge Indian Ocean the thickness of the bark does not differ from the Median Atlantic Ridge... The southern part of the Arabian Sea and the Bay of Bengal are distinguished by a relatively small thickness of the crust, despite their comparative youth.
Some features are characteristic of the thickness of the earth's crust in the Pacific Ocean. In the Bering and Okhotsk Seas, the crust is over 25 km thick. It is less thick only in the southern deep-water part of the Bering Sea. In the Sea of Japan, the capacity decreases sharply (up to 10-15 km), in the seas of Indonesia it increases again (more than 25 km), remaining so to the south - up to and including the Arafura Sea. In the western part The Pacific, directly adjacent to the belt of geosynclinal seas, thicknesses from 7 to 10 km prevail, but in some depressions of the ocean floor they decrease to 5 km, in the regions of seamounts and islands they increase to 10-15 and often up to 20-25 km.
In the central part of the Pacific Ocean - the region of the deepest basins, as in other oceans, the thickness of the crust is the smallest - in the range from 2 to 7 km. In some depressions of the oceanic bottom, the crust is also thinner. In the most elevated parts of the ocean floor - on the middle underwater ridges and adjacent spaces, the crustal thickness increases to 7-10 km. The same thickness of the crust is characteristic of the eastern and southeastern parts ocean along the strike of the South Pacific and East Pacific ridges, as well as the underwater plateau Albatross.
Maps of the thickness of the earth's crust, compiled by R. M. Demenitskaya, give an idea of the total thickness of the crust. To clarify the structure of the crust, you need to refer to the data obtained through seismic studies.
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Have the globe there are several shells: - air shell, - aquatic shell, Is a hard shell.
The third behind the distance from the Sun planet Earth has a radius of 6370 km, an average density of 5.5 g / cm2. In internal structure It is customary to distinguish between the following layers of the earth:
Earth's crust- the upper layer of the Earth, in which living organisms can exist. The thickness of the earth's crust can be from 5 to 75 km.
mantle- a solid layer that is below the earth's crust. Its temperature is high enough, but the substance is in a solid state. The mantle is about 3,000 km thick.
core- the central part of the globe. Its radius is approximately 3,500 km. The core temperature is very high. The core is believed to be composed primarily of molten metal,
presumably iron.
Earth's crust
There are two main types of the earth's crust - continental and oceanic, plus intermediate, subcontinental.
The earth's crust is thinner under the oceans (about 5 km) and thicker - under the continents (up to 75 km.). It is heterogeneous, there are three layers: basalt (occurs below all), granite and sedimentary (upper). The continental crust consists of three layers, while the oceanic granite layer is absent. The earth's crust was formed gradually: first a basalt layer was formed, then a granite layer, the sedimentary layer continues to form at the present time.
- the substance of which the earth's crust consists. Rocks are classified into the following groups:
1. Igneous rocks. They are formed when magma solidifies in the earth's crust or on the surface.
2. Sedimentary rocks. They are formed on the surface, formed from the products of destruction or alteration of other rocks, biological organisms.
3. Metamorphic rocks. They are formed in the thickness of the earth's crust from other rocks under the influence of certain factors: temperature, pressure.
Until recently, ideas about the thickness of the earth's crust under the ocean floor were based on rather rare profiles of seismic studies of deep structure.
Some data on the possible thickness of the crust under the bottom of the oceans were obtained by V.F.Bonchkovsky based on the study of surface waves of earthquakes.
R. M. Demenitskaya, having developed a new method for determining the thickness of the earth's crust, based on its known connections with gravity anomalies (in the Bouguer reduction) and with the relief of the earth's surface, built schematic maps of the distribution of the thickness of the earth's crust of continents and oceans. Judging by these maps, the thickness of the earth's crust in the oceans is as follows.
In the Atlantic Ocean, within the continental shelf, the crust thickness varies from 35 to 25 km. It does not differ from that in the adjacent parts of the continent, since the continental structures directly continue on the shelf. In the area of the continental slope, with increasing depth, the thickness of the crust decreases from 25-15 km in the upper part of the slope to 15-10 and even less than 10 km in its lower part. The bottom of the Atlantic Ocean basins is characterized by a small crust - from 2 to 7 km, but where it forms submarine ridges or plateaus, its thickness increases to 15-25 km (Bermuda submarine plateau, Telegraph plateau).
We see a similar picture in the Arctic basin of the Arctic Ocean with a crust thickness of 15 to 25 km; only in its central parts it is less than 10-5 km. In the Scandic Basin, the crustal thickness (15 to 25 km) differs from that typical for oceanic basins. On the continental slope, the crustal thickness changes in the same way as in the Atlantic Ocean. We see the same analogy in the crust of the continental shelf of the Arctic Ocean with a crust thickness of 25 to 35 km; it thickens in the Laptev Sea, as well as in the adjacent parts of the Kara and East Siberian Seas and further on the Lomonosov Ridge. It is possible that the increase in the thickness of the crust here is associated with the spread of young - Mesozoic folded structures.
The Indian Ocean has a relatively thick crust (more than 25 km) in the Mozambique Strait and partly east of Madagascar up to the Seychelles ridge inclusive. The middle ridge of the Indian Ocean in crustal thickness does not differ from the Mid Atlantic ridge. The southern part of the Arabian Sea and the Bay of Bengal are distinguished by a relatively small thickness of the crust, despite their comparative youth.
Some features are characteristic of the thickness of the earth's crust in the Pacific Ocean. In the Bering and Okhotsk Seas, the crust is over 25 km thick. It is less thick only in the southern deep-water part of the Bering Sea. In the Sea of Japan, the capacity decreases sharply (up to 10-15 km), in the seas of Indonesia it increases again (more than 25 km), remaining so to the south - up to and including the Arafura Sea. In the western part of the Pacific Ocean, immediately adjacent to the belt of geosynclinal seas, thicknesses from 7 to 10 km prevail, but in some depressions of the ocean floor they decrease to 5 km, in the regions of seamounts and islands they increase to 10-15 and often up to 20- 25 km.
In the central part of the Pacific Ocean - the region of the deepest basins, as in other oceans, the thickness of the crust is the smallest - in the range from 2 to 7 km. In some depressions of the oceanic bottom, the crust is also thinner. In the most elevated parts of the ocean floor - on the middle underwater ridges and adjacent spaces, the crustal thickness increases to 7-10 km. The same crustal thicknesses are characteristic of the eastern and southeastern parts of the ocean along the strike of the South Pacific and East Pacific ridges, as well as the underwater plateau Albatross.
Maps of the thickness of the earth's crust, compiled by R. M. Demenitskaya, give an idea of the total thickness of the crust. To clarify the structure of the crust, you need to refer to the data obtained through seismic studies.