Tanushri(Structure of Earth)

8/4/2019 Tanushri(Structure of Earth)

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The interior structure of the Earth, similar to the outer, is layered. These layers can be defined by either

theirchemicalor theirrheologicalproperties. TheEarthhas an outersilicatesolidcrust, a

highlyviscousmantle, a liquidouter corethat is much less viscous than the mantle, and a solidinner

core. Scientific understanding of Earth's internal structure is based on observations

oftopographyandbathymetry, observations ofrockinoutcrop, samples brought to the surface from

greater depths by volcanic activity, analysis of theseismic wavesthat pass through the Earth,measurements of thegravityfield of the Earth, and experiments with crystalline solids at pressures and

temperatures characteristic of the Earth's deep interior

[edit]Assumptions

The force exerted byEarth's gravitycan be used to calculate its mass, and by estimating the volume of

the planet, its average density can be calculated. Astronomers can also calculate Earth's mass from its

orbit and effects on nearby planetary bodies. Observations of rocks, bodies of water and atmosphere

allow estimation of the mass, volume and density of rocks to a certain depth, so the remaining mass must

be in the deeper layers.

[edit]Structure

Earth's radial density distribution according to the preliminary reference earth model (PREM).
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Earth's gravity according to the preliminary reference earth model (PREM). Comparison to approximations using constant

and linear density for Earth's interior.

The structure of Earth can be defined in two ways: by mechanical properties such asrheology, or

chemically. Mechanically, it can be divided intolithosphere,asthenosphere,mesosphere,outer core, and

theinner core. The interior of the earth is divided into 5 important layers. Chemically, Earth can be divided

into the crust, upper mantle, lower mantle, outer core, and inner core. The geologic component layers of

Earth[1]

are at the following depths below the surface:

Depth

LayerKilometres Miles

060 037 Lithosphere (locally varies between 5 and 200 km)

035 022 Crust (locally varies between 5 and 70 km)

3560 2237 Uppermost part of mantle

352,890 221,790 Mantle

100200 62125 Asthenosphere

35660 22410 Upper mesosphere (upper mantle)
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6602,890 4101,790 Lower mesosphere (lower mantle)

2,8905,150 1,7903,160 Outer core

5,1506,360 3,1603,954 Inner core

Mapping the interior of theEarthwithearthquakewaves.

The layering of Earth has been inferred indirectly using the time of travel of refracted and reflected

seismic waves created by earthquakes. The core does not allow shear waves to pass through it, while the

speed of travel (seismic velocity) is different in other layers. The changes in seismic velocity between

different layers causes refraction owing toSnell's law. Reflections are caused by a large increase in

seismic velocity and are similar to light reflecting from a mirror.

[edit]Core

The average density of Earth is 5,515kg/m3. Since the average density of surface material is only around

3,000 kg/m3, we must conclude that denser materials exist within Earth's core. Further evidence for the

high density core comes from the study ofseismology.

Seismic measurements show that the core is divided into two parts, a solidinner corewith aradiusof

~1,220 km and a liquid outer core extending beyond it to a radius of ~3,400 km. The solid inner core was

discovered in 1936 byInge Lehmannand is generally believed to be composed primarily of iron and

some nickel. In early stages of Earth's formation about 4.5 billion (4.5109) years ago, melting would have

caused denser substances to sink toward the center in a process calledplanetary differentiation(see also

theiron catastrophe), while less-dense materials would have migrated to thecrust. The core is thus
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believed to largely be composed of iron (80%), along withnickeland one or more light elements, whereas

other dense elements, such asleadanduranium, either are too rare to be significant or tend to bind to

lighter elements and thus remain in the crust (seefelsic materials). Some have argued that the inner core

may be in the form of a single ironcrystal.[2][3]

The liquid outer core surrounds the inner core and is believed to be composed of iron mixed with nickel

and trace amounts of lighter elements.

Recent speculation suggests that the innermost part of the core is enriched ingold,platinumand

othersiderophile elements.[4]

The matter that comprises Earth is connected in fundamental ways to matter of

certainchondritemeteorites, and to matter of outer portion of the Sun.[5][6]

There is good reason to believe

that Earth is, in the main, like a chondrite meteorite. Beginning as early as 1940, scientists,

includingFrancis Birch, built geophysics upon the premise that Earth is like ordinary chondrites, the most

common type of meteorite observed impacting Earth, while totally ignoring another, albeit less abundant

type, calledenstatitechondrites. The principal difference between the two meteorite types is that enstatite

chondrites formed under circumstances of extremely limited available oxygen, leading to certain normally

oxyphile elements existing either partially or wholly in the alloy portion that corresponds to the core of

Earth.

Dynamo theorysuggests that convection in the outer core, combined with theCoriolis effect, gives rise

toEarth's magnetic field. The solid inner core is too hot to hold a permanent magnetic field (seeCurie

temperature) but probably acts to stabilize the magnetic field generated by the liquid outer core. The

average magnetic field strength in the Earth's outer core is estimated to be 25 Gauss, 50 times stronger

than the magnetic field at the surface.[7][8]

Recent evidence has suggested that the inner core of Earth may rotate slightly faster than the rest of the

planet.[9]

In August 2005 a team ofgeophysicistsannounced in the journalSciencethat, according to their

estimates, Earth's inner core rotates approximately 0.3 to 0.5 degrees per year relative to the rotation of

the surface.[10][11]

The current scientific explanation for theEarth's temperature gradientis a combination of heat left over

from the planet's initial formation, decay of radioactive elements, and freezing of the inner core.

[edit]Mantle

Main article:Mantle (geology)
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Schematic view of the interior of Earth. 1. continental crust - 2. oceanic crust - 3. upper mantle - 4. lower mantle - 5. outer

core - 6. inner core - A:Mohorovii discontinuity- B:Gutenberg Discontinuity- C:Lehmann discontinuity

Earth's mantleextends to a depth of 2,890 km, making it the thickest layer of the Earth. Thepressure, at

the bottom of the mantle, is ~140 GPa(1.4 Matm). The mantle is composed ofsilicaterocks that are rich

in iron and magnesium relative to the overlying crust. Although solid, the high temperatures within the

mantle cause the silicate material to be sufficientlyductilethat it can flow on very long

timescales.Convectionof the mantle is expressed at the surface through the motions oftectonic plates.

Themelting pointandviscosityof a substance depends on the pressure it is under. As there is intenseand increasing pressure as one travels deeper into the mantle, the lower part of the mantle flows less

easily than does the upper mantle (chemical changes within the mantle may also be important). The

viscosity of the mantle ranges between 1021

and 1024

Pas, depending on depth.[12]

In comparison, the

viscosity of water is approximately 103

Pasand that ofpitchis 107

Pas.

[edit]Crust

Main article:Crust (geology)

The crust ranges from 570 km in depth and is the outermost layer. The thin parts are theoceanic crust,

which underlie the ocean basins (510 km) and are composed of dense (mafic) ironmagnesiumsilicaterocks, likebasalt.The thicker crust iscontinental crust, which is less dense and

composed of (felsic)sodiumpotassiumaluminiumsilicate rocks, likegranite. The rocks of the crust fall

into two major categories - sial and sima (Suess,18311914). As the main mineral constituents of the

continental mass are silica and alumina, it is thus calledsial(si-silica, 6575% and al-alumina). The

oceanic crust mainly consists of silica and magnesium. it is therefore calledsima(si-silica and ma-
http://en.wikipedia.org/wiki/Mantle_(geology)http://en.wikipedia.org/wiki/Mantle_(geology)http://en.wikipedia.org/wiki/Mantle_(geology)http://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Gutenberg_Discontinuityhttp://en.wikipedia.org/wiki/Gutenberg_Discontinuityhttp://en.wikipedia.org/wiki/Gutenberg_Discontinuityhttp://en.wikipedia.org/wiki/Lehmann_discontinuityhttp://en.wikipedia.org/wiki/Lehmann_discontinuityhttp://en.wikipedia.org/wiki/Lehmann_discontinuityhttp://en.wikipedia.org/wiki/Earth%27s_mantlehttp://en.wikipedia.org/wiki/Earth%27s_mantlehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Pascal_(unit)http://en.wikipedia.org/wiki/Pascal_(unit)http://en.wikipedia.org/wiki/Atmospheric_pressurehttp://en.wikipedia.org/wiki/Atmospheric_pressurehttp://en.wikipedia.org/wiki/Silicatehttp://en.wikipedia.org/wiki/Silicatehttp://en.wikipedia.org/wiki/Silicatehttp://en.wikipedia.org/wiki/Ductilityhttp://en.wikipedia.org/wiki/Ductilityhttp://en.wikipedia.org/wiki/Ductilityhttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Tectonic_plateshttp://en.wikipedia.org/wiki/Tectonic_plateshttp://en.wikipedia.org/wiki/Tectonic_plateshttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Pascal_secondhttp://en.wikipedia.org/wiki/Pascal_secondhttp://en.wikipedia.org/wiki/Pascal_secondhttp://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-11http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-11http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-11http://en.wikipedia.org/wiki/Pascal_secondhttp://en.wikipedia.org/wiki/Pascal_secondhttp://en.wikipedia.org/wiki/Pascal_secondhttp://en.wikipedia.org/wiki/Pitch_drop_experimenthttp://en.wikipedia.org/wiki/Pitch_drop_experimenthttp://en.wikipedia.org/wiki/Pitch_drop_experimenthttp://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=5http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=5http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=5http://en.wikipedia.org/wiki/Crust_(geology)http://en.wikipedia.org/wiki/Crust_(geology)http://en.wikipedia.org/wiki/Crust_(geology)http://en.wikipedia.org/wiki/Oceanic_crusthttp://en.wikipedia.org/wiki/Oceanic_crusthttp://en.wikipedia.org/wiki/Oceanic_crusthttp://en.wikipedia.org/wiki/Mafichttp://en.wikipedia.org/wiki/Mafichttp://en.wikipedia.org/wiki/Mafichttp://en.wikipedia.org/wiki/Silicatehttp://en.wikipedia.org/wiki/Silicatehttp://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Basalthttp://en.wikipedia.org/wiki/Basalthttp://en.wikipedia.org/wiki/Basalthttp://en.wikipedia.org/wiki/Continental_crusthttp://en.wikipedia.org/wiki/Continental_crusthttp://en.wikipedia.org/wiki/Continental_crusthttp://en.wikipedia.org/wiki/Felsichttp://en.wikipedia.org/wiki/Felsichttp://en.wikipedia.org/wiki/Felsichttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Granitehttp://en.wikipedia.org/wiki/Granitehttp://en.wikipedia.org/wiki/Granitehttp://en.wikipedia.org/wiki/Sialhttp://en.wikipedia.org/wiki/Sialhttp://en.wikipedia.org/wiki/Sialhttp://en.wikipedia.org/wiki/Sima_(geology)http://en.wikipedia.org/wiki/Sima_(geology)http://en.wikipedia.org/wiki/Sima_(geology)http://en.wikipedia.org/wiki/File:Slice_earth.svghttp://en.wikipedia.org/wiki/File:Slice_earth.svghttp://en.wikipedia.org/wiki/File:Slice_earth.svghttp://en.wikipedia.org/wiki/File:Slice_earth.svghttp://en.wikipedia.org/wiki/Sima_(geology)http://en.wikipedia.org/wiki/Sialhttp://en.wikipedia.org/wiki/Granitehttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Felsichttp://en.wikipedia.org/wiki/Continental_crusthttp://en.wikipedia.org/wiki/Basalthttp://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Silicatehttp://en.wikipedia.org/wiki/Mafichttp://en.wikipedia.org/wiki/Oceanic_crusthttp://en.wikipedia.org/wiki/Crust_(geology)http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=5http://en.wikipedia.org/wiki/Pitch_drop_experimenthttp://en.wikipedia.org/wiki/Pascal_secondhttp://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-11http://en.wikipedia.org/wiki/Pascal_secondhttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Melting_pointhttp://en.wikipedia.org/wiki/Tectonic_plateshttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Ductilityhttp://en.wikipedia.org/wiki/Silicatehttp://en.wikipedia.org/wiki/Atmospheric_pressurehttp://en.wikipedia.org/wiki/Pascal_(unit)http://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Earth%27s_mantlehttp://en.wikipedia.org/wiki/Lehmann_discontinuityhttp://en.wikipedia.org/wiki/Gutenberg_Discontinuityhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuity


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magnesium). It is estimated that sima starts about 11 km below theConrad discontinuity(a second order

discontinuity). The uppermost mantle together with the crust constitutes thelithosphere. The crust-mantle

boundary occurs as two physically different events. First, there is a discontinuity in theseismicvelocity,

which is known as theMohorovii discontinuityor Moho. The cause of the Moho is thought to be a

change in rock composition from rocks containingplagioclase feldspar(above) to rocks that contain no

feldspars (below). Second, in oceanic crust, there is achemicaldiscontinuity

betweenultramaficcumulates and tectonizedharzburgites, which has been observed from deep parts of

the oceanic crust that have beenobductedonto the continental crust and preserved as

Earth's structure

The earth consists of several layers. The three main layers are the core, the mantle andthe crust. The core is the inner part of the earth, the crust is the outer part and between

them is the mantle. The earth is surrounded by the atmosphere. Till this moment ithasn't been possible to take a look inside the earth because the current technologydoesn't allow it. Therefore all kinds of research had to be done to find out, out of whichmaterial the earth consists, what different layers there are and which influence thosehave (had) on the earth's surface. This research is called seismology.

Full size

Earth cutawayHere, sections of the Earth havebeen removed to show its internalstructure.

Image by: Colin Rose,Dorling Kindersley

The core

The inner part of the earth is the core. This partof the earth is about 1,800 miles (2,900 km)below the earth's surface. The core is a dense

ball of the elements iron and nickel. It is dividedinto two layers, the inner core and the outercore. The inner core - the center of earth - issolid and about 780 miles (1,250 km) thick. Theouter core is so hot that the metal is alwaysmolten, but the inner core pressures are sogreat that it cannot melt, even thoughtemperatures there reach 6700F (3700C). Theouter core is about 1370 miles (2,200 km) thick.Because the earth rotates, the outer core spinsaround the inner core and that causes the

earth's magnetism.More info...

The Mantle

The layer above the core is the mantle. It begins about 6 miles(10 km) below theoceanic crust and about 19 miles(30 km) below the continental crust (see The Crust).The mantle is to divide into the inner mantle and the outer mantle. It is about 1,800
http://en.wikipedia.org/wiki/Conrad_discontinuityhttp://en.wikipedia.org/wiki/Conrad_discontinuityhttp://en.wikipedia.org/wiki/Conrad_discontinuityhttp://en.wikipedia.org/wiki/Lithospherehttp://en.wikipedia.org/wiki/Lithospherehttp://en.wikipedia.org/wiki/Lithospherehttp://en.wikipedia.org/wiki/Seismic_wavehttp://en.wikipedia.org/wiki/Seismic_wavehttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Feldsparhttp://en.wikipedia.org/wiki/Feldsparhttp://en.wikipedia.org/wiki/Feldsparhttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Ultramafichttp://en.wikipedia.org/wiki/Ultramafichttp://en.wikipedia.org/wiki/Ultramafichttp://en.wikipedia.org/wiki/Peridotitehttp://en.wikipedia.org/wiki/Peridotitehttp://en.wikipedia.org/wiki/Peridotitehttp://en.wikipedia.org/wiki/Obductionhttp://en.wikipedia.org/wiki/Obductionhttp://en.wikipedia.org/wiki/Obductionhttp://mediatheek.thinkquest.nl/~ll125/en/fullstruct.htmhttp://mediatheek.thinkquest.nl/~ll125/en/fullstruct.htmhttp://www.dk.com/http://www.dk.com/http://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/mantle.htmhttp://mediatheek.thinkquest.nl/~ll125/en/mantle.htmhttp://mediatheek.thinkquest.nl/~ll125/en/mantle.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://www.dk.com/http://mediatheek.thinkquest.nl/~ll125/en/fullstruct.htmhttp://en.wikipedia.org/wiki/Obductionhttp://en.wikipedia.org/wiki/Peridotitehttp://en.wikipedia.org/wiki/Ultramafichttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Feldsparhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Seismic_wavehttp://en.wikipedia.org/wiki/Lithospherehttp://en.wikipedia.org/wiki/Conrad_discontinuity


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miles(2,900 km) thick and makes up nearly 80 percent of the Earth's total volume.Moreinfo...

The Crust

The crust lays above the mantle and is the earth's hard outer shell, the surface on whichwe are living. In relation with the other layers the crust is much thinner. It floats upon thesofter, denser mantle. The crust is made up of solid material but these material is noteverywhere the same. There is an Oceanic crust and a Continental crust. The first oneis about 4-7 miles (6-11 km) thick and consists of heavy rocks, like basalt. TheContinental crust is thicker than the Oceanic crust, about 19 miles(30 km) thick. It ismainly made up of light material, like granite.More info...

-Plate Tectonics-Earthquakes-Volcanoes

The Atmosphere

The earth is surrounded by all kind of gases. This layer is called the earth's atmosphere.Without these atmosphere life on earth isn't possible. The atmosphere gives us air,water, warmth and is protecting us against harmful rays of the sun and againstmeteorites. This layer around the earth is a colorless, odorless, tasteless 'sea' of gases,water and fine dust. The atmosphere is made up of different layers with differentqualities. It consists of 78% nitrogen, 21% oxygen, 0,93% argon, 0,03% carbon dioxideand 0,04% of other gases. The Troposphere is the layer where the weather happens,above this layer is the Stratosphere. Within the Stratosphere is the Ozone layer, thatabsorbs the Sun's harmful ultraviolet rays. Above the Stratosphere is the Mesosphere,

the Thermosphere - in which the Ionosphere - and the Exosphere. The atmosphere isabout 500 miles (800 km) thick.More info...

Influence of the Sun and the Moon

The sun and the moon both have their influence on the earth. Sometimes theycooperate and sometimes they counteract each other. Such influences are: the gravity,the warmth of the sun, the sunlight and the chronology. Through the gravitational forceof the earth the moon orbits the earth. The moon also gravitates the earth, but lesspowerful. By the way gravity pulls the Earth and Moon toward each other, tides arecaused (high tide and low tide). The sun also has some influence here. The sun brings

light and is also responsible for the warming up of the earth.More info...

Relative sites

Home|Formation of the Earth|Earth's Structure|Life on Earth
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Earth's Structure:Structure|The Core|The Mantle|The Crust|The Atmosphere|The Influenceof the Sun and Moon

Plate Tectonics |Earthquakes|Volcanoes

Copyright 2000, ThinkQuest team ll125

All rights reserved.

http://ontwikkel.thinkquest.nl/~ll125/en/struct.htm

Many rocks now making up Earth's crust formed less than 100 million (1108) years ago; however, the

oldest known mineral grains are 4.4 billion (4.4109) years old, indicating that Earth has had a solid crust

for at least that long.[13]

[edit]Historical development of alternative conceptions

Main article:Hollow Earth

Edmond Halley's hypothesis.

In 1692Edmund Halley(in a paper printed in Philosophical Transactions of Royal Society of London) put

forth the idea ofEarthconsisting of a hollow shell about 500 miles thick, with two inner concentric shells

around an innermost core, corresponding to the diameters of the planets Venus, Mars, and Mercury

respectively.[14]

Halley's construct was a method of accounting for the (flawed) values of the relative

density of Earth and the Moon that had been given bySir Isaac Newton, in Principia(1687). "Sir Isaac

Newton has demonstrated the Moon to be more solid than our Earth, as 9 to 5," Halley remarked; "why

may we not then suppose four ninths of our globe to be cavity?"[14]

[edit]See also

Earth sciences portal

Rain-out model

Mohorovii discontinuity, boundary crust and mantle.

Core-mantle boundary

Hollow Earth
http://mediatheek.thinkquest.nl/~ll125/en/life-1.htmhttp://mediatheek.thinkquest.nl/~ll125/en/struct.htmhttp://mediatheek.thinkquest.nl/~ll125/en/struct.htmhttp://mediatheek.thinkquest.nl/~ll125/en/struct.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/mantle.htmhttp://mediatheek.thinkquest.nl/~ll125/en/mantle.htmhttp://mediatheek.thinkquest.nl/~ll125/en/mantle.htmhttp://mediatheek.thinkquest.nl/~ll125/en/crust.htmhttp://mediatheek.thinkquest.nl/~ll125/en/crust.htmhttp://mediatheek.thinkquest.nl/~ll125/en/crust.htmhttp://mediatheek.thinkquest.nl/~ll125/en/atmos.htmhttp://mediatheek.thinkquest.nl/~ll125/en/atmos.htmhttp://mediatheek.thinkquest.nl/~ll125/en/atmos.htmhttp://mediatheek.thinkquest.nl/~ll125/en/sunmoon.htmhttp://mediatheek.thinkquest.nl/~ll125/en/sunmoon.htmhttp://mediatheek.thinkquest.nl/~ll125/en/sunmoon.htmhttp://mediatheek.thinkquest.nl/~ll125/en/sunmoon.htmhttp://mediatheek.thinkquest.nl/~ll125/en/platetec.htmhttp://mediatheek.thinkquest.nl/~ll125/en/platetec.htmhttp://mediatheek.thinkquest.nl/~ll125/en/earthqke.htmhttp://mediatheek.thinkquest.nl/~ll125/en/earthqke.htmhttp://mediatheek.thinkquest.nl/~ll125/en/earthqke.htmhttp://mediatheek.thinkquest.nl/~ll125/en/volcano.htmhttp://mediatheek.thinkquest.nl/~ll125/en/volcano.htmhttp://mediatheek.thinkquest.nl/~ll125/en/volcano.htmhttp://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-12http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-12http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-12http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=6http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=6http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=6http://en.wikipedia.org/wiki/Hollow_Earthhttp://en.wikipedia.org/wiki/Hollow_Earthhttp://en.wikipedia.org/wiki/Hollow_Earthhttp://en.wikipedia.org/wiki/Edmond_Halleyhttp://en.wikipedia.org/wiki/Edmond_Halleyhttp://en.wikipedia.org/wiki/Edmund_Halleyhttp://en.wikipedia.org/wiki/Edmund_Halleyhttp://en.wikipedia.org/wiki/Edmund_Halleyhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-Kollerstrom-13http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-Kollerstrom-13http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-Kollerstrom-13http://en.wikipedia.org/wiki/Sir_Isaac_Newtonhttp://en.wikipedia.org/wiki/Sir_Isaac_Newtonhttp://en.wikipedia.org/wiki/Sir_Isaac_Newtonhttp://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-Kollerstrom-13http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-Kollerstrom-13http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-Kollerstrom-13http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=7http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=7http://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=7http://en.wikipedia.org/wiki/Portal:Earth_scienceshttp://en.wikipedia.org/wiki/Rain-out_modelhttp://en.wikipedia.org/wiki/Rain-out_modelhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Core-mantle_boundaryhttp://en.wikipedia.org/wiki/Core-mantle_boundaryhttp://en.wikipedia.org/wiki/Hollow_Earthhttp://en.wikipedia.org/wiki/Hollow_Earthhttp://en.wikipedia.org/wiki/File:DirkvdM_rocks.jpghttp://en.wikipedia.org/wiki/File:Hollow_Earth.svghttp://en.wikipedia.org/wiki/File:Hollow_Earth.svghttp://en.wikipedia.org/wiki/File:DirkvdM_rocks.jpghttp://en.wikipedia.org/wiki/File:Hollow_Earth.svghttp://en.wikipedia.org/wiki/File:Hollow_Earth.svghttp://en.wikipedia.org/wiki/File:DirkvdM_rocks.jpghttp://en.wikipedia.org/wiki/File:Hollow_Earth.svghttp://en.wikipedia.org/wiki/File:Hollow_Earth.svghttp://en.wikipedia.org/wiki/Hollow_Earthhttp://en.wikipedia.org/wiki/Core-mantle_boundaryhttp://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuityhttp://en.wikipedia.org/wiki/Rain-out_modelhttp://en.wikipedia.org/wiki/Portal:Earth_scienceshttp://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=7http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-Kollerstrom-13http://en.wikipedia.org/wiki/Sir_Isaac_Newtonhttp://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-Kollerstrom-13http://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Edmund_Halleyhttp://en.wikipedia.org/wiki/Edmond_Halleyhttp://en.wikipedia.org/wiki/Hollow_Earthhttp://en.wikipedia.org/w/index.php?title=Structure_of_the_Earth&action=edit&section=6http://en.wikipedia.org/wiki/Structure_of_the_Earth#cite_note-12http://mediatheek.thinkquest.nl/~ll125/en/volcano.htmhttp://mediatheek.thinkquest.nl/~ll125/en/earthqke.htmhttp://mediatheek.thinkquest.nl/~ll125/en/platetec.htmhttp://mediatheek.thinkquest.nl/~ll125/en/sunmoon.htmhttp://mediatheek.thinkquest.nl/~ll125/en/sunmoon.htmhttp://mediatheek.thinkquest.nl/~ll125/en/atmos.htmhttp://mediatheek.thinkquest.nl/~ll125/en/crust.htmhttp://mediatheek.thinkquest.nl/~ll125/en/mantle.htmhttp://mediatheek.thinkquest.nl/~ll125/en/core.htmhttp://mediatheek.thinkquest.nl/~ll125/en/struct.htm


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Lehmann discontinuity

Hydridic Earth theory

Receiver function

[edit]Notes

1. ^T. H. Jordan, "Structural Geology of the Earth's Interior", Proceedings of the National Academy of

Science, 1979, Sept., 76(9): 41924200.

2. ^Cohen, Ronald; Stixrude, Lars."Crystal at the Center of the Earth". Retrieved 2007-02-05.

3. ^Lars Stixrude and R. E. Cohen, "High-Pressure Elasticity of Iron and Anisotropy of Earth's Inner

Core", Science31 March 1995: Vol. 267. no. 5206, pp. 1972 - 1975 DOI: 10.1126/science.267.5206.1972

4. ^Wootton, Anne (September 2006) "Earth's Inner Fort Knox" Discover27(9): p.18;

5. ^Herndon, J. M., The chemical composition of the interior shells of the Earth. Proc. R. Soc. Lond, 1980,

A372, 149-154.

6. ^Herndon, J. M., Scientific basis of knowledge on Earth's composition. Curr.Sci., 2005, 88(7), 1034-1037.

7. ^http://www.science20.com/news_articles/first_measurement_magnetic_field_inside_earths_core

8. ^http://www.nature.com/nature/journal/v468/n7326/full/nature09643.html

9. ^Chang, Kenneth (2005-08-25)."Earth's Core Spins Faster Than the Rest of the Planet".The New York

Times. Retrieved 2010-05-24.

10. ^Kerr, Richard A. (26 August 2005) "Earth's Inner Core Is Running a Tad Faster Than the Rest of the

Planet" Science309(5739): p.1313;

11. ^Chang, Kenneth (26 August 2005) "Scientists Say Earth's Center Rotates Faster Than Surface" The New

York TimesSec. A, Col. 1, p.13;

12. ^http://www2.uni-jena.de/chemie/geowiss/geodyn/poster2.html

13. ^Spaceflight Now | Breaking News | Oldest rock shows Earth was a hospitable young planet

14. ^abN. Kollerstrom, 1992. "The hollow world of Edmond Halley"from Journal for History call thuis numba

66451146 and ask 4 leona of Astronomy23, 185-192

[edit]References

Kruglinski, Susan. "Journey to the Center of the Earth." Discover.

Lehmann, I. (1936) Inner Earth, Bur. Cent. Seismol. Int. 14, 3-31

Schneider, David (October 1996) A Spinning Crystal Ball, Scientific American

Wegener, Alfred (1915) "The Origin of Continents and Oceans"

[show]v d eTheEarth

[show]v d eStructure of the Earth
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Structure of the Earth

Geophysics, which studies the physics of the Earth, has led to manysignificant discoveries about the Earth and its make-up. Seismologic studiesof the Earth have uncovered new information about the interior of the Earththat has helped to give credence to plate tectonic theory.

Geophysical studies have revealed that the Earth has several distinct layers.Each of these layers has its own properties. The outermost layer of the Earthis the crust. This comprises the continents and ocean basins. The crust has a

variable thickness, being 35-70 km thick in the continents and 5-10 km thick inthe ocean basins. The crust is composed mainly of alumino-silicates.
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The next layer is themantle, which is composed mainly of ferro-magnesiumsilicates. It is about 2900 km thick, and is separated into the upper and lowermantle. This is where most of the internal heat of the Earth is located. Largeconvective cells in the mantle circulate heat and may drive plate tectonicprocesses.
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The last layer is the core, which is separated into the liquid outer core and thesolid inner core. The outer core is 2300 km thick and the inner core is 1200km thick. The outer core is composed mainly of a nickel-iron alloy, while theinner core is almost entirely composed of iron. Earth's magnetic field isbelieved to be controlled by the liquid outer core.

The Earth is separated into layers based on mechanical properties in additionto composition. The topmost layer is thelithosphere, which is comprised of thecrust and solid portion of the upper mantle. The lithosphere is divided intomany plates that move in relation to each other due to tectonic forces. Thelithosphere essentially floats atop a semi-liquid layer known astheasthenosphere. This layer allows the solid lithosphere to move aroundsince the asthenosphere is much weaker than the lithosphere.
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Structure of the Earth History of plate tectonics Plates Plateboundaries Forces in the Earth Faults Hypercard Resources

Plate tectonics Activities

Last modified on 8/14/98 by Maggi Glasscoe([email protected])

Earth's structure

The earth consists of several layers. The three main layers are the core, the mantle andthe crust. The core is the inner part of the earth, the crust is the outer part and betweenthem is the mantle. The earth is surrounded by the atmosphere. Till this moment it

hasn't been possible to take a look inside the earth because the current technologydoesn't allow it. Therefore all kinds of research had to be done to find out, out of whichmaterial the earth consists, what different layers there are and which influence thosehave (had) on the earth's surface. This research is called seismology.

Full size

Earth cutawayHere, sections of the Earth havebeen removed to show its internalstructure.

The core

The inner part of the earth is the core. This partof the earth is about 1,800 miles (2,900 km)below the earth's surface. The core is a denseball of the elements iron and nickel. It is divided

into two layers, the inner core and the outercore. The inner core - the center of earth - issolid and about 780 miles (1,250 km) thick. Theouter core is so hot that the metal is alwaysmolten, but the inner core pressures are sogreat that it cannot melt, even thoughtemperatures there reach 6700F (3700C). Theouter core is about 1370 miles (2,200 km) thick.
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Image by: Colin Rose,Dorling Kindersley

Because the earth rotates, the outer core spinsaround the inner core and that causes theearth's magnetism.More info...

The Mantle

The layer above the core is the mantle. It begins about 6 miles(10 km) below theoceanic crust and about 19 miles(30 km) below the continental crust (see The Crust).The mantle is to divide into the inner mantle and the outer mantle. It is about 1,800miles(2,900 km) thick and makes up nearly 80 percent of the Earth's total volume.Moreinfo...

The Crust

The crust lays above the mantle and is the earth's hard outer shell, the surface on whichwe are living. In relation with the other layers the crust is much thinner. It floats upon thesofter, denser mantle. The crust is made up of solid material but these material is noteverywhere the same. There is an Oceanic crust and a Continental crust. The first oneis about 4-7 miles (6-11 km) thick and consists of heavy rocks, like basalt. TheContinental crust is thicker than the Oceanic crust, about 19 miles(30 km) thick. It ismainly made up of light material, like granite.More info...

-Plate Tectonics-Earthquakes-Volcanoes

The Atmosphere

The earth is surrounded by all kind of gases. This layer is called the earth's atmosphere.Without these atmosphere life on earth isn't possible. The atmosphere gives us air,water, warmth and is protecting us against harmful rays of the sun and againstmeteorites. This layer around the earth is a colorless, odorless, tasteless 'sea' of gases,water and fine dust. The atmosphere is made up of different layers with differentqualities. It consists of 78% nitrogen, 21% oxygen, 0,93% argon, 0,03% carbon dioxideand 0,04% of other gases. The Troposphere is the layer where the weather happens,above this layer is the Stratosphere. Within the Stratosphere is the Ozone layer, thatabsorbs the Sun's harmful ultraviolet rays. Above the Stratosphere is the Mesosphere,the Thermosphere - in which the Ionosphere - and the Exosphere. The atmosphere isabout 500 miles (800 km) thick.More info...

Influence of the Sun and the Moon

The sun and the moon both have their influence on the earth. Sometimes theycooperate and sometimes they counteract each other. Such influences are: the gravity,the warmth of the sun, the sunlight and the chronology. Through the gravitational forceof the earth the moon orbits the earth. The moon also gravitates the earth, but lesspowerful. By the way gravity pulls the Earth and Moon toward each other, tides are
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caused (high tide and low tide). The sun also has some influence here. The sun bringslight and is also responsible for the warming up of the earth.More info...

Relative sites

Home|Formation of the Earth|Earth's Structure|Life on Earth

Earth's Structure:Structure|The Core|The Mantle|The Crust|The Atmosphere|The Influenceof the Sun and Moon

Plate Tectonics |Earthquakes|Volcanoes

Copyright 2000, ThinkQuest team ll125All rights reserved.

http://ontwikkel.thinkquest.nl/~ll125/en/struct.htm

The structure of the Earth

Imagine a Scotch egg......

1. The outer shell of the Earth is called

the CRUST (breadcrumbs)2. The next layer is called the MANTLE

(sausagemeat)3. The next layer is the liquid OUTER CORE

(egg white)4. The middle bit is called the solid INNER

CORE (egg yolk)

DEAD EASY !

The deepest anyone has drilled into the earth isaround 12 kilometres, we've only scratched thesurface. How do we know what's goingon deep underground?

There are lots of clues:

The overall density of the Earth is much higher than the density of the rocks wefind in the crust. This tells us that the inside must be made ofsomething much denser than rock.

Meteorites (created at the same time as the Earth, 4.6 billion years ago) havebeen analysed. The commonest type is called a chondrite and they contain iron,silicon, magnesium and oxygen (Others contain iron and nickel). A meteoritehas roughly the same density as the whole earth. A meteorite minus its iron

The Rock Cycle

Plate Tectonics

Earth Structure

Earth Origin

Volcanoes

Earth's Atmosphere

Fossil Fuels

Polymers

home

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protected]:[email protected]://www.moorlandschool.co.uk/index.htmlhttp://www.moorlandschool.co.uk/index.htmlhttp://www.moorlandschool.co.uk/index.htmlmailto:[email 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has a density roughly the same as Mantle rock (e.g. the mineral called olivine).

Iron and Nickel are both dense and magnetic. Scientists can follow the path of seismic waves fromearthquakesas they travel

through the Earth. The inner core of the Earth appears to be solid whilst theouter core is liquid (s waves do not travel through liquids). The mantle ismainly solid as it is under extreme pressure (see below). We know that the

mantle rocks are under extreme pressure, diamond is made from carbondeposits and is created in rocks that come from depths of 150-300 kilometresthat have been squeezed under massive pressures.

The Earth is sphere (as is the scotch egg!) with a diameter of about12,700Kilometres. As we go deeper and deeper into the earth the temperatureand pressure rises. The core temperature is believed to be an incredible 5000-6000c.

The crust is very thin (average 20Km). This does not sound very thin but if youwere to imagine the Earth as a football, the crust would be about millimetrethick. The thinnest parts are under the oceans (OCEANIC CRUST) and go to adepth of roughly 10 kilometres. The thickest parts are the continents(CONTINENTAL CRUST) which extend down to 35 kilometres on average. Thecontinental crust in the Himalayas is some 75 kilometres deep.

The mantle is the layer beneath the crust which extends about half way to thecentre. It's made of solid rock and behaves like an extremely viscous liquid -(This is the tricky bit... the mantle is asolid which flows????) The convectionof heat from the centre of the Earth is what ultimately drives the movement ofthetectonic platesand cause mountains to rise. Clickherefor more details

The outer core is the layer beneath the mantle. It is made of liquid iron andnickel. Complex convection currents give rise to a dynamo effect which isresponsible for the Earth's magnetic field.

The inner core is the bit in the middle!. It is made ofsolid iron and nickel.Temperatures in the core are thought to be in the region of 5000-6000c andit's solid due to the massive pressure.

THAT'S ALL WE REALLY NEED TO KNOW!

(If you haven't seen a solid that flows then go backhereand have a look)

EARTH STRUCTURETEST

HERE IS SOME EXTRA STUFF(IN A LOT MORE DETAILTHAN WE NEED FOR GCSE):

This diagram shows adetailed picture of the

Earth's interior. Crust isbeing created at the midocean ridges and being eatenat the subduction zones. Themovement processes aredriven by theconvectioncurrentscreated by the heatproduced by naturalradioactive processes deep
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within the Earth.

Inner core: depth of 5,150-6,370 kilometresThe inner core is made of solid iron and nickel and is unattached to the mantle,suspended in the molten outer core. It is believed to have solidified as a result ofpressure-freezing which occurs to most liquids under extreme pressure.

Outer core: depth of 2,890-5,150 kilometresThe outer core is a hot, electrically conducting liquid (mainly Iron and Nickel). Thisconductive layer combines with Earth's rotation to create a dynamo effect thatmaintains a system of electrical currents creating the Earth's magnetic field. It is alsoresponsible for the subtle jerking of Earth's rotation. This layer is not as dense as puremolten iron, which indicates the presence of lighter elements. Scientists suspect thatabout 10% of the layer is composed of sulphur and oxygen because these elementsare abundant in the cosmos and dissolve readily in molten iron.

D" layer: depth of 2,700-2,890 kilometresThis layer is 200 to 300 kilometres thick. Although it is often identified as part of the

lower mantle, seismic evidence suggests the D" layer might differ chemically from thelower mantle lying above it. Scientists think that the material either dissolved in thecore, or was able to sink through the mantle but not into the core because of itsdensity.

Lower mantle: depth of 650-2,890 kilometresThe lower mantle is probably composed mainly of silicon, magnesium, and oxygen. Itprobably also contains some iron, calcium, and aluminium. Scientists make thesedeductions by assuming the Earth has a similar abundance and proportion of cosmicelements as found in the Sun and primitive meteorites.

Transition region: depth of 400-650 kilometresThe transition region or mesosphere (for middle mantle), sometimes called the fertilelayer and is the source of basaltic magmas. It also contains calcium, aluminium, andgarnet, which is a complex aluminium-bearing silicate mineral. This layer is dense

when cold because of the garnet. It is buoyant when hot because these minerals melteasily to form basalt which can then rise through the upper layers as magma.

Upper mantle: depth of 10-400 kilometresSolid fragments of the upper mantle have been found in eroded mountain belts andvolcanic eruptions. Olivine (Mg,Fe)2SiO4 and pyroxene (Mg,Fe)SiO3 have been found.These and other minerals are crystalline at high temperatures. Part of the uppermantle called the asthenosphere might be partially molten.

Oceanic crust: depth of 0-10 kilometresThe majority of the Earth's crust was made through volcanic activity. The oceanic ridgesystem, a 40,000 kilometre network of volcanoes, generates new oceanic crust at therate of 17 km3 per year, covering the ocean floor with an igneous rock called basalt.Hawaii and Iceland are two examples of the accumulation of basalt islands.

Continental crust: depth of 0-75 kilometresThis is the outer part of the Earth composed essentially of crystalline rocks. These arelow-density buoyant minerals dominated mostly by quartz (SiO2) and feldspars (metal-poor silicates). The crust is the surface of the Earth. Because cold rocks deform slowly,we refer to this rigid outer shell as the lithosphere (the rocky or strong layer).

Back to theEarth Science zone
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Documents

Tanushri(Structure of Earth)