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aluminum A metallic element, the third most abundant in Earth's crust. It is light and soft, and used in many items from bicycles to spacecraft.

behavior The way something, often a person or other organism, acts towards others, or conducts itself.

continent (in geology) The huge land masses that sit upon tectonic plates. In modern times, there are six established geologic continents: North America, South America, Eurasia, Africa, Australia and Antarctica. In 2017, scientists also made the case for yet another: Zealandia.

convection The rising and falling of material in a fluid or gas due to uneven temperatures. This process occurs in the outer layers of some stars.

core Something - usually round-shaped - in the center of an object. (in geology) Earth's innermost layer. Or, a long, tube-like sample drilled down into ice, soil or rock. Cores allow scientists to examine layers of sediment, dissolved chemicals, rock and fossils to see how the environment at one location changed through hundreds to thousands of years or more.

crust (in geology) Earth's outermost surface, usually made from dense, solid rock.

crystal (adj. crystalline) A solid consisting of a symmetrical, ordered, three-dimensional arrangement of atoms or molecules. It's the organized structure taken by most minerals. Apatite, for example, forms six-sided crystals. The mineral crystals that make up rock are usually too small to be seen with the unaided eye.

current A fluid - such as of water or air - that moves in a recognizable direction. (in electricity) The flow of electricity or the amount of charge moving through some material over a particular period of time.

decay (for radioactive materials) The process whereby a radioactive isotope - which means a physically unstable form of some element - sheds energy and subatomic particles. In time, this shedding will transform the unstable element into a slightly different but stable element. For instance, uranium-238 (which is a radioactive, or unstable, isotope) decays to radium-222 (also a radioactive isotope), which decays to radon-222 (also radioactive), which decays to polonium-210 (also radioactive), which decays to lead-206 - which is stable. No further decay occurs. The rates of decay from one isotope to another can range from timeframes of less than a second to billions of years.

density The measure of how condensed some object is, found by dividing its mass by its volume.

diamond One of the hardest known substances and rarest gems on Earth. Diamonds form deep within the planet when carbon is compressed under incredibly strong pressure.

earthquake A sudden and sometimes violent shaking of the ground, sometimes causing great destruction, as a result of movements within Earth's crust or of volcanic action.

Earth's crust The outermost layer of Earth. It is relatively cold and brittle.

element A building block of some larger structure. (in chemistry) Each of more than one hundred substances for which the smallest unit of each is a single atom. Examples include hydrogen, oxygen, carbon, lithium and uranium.

field An area of study, as in: Her field of research was biology. Also a term to describe a real-world environment in which some research is conducted, such as at sea, in a forest, on a mountaintop or on a city street. It is the opposite of an artificial setting, such as a research laboratory. (in physics) A region in space where certain physical effects operate, such as magnetism (created by a magnetic field), gravity (by a gravitational field), mass (by a Higgs field) or electricity (by an electrical field).

iron A metallic element that is common within minerals in Earth's crust and in its hot core. This metal also is found in cosmic dust and in many meteorites.

Isaac Newton This English physicist and mathematician became most famous for describing his law of gravity. Born in 1642, he developed into a scientist with wide-ranging interests. Among some of his discoveries: that white light is made from a combination of all the colors in the rainbow, which can be split apart again using a prism; the mathematics that describe the orbital motions of things around a center of force; that the speed of sound waves can be calculated from the density of air; early elements of the mathematics now known as calculus; and an explanation for why things "fall:" the gravitational pull of one object towards another, which would be proportional to the mass of each. Newton died in 1727.

lithosphere The upper layer of Earth, which includes its thin brittle crust and upper mantle. The lithosphere is relatively rigid and is broken into slowly moving tectonic plates.

magnesium A metallic element that is number 12 on the periodic table. It burns with a white light and is the eighth most abundant element in Earth's crust.

magnetic field An area of influence created by certain materials, called magnets, or by the movement of electric charges.

mantle (in geology) The thick layer of the Earth beneath its outer crust. The mantle is semi-solid and generally divided into an upper and lower mantle.

metal Something that conducts electricity well, tends to be shiny (reflective) and malleable (meaning it can be reshaped with heat and not too much force or pressure).

moon The natural satellite of any planet.

nickel Number 28 on the periodic table of elements, this hard, silvery element resists oxidation and corrosion. That makes it a good coating for many other elements or for use in multi-metal alloys.

oxygen A gas that makes up about 21 percent of Earth's atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).

pressure Force applied uniformly over a surface, measured as force per unit of area.

radioactive decay A process by which an element is converted into a lighter element through the shedding of subatomic particles (and energy).

radius A straight line from the center to the circumference of a circle or sphere.

range The full extent or distribution of something. For instance, a plant or animal's range is the area over which it naturally exists.

semi An adjective meaning "somewhat."

shell The protective, hard outer covering of mollusk or crustacean, such as a mussel or crab.

silica A mineral, also known as silicon dioxide, containing silicon and oxygen atoms. It is a basic building block of much of the rocky material on Earth and of some construction materials, including glass.

silicon A nonmetal, semiconducting element used in making electronic circuits. Pure silicon exists in a shiny, dark-gray crystalline form and as a shapeless powder.

slide In microscopy, the piece of glass onto which something will be attached for viewing under the device's magnifying lens.

solid Firm and stable in shape; not liquid or gaseous.

sun The star at the center of Earth's solar system. It's an average size star about 26,000 light-years from the center of the Milky Way galaxy. Also a term for any sunlike star.

tectonic plates The gigantic slabs - some spanning thousands of kilometers (or miles) across - that make up Earth's outer layer.

thorium A naturally radioactive element which appears as a silvery metal when it is pure. It reacts chemically with air, turning black on its surface. It is found in some minerals, and can be used to trace the source of some mineral grains that are carried long distances by water or wind. Its scientific symbol is Th.

turbulent (n. turbulence) An adjective for the unpredictable fluctuation of a fluid (including air) in which its velocity varies irregularly instead of maintaining a steady or calm flow.

uranium The heaviest naturally occurring element known. It's called element 92, which refers to the number of protons in its nucleus. Uranium atoms are radioactive, which means they decay into different atomic nuclei.

wave A disturbance or variation that travels through space and matter in a regular, oscillating fashion.

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aluminum A metallic element, the third most abundant in Earth's crust. It is light and soft, and used in many items from bicycles to spacecraft. behavior The way something, often a person or other organism, acts towards others, or conducts itself. continent (in geology) The huge land masses that sit upon tectonic plates.

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Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.

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Over millions of years, the mantle cooled. Water trapped inside minerals erupted with lava, a process called " outgas sing." As more water was outgassed, the mantle solidified.

The rocks that make up Earth's mantle are mostly silicates-a wide variety of compound s that share a silicon and oxygen structure. Common silicates found in the mantle include olivine, garnet, and pyroxene. The other major type of rock found in the mantle is magnesium oxide. Other mantle elements include iron, aluminum, calcium, sodium, and potassium.

The temperature of the mantle varies greatly, from 1000° Celsius (1832° Fahrenheit) near its boundary with the crust, to 3700° Celsius (6692° Fahrenheit) near its boundary with the core. In the mantle, heat and pressure generally increase with depth. The geothermal gradient is a measurement of this increase. In most places, the geothermal gradient is about 25° Celsius per kilometer of depth (1° Fahrenheit per 70 feet of depth).

The viscosity of the mantle also varies greatly. It is mostly solid rock, but less viscous at tectonic plate boundaries and mantle plumes. Mantle rocks there are soft and able to move plastically (over the course of millions of years) at great depth and pressure.

The mantle is divided into several layers: the upper mantle, the transition zone, the lower mantle, and D" (D double-prime), the strange region where the mantle meets the outer core.

Two parts of the upper mantle are often recognized as distinct region s in Earth's interior: the lithosphere and the asthenosphere.

The most well-known feature associated with Earth's lithosphere is tectonic activity. Tectonic activity describes the interaction of the huge slabs of lithosphere called tectonic plate s. The lithosphere is divided into 15 major tectonic plates: the North American, Caribbean, South American, Scotia, Antarctic, Eurasian, Arabian, African, Indian, Philippine, Australian, Pacific, Juan de Fuca, Cocos, and Nazca.

The division in the lithosphere between the crust and the mantle is called the Mohorovicic discontinuity, or simply the Moho. The Moho does not exist at a uniform depth, because not all regions of Earth are equally balanced in isostatic equilibrium. Isostasy describes the physical, chemical, and mechanical differences that allow the crust to "float" on the sometimes more malleable mantle. The Moho is found at about 8 kilometers (5 miles) beneath the ocean and about 32 kilometers (20 miles) beneath continents.

Different types of rocks distinguish lithospheric crust and mantle. Lithospheric crust is characterized by gneiss ( continental crust) and gabbro ( oceanic crust). Below the Moho, the mantle is characterized by peridotite, a rock mostly made up of the minerals olivine and pyroxene.

The asthenosphere is the denser, weaker layer beneath the lithospheric mantle. It lies between about 100 kilometers (62 miles) and 410 kilometers (255 miles) beneath Earth's surface. The temperature and pressure of the asthenosphere are so high that rocks soften and partly melt, becoming semi-molten.

The asthenosphere is much more ductile than either the lithosphere or lower mantle. Ductility measures a solid material's ability to deform or stretch under stress. The asthenosphere is generally more viscous than the lithosphere, and the lithosphere-asthenosphere boundary (LAB) is the point where geologists and rheologist s-scientists who study the flow of matter-mark the difference in ductility between the two layers of the upper mantle.

Of course, tectonic plates are not really floating, because the asthenosphere is not liquid. Tectonic plates are only unstable at their boundaries and hot spots.

In the transition zone, rocks do not melt or disintegrate. Instead, their crystal line structure changes in important ways. Rocks become much, much more dense.

The transition zone prevents large exchanges of material between the upper and lower mantle. Some geologists think that the increased density of rocks in the transition zone prevents subducted slabs from the lithosphere from falling further into the mantle. These huge pieces of tectonic plates stall in the transition zone for millions of years before mixing with other mantle rock and eventually returning to the upper mantle as part of the asthenosphere, erupting as lava, becoming part of the lithosphere, or emerging as new oceanic crust at sites of seafloor spreading.

Some geologists and rheologists, however, think subducted slabs can slip beneath the transition zone to the lower mantle. Other evidence suggests that the transition layer is permeable, and the upper and lower mantle exchange some amount of material.

Perhaps the most important aspect of the mantle's transition zone is its abundance of water. Crystals in the transition zone hold as much water as all the oceans on Earth's surface.

Water in the transition zone is not "water" as we know it. It is not liquid, vapor, solid, or even plasma. Instead, water exists as hydroxide. Hydroxide is an ion of hydrogen and oxygen with a negative charge. In the transition zone, hydroxide ions are trapped in the crystalline structure of rocks such as ringwoodite and wadsleyite. These minerals are formed from olivine at very high temperatures and pressure.

Near the bottom of the transition zone, increasing temperature and pressure transform ringwoodite and wadsleyite. Their crystal structures are broken and hydroxide escapes as " melt." Melt particles flow upwards, toward minerals that can hold water. This allows the transition zone to maintain a consistent reservoir of water.

The lower mantle extends from about 660 kilometers (410 miles) to about 2,700 kilometers (1,678 miles) beneath Earth's surface. The lower mantle is hotter and denser than the upper mantle and transition zone.

The lower mantle is much less ductile than the upper mantle and transition zone. Although heat usually corresponds to softening rocks, intense pressure keeps the lower mantle solid.

Geologists do not agree about the structure of the lower mantle. Some geologists think that subducted slabs of lithosphere have settled there. Other geologists think that the lower mantle is entirely unmoving and does not even transfer heat by convection.

At the base of the mantle, about 2,900 kilometers (1,802 miles) below the surface, is the core-mantle boundary, or CMB. This point, called the Gutenberg discontinuity, marks the end of the mantle and the beginning of Earth's liquid outer core.

Mantle convection describes the movement of the mantle as it transfers heat from the white-hot core to the brittle lithosphere. The mantle is heated from below, cooled from above, and its overall temperature decreases over long periods of time. All these elements contribute to mantle convection.

Convection currents transfer hot, buoyant magma to the lithosphere at plate boundaries and hot spots. Convection currents also transfer denser, cooler material from the crust to Earth's interior through the process of subduction.

Geologists debate whether mantle convection is "whole" or "layered." Whole-mantle convection describes a long, long recycling process involving the upper mantle, transition zone, lower mantle, and even D''. In this model, the mantle convects in a single process. A subducted slab of lithosphere may slowly slip into the upper mantle and fall to the transition zone due to its relative density and coolness. Over millions of years, it may sink further into the lower mantle. Convection currents may then transport the hot, buoyant material in D'' back through the other layers of the mantle. Some of that material may even emerge as lithosphere again, as it is spilled onto the crust through volcanic eruptions or seafloor spreading.

Layered-mantle convection describes two processes. Plumes of superheated mantle material may bubble up from the lower mantle and heat a region in the transition zone before falling back. Above the transition zone, convection may be influenced by heat transferred from the lower mantle as well as discrete convection currents in the upper mantle driven by subduction and seafloor spreading. Mantle plumes emanating from the upper mantle may gush up through the lithosphere as hot spots.

The Hawaiian hot spot, in the middle of the North Pacific Ocean, sits above a likely mantle plume. As the Pacific plate moves in a generally northwestern motion, the Hawaiian hot spot remains relatively fixed. Geologists think this has allowed the Hawaiian hot spot to create a series of volcanoes, from the 85-million-year-old Meiji Seamount near Russia's Kamchatka Peninsula, to the Loihi Seamount, a submarine volcano southeast of the "Big Island" of Hawaii. Loihi, a mere 400,000 years old, will eventually become the newest Hawaiian island.

Geologists have identified two so-called "superplumes." These superplumes, or large low shear velocity provinces (LLSVPs), have their origins in the melt material of D''. The Pacific LLSVP influences geology throughout most of the southern Pacific Ocean (including the Hawaiian hot spot). The African LLSVP influences the geology throughout most of southern and western Africa.

Geologists think mantle plumes may be influenced by many different factors. Some may pulse, while others may be heated continually. Some may have a single diapir, while others may have multiple "stems." Some mantle plumes may arise in the middle of a tectonic plate, while others may be "captured" by seafloor spreading zones.

Some geologists have identified more than a thousand mantle plumes. Some geologists think mantle plumes don't exist at all. Until tools and technology allow geologists to more thoroughly explore the mantle, the debate will continue.

The mantle has never been directly explored. Even the most sophisticated drilling equipment has not reached beyond the crust.

Drilling all the way down to the Moho (the division between the Earth's crust and mantle) is an important scientific milestone, but despite decades of effort, nobody has yet succeeded. In 2005, scientists with the Integrated Ocean Drilling Project drilled 1,416 meters (4,644 feet) below the North Atlantic seafloor and claimed to have come within just 305 meters (1,000 feet) of the Moho.

Many geologists study the mantle by analyzing xenoliths. Xenoliths are a type of intrusion-a rock trapped inside another rock.

The xenoliths that provide the most information about the mantle are diamonds. Diamonds form under very unique conditions: in the upper mantle, at least 150 kilometers (93 miles) beneath the surface. Above depth and pressure, the carbon crystallizes as graphite, not diamond. Diamonds are brought to the surface in explosive volcanic eruptions, forming "diamond pipes" of rocks called kimberlites and lamprolites.

The diamonds themselves are of less interest to geologists than the xenoliths some contain. These intrusions are minerals from the mantle, trapped inside the rock-hard diamond. Diamond intrusions have allowed scientists to glimpse as far as 700 kilometers (435 miles) beneath Earth's surface-the lower mantle.

Xenolith studies have revealed that rocks in the deep mantle are most likely 3-billion-year old slabs of subducted seafloor. The diamond intrusions include water, ocean sediments, and even carbon.

Most mantle studies are conducted by measuring the spread of shock waves from earthquakes, called seismic waves. The seismic waves measured in mantle studies are called body waves, because these waves travel through the body of the Earth. The velocity of body waves differs with density, temperature, and type of rock.

Instruments placed around the world measure these waves as they arrive at different points on the Earth's surface after an earthquake. P-waves (primary waves) usually arrive first, while s-waves arrive soon after. Both body waves "reflect" off different types of rocks in different ways. This allows seismologists to identify different rocks present in Earth's crust and mantle far beneath the surface. Seismic reflections, for instance, are used to identify hidden oil deposits deep below the surface.

Sudden, predictable changes in the velocities of body waves are called "seismic discontinuities." The Moho is a discontinuity marking the boundary of the crust and upper mantle. The so-called "410-kilometer discontinuity" marks the boundary of the transition zone.

The Gutenberg discontinuity is more popularly known as the core-mantle boundary (CMB). At the CMB, S-waves, which can't continue in liquid, suddenly disappear, and P-waves are strongly refracted, or bent. This alerts seismologists that the solid and molten structure of the mantle has given way to the fiery liquid of the outer core.

Cutting-edge technology has allowed modern geologists and seismologists to produce mantle maps. Most mantle maps display seismic velocities, revealing patterns deep below Earth's surface.

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The mantle is the mostly-solid bulk of Earth's interior. The mantle lies between Earth's dense, super-heated core and its thin outer layer, the crust. The mantle is about 2,900 kilometers (1,802 miles) thick, and makes up a whopping 84% of Earth’s total volume.

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http://www.easybib.com/

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This link leads to a website that tells you the layers of the earth and some information about them.

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Broadly speaking, the Earth has four layers: the solid crust on the outside, the mantle and the core - split between the outer core and the inner core.

The crust is everything we can see and study directly. The thinnest layer of the Earth, the crust still measures about 40 km on average, ranging from 5-70 km (~3-44 miles) in depth. But at the scale of the planet, that's less than the skin of an apple.

There are two types of crust: continental and oceanic crust. Oceanic crust can be found at the bottom of the oceans or below the continental crust; it is generally harder and deeper, consisting of denser rocks like basalt, while continental crust contains granite-type rocks and sediments. The continental crust thicker on land.

The crust is not one rigid thing, but it's split into several tectonic plates. These tectonic plates are not stationary, but are in relative motion one from another. Depending on the relationship and geologic setting, there are three types of tectonic plate boundaries: convergent (moving one toward the other), divergent (moving away from the other) and transformant (moving laterally).

These plates "float" on the soft, plastic upper mantle.

The mantle extends down 2,890 km, making it the thickest layer of Earth. It makes up about 84% of Earth's volume. Everything we know about the mantle we know indirectly, as no human study managed to go beyond the crust. Most of the things we know about the mantle we know from seismologic studies (more on that later).

The mantle is also divided into several layers, based on seismologic properties. The upper mantle extends from where the crust ends to about 670 km. Even though this area is regarded as viscous, you can also consider it as formed from rock - a rock called peridotite to be more precise. Below that, the lower mantle extends from 670 to almost 2900 kilometers below the surface.

It's basically accepted by now that the mantle is not in a steady state, but rather in a state of constant motion. There is a general convective circulation, with hot material upwelling towards the surface and cooler material going deeper. It is generally thought that this convection actually directs the circulation of the plate tectonics in the crust.

Most earthquakes are formed on the surface, in the crust; as the plates ebb and tow tension creates, and when that tension releases or when something breaks you have an earthquake. However, earthquakes can also happen in the mantle, and at those pressures you can't possibly talk about faulting and breaking. In subduction areas, where one plane goes beneath another, earthquakes have been observed at depths of up to 670 km. The mechanism around these earthquakes is still not well understood, but one of the theories is that some minerals shift from one state to another, changing their volume in the process. This change in volume can lead to earthquakes.

However, we are getting closer and closer to understanding the mantle - even without getting there. In recent times, researchers have gone close to replicating the high temperature/pressure in the mantle, and high-level computer models are also revealing some of its secrets.

We sometimes refer to the core as one thing, although the inner core and the outer core are fundamentally different - not layers of the same thing. The "solid" inner core has a radius of ~1,220 km, while the "liquid" outer core extends up to a radius of ~3,400 km.

Wait, if we couldn't go to the mantle, how could we possibly know one is solid and one isn't? Well, as before, the answer is the same: seismic waves (we're almost there).
The inner core
The temperatures and pressures of the inner core are absolutely extreme, at approximately 5,400 °C (9,800 °F) and 330 to 360 gigapascals (3,300,000 to 3,600,000 atm).

It's generally believed that the inner core is growing very slowly - as the core cools down, more of the outer core solidifies and becomes a part of the inner core. The cooling rate is very low thought, at about 100 degrees Celsius per billion years. However, even this slow growth is thought to have a significant impact in the generation of Earth's magnetic field by dynamo action in the liquid outer core.

Rather interestingly, the inner core seems to be asymmetric on the East-West line. There is a model that explains this asymmetry with melting on one side and crystallization on the other. This anomaly also likely affects the Earth's magnetic field, creating an asymmetry on the crystallizing side.
The outer core
The outer core is a low viscosity fluid (about ten times the viscosity of liquid metals at the surface) - "liquid" is a rather improper term. Because it has a very low viscosity, it is easily deformed and malleable. It is the site of violent convection. It is also thought to suffer very violent convection currents - hey, and guess what? The churning of the outer core and its relative movement is responsible for the Earth's magnetic field.

The hottest part of the outer core is actually hotter than the inner core; temperatures can reach 6,000° Celsius (10,800° Fahrenheit)-as hot as the surface of the sun.

How we know about the Earth's layers

We can only see very small fractions of the Earth's crust, which itself is a small fraction of our planet - so how can we know all these things?

Well, the best source of information we have is seismic waves. When an earthquake takes place, it releases pressure waves which then propagate throughout the entire planet. These waves carry with them information from the layers they pass through - including the mantle and the core. By studying the propagation of By studying the propagation of waves through the Earth we can learn about the physical properties of the Earths interior. For example, some waves propagate only through solid mediums, while others propagate through both solid and liquid mediums - so they can show if some layer is solid or not. Seismic waves sample narrow swaths of the Earth's interior so we can also isolate the information they carry; by analyzing several earthquakes recorded at several seismic stations, we can produce a CAT scan-like analysis of an area.

Rays bend and reflect based on the properties of the environment it passes through, and the speed of the wave is also affected by the environment.

Furthermore, modern simulations in the lab showed how minerals likely behave at those temperatures and pressures, and we also have indirect gravitational and magnetic information, as well as studies on magma and crystals found on the surface - but the bulk of the information comes from global seismology. It's simply amazing that without even going close to it, we can know so much about the layers of the Earth.
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Broadly speaking, the Earth has four layers: the solid crust on the outside, the mantle and the core - split between the outer core and the inner core. The crust is everything we can see and study directly. The thinnest layer of the Earth, the crust still measures about 40 km on average, ranging from 5-70 km (~3-44 miles) in depth.

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Another Source for how the Earth Gets its Heat

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Another Source for how the Earth Gets its Heat

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There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.

It takes a rather long time for heat to move out of the earth. This occurs through both "convective" transport of heat within the earth's liquid outer core and solid mantle and slower "conductive" transport of heat through nonconvecting boundary layers, such as the earth's plates at the surface. As a result, much of the planet's primordial heat, from when the earth first accreted and developed its core, has been retained.

The amount of heat that can arise through simple accretionary processes, bringing small bodies together to form the proto-earth, is large: on the order of 10,000 kelvins (about 18,000 degrees Farhenheit). The crucial issue is how much of that energy was deposited into the growing earth and how much was reradiated into space. Indeed, the currently accepted idea for how the moon was formed involves the impact or accretion of a Mars-size object with or by the proto-earth. When two objects of this size collide, large amounts of heat are generated, of which quite a lot is retained. This single episode could have largely melted the outermost several thousand kilometers of the planet.

Additionally, descent of the dense iron-rich material that makes up the core of the planet to the center would produce heating on the order of 2,000 kelvins (about 3,000 degrees F). The magnitude of the third main source of heat--radioactive heating--is uncertain. The precise abundances of radioactive elements (primarily potassium, uranium and thorium) are poorly known in the deep earth.

In sum, there was no shortage of heat in the early earth, and the planet's inability to cool off quickly results in the continued high temperatures of the Earth's interior. In effect, not only do the earth's plates act as a blanket on the interior, but not even convective heat transport in the solid mantle provides a particularly efficient mechanism for heat loss. The planet does lose some heat through the processes that drive plate tectonics, especially at mid-ocean ridges. For comparison, smaller bodies such as Mars and the Moon show little evidence for recent tectonic activity or volcanism.

We derive our primary estimate of the temperature of the deep earth from the melting behavior of iron at ultrahigh pressures. We know that the earth's core depths from 2,886 kilometers to the center at 6,371 kilometers (1,794 to 3,960 miles), is predominantly iron, with some contaminants. How? The speed of sound through the core (as measured from the velocity at which seismic waves travel across it) and the density of the core are quite similar to those seen in of iron at high pressures and temperatures, as measured in the laboratory. Iron is the only element that closely matches the seismic properties of the earth's core and is also sufficiently abundant present in sufficient abundance in the universe to make up the approximately 35 percent of the mass of the planet present in the core.

The earth's core is divided into two separate regions: the liquid outer core and the solid inner core, with the transition between the two lying at a depth of 5,156 kilometers (3,204 miles). Therefore, If we can measure the melting temperature of iron at the extreme pressure of the boundary between the inner and outer cores, then this lab temperature should reasonably closely approximate the real temperature at this liquid-solid interface. Scientists in mineral physics laboratories use lasers and high-pressure devices called diamond-anvil cells to re-create these hellish pressures and temperatures as closely as possible.

Those experiments provide a stiff challenge, but our estimates for the melting temperature of iron at these conditions range from about 4,500 to 7,500 kelvins (about 7,600 to 13,000 degrees F). As the outer core is fluid and presumably convecting (and with an additional correction for the presence of impurities in the outer core), we can extrapolate this range of temperatures to a temperature at the base of Earth's mantle (the top of the outer core) of roughly 3,500 to 5,500 kelvins (5,800 to 9,400 degrees F) at the base of the earth's mantle.

The bottom line here is simply that a large part of the interior of the planet (the outer core) is composed of somewhat impure molten iron alloy. The melting temperature of iron under deep-earth conditions is high, thus providing prima facie evidence that the deep earth is quite hot.
Gregory Lyzenga is an associate professor of physics at Harvey Mudd College. He provided some additional details on estimating the temperature of the earth's core:
How do we know the temperature? The answer is that we really don't--at least not with great certainty or precision. The center of the earth lies 6,400 kilometers (4,000 miles) beneath our feet, but the deepest that it has ever been possible to drill to make direct measurements of temperature (or other physical quantities) is just about 10 kilometers (six miles).

Ironically, the core of the earth is by far less accessible more inaccessible to direct probing than would be the surface of Pluto. Not only do we not have the technology to "go to the core," but it is not at all clear how it will ever be possible to do so.

As a result, scientists must infer the temperature in the earth's deep interior indirectly. Observing the speed at which of passage of seismic waves pass through the earth allows geophysicists to determine the density and stiffness of rocks at depths inaccessible to direct examination. If it is possible to match up those properties with the properties of known substances at elevated temperatures and pressures, it is possible (in principle) to infer what the environmental conditions must be deep in the earth.

The problem with this is that the conditions are so extreme at the earth's center that it is very difficult to perform any kind of laboratory experiment that faithfully simulates conditions in the earth's core. Nevertheless, geophysicists are constantly trying these experiments and improving on them, so that their results can be extrapolated to the earth's center, where the pressure is more than three million times atmospheric pressure.

The bottom line of these efforts is that there is a rather wide range of current estimates of the earth's core temperature. The "popular" estimates range from about 4,000 kelvins up to over 7,000 kelvins (about 7,000 to 12,000 degrees F).

If we knew the melting temperature of iron very precisely at high pressure, we could pin down the temperature of the Earth's core more precisely, because it is largely made up of molten iron. But until our experiments at high temperature and pressure become more precise, uncertainty in this fundamental property of our planet will persist.

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Why is the earth's core so hot? And how do scientists measure its temperature?

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There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.

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https://www.windows2universe.org/earth/interior/how_plates_move.html

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Active subduction along the southern Alaska coast has formed a volcanic arc with features including the Katmai caldera and neighboring Mount Griggs. Katmai National Park and Preserve, Alaska.
NPS photo.

Introduction

The landscapes of our national parks, as well as geologic hazards such as earthquakes and volcanic eruptions, are due to the movement of the large plates of Earth's outer shell.

There are three types of tectonic plate boundaries:

Plates rip apart at a divergent plate boundary, causing volcanic activity and shallow earthquakes;

At a convergent plate boundary, one plate dives ("subducts") beneath the other, resulting in a variety of earthquakes and a line of volcanoes on the overriding plate;

Transform plate boundaries are where plates slide laterally past one another, producing shallow earthquakes but little or no volcanic activity.

Another large-scale feature is a hotspot, where a plate rides over a rising plume of hot mantle, creating a line of volcanoes on top of the plate. National Park Service lands contain not only active examples of all types of plate boundaries and hotspots, but also rock layers and landscapes that reveal plate-tectonic activity that occurred in the distant past.

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Types of Plate Boundaries - Geology (U.S. National Park Service)

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The landscapes of our national parks, as well as geologic hazards such as earthquakes and volcanic eruptions, are due to the movement of the large plates of Earth's outer shell.

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http://volcano.oregonstate.edu/earths-layers-lesson-1

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Here is a National Geographic article about the Mantle!

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Here is a National Geographic article about the Mantle!

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At one point you got to encounter the mantle. And since It's so big and might take up a large chunk of your project. Here is some info on it.
mantle | National Geographic Society

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http://publish.illinois.edu/alfredwegener/evidence/

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If you think about a volcano, you know Earth must be hot inside. The heat inside Earth moves continents, builds mountains and causes earthquakes. Where does all this heat inside Earth come from?

Earth was hot when it formed. A lot of Earth's heat is leftover from when our planet formed, four-and-a-half billion years ago. Earth is thought to have arisen from a cloud of gas and dust in space. Solid particles, called "planetesimals" condensed out of the cloud. They're thought to have stuck together and created the early Earth. Bombarding planetesimals heated Earth to a molten state.

So Earth started out with a lot of heat.

Earth makes some of its own heat. Earth is cooling now - but very, very slowly. Earth is close to a steady temperature state. Over the past several billion years, it might have cooled a couple of hundred degrees. Earth keeps a nearly steady temperature, because it makes heat in its interior.

In other words, Earth has been losing heat since it formed, billions of years ago. But it's producing almost as much heat as it's losing. The process by which Earth makes heat is called radioactive decay. It involves the disintegration of natural radioactive elements inside Earth - like uranium, for example. Uranium is a special kind of element because when it decays, heat is produced. It's this heat that keeps Earth from cooling off completely.

Many of the rocks in Earth's crust and interior undergo this process of radioactive decay . This process produces subatomic particles that zip away, and later collide with surrounding material inside the Earth. Their energy of motion is converted to heat.

Without this process of radioactive decay, there would be fewer volcanoes and earthquakes - and less building of Earth's vast mountain ranges.

How hot is it inside Earth? No one has come close to exploring Earth's interior directly. So not all geophysicists agree on how hot it is at Earth's core. But the rate of travel of waves from earthquakes - called "seismic waves" - tells scientists a lot about what materials make up the planet. Seismic data also reveal whether these materials are liquid, solid or partially solid. Meanwhile, laboratory data indicate at what temperatures and pressures the materials inside Earth should begin to melt.

From this evidence, Earth's core temperature is estimated to be around 5,000 to 7,000 degrees Celsius. That's about as hot as the surface of the sun, but vastly cooler than the sun's interior.

By the way, while the heat energy produced inside Earth is enormous, it's some 5,000 times less powerful than what Earth receives from the sun. The sun's heat drives the weather and ultimately causes erosion. So it's ironic that - while Earth's heat makes mountains - the sun's energy tears them down again, bit by bit.

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What is the source of the heat in Earth's interior? | EarthSky.org

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If you think about a volcano, you know Earth must be hot inside. The heat inside Earth moves continents, builds mountains and causes earthquakes. Where does all this heat inside Earth come from? Earth was hot when it formed. A lot of Earth's heat is leftover from when our planet formed, four-and-a-half billion years ago.