The Earth's Crust: Facts, Layers, Temperature & Composition - Video & Lesson Transcript | Study.com The Earth's Crust: Facts, Layers, Temperature & Composition Watch short & fun videos Start Your Free Trial Today An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching Register for a free trial Are you a student or a teacher? I am a student Start Your Free Trial To Continue Watching As a member, you'll also get unlimited access to over lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Coming up next: Temperature, Clouds, Wind & Humidity on the Atmospheric Cycle You're on a roll. Keep up the good work! Your next lesson will play in 10 seconds 0:02 What Is the Earth's Crust? 0:37 The Two Types of Crust 2:21 What Is the Crust Made of? 3:24 The Temperature of the Earth 3:55 Lesson Summary Add to Add to Add to Want to watch this again later? Log in or sign up to add this lesson to a Custom Course.

Custom Courses are courses that you create from Study.com lessons. Use them just like other courses to track progress, access quizzes and exams, and share content. Teachers Organize and share selected lessons with your class. Make planning easier by creating your own custom course. Students Create a new course from any lesson page or your dashboard. From any lesson page: Click "Add to" located below the video player and follow the prompts to name your course and save your lesson. From your dashboard: Click on the "Custom Courses" tab, then click "Create course". Next, go to any lesson page and begin adding lessons. Edit your Custom Course directly from your dashboard. Personalize: Name your Custom Course and add an optional description or learning objective. Organize: Create chapters to group lesson within your course. Remove and reorder chapters and lessons at any time. Share your Custom Course or assign lessons and chapters. Teacher Edition: Share or assign lessons and chapters by clicking the "Teacher" tab on the lesson or chapter page you want to assign. Students' quiz scores and video views will be trackable in your "Teacher" tab. Premium Edition: You can share your Custom Course by copying and pasting the course URL.

Only Study.com members will be able to access the entire course. Create an account to start this course today Try it free for 5 days! Lesson Transcript Instructor: Ryan Hultzman The Earth's crust is just a thin layer surrounding our world. Although it is the only part of the Earth any of us see, it makes up just one percent of the planet's total volume. What Is the Earth's Crust? The Earth is not just a solid ball of rock. That rock is made up of layers characterized by different elements and different types of rock that are either solid or fluid. It also possesses different temperatures and thicknesses. The outermost layer of the Earth is the crust. It's thin compared to the other layers, a little bit like the peel of an orange. Unlike a fruit peel, though, the crust is broken up into several pieces, called tectonic plates. These plates move relative to each other so that the surface of the Earth's crust is always changing, although very slowly. The Two Types of Crust There are two types of crust. Oceanic crust is the crust that is under the world's oceans, and continental crust is that under the continents and other large land masses, like Greenland and Madagascar.

Oceanic crust is denser and heavier than continental crust. It is made mostly of basaltic rock. Basalt is a volcanic rock and it forms the oceanic crust as the mantle, the molten rock under the crust, wells up and hardens. This happens at mid-ocean ridges where the crust is being pulled apart due to the motion of tectonic plates. Oceanic crust is about four miles thick. Oceanic crust may be heavier and denser, but continental crust is a thicker and older part of the Earth's crust. The depth of continental crust varies more than oceanic crust and can be anywhere between six and 47 miles thick. The rocks that make up continental crust are less dense and heavy than basaltic ocean crust. Granite is a mineral that's a major component of continental crust. The crust of the continents is also much older than ocean crust. Unlike the ocean floor, continental crust is not constantly reforming. You can find rocks as old as four billion years in continental crust. Because oceanic crust is denser than continental crust, it is always sinking relative to the continents. New ocean crust forms at mid-ocean ridges, but old ocean crust gets recycled in regions called subduction zones.

These are tectonic plate boundaries at which two plates are moving toward each other, rather than pulling apart. When ocean crust meets continental crust at a subduction zone, the heavier oceanic crust sinks under the continent and becomes part of the molten mantle again. What Is the Crust Made of? The simple answer is that the Earth's crust is made of rock, which is made of minerals. To get a little more detailed, we can talk about specific minerals. Feldspars, a group of minerals are the most abundant in all of the Earth's crust, both continental and oceanic. Feldspar minerals are made of silicon, oxygen, and various metals, most commonly aluminum. Silica, which is silicon dioxide and also called quartz, is the second most abundant mineral overall. However, if we are looking at continental crust only, it is the most abundant and makes up 60% of the continents on Earth. Oxygen is the most abundant element in the crust and accounts for 47% of it by weight. Silicon comes in second with 28% of the weight. Aluminum is the most abundant metal and iron, calcium, sodium, potassium, and magnesium round out the top eight crustal elements.

Only eight percent of the minerals in the crust are anything other than silicate, silicon-based, minerals. × mantle - National Geographic Society mantle The mantle, between the brittle crust and super-dense core, makes up a whopping 84% of Earth’s total volume. Illustration by Ewalde1, courtesy Wikimedia. CC-BY-SA-3.0 Earth’s Active Mantle Earth is the only planet in our solar system with a continually active mantle. Mercury and Mars have solid, unmoving interior structures. Venus has an active mantle, but the structure of its crust and atmosphere prevent it from changing the Venusian landscape very often. Explosive Study Explosions, just like earthquakes, trigger seismic waves. Body waves from powerful nuclear explosions may have revealed clues about Earth’s interior—but such seismic study is prohibited as part of the Comprehensive Nuclear Test Ban Treaty. Mantling Conductivity Some mantle maps display electrical conductivity, not seismic waves. By mapping disturbances in electrical patterns, scientists have helped identify hidden “reservoirs” of water in the mantle. 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 . As Earth began to take shape about 4.5 billion years ago, iron and nickel quickly separated from other rock s and mineral s to form the core of the new planet. The molten material that surrounded the core was the early mantle. Over millions of years, the mantle cooled. Water trapped inside minerals erupt ed 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 silicate s—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 more 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 transfer of heat and material in the mantle helps determine the landscape of Earth. Activity in the mantle drives plate tectonics , contributing to volcano es, seafloor spreading , earthquake s, and orogeny (mountain-building). 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 . Upper Mantle The upper mantle extends from the crust to a depth of about 410 kilometers (255 miles). The upper mantle is mostly solid, but its more malleable regions contribute to tectonic activity .

Two parts of the upper mantle are often recognized as distinct region s in Earth’s interior: the lithosphere and the asthenosphere. Lithosphere The lithosphere is the solid, outer part of the Earth, extending to a depth of about 100 kilometers (62 miles). The lithosphere includes both the crust and the brittle upper portion of the mantle. The lithosphere is both the coolest and the most rigid of Earth’s layers. The most well-known feature associated with Earth’s lithosphere is tectonic activity. Tectonic activity describes the interaction of the huge slab s 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 characterize d 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. Asthenosphere 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 geologist s and rheologist s—scientists who study the flow of matter—mark the difference in ductility between the two layers of the upper mantle. The very slow motion of lithospheric plates “floating” on the asthenosphere is the cause of plate tectonics, a process associated with continental drift , earthquakes, the formation of mountains, and volcanoes. In fact, the lava that erupts from volcanic fissure s is actually the asthenosphere itself, melted into magma . 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. Transition Zone From about 410 kilometers (255 miles) to 660 kilometers (410 miles) beneath Earth’s surface, rocks undergo radical transform ations. This is the mantle’s transition zone . 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. Water 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. Geologists and rheologists think that water entered the mantle from Earth’s surface during subduction. Subduction is the process in which a dense tectonic plate slips or melts beneath a more buoyant one. Most subduction happens as an oceanic plate slips beneath a less-dense plate. Along with the rocks and minerals of the lithosphere, tons of water and carbon are also transported to the mantle. Hydroxide and water are returned to the upper mantle, crust, and even atmosphere through mantle convection, volcanic eruptions, and seafloor spreading.

Lower Mantle 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 correspond s 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. D Double-Prime (D’’) Beneath the lower mantle is a shallow region called D'' , or “d double-prime.” In some areas, D’’ is a nearly razor-thin boundary with the outer core. In other areas, D’’ has thick accumulation s of iron and silicates. In still other areas, geologists and seismologist s have detected areas of huge melt. The unpredictable movement of materials in D’’ is influence d by the lower mantle and outer core.

The iron of the outer core influences the formation of a diapir , a dome -shaped geologic feature ( igneous intrusion ) where more fluid material is forced into brittle overlying rock. The iron diapir emits heat and may release a huge, bulging pulse of either material or energy—just like a Lava Lamp. This energy blooms upward, transferring heat to the lower mantle and transition zone, and maybe even erupting as a mantle plume. 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 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 current s also transfer denser, cooler material from the crust to Earth’s interior through the process of subduction. Earth's heat budget , which measures the flow of thermal energy from the core to the atmosphere, is dominate d by mantle convection. Earth’s heat budget drives most geologic processes on Earth, although its energy output is dwarf ed by solar radiation at the surface. 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. Mantle Plumes A mantle plume is an upwell ing of superheated rock from the mantle. Mantle plumes are the likely cause of “ hot spot s,” volcanic regions not created by plate tectonics. As a mantle plume reaches the upper mantle, it melts into a diapir. This molten material heats the asthenosphere and lithosphere, triggering volcanic eruptions. These volcanic eruptions make a minor contribution to heat loss from Earth’s interior, although tectonic activity at plate boundaries is the leading cause of such heat loss. 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 ( LLSVP s), 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. Exploring the Mantle 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. Xenoliths Many geologists study the mantle by analyzing xenoliths. Xenolith s 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 sediment s, and even carbon. Seismic Waves Most mantle studies are conducted by measuring the spread of shock wave s from earthquakes, called seismic wave s. The seismic waves measured in mantle studies are called body wave s, because these waves travel through the body of the Earth. The velocity of body waves differs with density, temperature, and type of rock. There are two types of body waves: primary waves, or P-waves, and secondary waves, or S-waves. P-wave s, also called pressure waves, are formed by compression s.

Sound waves are P-waves—seismic P-waves are just far too low a frequency for people to hear. S-wave s, also called shear waves, measure motion perpendicular to the energy transfer. S-waves are unable to transmit through fluids or gases. 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 refract ed, 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. Mantle Maps 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. Geoscientists hope that sophisticated mantle maps can plot the body waves of as many as 6,000 earthquakes with magnitude s of at least 5.5. These mantle maps may be able to identify ancient slabs of subducted material and the precise position and movement of tectonic plates. Many geologists think mantle maps may even provide evidence for mantle plumes and their structure. Term layer in Earth's mantle between the lithosphere (above) and the upper mantle (below). atmosphere name given to someone by their parents or leaders at their birth. body wave seismic wave that travels through the interior of the Earth. boundary to describe the characteristics of something. compound substance having at least two chemical elements held together with chemical bonds.

compression instance of being pressed together or forced into less space. consistent maintaining a steady, reliable quality. continent thick layer of Earth that sits beneath continents. continental drift movement of a fluid from a cool area to a warm area. core to match or be similar to. crust crystal Noun type of mineral that is clear and, when viewed under a microscope, has a repeating pattern of atoms and molecules. D'' deepest layer of Earth's mantle, about 2,700 kilometers (1,678 miles) beneath Earth’s surface. dense having parts or molecules that are packed closely together. diapir dome-shaped geologic feature (intrusion) where more fluid material is forced into brittle overlying rock. diapir dome-shaped geologic feature (intrusion) where more fluid material is forced into brittle overlying rock. discrete to fall apart and disappear. distinct to differentiate or recognize as different. dome capable of withstanding a certain amount of force by changing form before fracturing or breaking. dwarf to make something appear small by having it appear next to something much larger. earthquake Noun the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity.

Earth's heat budget Noun measurement of the flow of thermal energy from the core to the atmosphere, dominated by absorbed and reflected solar radiation. equipment tools and materials to perform a task or function. erupt to explode or suddenly eject material. fissure material that is able to flow and change shape. frequency Noun rate of occurrence, or the number of things happening in a specific area over specific time period. geologist person who studies the physical formations of the Earth. geothermal gradient Noun gradual change in temperature from the Earth's core (hot) to its crust (cool), about 25° Celsus per kilometer of depth (1° Fahrenheit per 70 feet of depth). glimpse graphite Noun soft, common allotrope of carbon that is the highest rank of coal. Also called black lead. Gutenberg discontinuity point between the Earth's mantle and the core below. hot spot Noun intensely hot region deep within the Earth that rises to just underneath the surface. Some hot spots produce volcanoes. chemical compound containing the OH‾ ion. igneous intrusion Noun rock formation created by magma as it is pushed from the Earth's mantle into cracks or holes in the crust.

influence force that effects the actions, behavior, or policies of others. ion Noun electrically charged atom or group of atoms, formed by the atom having gained or lost an electron. isostasy Noun equilibrium of Earth's crust, where the forces tending to elevate landmasses balance those tending to depress them. Also called isostatic equilibrium. layered-mantle convection process in which mantle convection is primarly carried out by activity in the upper mantle. lithosphere chemical and mechanical distinction between the cool, rigid lithosphere and the warmer, more ductile asthenosphere. LLSVP Noun (large low shear velocity province) seismically anomalous region at the deepest part of Earth's mantle. Also called a superplume or thermo-chemical pile. lower mantle bottom layer in Earth's mantle, closest to the core. magma intensity of an earthquake, represented by numbers on a scale. malleable flexible and capable of reforming itself without breaking when under stress. mantle mantle convection Noun slow movement of Earth's solid mantle caused by convection currents transferring heat from the interior of the Earth to the surface. mantle plume upwelling of magma within Earth's mantle.

melt inorganic material that has a characteristic chemical composition and specific crystal structure. Mohorovicic discontinuity point between Earth's crust and the mantle below. Also called the Moho. molten solid material turned to liquid by heat. oceanic crust thin layer of the Earth that sits beneath ocean basins. oil Noun fossil fuel formed from the remains of marine plants and animals. Also known as petroleum or crude oil. orogeny the way mountains are formed. outer core liquid, iron-nickel layer of the Earth between the solid inner core and lower mantle. outgas to release a gas that was dissolved, trapped, frozen or absorbed in another material. permeable allowing liquid and gases to pass through. perpendicular at a right angle to something. planet state of matter with no fixed shape and molecules separated into ions and electrons. plastically in a moldable, alterable manner. plate tectonics movement and interaction of the Earth's plates. precise force pressed on an object by another object or condition, such as gravity. P-wave seismic shock wave that represents longitudinal motion. Also called a primary wave or pressure wave. radical to bend or change the path of something.

region Noun any area on Earth with one or more common characteristics. Regions are the basic units of geography. large, concentrated supply or reserve. rheologist scientist who studies the flow and shape-changing (deformation) of matter. rigid natural substance composed of solid mineral matter. seafloor spreading shock wave of force or pressure that travels through the Earth. seismologist moving, measurable change in pressure and density of a material. silicate Noun most common group of minerals, all of which include the elements silicon (Si) and oxygen (O). slab flat, thick piece of material such as earth or stone. solar radiation light and heat from the sun. solar radiation light and heat from the sun. sophisticated to cause to slow or come to a stop. subduct to pull downward or beneath something. subduction process of one tectonic plate melting, sliding, or falling beneath another. S-wave seismic shock wave that represents perpendicular motion. Also called a secondary wave or shear wave. technology Noun the science of using tools and complex machines to make human life easier or more profitable. tectonic activity movement of tectonic plates resulting in geologic activity such as volcanic eruptions and earthquakes.

tectonic plate Noun massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate. temperature having to do with heat or temperature. transform to change from one form into another. transition zone Noun areas in the Earth's interior between the upper mantle, near the Earth's crust, and the lower mantle, near the Earth's core. upper mantle layer in Earth's mantle between the asthenosphere (above) and the lower mantle (below). upwell to rise, grow, or gush upward. vapor visible liquid suspended in the air, such as fog. velocity measurement of the rate and direction of change in the position of an object. viscosity measure of the resistance of a fluid to a force or disturbance. volcano Noun an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions. whole-mantle convection Noun process in which mantle convection is a result of activity in both the upper and lower mantle. xenolith What is Plate Tectonics? | Plate Tectonics What Is Plate Tectonics?

By Becky Oskin, Contributing Writer | March 21, 2016 04:52pm ET MORE Tectonic plates of the Earth. Credit: USGS From the deepest ocean trench to the tallest mountain, plate tectonics explains the features and movement of Earth's surface in the present and the past. Plate tectonics is the theory that Earth's outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core. The plates act like a hard and rigid shell compared to Earth's mantle . This strong outer layer is called the lithosphere. Developed from the 1950s through the 1970s, plate tectonics is the modern version of continental drift , a theory first proposed by scientist Alfred Wegener in 1912. Wegener didn't have an explanation for how continents could move around the planet, but researchers do now. Plate tectonics is the unifying theory of geology, said Nicholas van der Elst, a seismologist at Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York.

"Before plate tectonics, people had to come up with explanations of the geologic features in their region that were unique to that particular region," Van der Elst said. "Plate tectonics unified all these descriptions and said that you should be able to describe all geologic features as though driven by the relative motion of these tectonic plates." The driving force behind plate tectonics is convection in the mantle. Hot material near the Earth's core rises, and colder mantle rock sinks. "It's kind of like a pot boiling on a stove," Van der Elst said. The convection drive plates tectonics through a combination of pushing and spreading apart at mid-ocean ridges and pulling and sinking downward at subduction zones, researchers think. Scientists continue to study and debate the mechanisms that move the plates. Mid-ocean ridges are gaps between tectonic plates that mantle the Earth like seams on a baseball. Hot magma wells up at the ridges, forming new ocean crust and shoving the plates apart. At subduction zones , two tectonic plates meet and one slides beneath the other back into the mantle, the layer underneath the crust. The cold, sinking plate pulls the crust behind it downward.

Many spectacular volcanoes are found along subduction zones, such as the "Ring of Fire" that surrounds the Pacific Ocean. Plate boundaries Subduction zones, or convergent margins, are one of the three types of plate boundaries. The others are divergent and transform margins. At a divergent margin, two plates are spreading apart, as at seafloor-spreading ridges or continental rift zones such as the East Africa Rift. Transform margins mark slip-sliding plates, such as California's San Andreas Fault , where the North America and Pacific plates grind past each other with a mostly horizontal motion. In the 20th century, researchers realized that the Earth's crust is not one piece, but is made up of many huge tectonic plates upon which the continents ride. Credit: by Karl Tate, Infographics Artist Reconstructing the past While the Earth is 4.54 billion years old, because oceanic crust is constantly recycled at subduction zones, the oldest seafloor is only about 200 million years old. The oldest ocean rocks are found in the northwestern Pacific Ocean and the eastern Mediterranean Sea. Fragments of continental crust are much older, with large chunks at least 3.8 billion years found in Greenland.

With clues left behind in rocks and fossils, geoscientists can reconstruct the past history of Earth's continents. Most researchers think modern plate tectonics began about 3 billion years ago , based on ancient magmas and minerals preserved in rocks from that period. "We don't really know when plate tectonics as it looks today got started, but we do know that we have continental crust that was likely scraped off a down-going slab [a tectonic plate in a subduction zone] that is 3.8 billion years old," Van der Elst said. "We could guess that means plate tectonics was operating, but it might have looked very different from today ." As the continents jostle around the Earth, they occasionally come together to form giant supercontinents , a single landmass. One of the earliest big supercontinents, called Rodinia, assembled about 1 billion years ago. Its breakup is linked to a global glaciation called Snowball Earth. A more recent supercontinent called Pangaea formed about 300 million years ago. Africa, South America, North America and Europe nestled closely together, leaving a characteristic pattern of fossils and rocks for geologists to decipher once Pangaea broke apart.

The puzzle pieces left behind by Pangaea, from fossils to the matching shorelines along the Atlantic Ocean, provided the first hints that the Earth's continents move. Follow Becky Oskin @beckyoskin . Follow LiveScience @livescience , Facebook & Google+ . Editor's Recommendations Earth's Internal Layers: Crust, Mantle & Core - Video & Lesson Transcript | Study.com Earth's Internal Layers: Crust, Mantle & Core Watch short & fun videos Start Your Free Trial Today An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching Register for a free trial Are you a student or a teacher? I am a student Start Your Free Trial To Continue Watching As a member, you'll also get unlimited access to over lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Coming up next: How Scientists Study Earth's Interior Structure You're on a roll. Keep up the good work! Your next lesson will play in 10 seconds 0:06 Earth's Core Add to Add to Add to Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course. Custom Courses are courses that you create from Study.com lessons. Use them just like other courses to track progress, access quizzes and exams, and share content. Teachers Organize and share selected lessons with your class. Make planning easier by creating your own custom course. Students Create a new course from any lesson page or your dashboard. From any lesson page: Click "Add to" located below the video player and follow the prompts to name your course and save your lesson. From your dashboard: Click on the "Custom Courses" tab, then click "Create course". Next, go to any lesson page and begin adding lessons. Edit your Custom Course directly from your dashboard. Personalize: Name your Custom Course and add an optional description or learning objective. Organize: Create chapters to group lesson within your course. Remove and reorder chapters and lessons at any time. Share your Custom Course or assign lessons and chapters. Teacher Edition: Share or assign lessons and chapters by clicking the "Teacher" tab on the lesson or chapter page you want to assign. Students' quiz scores and video views will be trackable in your "Teacher" tab.

Premium Edition: You can share your Custom Course by copying and pasting the course URL. Only Study.com members will be able to access the entire course. Create an account to start this course today Try it free for 5 days! Lesson Transcript Instructor: Sarah Friedl Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology. Earth is made up of several different layers, each with unique properties. In this video lesson, you will identify each layer of Earth and how it relates to Earth as a whole. Earth's Core You may have heard that ogres are like onions because they have many layers. Well, Earth is the same way! Earth is made up of several different layers, each of which has unique properties. Let's start from the inside and work our way out. Earth has a core, but this is really two distinct parts: the inner core and the outer core. Both parts of the core are made up of mostly iron and some nickel. The difference is that in the inner core, those minerals are solid and in the outer core, they're liquid.

The inner core of the earth is incredibly hot - so hot that if you tried to dig a hole to China, you'd burn up on your way through the earth! What's amazing about the inner core is that even though it's about as hot as the surface of the sun, there's so much pressure from the weight of the world pushing down on it that it can't melt. This is the same reason that water in a pressure cooker doesn't boil, no matter how hot it gets! The outer core is also made up of iron and nickel, but it's quite different because it is a liquid. This is because there is much less pressure on this layer than the one below it (the outer core adds a lot of pressure to the inner core!). Though the flow of this liquid layer is very slow-moving (about a few kilometers a year), it is what produces Earth's magnetic field. Our North and South Poles exist because of this liquid outer core, even though it's almost 2,000 miles below us. The Mantle Sitting on top of the outer core, we find the mantle. This layer is by far the thickest layer of Earth, about 1,800 miles thick!

It also makes up about 85% of Earth's volume. Like the core, the mantle contains mostly iron, but in the form of silicate rocks. You might be surprised to learn that this rock actually moves like a fluid, similar to how silly putty moves. If you poke silly putty hard, it acts like a solid, but if you slowly pull it apart, it acts like a liquid. We call this ability of rock to move without breaking plasticity. The mantle can also be divided into two portions, the upper mantle and the lower mantle. The lower mantle is completely solid because, like the solid inner core of Earth, the pressure is just too great for it to melt and flow. The upper mantle is also known as the asthenosphere, which flows as convection currents. Convection occurs in all fluids and is the rising of warm particles and sinking of cool particles. So, as the material in the upper mantle warms, it rises straight up, and as it rises, it cools and then sinks back down. The Lithosphere This convection flow of the asthenosphere has a large impact on Earth's lithosphere, the outermost layer of the planet.

The lithosphere is only about 60 miles thick and contains both the crust and a small portion of the upper mantle. The lithosphere is very rigid; it does not flow like the asthenosphere but instead floats on top of it like ice on a pond. This layer of Earth is broken up into several different pieces, like a jigsaw puzzle called tectonic plates. The convection currents below in the mantle move these plates around on the surface of Earth. Though the 'flow' of the asthenosphere is on par with a snail's pace, these enormous plates running into each other is what causes earthquakes, volcanoes and mountain range formation. The Crust The crust itself, which is contained in the lithosphere, can also be divided into two parts (have you noticed a pattern yet?). We live on the continental crust, and the ocean floor is made up of the oceanic crust. The continental crust is thicker than the oceanic crust, but it's made up of rock that is less dense than the oceanic crust, so it sits on top of it, above sea level. Still not a believer? It might help to think of the earth's crust like a cargo ship in the ocean.

An empty ship floats higher in the water than a ship that has been loaded up with goods to carry across the sea, right? Well, in this analogy, the continental crust is the empty ship sitting higher on top of the liquid mantle, and the oceanic crust is the fully loaded ship sinking down lower into this liquid layer. It's all because of gravity! × Earth's Continental Plates - ZoomSchool.com All About Plate Tectonics: Earth's Plates and Continental Drift The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle. The plates are made of rock and drift all over the globe; they move both horizontally (sideways) and vertically (up and down). Over long periods of time, the plates also change in size as their margins are added to, crushed together, or pushed back into the Earth's mantle . These plates are from 50 to 250 miles (80 to 400 km) thick. Forward Backward The map of the Earth is always changing; not only are the underlying plates moving, but the plates change in size.

Also, the sea level changes over time (as the temperature on Earth varies and the poles melt or freeze to varied extents), covering or exposing different amounts of crust. Earth's Major Plates: The current continental and oceanic plates include: the Eurasian plate, Australian-Indian plate, Philippine plate, Pacific plate, Juan de Fuca plate, Nazca plate, Cocos plate, North American plate, Caribbean plate, South American plate, African plate, Arabian plate, the Antarctic plate, and the Scotia plate. These plates consist of smaller sub-plates. PLATE TECTONICS Generally 70 to 100 million years old Basalt The theory of plate tectonics (meaning "plate structure") was developed in the 1960's. This theory explains the movement of the Earth's plates (which has since been documented scientifically) and also explains the cause of earthquakes, volcanoes, oceanic trenches, mountain range formation, and many other geologic phenomenon. The plates are moving at a speed that has been estimated at 1 to 10 cm per year. Most of the Earth's seismic activity (volcanoes and earthquakes) occurs at the plate boundaries as they interact.

The top layer of the Earth's surface is called the crust (it lies on top of the plates). Oceanic crust (the thin crust under the oceans) is thinner and denser than continental crust. Crust is constantly being created and destroyed; oceanic crust is more active than continental crust. Under the crust is the rocky mantle, which is composed of silicon, oxygen, magnesium, iron, aluminum, and calcium. The upper mantle is rigid and is part of the lithosphere (together with the crust). The lower mantle flows slowly, at a rate of a few centimeters per year. The asthenosphere is a part of the upper mantle that exhibits plastic properties. It is located below the lithosphere (the crust and upper mantle), between about 100 and 250 kilometers deep. TYPES OF PLATE MOVEMENT: Divergence, Convergence, and Lateral Slipping At the boundaries of the plates, various deformations occur as the plates interact; they separate from one another (seafloor spreading), collide (forming mountain ranges), slip past one another (subduction zones, in which plates undergo destruction and remelting), and slip laterally.

Divergent Plate Movement: Seafloor Spreading Seafloor spreading is the movement of two oceanic plates away from each other (at a divergent plate boundary), which results in the formation of new oceanic crust (from magma that comes from within the Earth's mantle) along a a mid-ocean ridge. Where the oceanic plates are moving away from each other is called a zone of divergence. Ocean floor spreading was first suggested by Harry Hess and Robert Dietz in the 1960's. Convergent Plate Movement: When two plates collide (at a convergent plate boundary), some crust is destroyed in the impact and the plates become smaller. The results differ, depending upon what types of plates are involved. Oceanic Plate and Continental Plate - When a thin, dense oceanic plate collides with a relatively light, thick continental plate, the oceanic plate is forced under the continental plate; this phenomenon is called subduction. Two Oceanic Plates - When two oceanic plates collide, one may be pushed under the other and magma from the mantle rises, forming volcanoes in the vicinity. Two Continental Plates - When two continental plates collide, mountain ranges are created as the colliding crust is compressed and pushed upwards.

Lateral Slipping Plate Movement: When two plates move sideways against each other (at a transform plate boundary), there is a tremendous amount of friction which makes the movement jerky. The plates slip, then stick as the friction and pressure build up to incredible levels. When the pressure is released suddenly, and the plates suddenly jerk apart, this is an earthquake. ALFRED WEGENER AND PANGAEA In 1915, the German geologist and meteorologist Alfred Wegener (1880-1930) first proposed the theory of continental drift, which states that parts of the Earth's crust slowly drift atop a liquid core. The fossil record supports and gives credence to the theories of continental drift and plate tectonics. Wegener hypothesized that there was an original, gigantic supercontinent 200 million years ago, which he named Pangaea, meaning "All-earth". Pangaea was a supercontinent consisting of all of Earth's land masses. It existed from the Permian through Jurassic periods . It began breaking up during the Jurassic period, forming continents Gondwanaland and Laurasia , separated by the Tethys Sea.

Pangaea started to break up into two smaller supercontinents, called Laurasia and Gondwanaland, during the Jurassic period. By the end of the Cretaceous period, the continents were separating into land masses that look like our modern-day continents. Wegener published this theory in his 1915 book, On the Origin of Continents and Oceans. In it he also proposed the existence of the supercontinent Pangaea , and named it (Pangaea means "all the land" in Greek). Fossil Evidence in Support of the Theory Eduard Suess was an Austrian geologist who first realized that there had once been a land bridge between South America, Africa, India, Australia, and Antarctica. He named this large land mass Gondwanaland (named after a district in India where the fossil plant Glossopteris was found). This was the southern supercontinent formed after Pangaea broke up during the Jurassic period . He based his deductions on the plant Glossopteris, which is found throughout India, South America, southern Africa, Australia, and Antarctica.

Fossils of Mesosaurus (one of the first marine reptiles, even older than the dinosaurs) were found in both South America and South Africa. These finds, plus the study of sedimentation and the fossil plant Glossopteris in these southern continents led Alexander duToit, a South African scientist, to bolster the idea of the past existence of a supercontinent in the southern hemisphere, Eduard Suess's Gondwanaland . This lent further support to A. Wegener's Continental Drift Theory Glossopteris, a tree-like plant from the Permian through the Triassic Period . It had tongue-shaped leaves and was about 12 ft (3.7 m) tall. It was the dominant plant of Gondwana . ACTIVITIES ABOUT EARTH'S CONTINENTAL PLATES AND CRUST Earth's crust | geology | Britannica.com A cross section of Earth’s outer layers, from the crust through the lower mantle. Encyclopædia Britannica, Inc. Crustal abundances of elements of atomic numbers 1 to 93. Encyclopædia Britannica, Inc.

Figure 22: The topographic expressions of eroded anticlines and synclines. Encyclopædia Britannica, Inc. Figure 21: Three basic fault types: (top) normal fault, (middle) reverse fault, and (bottom) strike-slip fault. Encyclopædia Britannica, Inc. Figure 20: The forms of three types of folds. Encyclopædia Britannica, Inc. Figure 23: Two transform faults offsetting a mid-oceanic ridge. Encyclopædia Britannica, Inc. Volcanic activity and the Earth’s tectonic plates Stratovolcanoes tend to form at subduction zones, or convergent plate margins, where an oceanic plate slides beneath a continental plate and contributes to the rise of magma to the surface. At rift zones, or divergent margins, shield volcanoes tend to form as two oceanic plates pull slowly apart and magma effuses upward through the gap. Volcanoes are not generally found at strike-slip zones, where two plates slide laterally past each other.

“Hot spot” volcanoes may form where plumes of lava rise from deep within the mantle to the Earth’s crust far from any plate margins. Encyclopædia Britannica, Inc. Earth is composed of three layers: the crust, the mantle, and the core. Created and produced by QA International. © QA International, 2010. All rights reserved. Geologic materials cycle through various forms. Sediments composed of weathered rock lithify to form sedimentary rock, which then becomes metamorphic rock under the pressure of Earth’s crust. When tectonic forces thrust sedimentary and metamorphic rocks into the hot mantle, they may melt and be ejected as magma, which cools to form igneous, or magmatic, rock. Created and produced by QA International. © QA International, 2010. All rights reserved. John P. Rafferty, biological and earth science editor of Encyclopædia Britannica, discussing the connection between Earth’s tectonic plates and earthquake development. Encyclopædia Britannica, Inc.

At the margins of Earth’s plates, where two plates pull apart or one plate dives beneath another, magma (molten underground rock) frequently rises to the surface through volcanic vents. Encyclopædia Britannica, Inc. The Earth's Inside The Earth's Inside Thanks to earthquakes, the seimic waves they give off and the instruments used to gather data abouth such events, we now know the chemical composition , temperature, density and depth of the layer's of the Earth's inside. The earth is divided in to four layers: CRUST, MANTLE, OUTER CORE and INNER CORE. CRUST Echo-sounding techniques are used to explore the Earth's crust. Images, similar to sonograms, are produced. A sonogram in the crust is called a seismic reflection. Seiscmic waves from "small explosions or thumper trucks" return echoes from rock layers. Seismographs pick up these echoes.

Some facts about the CRUST: ***two types: oceanic and continental ***calcium (Ca) and sodium (na) aluminium-silicates ***rocky and brittle ***depth of 0-50 kilometers (0-31 miles) ***O0 C Some facts about the MANTLE: ***iron (Fe), magnesium (Mg), aluminium (Al), silicon (Si) and oxygen (O) silicate compunds ***solid but can slowly deform in a plastic manner ***67.3% of Earth's mass ***depth of 10-2890 kilometers(6-1806 miles) ***+10000 C *** convection in this region drives plate tectonics Convection in the MANTLE: Data about P waves and S waves traveling through the mantle has been used to map out convection in the mantle. Waves tell researchers whether the mantle is more or less dense than average, hotter or cooler than average and whether it is rising and falling. The Earth releases internal heat by convecting. Hot mantle rises to the surface and spreads laterally, transporting oceanic and continental plates. Speed of this motion is a few centimeters per year.

The new lithosphere, created at the ocean spreading centers, cools and evetuallu sinks back into the mantle. The subducted crust releases water to form island chains above. Below are two images of mantle convection. Both were created at the Harvard Univerisity Seismology Lab. Red blobs are warmer plumes of less dense material, rising mostly into the ocean-ridge spreading centers. Most of the heat from the Earth's inside emerges at the fast-spreading East Pacific Rise. A huge plume, directly from the Earth's core seems to be spreading there. Blue blobs show where colder, denser material is sinking into the mantle.

OUTER CORE Some facts about the OUTER CORE: ***iron and 10% sulphur (S) and/or oxygen ***molten ***depth of 2890-5150 kilomters (1806-3219 miles) ***37000 C ***convection motion within this region, along with the rotation of the Earth creates an effect that maintains the Earth's magnetic field Convection in the CORE: Some facts about the INNER CORE: ***Iron ***solid and unattached to the mantle ***suspended in molten outer core ***1.7% of the Earth's mass ***depth of 5150-6370 kilometers (3219-3981 miles) In the years since the practice of seismic tomography was first introduced researchers have gathered enough data to provide the world with detailed accurate maps of the layers of the Earth's inside. More recently, scientists have begun to focus more attention on the boundaries between layers, rather that the layers themselves. Many believe that the future of seismic tomography, geophysics and earthquake prediction lies in understanding these boundaries, chemical processes that occur in their vecinity and how such events affect the Earth's surface.

Forces In Earth's Crust - StudyBlue Good to have you back! If you've signed in to StudyBlue with Facebook in the past, please do that again. Forces In Earth's Crust Size: 55 Views: 28 Stress Forces created by movement of the Earth's plates. Adds energy to rock until the rock changes shape or break. What are three kinds of stress Tension,compression, and shearing What works over millions of years to change the shape of a rock Shearing,compression, and tension tension The stress force that pulls on the crust and thins the rock in the middle. It happens when two plates pull apart. Compression The stress force that squeezes rock until it folds or breaks. Shearing The stress force that pushes rock in two opposite directions. It happens when two plates slip past each other. What happens when enough stress build up in rock? The rock breaks and makes a fault What are the three main types of faults? Normal fault, reverse fault, and strike-slip faults Normal faults Form where rock is pulled apart by tension in earths crust. Tension occurs at a divergent boundary creating a normal fault. What is the block above the normal fault?

Hanging wall What is the rock under the normal fault Footwall What happens when rock moves along the normal fault The hanging wall slips downward Reverse fault Has the same structure as a normal fault, but the hanging wall moves up and the footwall moves down. Where does reverse fault form? Where compression pushes the rock of the crust together. What does shearing produce? They slip past eachother and have little up or down motion. Transform boundary A boundary that occura at a strike slip fault Plateau A large area of flat land that was lifted up high above sea level. Volcano A mountain that forms in Earth's crust when molten material, or magma, reaches the surface. Magma A molten mixture of rock-forming substances, gases, and water from the mantle that is below the earths surface. Lava When magma reaches the surface What happens after magma and lava cool? They form solid rock Where do volcano belts form along The boundaries of Earths plates Ring of fire One major belt of volcanoes. Includes the many volcanoes that rim the pacific ocean island arc Island arc A string of islands created by volcanoes that are near converging plate boundaries.

Hot spot An area where material from deep within earths mantle rises to the crust And melts to form magma Magma chamber A pocket of magma deep within the earths crust inside a volcano. Pipe A long tube that extends from Earth's crust up though the top of the volcano, connecting the magma chamber to Earth's surface. Vent The opening through which molten rock and gas leave the volcano. Lava flow The spread of lava as it pours out of a vent Crater A bowl-shaped area that may form at the top of a volcano around the central vent Silica A material found in magma that forms from the elements oxygen and silicon Pyroclastic flow A mixture of hot gases, ash, cinders, and bombs that flow down the sides of a volcano when it erupts explosively Dormant A sleeping volcano that may awaken in the future and may become active. Anticline A fold in rock that bends upward into an arch. Forces in earths crust A fold in rock that bends downward in a v shape. Forces in Earths crust Fault block mountain Forms when the hanging walls of two normal faults drop down on either side of the foot wall. Volcanoes and plate tectonics 1.

Divergent boundaries along the mid ocean ridge2. Converging plate boundaries 3. Where an oceanic plate is subducted beneath a continental plate Volcanic eruptions What forces magma from the magma chamber through the pipe and out of the vent? The force of the expanding gases. Volcanic eruptionsWhat are the two types of volcanic eruptions. They can be quiet or explosive. Volcanic eruptions What causes a quiet eruption? If the magma is hot or low in silica the gases bubble out gently and lava oozes quietly from the vent. Volcanic eruptions What causes a volcano to erupt explosively? If the magma is high in silica gases get trapped and pressure builds until it explodes. Extinct A dead volcano that s unlikely to ever erupt again. Active A live volcano that is erupting or may erupt in the future. Name some landforms created by volcanic eruptions Shield volcanoes, cinder cone volcanoes, composite volcanoes, lava plateaus, and calderas. Cinder cone A cone shaped hill or small mountain thats builds up around the vent in an explosive eruption. It is made of ash, cinders, and bombs.

Composite volcano A tall cone shaped mountain in which layers of lava alternate with layers of ash. Shield volcano A wide gently sloping mountain made of thin layers of lava. Hot spot volcanoes on the ocean floor are usually shield volcanoes. Lava plateau A high, level plateau made from repeated floods of lava.what What are the kand forms created by magma below the Earth's surface. Volcanic necks, dikes, sills, dome mountains, batholiths Volcanic neck Forms when magma hardens in a volcanoes pipe and the surrounding rock later wears away. Dike Hardened magma that has forced itself across rock layers Sill Hardened magma that has squeezed between horazontal rock layers. Dome mountain

Question: What is the name of the study of the motion of the earth's crust?
Answer: Plate Tectonics