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Keyword why tectonic plates float on top of the mantle
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do tectonic plates float on the mantlehttps://www.google.co.uk/search?num=30&newwindow=1&hl=en&gl=gb&q=Do+tectonic+plates+float+on+the+mantle&sa=X&ved=2ahUKEwiJ7cew_aP1AhUEvYsKHZuuA-sQ1QJ6BAgYEAE
the partly melted lower mantle is calledhttps://www.google.co.uk/search?num=30&newwindow=1&hl=en&gl=gb&q=The+partly+melted+lower+mantle+is+called&sa=X&ved=2ahUKEwiJ7cew_aP1AhUEvYsKHZuuA-sQ1QJ6BAglEAE
float on the mantle calledhttps://www.google.co.uk/search?num=30&newwindow=1&hl=en&gl=gb&q=Float+on+the+mantle+called&sa=X&ved=2ahUKEwiJ7cew_aP1AhUEvYsKHZuuA-sQ1QJ6BAgaEAE
large pieces of the lithosphere that float on the asthenosphere are calledhttps://www.google.co.uk/search?num=30&newwindow=1&hl=en&gl=gb&q=Large+pieces+of+the+lithosphere+that+float+on+the+asthenosphere+are+called&sa=X&ved=2ahUKEwiJ7cew_aP1AhUEvYsKHZuuA-sQ1QJ6BAgjEAE
do tectonic plates float on the asthenospherehttps://www.google.co.uk/search?num=30&newwindow=1&hl=en&gl=gb&q=Do+tectonic+plates+float+on+the+asthenosphere&sa=X&ved=2ahUKEwiJ7cew_aP1AhUEvYsKHZuuA-sQ1QJ6BAgiEAE
the movement of the earth's plate causes earthquakes andhttps://www.google.co.uk/search?num=30&newwindow=1&hl=en&gl=gb&q=The+movement+of+the+Earth%27s+plate+causes+earthquakes+and&sa=X&ved=2ahUKEwiJ7cew_aP1AhUEvYsKHZuuA-sQ1QJ6BAghEAE
tectonic plates float on the blankhttps://www.google.co.uk/search?num=30&newwindow=1&hl=en&gl=gb&q=Tectonic+plates+float+on+the+blank&sa=X&ved=2ahUKEwiJ7cew_aP1AhUEvYsKHZuuA-sQ1QJ6BAgkEAE
a boundary where plates move away from each other is calledhttps://www.google.co.uk/search?num=30&newwindow=1&hl=en&gl=gb&q=A+boundary+where+plates+move+away+from+each+other+is+called&sa=X&ved=2ahUKEwiJ7cew_aP1AhUEvYsKHZuuA-sQ1QJ6BAgZEAE
Result 1
TitleWhat keeps the continents floating on a sea of molten rock? | Science Questions with Surprising Answers
Urlhttps://wtamu.edu/~cbaird/sq/2013/07/18/what-keeps-the-continents-floating-on-a-sea-of-molten-rock/
DescriptionThe continents do not float on a sea of molten rock. The continental and oceanic crusts sit on a thick layer of solid rock known as the mantle. Whi..
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BodyWhat keeps the continents floating on a sea of molten rock? Category: Earth Science      Published: July 18, 2013 Under the continents is a layer of solid rock known as the upper mantle or asthenosphere. Though solid, this layer is weak and ductile enough to slowly flow under heat convection, causing the tectonic plates to move. Public Domain Image, source: Christopher S. Baird. The continents do not float on a sea of molten rock. The continental and oceanic crusts sit on a thick layer of solid rock known as the mantle. While there is a layer of liquid rock in the earth known as the outer core, this layer is about 3000 km below earth's surface and is separated from the surface by the thick solid mantle. The tectonic plates do not slowly drift over time because they are floating on a layer of liquid rock. They drift because they are sitting on a layer of solid rock (the upper mantle or "asthenosphere") that is weak and ductile enough that it can flow very slowly under heat convection, somewhat like a liquid. If there is not a giant sea of magma under the continents, where does lava come from? The molten lava that spews out of volcanoes is created locally right under the volcano rather than being released from a global sea of magma. Magma is created when pressure changes melt the rock. For instance, as two tectonic plates collide, one plate may get forced under the other plate. As it does so, the plate that is forced down (subducted) releases water into the upper mantle which lowers the pressure enough to melt the rock. Localized regions of magma form in the mantle near subduction zones. The mantle can then rise and create volcanoes. The point is that magma is created in small pockets (small relative to the size of the earth) as part of the tectonic plate movement, and does not exist as a global sea of magma just under the crust. The confusion about the state of the upper mantle perhaps arises from the way diagrams are presented. For instance, the image above shows the mantle in a glowing orange color. This coloring can be confused to mean that this layer is hot liquid rock, like lava. In reality, the mantle is solid, and the coloring is just meant to indicate that the rock is hot and flowing slowly under heat convention. The textbook Physical Geography by Robert Gabler, James Peterson, L. Trapasso, and Dorothy Sack states, "Extending down from the base of the lithosphere about 600 kilometers (375 mi) farther into the mantle is the asthenosphere (from Greek: asthenias, without strength), a thick layer of plastic mantle material. The material in the asthenosphere can flow both vertically and horizontally, dragging segments of the overlying, rigid lithosphere along with it." Topics: astheosphere, geology, heat, heat convection, lava, magma, mantle, molten, subduction, tectonic plate movement, temperature
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TitleDo tectonic plates 'float' over the mantle and 'collide' like icebergs? - Quora
Urlhttps://www.quora.com/Do-tectonic-plates-float-over-the-mantle-and-collide-like-icebergs
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TitleWhy do tectonic plates float on the mantle? | Study.com
Urlhttps://study.com/academy/answer/why-do-tectonic-plates-float-on-the-mantle.html
DescriptionAnswer to: Why do tectonic plates float on the mantle? By signing up, you'll get thousands of step-by-step solutions to your homework questions...
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BodyWhy do tectonic plates float on the mantle? Question:. Why do tectonic plates float on the mantle? Tectonic Plates:. Tectonic plates are the rocky pieces of the Earth's crust. These pieces float on top of the melted rock of the mantle, another layer of the Earth found between the core and the crust. Answer and Explanation: 1 . Become a Study.com member to unlock this answer! Create your account View this answer The reason tectonic plates float on top of the mantle has to do with density. Even though the mantle is made of melted, flowing rock, the material is... See full answer below. Become a member and unlock all Study Answers. Try it risk-free for 30 days Try it risk-free Ask a question. Our experts can answer your tough homework and study questions. Ask a question Ask a question Search Answers. Learn more about this topic:. Get access to this video and our entire Q&A library Try it risk-free Plate Tectonics: A Unified Theory for Change of the Earth's Surface from Chapter 13 / Lesson 7 46K Plate tectonics involve a unifying theory of how the surface of the earth changes. Explore this theory, what causes plates to move, and learn about the term lithosphere, asthenosphere, mantle, and core. Related to this Question. Related Answers Related Lessons Related Courses What tectonic plate is subducting under... What major tectonic event occurred around 40... What is the difference between plate tectonics... What is tectonic uplift? How was Mount Lamington formed? What island is West Maui Mountains volcano... Where are the Pitcairn Islands located? Where is the Pacific Rim? What is the Pacific Rim? Do Earthquakes occur in the... Is the Ring of Fire around the Pacific... Is Hawaii on the South American Plate? What is the definition of tectonic... Where does rhyolite form? What features of the Hawaiian Islands are not... Explain how the patterns of volcanoes and... The current density inside a long, solid,... What are the two most common elements in the... Stratovolcanoes are generally associated with:... Which direction is the South American Plate... Evidence for the Mechanism of Continental Drift Scientists discovered evidence for the mechanism of continual drift. Learn about the lithosphere, plates, and faults, and consider the evidence in support of the continental drift theory. The Center of Population: Definition & Significance In business, the center of population in a country can be more significant to know than its geographic center. Learn more about the definition of the center of population, the geometric median, median center, and mean center. Plate Tectonics Theory & Summary This lesson provides a definition of plate tectonics, explains the theory of plate tectonics, and what phenomena in the natural world that the theory explains. Facts About Stars | The Study of Stars Discover incredible facts about the study of stars. Learn about branches of astronomy, stars' composition, and their life cycle. Alfred Wegener's Theory of Continental Drift Alfred Wegener theorized the movement of continents, the theory of continental drift, by gathering evidence unexplained by the accepted model of his time. Explore how he studied coastlines, fossils, and geologic features to develop his theory and discover the challenges he faced. Rock Cycle: Igneous, Sedimentary, and Metamorphic Rocks The rock cycle describes the creation, alteration and destruction of the rocks that form from magma. Learn more about the rock cycle, including the three main rock types - igneous (magma that solidifies), sedimentary (rock made from eroded materials that are cemented together), and metamorphic (rocks that are transformed into new substances when exposed to intense heat and pressure) - and how they are formed. How Thick is the Earth's Crust? | Earth's Crust Facts, Composition & Temperature Learn fascinating Earth's crust facts in this lesson, including the two types of Earth crust, its temperature, its thickness and the Earth's crust composition. Weathering, Erosion & Deposition | Overview & Effects on Landforms Learn how erosion changes the Earth's surface. Read about the process of weathering, erosion, and deposition and be able to describe landforms created by deposition. Adiabatic vs. Diabatic Processes: Cloud Formation When clouds form, they do so through either the adiabatic process or the diabatic process. In this lesson, explore the adiabatic and diabatic processes and learn how different conditions lead to cloud formation. What is Pangaea? - Theory & Definition The world's continents as we know them today were formed millions of years ago when Pangaea broke apart. Learn about the origin of the continents and understand what the theory of Pangaea entails. Explore the idea of supercontinents, review the continents of Pangaea, and recognize the evidence that supports continental drift theories. Seafloor Spreading Theory Overview & Diagram | Who Discovered Seafloor Spreading? Learn what seafloor spreading is, who discovered it, and how it explains the movement of continents and plates. Learn about the evidence for seafloor spreading and analyze diagrams that illustrate it. Plate Tectonics | Causes & Effects of Tectonic Plate Movement Learn about tectonic plates, and discover what causes the earth's plates to move. Understand tectonic boundary types and the effects of tectonic plate movement. The Layers of the Earth: Facts, Composition & Temperature The three layers of planet Earth are classified based on their chemical composition. Explore the Earth's crust, mantle, and core, and discover facts about the temperature of each layer and the other types of layers above and below ground. 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Result 5
TitleWhat tectonic plates float on
Urlhttps://cosmosmagazine.com/earth/earth-sciences/geologists-solve-the-mystery-of-what-tectonic-plates-float-on/
DescriptionAny geologist will tell you the Earth’s crust is broken into tectonic plates that “float” around like gigantic rafts
Date16 Feb 2015
Organic Position4
H1What tectonic plates float on
H2Dynamite shakes the truth from the Earth’s underbelly.
H3Cathal O’Connell
Read science facts, not fiction..
H2WithAnchorsDynamite shakes the truth from the Earth’s underbelly.
BodyWhat tectonic plates float on Dynamite shakes the truth from the Earth’s underbelly. . Share Tweet New research shows a lubricating jelly layer beneath the tectonic plates that allows them to slide. Credit: Dorling Kindersley / Getty Images Any geologist will tell you the Earth’s crust is broken into tectonic plates that “float” around like gigantic rafts. But just what these rafts have been floating upon, has been a mystery – until now. A team of New Zealand scientists detonated tons of dynamite and listened for echoes to reveal the underbelly of the Pacific plate. They found a 10 kilometre thick channel of lubricating jelly-like rock, which they say allows the plate to slide above it, according to a report in Nature. German meteorologist Alfred Wegener proposed the idea of rafting continents back in 1912 after perusing maps and noticing that the east coast of South America and the west coast of Africa would fit together like jigsaw pieces. But scientists only started taking the idea seriously in 1963 when geophysicists Fred Vine and Drummond Matthews showed that the crust on the ocean floor, on either side of the mid-oceanic ridges, was indeed moving. These days plate tectonics is “obvious”, says Louis Moresi, a geologist at the University of Melbourne. “You can log on to Google Earth and actually plot the movement.” The plates themselves are composed of a thick layer of hard rock known as the lithosphere that lies above a softer layer known as the asthenosphere. But no one knew what lay at the lithosphere asthenosphere boundary (LAB). In the past geologists relied on earthquakes originating on the other side of the planet of the planet to try and find out. Like doctors placing a stethoscope to the Earth’s surface, they detected seismic waves. The fact these waves move at different speeds through different layers allowed geologists to sketch a coarse picture of the medium through which they travelled. But natural seismic waves are 10-40 kilometres in length – too long to resolve the fine-grained structure below the plates. So the New Zealanders took matters into their own hands. “Rather than relying on earthquake waves that come from below we create our own ‘earthquakes’ with dynamite shots,” says Tim Stern at Victoria University, Wellington, who led the project. The resulting waves are about 500 metres long and  able to resolve finer structures. The blast zone was sited on the southern tip of New Zealand’s North Island where the 73-kilometre thick Pacific plate dips beneath the Australian plate at the rate of about 40 millimetres a year. The team set up 877 Coke can-sized seismometers strung like beads along 85 kilometres. Then from multiple boreholes they detonated half a tonne of TNT in each. The seismic echoes revealed something unusual stuck to the Pacific plate’s underbelly – a channel of jelly-like rock about 10 kilometres thick. Researchers used blast waves to get a view of what lies beneath the Pacific plate as it dives below New Zealand’s North Island. At the base of the plate they found a 10 km thick jelly-like channel, the lithosphere asthenosphere boundary (LAB), which decouples it from the underlying asthenosphere. Credit: Cosmos Magazine “We always thought the boundary would be gradual and defined by temperature. This study shows it’s an abrupt transition and requires something more than temperature alone to explain it,” says geologist Andrew Gleadow, also at the University of Melbourne. The New Zealand team suggests the jelly rock gains its consistency from a higher concentration of water or magma than is present in the lithosphere above it. But it would not have to be too high. While the lithosphere contains 0.1% magma, even a 2% concentration of magma might be enough to explain the consistency of the rock in the channel. “On a million-year time scale this would appear weak and jelly-like,” explains Stern. The finding of the jelly channel might also help resolve a 50-year debate about whether the plates move as a result of being pushed or pulled. An early idea was that magma being extruded from the mid-oceanic ridges was pushing the plates apart. Another pushing force might come from slowly creeping convection currents beneath the plates that act like rollers beneath a conveyer belt. On the other hand the major force might be a pulling one. As one edge of an oceanic plate dives back into the mantle beneath – as the Pacific one is doing – it pulls the rest of the slab after it. The finding of the jelly layer makes the pushing and rolling mechanisms less likely, says Gleadow. “If the plates are mechanically disconnected from the mantle below, there can’t be good coupling to underlying convection movements.” On the other hand, the jelly layer adds weight to the idea that gravity is the driving force pulling the plates along. As one edge of the plate is being dragged under, the low friction jelly layer means the rest of the plate just slithers after it like a ski on snow. The next question is how this channel was formed and if it is present all over the world, says Moresi. Evidence from previous studies hints at a similar structure beneath the coast of Norway and another off Costa Rica. If it is found everywhere, “it would change our understanding of the internal dynamics quite a lot”. Additional reporting by Elizabeth Finkel Get an update of science stories delivered straight to your inbox. Originally published by Cosmos as What tectonic plates float on Cathal O’Connell. Cathal O'Connell is a science writer based in Melbourne. More from: Cathal O’Connell A telescope the size of the Earth A bird? A plane? Car, actually. The search for cosmic strings What is energy? The future of in-space manufacturing Read science facts, not fiction... There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today. Make a donation Go to mobile version
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Result 6
Titlewhat do plates float on - Lisbdnet.com
Urlhttps://lisbdnet.com/what-do-plates-float-on/
DescriptionTectonic plates float on the asthenosphere. The asthenosphere is immediately below the top layer of Earth's surface (lithosphere).Tectonic plates float on the
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H1what do plates float on
H2What Do Plates Float On?
What do the tectonic plates float on?
Do plates float on top of mantle?
What do plates rest on?
What are the plates composed of and what do they float on?
Where does the crust float?
What does a tectonic plate float on and move over the top of?
Which layer of the Earth do these tectonic plates float on top of?
Does land float on water?
Do tectonic plates float over the?
How do the plates move when we feel that the ground is shaking?
Are continents still moving?
What parts of the Earth’s crust float on top of the mantle?
What is the float on the mantle?
Is Earth a floating rock?
What happens when Earth’s plates move?
Are the continents sinking?
Why plates are moving explain?
Why do continental plates float on top of magma?
Is Japan a floating island?
Why do islands not sink?
Do any islands float?
Where does the tectonic plates float over crust magma core?
Where does subduction happen?
What happens when two plates slide?
What is the best type to build on?
What happens when two plates rub against each other as they move in opposite directions?
What will the world look like in 200 million years?
Can Pangea happen again?
Will Australia and Asia collide?
What area of the mantle does the lithosphere float on?
What is the Earth’s only liquid layer?
How deep the earth is?
What does the plate tectonic model explain?
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H2WithAnchorsWhat Do Plates Float On?
What do the tectonic plates float on?
Do plates float on top of mantle?
What do plates rest on?
What are the plates composed of and what do they float on?
Where does the crust float?
What does a tectonic plate float on and move over the top of?
Which layer of the Earth do these tectonic plates float on top of?
Does land float on water?
Do tectonic plates float over the?
How do the plates move when we feel that the ground is shaking?
Are continents still moving?
What parts of the Earth’s crust float on top of the mantle?
What is the float on the mantle?
Is Earth a floating rock?
What happens when Earth’s plates move?
Are the continents sinking?
Why plates are moving explain?
Why do continental plates float on top of magma?
Is Japan a floating island?
Why do islands not sink?
Do any islands float?
Where does the tectonic plates float over crust magma core?
Where does subduction happen?
What happens when two plates slide?
What is the best type to build on?
What happens when two plates rub against each other as they move in opposite directions?
What will the world look like in 200 million years?
Can Pangea happen again?
Will Australia and Asia collide?
What area of the mantle does the lithosphere float on?
What is the Earth’s only liquid layer?
How deep the earth is?
What does the plate tectonic model explain?
PLATE TECTONICS
Introduction to Plate Tectonics
Float or Sink – Why do things float- Why do things sink- Lesson for kids
Tectonic Plates – The Skin of Our Planet | Down to Earth
Bodywhat do plates float on admin Send an email November 30, 2021 16 7 minutes read You are watching: what do plates float on In Lisbdnet.com Contents1 What Do Plates Float On?2 What do the tectonic plates float on?3 Do plates float on top of mantle?4 What do plates rest on?5 What are the plates composed of and what do they float on?6 Where does the crust float?7 What does a tectonic plate float on and move over the top of?8 Which layer of the Earth do these tectonic plates float on top of?9 Does land float on water?10 Do tectonic plates float over the?11 How do the plates move when we feel that the ground is shaking?12 Are continents still moving?13 What parts of the Earth’s crust float on top of the mantle?14 What is the float on the mantle?15 Is Earth a floating rock?16 What happens when Earth’s plates move?17 Are the continents sinking?18 Why plates are moving explain?19 Why do continental plates float on top of magma?20 Is Japan a floating island?21 Why do islands not sink?22 Do any islands float?23 Where does the tectonic plates float over crust magma core?24 Where does subduction happen?25 What happens when two plates slide?26 What is the best type to build on?27 What happens when two plates rub against each other as they move in opposite directions?28 What will the world look like in 200 million years?29 Can Pangea happen again?30 Will Australia and Asia collide?31 What area of the mantle does the lithosphere float on?32 What is the Earth’s only liquid layer?33 How deep the earth is?34 What does the plate tectonic model explain?35 PLATE TECTONICS36 Introduction to Plate Tectonics37 Float or Sink – Why do things float- Why do things sink- Lesson for kids38 Tectonic Plates – The Skin of Our Planet | Down to Earth What Do Plates Float On? Tectonic plates float on the asthenosphere. The asthenosphere is immediately below the top layer of Earth’s surface (lithosphere).Tectonic plates float on the asthenosphere asthenosphere It lies below the lithosphere, between approximately 80 and 200 km (50 and 120 miles) below the surface. The lithosphere–asthenosphere boundary is usually referred to as the LAB. The asthenosphere is almost solid, although some of its regions are molten (e.g., below mid-ocean ridges). What do the tectonic plates float on? Earth’s thin outer shell is broken into big pieces called tectonic plates. These plates fit together like a puzzle, but they’re not stuck in one place. They are floating on Earth’s mantle, a really thick layer of hot flowing rock. Do plates float on top of mantle? Tectonic plates are the rocky pieces of the Earth’s crust. These pieces float on top of the melted rock of the mantle, another layer of the Earth found between the core and the crust. What do plates rest on? The plates can be thought of like pieces of a cracked shell that rest on the hot, molten rock of Earth’s mantle and fit snugly against one another. The heat from radioactive processes within the planet’s interior causes the plates to move, sometimes toward and sometimes away from each other. What are the plates composed of and what do they float on? Any geologist will tell you the Earth’s crust is broken into tectonic plates that “float” around like gigantic rafts. … The plates themselves are composed of a thick layer of hard rock known as the lithosphere that lies above a softer layer known as the asthenosphere. Where does the crust float? Because both continental and oceanic crust are less dense than the mantle below, both types of crust “float” on the mantle. What does a tectonic plate float on and move over the top of? They Really Float? These plates make up the top layer of the Earth called the lithosphere. Directly under that layer is the asthenosphere. … The tectonic plates are floating on top of the molten rock and moving around the planet. See also  how to use civilization in a sentenceWhich layer of the Earth do these tectonic plates float on top of? In plate tectonics, Earth’s outermost layer, or lithosphere—made up of the crust and upper mantle—is broken into large rocky plates. These plates lie on top of a partially molten layer of rock called the asthenosphere. Does land float on water? Yes, the land really does go all the way down. An island is mostly rock, so if it didn’t go all the way down it would sink! The exception is ice-bergs, which do float, ice being less dense than water. Do tectonic plates float over the? Tectonic plates float on the asthenosphere. The asthenosphere is immediately below the top layer of Earth’s surface (lithosphere). How do the plates move when we feel that the ground is shaking? The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth’s crust and cause the shaking that we feel. Are continents still moving? Today, we know that the continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics. The continents are still moving today. … The two continents are moving away from each other at the rate of about 2.5 centimeters (1 inch) per year. What parts of the Earth’s crust float on top of the mantle? lithosphereTogether the crust and upper mantle are called the lithosphere and they extend about 80 km deep. The lithosphere is broken into giant plates that fit around the globe like puzzle pieces. These puzzle pieces move a little bit each year as they slide on top of a somewhat fluid part of the mantle called the asthenosphere.May 21, 2008 What is the float on the mantle? Rocks in the Earth’s crust are lighter (less dense) than those in the Earth’s mantle. Thus, the crust floats on the mantle just as ice floats on water. When ice floats, thicker pieces of ice will rise higher above the water. Is Earth a floating rock? The Earth is not floating in space; it is orbiting the “gravity well” of a star which is, in turn, orbiting the “gravity well” of the Milky Way galaxy which is, in turn, moving through the universe (sorry, my knowledge gets fuzzy here). We are on an oblate spheroid. What happens when Earth’s plates move? When the plates move they collide or spread apart allowing the very hot molten material called lava to escape from the mantle. When collisions occur they produce mountains, deep underwater valleys called trenches, and volcanoes. … The Earth is producing “new” crust where two plates are diverging or spreading apart. See also  the point within earth where an earthquake takes place is termed the ________.Are the continents sinking? The continents, “floating” on the earth’s denser interior, have sunk as much as two miles below their “proper” height, according to a report in the February issue of Geophysical Research Letters. … It has long been assumed that the continents float on the underlying rock, just as an iceberg floats in water. Why plates are moving explain? Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again. Why do continental plates float on top of magma? They drift because they are sitting on a layer of solid rock (the upper mantle or “asthenosphere”) that is weak and ductile enough that it can flow very slowly under heat convection, somewhat like a liquid. Is Japan a floating island? Instead the undecomposed dead plants accumulate into layers that gradually raise the lake bed to the water surface. Upon this layer, bushes and eventually trees will colonize. This was the beginning of Ukishima. Peat bogs are called deitan-shitsugen in Japanese; a bog woodland is a shotakurin. Why do islands not sink? Islands are not floating at all. They are actually mountains or volcanos that are mostly underwater. … If an island does disappear under the ocean, it’s because the land underneath has moved or the bottom of the volcano has broken apart. But they simply can not sink. Do any islands float? Island do not float on anything. … An island is mostly rock, so if it didn’t go all the way down it would sink! The exception is ice-bergs, which do float, ice being less dense than water. No they do not float, islands are the tops of underwater mountains. Where does the tectonic plates float over crust magma core? Note: The sea of magma in the lower mantle, on which the tectonic plates float, is known as the asthenosphere. The upper boundary of the asthenosphere is called the lithosphere-asthenosphere boundary or LAB and is a well-defined region. Where does subduction happen? the Pacific OceanSubduction zones occur all around the edge of the Pacific Ocean, offshore of Washington, Canada, Alaska, Russia, Japan and Indonesia. Called the “Ring of Fire,” these subduction zones are responsible for the world’s biggest earthquakes, the most terrible tsunamis and some of the worst volcanic eruptions.May 6, 2015 What happens when two plates slide? When oceanic or continental plates slide past each other in opposite directions, or move in the same direction but at different speeds, a transform fault boundary is formed. No new crust is created or subducted, and no volcanoes form, but earthquakes occur along the fault. See also  what are the three groups of protistsWhat is the best type to build on? Loam is the best soil type for construction due to its ideal combination of silt, sand, and clay. What happens when two plates rub against each other as they move in opposite directions? Plates Slide Past One Another Plates grinding past each other in opposite directions create faults called transform faults. Powerful earthquakes often strike along these boundaries. … The molten rock rises through the crust and erupts at the surface of the overriding plate. What will the world look like in 200 million years? Pangea broke apart about 200 million years ago, its pieces drifting away on the tectonic plates — but not permanently. The continents will reunite again in the deep future. … The planet could end up being 3 degrees Celsius warmer if the continents all converge around the equator in the Aurica scenario. Can Pangea happen again? The answer is yes. Pangaea wasn’t the first supercontinent to form during Earth’s 4.5-billion-year geologic history, and it won’t be the last. … So, there’s no reason to think that another supercontinent won’t form in the future, Mitchell said. Will Australia and Asia collide? Australia is also likely to merge with the Eurasian continent. “Australia is moving north, and is already colliding with the southern islands of Southeast Asia,” he continued. … Still, over millions of years that minute movement will drive the continents apart. What area of the mantle does the lithosphere float on? the asthenosphere Lithospheric plates float on the uppermost part of the mantle called the asthenosphere. The asthenosphere is made up of solid rocks that become… What is the Earth’s only liquid layer? The outer core The outer core is the liquid largely iron layer of the earth that lies below the mantle. Geologists have confirmed that the outer core is liquid due to seismic surveys of Earth’s interior. How deep the earth is? Definitions Depth (km) Chemical layer Depth (km) 670–2,890 Lower mantle 670–2,890 2,890–5,150 Outer core 2,890–5,150 5,150–6,370 Inner core 5,150–6,370 * Depth varies locally between 5 and 200 km. † Depth varies locally between 5 and 70 km. What does the plate tectonic model explain? The theory of plate tectonics states that the Earth’s solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper portion of the mantle. … Thus, at divergent boundaries, oceanic crust is created. PLATE TECTONICS. Introduction to Plate Tectonics. Float or Sink – Why do things float- Why do things sink- Lesson for kids. Tectonic Plates – The Skin of Our Planet | Down to Earth. Related Searches plates float on the surface of the mantledo tectonic plates float on the asthenospherethese float on the mantle calledwhat is the other term of tectonic platestectonic plates float on the blanklarge pieces of the lithosphere that float on the asthenosphere are calledplates can See more articles in category: FAQ admin Send an email November 30, 2021 16 7 minutes read admin. Website what region of north america is most densely populated. what is limited resources. 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Titlemodels - Do tectonic plates "float" over the mantle and "collide" like icebergs? - Earth Science Stack Exchange
Urlhttps://earthscience.stackexchange.com/questions/18422/do-tectonic-plates-float-over-the-mantle-and-collide-like-icebergs
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H1Do tectonic plates "float" over the mantle and "collide" like icebergs?
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BodyDo tectonic plates "float" over the mantle and "collide" like icebergs? Ask Question Asked 2 years, 2 months ago Active 2 years, 1 month ago Viewed 301 times 3 $\begingroup$ I'm always hearing about tectonic plates as large chunks of crust floating on the mantle just like boats. In timescales of millions of years they move and even collide. But I'm starting to think this is just a pop-science model, or a methaphor, for a much more complex situation. I didn't made the calculation but I feel that the mass of the Indian plate is not as large to account for the uplifting of the Himalayas just by kinetic energy transfer. At those speeds (puny, even if large compared to other plate movements) wouldn't the material stress of the Eurasian plate had absorbed all the momentum by now? I get that the inertia of India is huge, but is it really as much as to keep pushing even today? Does it has so much inertia that it is still slowing down as it pushes Eurasia? I feel like there is a constant force been applied tangentially to the surface of the plate that could account for this instead of just a freely moving plate smashing another like two icebergs in the artic sea. Does the idea of plates floating like boats and the idea of them interacting by mechanical collisions is really somehting more than a suggestive way of viewing a process that takes enourmous amounts of time, energy and mass so that we, insignificant and ephimeral creatures, can have a toy model in our minds? Is India been pushed by a force or is it really just moving like a billiard ball until it collides with another and changes its momentum? EDIT: Ok, so I've actually done the calculation now: According to the USGS, the Indian plate had a speed of $v =9 \; m/century = 2.85\cdot 10 ^{-9}\; m/s$. The surface area of the plate is $A = 1.19\cdot 10^{7}\; km^2$. If we suppose the thickness of the crust here to be of $h = 50\; km$ (which is thicker than it probably is) then the volume of the plate is $V = A\cdot h= 5.95\cdot 10^{8}\; km^3 = 5.95\cdot 10^{17}\; m^3$. We can estimate the mass of the plate by assuming a density of $\rho = 3\; g/cm^3 = 3\cdot 10^3\; kg/m^3$ (this density is higher than the average we should expect for the crust so we are not been very conservative at all). Thus the mass of the Indian plate is around $m = \rho V = 1.79\cdot 10^{21}\; kg$ in the best case scenario. Then the kinetic energy of the Indian plate had to be lower than $E_k = \frac{1}{2}mv^2 = 7269\; J = 1.7 \; cal$, which is even less than what @Keith McClary has suggested since this is less than a $1/300 \; th$ of the energy of a candy bar. Now, we can use Newton's Second Law of Motion in the form $\Delta t = mv/F$, where $m$ is the mass of the Indian plate and $v$ is its velocity, to get the time needed to stop the plate, $\Delta t$, when we apply a constant force, $F$, against its motion. Even if the kinetic energy is insignificant it is not easily absorbed during a collision due to the huge inertia of the plate. But still if we suppose $1$ million people, each person pushing with $3000 \; N$ of force then those people could have stopped the continent in less than $\Delta t = 30\; minutes$. A single weight-lifter would have been able to stop the entire Indian continental plate if he pushed with $F = 8000\; N$ for about $\Delta t = 20.2\; years$. I think that the mechanical stress of the entire eurasian continent creates larger forces that a single human and this "collision" has been going on for millions of years (not 20 years) and is still going on. So this is where it looks absurd to me to talk about a "collision" of plates for the formation of the Himalayas. The driving mechanism has to be a huge force pressing the Indian plate against Eurasia. plate-tectonics models crust Share Improve this question Follow edited Nov 9 '19 at 21:35 Swike asked Nov 9 '19 at 16:53 SwikeSwike 28411 silver badge66 bronze badges $\endgroup$ 6 2 $\begingroup$ One Chocolate Chip. $\endgroup$ – Keith McClary Nov 10 '19 at 3:03 3 $\begingroup$ The driving forces are mantle convection and slab-pull. This isn’t about billiard balls just randomly moving around. The “billiard balls” are being actively pushed and pulled by forces underneath them. $\endgroup$ – Gimelist Nov 10 '19 at 4:45 1 $\begingroup$ Plate thickness is estimated here to be 80-120 miles. That doesn't change your small energy calculation all that much, but worth noting. theatlantic.com/science/archive/2017/08/… $\endgroup$ – userLTK Nov 10 '19 at 7:08 $\begingroup$ I'm not sure this is an actual law, but I want to call it the law of large numbers. Energy is very low, due to the slow velocity squared but momentum is still quite high (only one multiple of the slow velocity). Similarly the ability to do work (energy over time) is low but the force is high. If you trace the movement back to the circulating convection inside the mantle, not the plate riding on the mantle, you would probably get better numbers but still low energy, high momentum. $\endgroup$ – userLTK Nov 11 '19 at 14:00 $\begingroup$ Just a note to your unit conversions. 7269 J = 1737 cal = 1.74 kcal = 1.74 Cal. It's important to differentiate between standard and 'food' calories since they differ by a factor of 1000 and it's usually done by capitalising the name of 'food-calorie'. $\endgroup$ – pavel Mar 3 '20 at 22:18  |  Show 1 more comment 2 Answers 2 . Active Oldest Votes 8 $\begingroup$ you are missing a big factor, the plates are not moving due to the momentum of an initial impulse. They are being actively moved by the push and pull of mantle convection. Much like how icebergs are pulled along by ocean currents. the iceberg analog however breaks down because icebergs melt before they can do much complex interaction, where as continental plate material is more or less permanent. also icebergs are subjected to far lower forces than continents, a closer analogy would be ice in glacier. The amount of energy the mantle is supplying is massive, far far more proportionally than an iceberg is subjected to, more than enough to drive continental plate together and build mountains. if you are interested in the detailed mathematics you can start here. The continents float on the mantle becasue they are less dense, but they are moved by mantle movement transferring energy. Share Improve this answer Follow edited Nov 15 '19 at 4:44 answered Nov 15 '19 at 3:06 JohnJohn 6,3771616 silver badges2929 bronze badges $\endgroup$ 1 $\begingroup$ "you are missing a big factor". That was the question indeed. $\endgroup$ – Swike Nov 15 '19 at 10:10 Add a comment  |  0 $\begingroup$ Both mechanisms are at work. Continental crust is lighter than oceanic crust and lighter than mantle material, therefore it floats. But in addition to that, the very mantle forces that caused the plate to break off from a larger plate are still operating. The usual cause of a continental rift developing, as may be seen in East Africa's rift valley, are gigantic mantle plumes of hot magma rising from far below, and these continue to supply motive power long after a rift develops. The Indian plate, though moving at only a few centimetres per year, has enormous mass and therefore enormous kinetic energy. In addition to that, the mantle forces which broke it off from the Australian plate are pushing it north. It is likely getting some additional impetus from the adjacent African plate. The iceberg model therefore has some validity, but is not the whole story. Share Improve this answer Follow answered Nov 9 '19 at 17:41 Michael WalsbyMichael Walsby 4,37311 gold badge55 silver badges1212 bronze badges $\endgroup$ 2 4 $\begingroup$ The kinetic energy of the Indian plate was about the energy you get from eating a small candy bar. $\endgroup$ – Keith McClary Nov 9 '19 at 19:53 $\begingroup$ Now I'm curious enough to calculate the kinetic energy of a slow moving continental plate. That said, I think the idea is still accurate, though I'd say momentum rather than kinetic energy. The momentum, calculated based on the drift and mass of the plate but maintained by the convection below, was/is sufficient enough to create the Himalayas. Calculate the energy required to create the Himalayas, divide by 30 million years (give or take), be sure to convert your answer to candybars. ;-) While that may sound glib, I like both the answer and the comment. I'd change to momentum though. $\endgroup$ – userLTK Nov 10 '19 at 7:05 Add a comment  |  Not the answer you're looking for? Browse other questions tagged plate-tectonics models crust or ask your own question. . The Overflow Blog The Bash is over, but the season lives a little longer Featured on Meta Providing a JavaScript API for userscripts Congratulations to the 59 sites that just left Beta Linked. 6 If people aim to reach the mantle, why don't they just use volcano craters? 2 Amount of Distortion at Continental Collisions Related. 11 Equatorial bulge and tectonic plates 7 Why do tectonic plates have a tendency to drift closer to the equator? 9 What tectonic structures delineate the split between the Australian and Indian tectonic plates? 14 Is continental drift caused by lava pushing the seabed apart? 6 The age of tectonic plates 5 The edges of the tectonic plates 9 Do Tectonic Plates Merge? 4 where are the poles of rotation of the tectonic plates located? 3 Slab-breakoff - always connected to continent/continent collision? Hot Network Questions . Can my proprietary app automatically download a GPL-licensed binary? Calculate the area (in %) for polygon categories? 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TitleMystery solved of how Earth's tectonic plates move solved: Plates 'float' on jelly-like layer of soft rock | Daily Mail Online
Urlhttps://www.dailymail.co.uk/sciencetech/article-2958542/Mystery-solved-Earth-s-tectonic-plates-solved-Plates-float-jelly-like-layer-soft-rock.html
DescriptionTogether with experts from the US and Japan, a team of geologists from Victoria University of Wellington, in New Zealand, produced their own seismic waves using dynamite to discover the unusual layer of rock
Date18 Feb 2015
Organic Position7
H1Mystery solved of how Earth's tectonic plates move solved: Plates 'float' on jelly-like layer of soft rock
H2Mystery solved of how Earth's tectonic plates move solved: Plates 'float' on jelly-like layer of soft rock
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H3THE JELLY-LIKE ROCK
HOW EARTH GOT ITS CRUST: TINY GRAINS LED TO PLATE FORMATION
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H2WithAnchorsMystery solved of how Earth's tectonic plates move solved: Plates 'float' on jelly-like layer of soft rock
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Hugh Jackman returns to the stage as Harold Hill in The Music Man on Broadway after having Covid   Valerie Bertinelli gave up on the scale after tying her self-worth to it... as she reveals losing Eddie Van Halen made her realize what truly mattered: 'The goal is to live in the moment'   Heidi Klum bares her G-string while dancing around in sweats... as she jumps on the 'whale tail' fashion trend   Spider-Man star Tom Holland reveals he pitched young James Bond origin film but was rejected by 007 bosses because concept 'didn't make sense'   Prince Andrew 'is trying to force through sale of his $23m Swiss chalet as Queen refuses to foot legal bills from Virginia Giuffre sex abuse case', sources say    Gucci Mane gifts wife Keyshia Ka'oir $1million in CASH during her birthday celebration as a 'push present' following birth of their son Ice   Bindi Irwin, 23, gets her first tattoos and reveals they are a tribute to her young family and late father Steve   Dakota Johnson shows off her new blonde highlights as she rocks double denim at Santa Monica studio   Ashley Roberts looks typically stylish in a bright red ensemble to head to Heart FM... before showing off her pert posterior in fun video in the studios   A hole in one! 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Rita Ora wears a lacy crop top as she and boyfriend Taika Waititi arrive in Sydney via private jet after a break in Byron Bay   Dame Joan Collins, 88, leaves dinner out looking glamorous in a fur coat after revealing her first husband drugged and raped her   Jessica Simpson considered 'borrowing against her homes' during determined two-year battle to buy back her billion-dollar Jessica Simpson Collection brand   Sharon Osbourne looks chic as she steps out in a blazer and jeans for a designer shopping trip in Beverly Hills   Rooney Mara tapped to play Audrey Hepburn in biopic from director of Call Me By Your Name   Advertisement From the Makers of Candy Crush. Farm Heroes Saga, the #4 Game on iTunes. Play it now! more GADGET REVIEWS. iPad Pro review: Apple takes the tablet to new heights (at a price) Apple's new iPad is blazingly fast, gorgeous to look at, and quite simply the best tablet out there - and for a lot of people, probably the best computer out there. 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The $250 beauty device that works like 'Photoshop for your face' Israeli beauty-tech firm Pollogen has launched its Geneo Personal device, which stimulates oxygen from beneath the skin's surface to give you a clearer, fresher face within minutes. iOS 12 review: The update that really will improve your iPhone Rather than cram in a plethora of new features, Apple's latest update is about boosting stability, with improvements in everything from FaceID and battery life. Naim Atom: The hifi that will change the way you listen to music It's eye-wateringly expensive at $2,999, but Naim's Uniti Atom is a revelation, an integrated amplifier than makes it easy to stream music at a quality you've probably never heard before. The $1,000 wireless speaker that really IS worth the price: Naim Mu-so Qb review Naim's incredible Mu-So Qb takes you back to the good old days - where the music captivates and enthralls, rather that simply being something in the background. The hi-tech $2,000 spin bike that really could change your life Peloton's hi-tech bike lets you stream live and on demand rides to your home - and it's one of the best examples of fitness technology out there - at a price. The best all in one wireless speaker you'll ever hear: Naim Mu-so review It might not be a name familiar to the US market, but Naim is a legendary British brand hoping to make a splash with the American launch of its $1499 Mu:So speaker. Advertisement From the Makers of Candy Crush. Farm Heroes Saga, the #4 Game on iTunes. Play it now! more Head Start to Home Cooked. Get Recipes more Download our iPhone app Download our Android app Next story. Shocking moment Brazilian cliff collapses on two tourist boats near popular sightseeing spot, killing at least seven people, seriously injuring nine and leaving three missing 553 comments 3 videos NEW ARTICLESHomeTop Share Back to top Home U.K. News Sports U.S. Showbiz Australia Femail Health Science Money Video Travel Shop DailyMailTV Sitemap Archive Video Archive Topics Index Mobile Apps Screensaver RSS Text-based site Reader Prints Our Papers Top of page Daily Mail Mail on Sunday This is Money Metro Jobsite Mail Travel Zoopla.co.uk Prime Location Published by Associated Newspapers Ltd Part of the Daily Mail, The Mail on Sunday & Metro Media Group dmg media Contact us How to complain Leadership Team Advertise with us Contributors Work with Us Terms Do not sell my info CA Privacy Notice Privacy policy & cookies Advertisement Advertisement      
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Result 9
TitlePlate Tectonics | National Geographic Society
Urlhttps://www.nationalgeographic.org/encyclopedia/plate-tectonics/
DescriptionThe theory of plate tectonics revolutionized the earth sciences by explaining how the movement of geologic plates causes mountain building, volcanoes, and earthquakes
Date10 Jun 2020
Organic Position8
H1Plate Tectonics
H2Resource Library | Encyclopedic Entry
Resource LibraryEncyclopedic Entry
H3San Andreas Fault
Educational Resources in Your Inbox
H2WithAnchorsResource Library | Encyclopedic Entry
Resource LibraryEncyclopedic Entry
BodyPlate Tectonics Plate Tectonics The theory of plate tectonics revolutionized the earth sciences by explaining how the movement of geologic plates causes mountain building, volcanoes, and earthquakes.Grades5 - 8SubjectsEarth Science, Geology, Oceanography, Geography, Physical Geography Image San Andreas Fault. Tectonic plate boundaries, like the San Andreas Fault pictured here, can be the sites of mountain-building events, volcanoes, or valley or rift creation. Photograph by Georg Gerster Twitter Facebook Pinterest Google Classroom Email Print Encyclopedic Entry Vocabulary Plate tectonics is a scientific theory that explains how major landforms are created as a result of Earth’s subterranean movements. The theory, which solidified in the 1960s, transformed the earth sciences by explaining many phenomena, including mountain building events, volcanoes, and earthquakes.In plate tectonics, Earth’s outermost layer, or lithosphere—made up of the crust and upper mantle—is broken into large rocky plates. These plates lie on top of a partially molten layer of rock called the asthenosphere. Due to the convection of the asthenosphere and lithosphere, the plates move relative to each other at different rates, from two to 15 centimeters (one to six inches) per year. This interaction of tectonic plates is responsible for many different geological formations such as the Himalaya mountain range in Asia, the East African Rift, and the San Andreas Fault in California, United States.The idea that continents moved over time had been proposed before the 20th century. However, a German scientist named Alfred Wegener changed the scientific debate. Wegener published two articles about a concept called continental drift in 1912. He suggested that 200 million years ago, a supercontinent he called Pangaea began to break into pieces, its parts moving away from one another. The continents we see today are fragments of that supercontinent. To support his theory, Wegener pointed to matching rock formations and similar fossils in Brazil and West Africa. In addition, South America and Africa looked like they could fit together like puzzle pieces. Despite being dismissed at first, the theory gained steam in the 1950s and 1960s as new data began to support the idea of continental drift. Maps of the ocean floor showed a massive undersea mountain range that almost circled the entire Earth. An American geologist named Harry Hess proposed that these ridges were the result of molten rock rising from the asthenosphere. As it came to the surface, the rock cooled, making new crust and spreading the seafloor away from the ridge in a conveyer-belt motion. Millions of years later, the crust would disappear into ocean trenches at places called subduction zones and cycle back into Earth. Magnetic data from the ocean floor and the relatively young age of oceanic crust supported Hess’s hypothesis of seafloor spreading.There was one nagging question with the plate tectonics theory: Most volcanoes are found above subduction zones, but some form far away from these plate boundaries. How could this be explained? This question was finally answered in 1963 by a Canadian geologist, John Tuzo Wilson. He proposed that volcanic island chains, like the Hawaiian Islands, are created by fixed “hot spots” in the mantle. At those places, magma forces its way upward through the moving plate of the sea floor. As the plate moves over the hot spot, one volcanic island after another is formed. Wilson’s explanation gave further support to plate tectonics. Today, the theory is almost universally accepted.   Tectonic plate boundaries, like the San Andreas Fault pictured here, can be the sites of mountain-building events, volcanoes, or valley or rift creation. Photograph by Georg Gerster asthenosphere Noun layer in Earth's mantle between the lithosphere (above) and the upper mantle (below). continental drift Noun the movement of continents resulting from the motion of tectonic plates. convection Noun transfer of heat by the movement of the heated parts of a liquid or gas. earthquake Noun the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity. geologist Noun person who studies the physical formations of the Earth. interaction Noun relationship between two or more forces, objects, or organisms. lithosphere Noun outer, solid portion of the Earth. Also called the geosphere. molten Adjective solid material turned to liquid by heat. plate tectonics Noun movement and interaction of the Earth's plates. seafloor spreading Noun rift in underwater mountain range where new oceanic crust is formed. subduction Noun process of one tectonic plate melting, sliding, or falling beneath another. supercontinent Noun ancient, giant landmass that split apart to form all the continents we know today. tectonic plate Noun massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate. volcano Noun an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions. Credits Media Credits. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited. Director . Tyson Brown, National Geographic Society Author . National Geographic Society Production Managers . Gina Borgia, National Geographic Society Jeanna Sullivan, National Geographic Society Program Specialists . Sarah Appleton, National Geographic Society Margot Willis, National Geographic Society Producer . Clint Parks Last Updated. June 10, 2020 User Permissions For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource. Media. If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media. Text. Text on this page is printable and can be used according to our Terms of Service. Interactives. Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. Related Resources Continental Drift versus Plate Tectonics A scientific idea that was initially ridiculed paved the way for the theory of plate tectonics, which explains how Earth’s continents move. View Article Plate Tectonics In 1977, after decades of tediously collecting and mapping ocean sonar data, scientists began to see a fairly accurate picture of the seafloor emerge. The Tharp-Heezen map illustrated the geological features that characterize the seafloor and became a crucial factor in the acceptance of the theories of plate tectonics and continental drift. Today, these theories serve as the foundation upon which we understand the geologic processes that shape the Earth.  View Video Plate Boundaries Earth’s tectonic plates fit together in a jigsaw puzzle of plate boundaries. View Article Related Resources Continental Drift versus Plate Tectonics A scientific idea that was initially ridiculed paved the way for the theory of plate tectonics, which explains how Earth’s continents move. View Article Plate Tectonics In 1977, after decades of tediously collecting and mapping ocean sonar data, scientists began to see a fairly accurate picture of the seafloor emerge. The Tharp-Heezen map illustrated the geological features that characterize the seafloor and became a crucial factor in the acceptance of the theories of plate tectonics and continental drift. Today, these theories serve as the foundation upon which we understand the geologic processes that shape the Earth.  View Video Plate Boundaries Earth’s tectonic plates fit together in a jigsaw puzzle of plate boundaries. View Article Educational Resources in Your Inbox Join our community of educators and receive the latest information on National Geographic's resources for you and your students. sign up Educational Resources in Your Inbox . Join our community of educators and receive the latest information on National Geographic's resources for you and your students. sign up
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Result 10
TitleTectonic plates float independently over the . - Toppr
Urlhttps://www.toppr.com/ask/en-ca/question/tectonic-plates-float-independently-over-the/
DescriptionTectonic plates are the rocky pieces of the Earth's crust. These pieces float on top of the melted rock of the mantle, another layer of the Earth found ...
Date
Organic Position9
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H2
H3
H2WithAnchors
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TitleTerri Mathews
Urlhttps://www.odu.edu/~tmmathew/geolgreece/plate.shtml
Description
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BodyA to Z Index  |  Directories Geology 195 home Minerals Igneous Rocks Sedimentary Rocks Metamorphic Rocks Plate Tectonics Plate Tectonic History Plate Tectonic Theory Plate Boundaries Volcanoes Volcanic Eruptions Volcanic Landscapes Earthquakes Coastlines Plate Tectonics The Earth is composed of several lithospheric plates that float atop the asthenosphere and are in constant motion. Plate Tectonics is essentially the study of the movement of the lithospheric plates and the consequences of that movement. The interior of the Earth is composed of different materials. Geologists know the composition of the Earth through study of seismic waves. The composition and density of the materials in the Earth cause energy waves to either slow down or speed up. By measuring the speed of seismic waves, scientists are able to determine the approximate location and composition of material within the Earth. The traditional model of the Earth has been refined: Lithosphere: includes the crust and upper mantle.  Is composed of a rigid solid. Asthenosphere: lower mantle, composed of "plastic solid" akin to playdoh. Outer core: liquid Inner core: solid     The term Lithosphere is Greek for "rock layer."   Comprised of the crust and uppermost part of the mantle, the lithosphere consists of cool, rigid and brittle materials. Most earthquakes originate in the lithosphere. Because it is close to the surface, both temperatures and pressures are relatively low in comparison to the other layers. Two different types of crustal material are found in the lithosphere: Continental Crust Crust is thicker and composed of light materials; both in color and density. Oceanic Crust Crust is thin and composed of more dense materials.       Mantle & Asthenosphere The Mantle lies below the Lithosphere. The mantle makes up 80% of the Earth�s material and is composed of an upper Mantle and a lower Mantle. The upper Mantle ranges from a depth of approximately 100 kilometers below the Earth�s surface to a depth of approximately 670 kilometers. The portion of the upper Mantle from a depth of 100 to approximately 350 kilometers below the surface is known as the Asthenosphere. The Asthenosphere is made up of semi-plastic rock. Since the Lithosphere has a lower density, it floats on top of the Asthenosphere similar to the way in which an iceberg or a block of wood floats on water. The lower mantle below the Asthenosphere is more rigid and less plastic.     Outer and Inner Core Below the Mantle is the outer core. The outer core is composed of a liquid. Within the liquid outer core sits the solid inner core. It is believed that the inner core is composed of iron and nickel. The inner core is spinning within the liquid outer core. It spins faster than the crust and this spin is believed responsible for the Earth's magnetic field. The table below shows the depths and properties of the earth's layers as well as the composition of those layers.        Continue on to "History of Plate Tectonics"  Maintained by: Terri Mathews Updated: 11/2/07 | © 2006 Old Dominion University, Norfolk, VA 23529 | Privacy
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Result 12
TitleThe Geological Society
Urlhttps://www.geolsoc.org.uk/Plate-Tectonics/Chap2-What-is-a-Plate/Plate-Movement
DescriptionAn online resource from the Geological Society, outlining the chemical and mechanical properties of tectonic plates and how they move
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TitleTectonic plates float individually over the A Crust class 7 social science CBSE
Urlhttps://www.vedantu.com/question-answer/tectonic-plates-float-individually-over-the-a-class-7-social-science-cbse-60b8c40db8d0151e8669e427
DescriptionTectonic plates float individually over the A Crust B Mantle C Inner core D Outer core
Date
Organic Position12
H1Tectonic plates float individually over the _____.A) CrustB) MantleC) Inner coreD) Outer core
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BodyTectonic plates float individually over the _____.A) CrustB) MantleC) Inner coreD) Outer coreAnswerVerified58.5k+ viewsHint: The tectonic plates are huge pieces of rocks in the form of plates that make up the crust and the upper mantle. The entire crust along with the upper mantle forms the lithosphere of the earth. The tectonic plates are hence part of the lithosphere of the earth. In other words, we can say that the lithosphere itself is broken into tectonic plates. Complete answer:The earth is divided into layers i.e. the crust, upper mantle, lower mantle, outer core and the inner core. As we know that the lower regions of the crust and the upper mantle together form the tectonic plates, this knowledge can be used to identify over which layer they must be floating.Now let us look into the given options:Option A) Crust – The crust is the uppermost or the outermost layer of the Earth. It is rocky and made up of tectonic plates. These plates either form the continents and are called continental plates, or they may form the ocean bed and be called the oceanic plates. The crust itself is part of the tectonic plate, hence we cannot say that the tectonic plate floats over the crust. Therefore, this option is wrong.Option B) Mantle – The mantle is the layer of silicate rock that behaves like a viscous liquid. Its uppermost layer forms the base of the crust and the tectonic plate. The lower mantle is the liquid region where the magma flows. On this sea of magma in the lower mantle, the tectonic plates float individually. Thus, this is the correct option.Option C) Inner Core – The inner core lies below the outer core and is a solid hardball with a radius of 1220 kilometres. This region is also believed to be made of iron and nickel and some other alloys. This region is solid, unlike the mantle, because of the extremely high pressure from the weight of the earth. Since it is solid, tectonic plates cannot float on it. Thus, this option is also incorrect.Option D) Outer Core – The lower mantle transitions into the outer core which is also a liquid layer. It is composed of iron and nickel, but the temperature here is so high that these metals exist in their molten state. This layer has no contact with the tectonic plates. Therefore, this option is incorrect.Thus, the correct answer is Option (B) Tectonic plates float individually over the mantle.Note: The sea of magma in the lower mantle, on which the tectonic plates float, is known as the asthenosphere. The upper boundary of the asthenosphere is called the lithosphere-asthenosphere boundary or LAB and is a well-defined region. The lower boundary of the asthenosphere, however, is not well defined and it merges into the lower mantle. The presence of this region was suspected in 1926 and confirmed in 1960.NCERT Book SolutionsNCERTNCERT SolutionsNCERT Solutions for Class 12 MathsNCERT Solutions for Class 12 PhysicsNCERT Solutions for Class 12 ChemistryNCERT Solutions for Class 12 BiologyNCERT Solutions for Class 11 MathsNCERT Solutions for Class 11 PhysicsNCERT Solutions for Class 11 ChemistryNCERT Solutions for Class 11 BiologyNCERT Solutions for Class 10 MathsNCERT Solutions for Class 10 ScienceNCERT Solutions for Class 9 MathsNCERT Solutions for Class 9 ScienceReference Book SolutionsHC Verma SolutionsRD Sharma SolutionsRD Sharma Class 10 SolutionsRD Sharma Class 9 SolutionsRS Aggarwal SolutionsRS Aggarwal Class 10 SolutionsICSE Class 10 solutionsLakmir Singh SolutionsText Book SolutionsImportant FormulasMath FormulaPhysics FormulaChemistry FormulaQuestion PapersPrevious Year Question PaperCBSE Previous Year Question Paper for Class 10CBSE Previous Year Question Paper for Class 12Sample PaperCBSE Class 12 Sample PapersCBSE Class 10 Sample PapersICSE Class 10 Sample PapersMathsPhysicsChemistryBiologyPractice QuestionsExamsIIT JEENEETAIIMSKVPYKCETCOMEDKBITSATVITEEEOLYMPIADSTATE BOARDSQuick LinksJEE Crash CourseNCERT BooksCBSE BoardCBSE SyllabusICSE BoardFree Study MaterialsQuestion & AnswersRevision NotesImportant QuestionsWorksheetsChild SafetyTerms and ConditionsPrivacy PolicyToll Free:1800-120-456-456Mobile:+91 988-660-2456(Mon-Sun: 9am - 11pm IST)Questions?Chat with us
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TitleContinental Movement by Plate Tectonics | manoa.hawaii.edu/ExploringOurFluidEarth
Urlhttps://manoa.hawaii.edu/exploringourfluidearth/node/1348
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H1Exploring Our Fluid Earth
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Teaching Science as Inquiry
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Earth’s Tectonic Plates
Voice of the Sea: Volcanoes
Activity: Modeling Plate Spreading
Activity: Earth’s Plates
Compare-Contrast-Connect: Volcanoes
Activity: Continental Movement over Long Time Scales
Evidence for the Movement of Continents
Practices of Science: Opinion, Hypothesis & Theory
Seafloor Spreading at Mid-Ocean Ridges
Hot Spots
Question Set: Ocean Floor and Volcanoes
Further Investigations: Continental Movement by Plate Tectonics
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Exploring Our Fluid Earth
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Professional Development
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H3NGSS Performance Expectations:
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Paid Content
H2WithAnchorsheader
Teaching Science as Inquiry
advanced_search_link
Main menu
Earth’s Tectonic Plates
Voice of the Sea: Volcanoes
Activity: Modeling Plate Spreading
Activity: Earth’s Plates
Compare-Contrast-Connect: Volcanoes
Activity: Continental Movement over Long Time Scales
Evidence for the Movement of Continents
Practices of Science: Opinion, Hypothesis & Theory
Seafloor Spreading at Mid-Ocean Ridges
Hot Spots
Question Set: Ocean Floor and Volcanoes
Further Investigations: Continental Movement by Plate Tectonics
Table of Contents
Exploring Our Fluid Earth
Partner Organizations
Professional Development
Paid Content
BodyExploring Our Fluid Earth Teaching Science as Inquiry.   About this SiteStart Here Start Here Community Frequently Asked Questions About This Site Authors & Partners Staff Bios Table of ContentsPhysicalWayfinding and NavigationWeird Science: Animal Migration Traditional Ways of Knowing: Polynesian Stick Charts Weird Science: Compasses and Magnetic North Further Investigations: Wayfinding and Navigation Activity: Floating Magnetic Compass Chemical Biological Standards Alignment advanced_search_link. Use Advanced Search to search by activities, standards, and more. Main menu. About this Site Table of Contents HomePhysicalOcean FloorContinental Movement by Plate Tectonics Printer Friendly Continental Movement by Plate Tectonics NGSS Performance Expectations:. MS-ESS1-4 Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth's 4.6-billion-year-old history. MS-ESS2-3 Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions. HS-ESS1-5 Evaluate evidence of the past and current movements of continental and oceanic crust and the theory of plate tectonics to explain the ages of crustal rocks. HS-ESS2-3 Develop a model based on evidence of Earth’s interior to describe the cycling of matter by thermal convection. The content and activities in this topic will work towards building an understanding of how the surface of the earth has changed over time by the process of plate tectonics.Earth’s Tectonic Plates. The earth’s crust is broken into separate pieces called tectonic plates (Fig. 7.14). Recall that the crust is the solid, rocky, outer shell of the planet. It is composed of two distinctly different types of material: the less-dense continental crust and the more-dense oceanic crust. Both types of crust rest atop solid, upper mantle material. The upper mantle, in turn, floats on a denser layer of lower mantle that is much like thick molten tar. Each tectonic plate is free-floating and can move independently. Earthquakes and volcanoes are the direct result of the movement of tectonic plates at fault lines. The term fault is used to describe the boundary between tectonic plates. Most of the earthquakes and volcanoes around the Pacific ocean basin—a pattern known as the “ring of fire”—are due to the movement of tectonic plates in this region. Other observable results of short-term plate movement include the gradual widening of the Great Rift lakes in eastern Africa and the rising of the Himalayan Mountain range. The motion of plates can be described in four general patterns: Collision: when two continental plates are shoved together Subduction: when one plate plunges beneath another (Fig. 7.15) Spreading: when two plates are pushed apart (Fig. 7.15) Transform faulting: when two plates slide past each other (Fig. 7.15)   The rise of the Himalayan Mountain range is due to an ongoing collision of the Indian plate with the Eurasian plate. Earthquakes in California are due to transform fault motion.   Geologists have hypothesized that the movement of tectonic plates is related to convection currents in the earth’s mantle. Convection currents describe the rising, spread, and sinking of gas, liquid, or molten material caused by the application of heat. An example of convection current is shown in Fig. 7.16. Inside a beaker, hot water rises at the point where heat is applied. The hot water moves to the surface, then spreads out and cools. Cooler water sinks to the bottom. Earth’s solid crust acts as a heat insulator for the hot interior of the planet. Magma is the molten rock below the crust, in the mantle. Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth’s crust.   Voice of the Sea Voice of the Sea: Volcanoes. Activity Activity: Modeling Plate Spreading. Simulate tectonic plate spreading by modeling convection currents that occur in the mantle. Activity Activity: Earth’s Plates. Examine a map of the earth’s tectonic plates. Based on evidence that has been found at plate boundaries, make some hypotheses about the movement of those plates. Compare-Contrast-Connect Compare-Contrast-Connect: Volcanoes.   The earth has changed in many ways since it first formed 4.5 billion years ago. The locations of Earth’s major landmasses today are very different from their locations in the past (Fig. 7.18). They have gradually moved over the course of hundreds of millions of years—alternately combining into supercontinents and pulling apart in a process known as continental drift. The supercontinent of Pangaea formed as the landmasses gradually combined roughly between 300 and 100 mya. The planet’s landmasses eventually moved to their current positions and will continue to move into the future. Plate tectonics is the scientific theory explaining the movement of the earth’s crust. It is widely accepted by scientists today. Recall that both continental landmasses and the ocean floor are part of the earth’s crust, and that the crust is broken into individual pieces called tectonic plates (Fig. 7.14). The movement of these tectonic plates is likely caused by convection currents in the molten rock in Earth’s mantle below the crust. Earthquakes and volcanoes are the short-term results of this tectonic movement. The long-term result of plate tectonics is the movement of entire continents over millions of years (Fig. 7.18). The presence of the same type of fossils on continents that are now widely separated is evidence that continents have moved over geological history.   Activity Activity: Continental Movement over Long Time Scales. Evaluate and interpret several lines of evidence for continental drift over geological time scales. Evidence for the Movement of Continents. The shapes of the continents provide clues about the past movement of the continents. The edges of the continents on the map seem to fit together like a jigsaw puzzle. For example, on the west coast of Africa, there is an indentation into which the bulge along the east coast of South America fits. The shapes of the continental shelves—the submerged landmass around continents—shows that the fit between continents is even more striking (Fig. 7.19). Some fossils provide evidence that continents were once located nearer to one another than they are today. Fossils of a marine reptile called Mesosaurus (Fig. 7.20 A) and a land reptile called Cynognathus (Fig. 7.20 B) have been found in South America and South Africa. Another example is the fossil plant called Glossopteris, which is found in India, Australia, and Antarctica (Fig. 7.20 C). The presence of identical fossils in continents that are now widely separated is one of the main pieces of evidence that led to the initial idea that the continents had moved over geological history. Evidence for continental drift is also found in the types of rocks on continents. There are belts of rock in Africa and South America that match when the ends of the continents are joined. Mountains of comparable age and structure are found in the northeastern part of North America (Appalachian Mountains) and across the British Isles into Norway (Caledonian Mountains). These landmasses can be reassembled so that the mountains form a continuous chain.   Paleoclimatologists (paleo = ancient; climate = long term temperature and weather patterns) study evidence of prehistoric climates. Evidence from glacial striations in rocks, the deep grooves in the land left by the movement of glaciers, shows that 300 mya there were large sheets of ice covering parts of South America, Africa, India, and Australia. These striations indicate that the direction of glacial movement in Africa was toward the Atlantic ocean basin and in South America was from the Atlantic ocean basin. This evidence suggests that South America and Africa were once connected, and that glaciers moved across Africa and South America. There is no glacial evidence for continental movement in North America, because there was no ice covering the continent 300 million years ago. North America may have been nearer the equator where warm temperatures prevented ice sheet formation.   Practices of Science Practices of Science: Opinion, Hypothesis & Theory. Seafloor Spreading at Mid-Ocean Ridges. Convection currents drive the movement of Earth’s rigid tectonic plates in the planet’s fluid molten mantle. In places where convection currents rise up towards the crust’s surface, tectonic plates move away from each other in a process known as seafloor spreading (Fig. 7.21). Hot magma rises to the crust’s surface, cracks develop in the ocean floor, and the magma pushes up and out to form mid-ocean ridges. Mid-ocean ridges or spreading centers are fault lines where two tectonic plates are moving away from each other.   Mid-ocean ridges are the largest continuous geological features on Earth. They are tens of thousands of kilometers long, running through and connecting most of the ocean basins. Oceanographic data reveal that seafloor spreading is slowly widening the Atlantic ocean basin, the Red Sea, and the Gulf of California (Fig. 7.22).   The gradual process of seafloor spreading slowly pushes tectonic plates apart while generating new rock from cooled magma. Ocean floor rocks close to a mid-ocean ridge are not only younger than distant rocks, they also display consistent bands of magnetism based on their age (Fig. 7.22.1). Every few hundred thousand years the earth’s magnetic field reverses, in a process known as geomagnetic reversal. Some bands of rock were produced during a time when the polarity of the earth’s magnetic field was the reverse of its current polarity. Geomagnetic reversal allows scientists to study the movement of ocean floors over time.   Paleomagnetism is the study of magnetism in ancient rocks. As molten rock cools and solidifies, particles within the rocks align themselves with the earth’s magnetic field. In other words, the particles will point in the direction of the magnetic field present as the rock was cooling. If the plate containing the rock drifts or rotates, then the particles in the rock will no longer be aligned with the earth’s magnetic field. Scientists can compare the directional magnetism of rock particles to the direction of the magnetic field in the rock’s current location and estimate where the plate was when the rock formed (Fig. 7.22.1).   Seafloor spreading gradually pushes tectonic plates apart at mid-ocean ridges. When this happens, the opposite edge of these plates push against other tectonic plates. Subduction occurs when two tectonic plates meet and one moves underneath the other (Fig. 7.23). Oceanic crust is primarily composed of basalt, which makes it slightly denser than continental crust, which is composed primarily of granite. Because it is denser, when oceanic crust and continental crust meet, the oceanic crust slides below the continental crust. This collision of oceanic crust on one plate with the continental crust of a second plate can result in the formation of volcanoes (Fig. 7.23). As the oceanic crust enters the mantle, pressure breaks the crustal rock, heat from friction melts it, and a pool of magma develops. This thick magma, called andesite lava, consists of a mixture of basalt from the oceanic crust and granite from the continental crust. Forced by tremendous pressure, it eventually flows along weaker crustal channels toward the surface. The magma periodically breaks through the crust to form great, violently explosive composite volcanoes—steep-sided, cone-shaped mountains like those in the Andes at the margin of the South American Plate (Fig. 7.23).   Continental collision occurs when two plates carrying continents collide. Because continental crusts are composed of the same low-density material, one does not sink under the other. During collision, the crust moves upward, and the crustal material folds, buckles, and breaks (Fig. 7.24 A). Many of the world’s largest mountain ranges, like the Rocky Mountains and the Himalayan Mountains, were formed by the collision of continents resulting in the upward movement of the earth’s crust (Fig. 7.24 B). The Himalayan Mountains were formed by the collision between Indian and Eurasian tectonic plates.     Ocean trenches are steep depressions in the seafloor formed at subduction zones where one plate moves downward beneath another (Fig. 7.24 C). These trenches are deep (up to 10.8 km), narrow (about 100 km), and long (from 800 to 5,900 km), with very steep sides. The deepest ocean trench is the Mariana Trench just east of Guam. It is located at the subduction zone where the Pacific plate plunges underneath the edge of the Filipino plate. Subduction zones are also sites of deepwater earthquakes.   Transform faults are found where two tectonic plates move past each other. As the plates slide past one another, there is friction, and great tension can build up before slippage occurs, eventually causing shallow earthquakes. People living near the San Andreas Fault, a transfom fault in California, regularly experience such quakes.   Hot Spots. Recall that some volcanoes form near plate boundaries, particularly near subduction zones where oceanic crust moves underneath continental crust (Fig. 7.24). However, some volcanoes form over hot spots in the middle of tectonic plates far away from subduction zones (Fig. 7.25). A hot spot is a place where magma rises up from the earth’s mantle toward the surface crust. When magma erupts and flows at the surface, it is called lava. The basalt lava commonly found at hot spots flows like hot, thick syrup and gradually forms shield volcanoes. A shield volcano is shaped like a dome with gently sloping sides. These volcanoes are much less explosive than the composite volcanoes formed at subduction zones.   Some shield volcanoes, such as the islands in the Hawaiian archipelago, began forming on the ocean floor over a hot spot. Each shield volcano grows slowly with repeated eruptions until it reaches the surface of the water to form an island (Fig. 7.25). The highest peak on the island of Hawai‘i reaches 4.2 km above sea level. However, the base of this volcanic island lies almost 7 km below the water surface, making Hawai‘i’s peaks some of the tallest mountains on Earth—much higher than Mount Everest. Almost all of the mid-Pacific and mid-Atlantic ocean basin islands formed in a similar fashion over volcanic hot spots. Over millions of years as the tectonic plate moves, a volcano that was over the hot spot moves away, ceases to erupt, and becomes extinct (Fig. 7.25). Erosion and subsidence (sinking of the earth’s crust) eventually causes older islands to sink below sea level. Islands can erode through natural processes such as wind and water flow. Reefs continue to grow around the eroded land mass and form fringing reefs, as seen on Kauaʻi in the main Hawaiian Islands (Fig. 7.26).   Eventually all that remains of the island is a ring of coral reef. An atoll is a ring-shaped coral reef or group of coral islets that has grown around the rim of an extinct submerged volcano forming a central lagoon (Fig. 7.27). Atoll formation is dependent on erosion of land and growth of coral reefs around the island. Coral reef atolls can only occur in tropical regions that are optimal for coral growth. The main Hawaiian Islands will all likely become coral atolls millions of years into the future. The older Northwestern Hawaiian Islands, many of which are now atolls, were formed by the same volcanic hot spot as the younger main Hawaiian Islands. Question Set Question Set: Ocean Floor and Volcanoes. Further Investigations Further Investigations: Continental Movement by Plate Tectonics. Table of Contents:. Continental Movement by Plate Tectonics Activities:  Activity: Modeling Plate Spreading Activity: Earth’s Plates Activity: Continental Movement over Long Time Scales Special Features:  Voice of the Sea: Volcanoes Compare-Contrast-Connect: Volcanoes Practices of Science: Opinion, Hypothesis & Theory Question Set: Ocean Floor and Volcanoes Further Investigations: Continental Movement by Plate Tectonics Representative Image:  Table of Contents. PhysicalWorld OceanIntroduction to the World Ocean Ocean Basins and ContinentsActivity: Locate Ocean Basins and Continents Weird Science: The Southern Ocean Basin Weird Science: Continent Confusion Further Investigations: Ocean Basins and Continents Map DistortionCompare-Contrast-Connect: Maps Through Time Activity: How Much Water? Practices of Science: Scientific Error Practices of Science: Precision vs. Accuracy Compare-Contrast-Connect: Map Orientation and Shape Further Investigations: Map Distortion Locating Points on a GlobeWeird Science: Polar Circles and Tropical Circles Weird Science: The Prime Meridian and Time Zones Compare-Contrast-Connect: Converting Decimal Degrees Activity: Locating Points on a Globe Activity: Mapping the Globe Activity: Pacific Scavenger Hunt Further Investigations: Locating Points on a Globe Density EffectsIntroduction to Density Density, Temperature, and SalinityWeird Science: Macroscopic Changes in Liquid Water Volume Compare-Contrast-Connect: Human Density Practices of Science: Making Simulated Seawater Activity: Density Bags Voice of the Sea: Submarines and Ocean Circulation Weird Science: Floating Aircraft Carriers Further Investigations: Density, Temperature, and Salinity Ocean Temperature ProfilesActivity: Water Layers Compare-Contrast-Connect: Seasonal Variation in Ocean Temperature Vertical Profiles Further Investigations: Ocean Temperature Profiles Measuring SalinityQuestion Set: Using a Hydrometer to Determine Density and Salinity Weird Science: Salty Lakes Weird Science: Hydrometers and Specific Gravity Activity: Measuring Salinity Further Investigations: Measuring Salinity Density Driven CurrentsActivity: Gravitational Currents Activity: Modeling Thermohaline Water Flow Climate Connection: Global Conveyor Belt Practices of Science: Using Models Further Investigations: Density Driven Currents Circulation in Marginal Seas and EstuariesQuestion Set: Circulation in Marginal Seas and Estuaries Further Investigations: Circulation in Marginal Seas and Estuaries Atmospheric EffectsIntroduction to Atmospheric Effects Wind FormationQuestion Set: Wind Formation and Precipitation Activity: The Coriolis Effect Further Investigations: Wind Formation Wind SystemsWeird Science: Equator Mythology Climate Connection: Monsoons Question Set: Prevailing Winds Further Investigations: Wind Systems Ocean Surface CurrentsQuestion Set: Wind Generated Currents Weird Science: Marine Debris and Oceanic Gyres Weird Science: From Observation to Inference to Testable Hypothesis Compare-Contrast-Connect: Biogeography Activity: Current Observation Methods Activity: Build a Drifter Further Investigations: Ocean Surface Currents Effect of Surface CurrentsClimate Connections: Sea Level Rise Activity: Sea Level and Gravitational Flow Question Set: Effects of Surface Currents Further Investigation: Effects of Surface Currents Climate and AtmosphereActivity: Climate Comparison Question Set: Climate and the Atmosphere Activity: Stability of Water Layers Further Investigations: Climate and the Atmosphere WavesIntroduction to Waves Wave and Wave PropertiesCompare-Contrast-Connect: The Origin and Diversity of Surf Crafts Compare-Contrast-Connect: Estimating Wave Height Activity: Watching Waves Weird Science: Communicating Wave Sizes—Local Scale Question Set: Waves and Wave Properties Activity: Make Your Own Wave Activity: Standing Waves Further Investigations: Waves and Wave Properties Sea StatesQuestion Set: Sea States Weird Science: Rogue Waves Activity: Wave Interference Question Set: Storms Voice of the Sea: Surf Forcasting Compare-Contrast-Connect: Swell Forecasting From Weather Patterns Further Investigations: Sea States Wave Energy and Wave Changes with DepthClimate Connections: Wave Power Activity: Orbital Motion of Waves Activity: Simulate Deep-Water, Transitional, and Shallow-Water Waves Further Investigations: Wave Energy and Wave Changes with Depth Coastal InteractionsIntroduction to Coastal Interactions Wave-Coast InteractionsVoice of the Sea: Lidar Weird Science: Extreme Surf Activity: Locating Surf Breaks Activity: Beach Profile Mapping Activity: Wave Patterns in a Ripple Tank Practices of Science: Variables Activity: Coastline Wave Tank Further Investigations: Wave-Coast Interactions Beaches and SandWeird Science: Parrotfish and Sand Activity: Observing Sand Activity: Beach Sand Survey Voice of the Sea: Saving Hawaii’s Beaches Activity: Coastal Engineering Further Investigations: Beaches and Sand TsunamisQuestion Set: Tsunamis Voice of the Sea: Engineering Tsunami Resilience Activity: Sendai, Japan Tsunami Animation Activity: Tsunami Warning System Poster Further Investigations: Tsunamis TidesIntroduction to Tides Tidal MovementsWeird Science: The Origin and Features of the Moon Activity: Kinesthetic Model of the Sun, the Moon, and the Earth Weird Science: Eclipses Weird Science: Tidal Locking—Why the Man in the Moon Can Always See You Further Investigations: Tidal Movements Tide Formation—Gravitational PullVoice of the Sea: Sir Isaac Newton Weird Science: Phases of the Moon Activity: Tide Formation—Gravitational Pull Further Investigations: Tide Formation—Gravitational Pull Tide Formation—Tide HeightQuestion Set: Moon Declination and Tide Height Weird Science: Seasons Practices of Science: Scaling Activity: Modeling Amphidromic Points Weird Science: Extreme Tidal Ranges Question Set: Elliptical Orbits and Geography Further Investigations: Tide Formation—Tide Height Tide PredictionCompare-Contrast-Connect: Measuring Tides Activity: Tide Prediction Further Investigations: Tide Prediction Tide Patterns and CurrentsClimate Connection: Tidal Power Weird Science: Tidal Bores: The Longest Waves Ever Ridden Activity: Tidal Patterns Across the Globe Further Investigations: Tidal Patterns and Currents Ocean FloorIntroduction to the Ocean Floor Layers of EarthQuestion Set: Layers of Earth Compare-Contrast-Connect: Seismic Waves and Determining Earth’s Structure Activity: Modeling Earth’s Dimensions Weird Science: Earth’s Magnetic Field Further Investigations: Layers of Earth Change Over TimePractices of Science: How Do We Know How Old It Is Activity: Timeline of Earth Compare-Contrast-Connect: Mass Extinctions in Earth’s History Question Set: Change Over Time Further Investigations: Change Over Time Continental Movement by Plate TectonicsVoice of the Sea: Volcanoes Activity: Modeling Plate Spreading Activity: Earth’s Plates Compare-Contrast-Connect: Volcanoes Activity: Continental Movement over Long Time Scales Practices of Science: Opinion, Hypothesis & Theory Question Set: Ocean Floor and Volcanoes Further Investigations: Continental Movement by Plate Tectonics Seafloor Features and Mapping the SeafloorActivity: Interpreting Contour Maps Activity: Contour and Raised Relief Maps Activity: Contour Lines and Nautical Charts Activity: Simulating Sonar Mapping of The Ocean Floor Question Set: Using Technology to Map the Ocean Floor Further Investigations: Seafloor Features and Mapping the Seafloor The Oceanic Crust and SeafloorActivity: Crayon Rock Cycle Activity: Sediment Cores Question Set: The Oceanic Crust and Seafloor Compare-Contrast-Connect: Minerals and Rocks Weird Science: Oceanic Microfossils Further Investigations: The Oceanic Crust and Seafloor Navigation and TransportationIntroduction to Navigation and Transportation Wayfinding and NavigationVoice of the Sea: Tara Oceans Expeditions Weird Science: Animal Migration Traditional Ways of Knowing: Polynesian Stick Charts Activity: Floating Magnetic Compass Activity: Determine Your Latitude Traditional Ways of Knowing: Estimating Latitude Voice of the Sea: Traditional Voyaging Activity: Navigating with Nautical Charts Question Set: Wayfinding and Navigation Further Investigations: Wayfinding and Navigation Transportation and Ship DesignActivity: Boat Floatation Weird Science: Giant Ships and Canals Question Set: Transportation and Ship Design Activity: Ship Stability Activity: Evaluating Cargo Transportation Activity: Design a Ship Activity: Ship Speed and Efficiency Further Investigations: Transportation and Ship Design Ocean DepthsIntroduction to Ocean Depths Light in the OceanActivity: Colors of the Light Spectrum Practices of Science: Underwater Photography and Videography Question Set: Light in the Ocean Further Investigations: Light in the Ocean PressureActivity: The Effects of Pressure Compare-Contrast-Connect: The Deep Divers Question Set: Pressure Further Investigations: Pressure Depth ZonesCompare-Contrast-Connect: Life in the Depth Zones Question Set: Depth Zones Further Investigations: Depth Zones Diving TechnologyPractices of Science: Blue Water Diving Activity: Dive Planning Question Set: Diving Technology Further Investigations: Diving Technology BiologicalWhat is AliveIntroduction to What is Alive? Properties of LifeActivity: Is It Alive? Question Set: Properties of Life Weird Science: Cryptobiosis Practices of Science: The Language of Science Further Investigations: Properties of Life Evolution by Natural SelectionWeird Science: Species Flocks Activity: Modeling Evolution Practices of Science: Communication & Collaboration in the Scientific Community Weird Science: Deadly Flu Activity: Simulate Natural Selection Compare-Contrast-Connect: Natural and Sexual Selection Compare-Contrast-Connect: Marsupial Mammals versus Placental Mammals Practices of Science: Common Misconceptions on Evolution Further Investigations: Evolution by Natural Selection Classification of LifeActivity: What’s in a Name? Activity: Identifying Butterflyfish Using Dichotomous Keys Question Set: Classification of Life Further Investigations: Classification of Life Aquatic Plants and AlgaeIntroduction to Algae and Aquatic Plants What Are Aquatic Plants and AlgaeQuestion Set: What are Aquatic Plants and Algae Further Investigations: What are Aquatic Plants and Algae Structure and FunctionWeird Science: Penicillin and the Cell Wall Practices of Science: Microscope Use Weird Science: Kleptoplasty Activity: Identifying Cells and Cell Parts Using a Microscope Activity: Structure of Algae with Comparisons to Vascular Plants Further Investigations: Where are photosynthetic autotrophs found in your life? Evidence of Common Ancestry and DiversityWeird Science: Serial Endosymbiosis Question Set: Evidence of Common Ancestry and Diversity Activity: Algae Identification with Dichotomous Key Activity: Making Algae Presses Further Investigations: Evidence of Common Ancestry and Diversity Energy AcquisitionWeird Science: Hydrothermal Vents and Cold Seeps Activity: Effect of Light Wavelengths on Photosynthesis Further Investigations: Energy Acquisition AdaptationsQuestion Set: Adaptations Growth, Development, and ReproductionWeird Science: Invasive Algae Voice of the Sea: Macroalgae Attack! Voice of the Sea: Sammy's Reef Question Set: Growth, Development, and Reproduction Further Investigations: Growth Development and Reproduction BehaviorQuestion Set: Behavior Further Investigations: Behavior InvertebratesIntroduction to Invertebrates What is an Invertebrate?Weird Science: Cool Invertebrate Facts Question Set: What is an Invertebrate? Further Investigations: What is an Invertebrate? Evidence of Common Ancestry and DiversityQuestion Set: Evidence of Common Ancestry and Diversity Further Investigations: Evidence of Common Ancestry and Diversity Structure and FunctionActivity: Invertebrate Phylum Project Question Set: Structure and Function Further Investigations: Structure and Function Phylum PoriferaQuestion Set: Phylum Porifera Further Investigation: Phylum Porifera Phylum CnidariaVoice of the Sea: Jellyfish Lake Weird Science: Deadly Box Jellyfish Voice of the Sea: Corals Activity: Nematocysts Activity: Corals Question Set: Phylum Cnidaria Further Investigations: Phylum Cnidaria Worms: Phyla Platyhelmintes, Nematoda, and AnnelidaQuestion Set: Worms Further Investigations: Worms Phylum MolluscaVoice of the Sea: Snails Activity: Gastropod Shell Description Traditional Ways of Knowing: ʻOpihi in Hawaiʻi Activity: Squid Dissection Question Set: Phylum Mollusca Further Investigations: Phylum Mollusca Phylum ArthropodaWeird Science: An Inordinate Fondness for Beetles Activity: Aquatic Invertebrate Behavior Question Set: Phylum Arthropoda Further Investigations: Phylum Arthropoda Phylum EchinodermataVoice of the Sea: Stella’s Sea Urchins Voice of the Sea: Crown of Thorns Activity: Comparing Echinoderms Question Set: Phylum Echinodermata Further Investigations: Phylum Echinodermata Phylum ChordataActivity: Tunicate Life History Question Set: Phylum Chordata Further Investigations: Phylum Chordata FishIntroduction to Fish What is a FishVoice of the Sea: Deep Sea Lab Activity: Draw a Fish Activity: What is a Fish Question Set: What is a fish Further Investigations: What is a Fish Evidence of Common Ancestry and Diversity - FishVoice of the Sea: Farming Fish Compare-Contrast-Connect: Comparing Different Classes of Fish: Sharks verses Bony Fish Question Set: Evidence of Common Ancestry and Diversity - Fish Structure and Function - FishActivity: Fish Printing for Form and Function Practices of Science: Scientific Drawing Activity: Observing Fish Scales Activity: Fish Terminology Behavior and Sensory Systems - FishActivity: Fish Behavior Energy Acquisition, Growth, Development, and Reproduction - FishVoice of the Sea: Fish Spawning Aggregations Voice of the Sea: Food Webs of the Open Ocean Voices of the Sea: Fish No Take Question Set: Energy Acquisition, Growth, and Reproduction - Fish Further Investigations: Energy Acquisition, Growth, and Reproduction - Fish Adaptations - FishCompare-Contrast-Connect: Adaptations to Extreme Environments Question Set: Adaptations - FishVoice of the Sea: Shark and Tuna Tagging Voice of the Sea: Strange Fish of The Deep Further Investigations: Adaptations - Fish Amphibians Reptiles and BirdsIntroduction to Amphibians, Reptiles, and Birds AmphibiansWeird Science: Amphibians in Decline Activity: Identifying Amphibians Question Set: Amphibians Further Investigations: Amphibians ReptilesActivity: Identifying Sea Turtles Activity: In Cold Blood Question Set: Reptiles Further Investigations: Reptiles BirdsActivity: Local Bird Guide Activity: Alert and Escape Behavior Question Set: Birds Further Investigations: Birds MammalsIntroduction to Mammals What is a Mammal?Question Set: What is a Mammal? Further Investigations: What is a Mammal? Evidence of Common Ancestry and DiversityCompare-Contrast-Connect: Marine Mammal Decline and Conservation Question Set: Evidence of Common Ancestry and Diversity Further Investigations: Evidence of Common Ancestry and Diversity Structure and FunctionActivity: Identifying Cetaceans Activity: Measuring Whale Dimensions Question Set: Structure and Function Further Investigations: Structure and Function AdaptationsActivity: Insulation in Marine Mammals Question Set: Adaptations Further Investigations: Adaptations Energy AcquisitionActivity: Whale Feeding Strategies Question Set: Energy Acquisition Further Investigation: Mammals Energy Acquisition Growth, Development and ReproductionQuestion Set: Growth, Development and Reproduction Further Investigations: Growth, Development and Reproduction BehaviorQuestion Set: Behavior Further Investigations: Behavior Marine Microbes ChemicalMatterIntroduction to Matter Definition of MatterActivity: Matter Concept Map Further Investigations: Definition of Matter Properties of MatterPractices of Science: Interpreting Safety Information Weird Science: Chemical Symbols Activity: Where is Water? Practices of Science: False Positives and False Negatives Weird Science: We Are Water Question Set: Properties of Matter Further Investigations: Properties of Matter Composing and Decomposing MatterActivity: Electrolysis of Water Activity: Hoffman Apparatus Weird Science: John Dalton, Atomic Theory and Color Blindness Further Investigations: Composing and Decomposing Matter Chemistry and SeawaterIntroduction to Chemistry and Seawater The Salty SeaActivity: Recovering Salts From Seawater Weird Science: Types of Salts in Seawater Weird Science: Salt is Essential to Life Traditional Ways of Knowing: Salt Harvesting Weird Science: Pure Water and Water Mixtures Further Investigations: The Salty Sea The Nature and Organization of ElementsActivity: Organizing the Elements Compare-Contrast-Connect: The History of Mendeleev's Table Further Investigations: The Nature and Organization of Elements Atoms, Molecules, and CompoundsActivity: Electrostatic Forces Question Set: Atoms, Molecules, and Compounds Further Investigations: Atoms, Molecules, and Compounds Elemental AbundanceActivity: Concentration and Dilution Question Set: Concentration Practices of Science: “Parts per” Notation Weird Science: Compare Your Sense of Smell to a Shark’s Sense of Smell Activity: Elemental Abundance in Nature Activity: Parts Per Thousand Further Investigations: Elemental Abundance Ionic CompoundsQuestion Set: Using The Periodic Table to Predict Ion Formation Question Set: Ions in Seawater Question Set: Ionic Compounds Question Set: Salts are Ionic Compounds Weird Science: Salt Fortification and Additives Compare-Contrast-Connect: The Role of Salt in Human History Further Investigations: Ionic Compounds Covalent CompoundsCompare-Contrast-Connect: Chemical Structures—Visualizing the Invisible Question Set: Comparing Ionic and Covalent Compounds Further Investigations: Ionic and Covalent Compounds Properties of WaterIntroduction to Properties of Water Types of Covalent Bonds: Polar and NonpolarActivity: Water and Electrostatic Forces Question Set: Polar and Nonpolar Further Investigations: Polar and Nonpolar Hydrogen Bonds Make Water StickyWeird Science: Rain Drops Are Not Really Drop Shaped! Compare-Contrast-Connect: Water Experiments in Space Activity: Cohesion and Adhesion Compare-Contrast-Connect: Capillarity, Transpiration, and Wicking Question Set: Water Properties Further Investigations: Water Properties Comparison of Water with Other LiquidsActivity: Comparison of Water With Other Liquids Activity: Solubility Compare-Contrast-Connect: Dilution of Pollution and Vital Gases Question Set: Comparison of Liquids and Compounds Further Investigations: Comparison of Liquids and Compounds ConductivityActivity: Conductivity Compare-Contrast-Connect: Corrosion Question Set: Conductivity Further Investigations: Conductivity Chemicals as Tracers of Water Movement Energy and the Water CycleIntroduction to Energy and the Water Cycle Phases of MatterCompare-Contrast-Connect: Water on Mars Question Set: Phase Changes and Pressure Question Set: Melting and Boiling Points Further Investigations: Phases of Matter IceCompare-Contrast-Connect: Celsius Versus Fahrenheit Activity: Ice Formation Further Investigations: Ice Formation Salinity and Ice FormationActivity: Ice Cream Weird Science: Milk Quality Further Investigations: Salinity and Ice Formation Liquid and Gaseous WaterWeird Science: Pressure and Boiling Point Activity: Cooling and Heating Water Question Set: Latent Heat Compare-Contrast-Connect: Water Power Further Investigations: Heating and Cooling Water The Water CycleActivity: Simulate the Water Cycle Question Set: Still Question Set: Evaporation and Humidity Compare-Contrast-Connect: Water Droplets Weird Science: Objects in Air Climate Connection: Storm Clouds Question Set: Condensation and Precipitation Compare-Contrast-Connect: Water Needs and Water Use Compare-Contrast-Connect: Sea Surface Salinity Question Set: Water Cycle Question Set: Sublimation and Deposition Further Investigations: Water Cycle Specific HeatActivity: Climate Comparision Further Investigations: Climate Comparisons Biogeochemical CyclesIntroduction to Biogeochemical Cycles Atmospheric Chemistry and Air to Sea Exchange Carbon CycleQuestion Set: Carbon Cycle Compare-Contrast-Connect: Carbon Monoxide Verses Carbon Dioxide Nitrogen Cycle and the Dead Sea Acid RainActivity: Measuring pH Question Set: Acid Rain Activity: Acid Rain Activity: Acidification Global Climate ChangeActivity: Sea Level Rise Question Set: Global Climate Change Further Investigations: Global Warming Seafloor ChemistryIntroduction to Sea Floor Chemistry Building Blocks of LifeIntroduction to Building Blocks of Life SEA Curriculum OPIHI Curriculum Standards AlignmentOcean Literacy Principles (OLP)Introduction to Ocean Literacy Principles (OLP) OLP 1: The Earth has one big ocean with many features OLP 2: The ocean and life in the ocean shape the features of the Earth OLP 3: The ocean is a major influence on weather and climate OLP 4: The ocean makes Earth habitable OLP 5: The ocean supports a great diversity of life and ecosystems OLP 6: The ocean and humans are inextricably interconnected OLP 7: The ocean is largely unexplored Next Generation Science Standards (NGSS)Introduction to NGSS Science and Engineering PracticesAsking Questions and Defining Problems Developing and Using Models Planning and Carrying Out Investigations Analyzing and Interpreting Data Using Mathematics and Computational Thinking Constructing Explanations and Designing Solutions Engaging in Argument from Evidence Obtaining, Evaluating, and Communicating Information Crosscutting ConceptsPatterns Cause and Effect Scale, Proportion, and Quantity System and System Models Energy and Matter Structure and Function Stability and Chance Disciplinary Core Ideas (DCI)DCI in Physical Science DCI in Life Science DCI in Earth and Space DCI in Engineering, Technology, and the Application of Science Physical Science Performance ExpectationsPS1: Matter and its Interactions PS2: Motion and Stability: Forces and Interactions PS3: Energy PS4: Waves and Their Applications in Technologies for Information Transfer Life Science Performance ExpectationsLS1: From Molecules to Organisms: Structures and Processes LS2: Ecosystems: Interactions, Energy, and Dynamics LS3: Heredity: Inheritance and Variation of Traits LS4: Biological Evolution: Unity and Diversity Earth and Space Sciences Performance ExpectationsESS1: Earth’s Place in the Universe ESS2: Earth’s Systems ESS3: Earth and Human Activity Engineering, Technology, and the Application of Science Performance ExpectationsETS1: Engineering design ETS2: Links among engineering, technology, science, and society Share and Connect We invite you to share your thoughts, ask for help or read what other educators have to say by joining our community. Learn More About the TSI Community   Exploring Our Fluid Earth. About Us Staff Bios Authors & Partners Contact Us Partner Organizations. Professional Development. Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. © University of Hawai‘i, 2022. This document may be freely reproduced and distributed for non-profit educational purposes. Paid Content. × Paid Content. Purchase a membership! Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. � University of Hawai�i, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.
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Result 15
TitleGeography4Kids.com: Earth Structure: Plate Tectonics
Urlhttp://www.geography4kids.com/files/earth_tectonics.html
DescriptionGeography4Kids.com! This tutorial introduces plate tectonics. Other sections include the atmosphere, biosphere, hydrosphere, climates, and ecosystems
Date
Organic Position14
H1Plates Are Moving Beneath You
H2
H3
H2WithAnchors
BodyPlates Are Moving Beneath You The basic idea behind plate tectonics is that there are eight major plates on the surface of the Earth. There are also bunches of minor plates. The plates are like the skin of the planet. They constantly move around the planet. When we say constantly moving, we're talking centimeters each year. You couldn't sit down and watch it happen. Or can you? You could watch it happen if you watched an earthquake. They Really Float? These plates make up the top layer of the Earth called the lithosphere. Directly under that layer is the asthenosphere. It's a flowing area of molten rock. There is constant heat and radiation given off from the center of the Earth. That energy is what constantly heats the rocks and melts them. The tectonic plates are floating on top of the molten rock and moving around the planet. Think of it as ice floating at the top of your soda. When the continents and plates move it's called continental drift. Think of the molten rock in the asthenosphere, not as rock, but as a liquid. It has currents and it flows just like any other liquid. When the floating plates spread apart, it's called a spreading center. When they are moving together, it's called a subduction zone. When they are forced together, it is called a zone of convergence. One of the plates usually moves under the other in a zone of convergence. As the plate moves down into the asthenosphere it begins to melt. The place where they meet has a crack or a trench. Some of the deepest parts of the oceans are these trenches. Scientific Evidence How do we back up these ideas? Scientists have traveled all over the Earth and found evidence that supports the ideas of plate tectonics. First, they looked at the continents. Ever notice how Africa and South America look like they could fit together? Scientists did. They cut up a map, moved the continents close together, and came up with a huge landmass called Pangaea (one super-continent). Scientists also looked at the fossils (long-dead animal bones and plants) on the different continents. They found that fossils on Australia were similar to the ones in Southern Asia. They think the same plants once lived on the continents, but when they split apart, new plants developed. When they were digging, they also looked at the types of rocks. The West Coast of Africa has very similar rock formations to those on the East Coast of South America. They are too similar to be a coincidence. Or search the sites for a specific topic. Overview Composition Magnetic Field Structure Rock Types Tectonics Faulting Earthquakes Volcanoes More Topics Fossils and Plate Tectonics (NASA SciFiles Video) Related Links Geography4Kids: Faulting Chem4Kids: Solids Chem4Kids: Environmental Chemistry Chem4Kids: Elements Cosmos4Kids: Earth Cosmos4Kids: Mars Cosmos4Kids: Space Exploration Physics4Kids: Magnetic Fields Physics4Kids: Gravity NASA: Kennedy Space Center NASA: Goddard Spaceflight Center Useful Reference Materials Encyclopedia.com (Plate Tectonics): http://www.encyclopedia.com/topic/plate_tectonics.aspx Wikipedia: http://en.wikipedia.org/wiki/Plate_tectonics Encyclopædia Britannica: http://www.britannica.com/EBchecked/topic/463912/plate-tectonics Physics4Kids Sections Earth Energy | Earth Structure | Biosphere | Atmosphere | HydrosphereClimate | Biogeochemical Cycles Site Tour | Site Map | Live Cameras | Activities & Quizzes Rader's Network of Science and Math Sites Cosmos4Kids | Biology4Kids | Chem4Kids | Geography4Kids | Physics4Kids | NumberNut Go for site help or a list of earth science and geography topics at the site map! ©copyright 1997-2015 Andrew Rader Studios, All rights reserved. Current Page: Geography4Kids.com | Physical Geography | Earth Structure | Plate Tectonics ** Andrew Rader Studios does not monitor or review the content available at external web sites. They are paid advertisements and neither partners nor recommended web sites. Specific links for books on Amazon.com are only suggested starting points for further research. Please browse, research options, and choose the appropriate materials for your needs.
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Result 16
Titleplate tectonics | Definition, Theory, Facts, & Evidence | Britannica
Urlhttps://www.britannica.com/science/plate-tectonics
DescriptionPlate tectonics, theory dealing with the dynamics of Earth’s outer shell that revolutionized Earth sciences by providing a uniform context for understanding mountain-building processes, volcanoes, and earthquakes as well as the evolution of Earth’s surface and reconstructing its past continents and oceans
Date
Organic Position15
H1plate tectonics
H2Principles of plate tectonics
H3Who first proposed the idea of plate tectonics?
What is the cause of plate tectonics?
What is the Ring of Fire, and where is it?
Why are there tectonic plates?
H2WithAnchorsPrinciples of plate tectonics
Bodyplate tectonics geology Print print Print Please select which sections you would like to print: Cite verifiedCite While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Select Citation Style MLA APA Chicago Manual of Style Copy Citation Share Share Share to social media Facebook Twitter URL https://www.britannica.com/science/plate-tectonics More Give Feedback External Websites Feedback Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article. Join Britannica's Publishing Partner Program and our community of experts to gain a global audience for your work! External Websites University of California Museum of Paleontology - Biography of Alfred Wegener University of California Museum of Paleontology - Plate Tectonics Australian Museum - Plate Tectonic processes National Geographic - Science - Plate Tectonics The Geological Society - Plate Tectonics Britannica Websites Articles from Britannica Encyclopedias for elementary and high school students. plate tectonics - Children's Encyclopedia (Ages 8-11) plate tectonics - Student Encyclopedia (Ages 11 and up) By Tjeerd H. van Andel | See All Contributors | View Edit History Fast Facts 2-Min Summary Earth's tectonic plates See all media Key People: J. Tuzo Wilson Drummond Hoyle Matthews Walter Alvarez ...(Show more) Related Topics: earthquake continental drift continent volcanism diastrophism ...(Show more) See all related content → Top QuestionsWho first proposed the idea of plate tectonics?German meteorologist Alfred Wegener is often credited as the first to develop a theory of plate tectonics, in the form of continental drift. Bringing together a large mass of geologic and paleontological data, Wegener postulated that throughout most of geologic time there was only one continent, which he called Pangea, and the breakup of this continent heralded Earth’s current continental configuration as the continent-sized parts began to move away from one another. (Scientists discovered later that Pangea fragmented early in the Jurassic Period.) Wegener presented the idea of continental drift and some of the supporting evidence in a lecture in 1912, followed by his major published work, The Origin of Continents and Oceans (1915). Read more below: Development of tectonic theoryPangeaLearn more about Pangea.What is the cause of plate tectonics?Although this has yet to be proven with certainty, most geologists and geophysicists agree that plate movement is caused by the convection (that is, heat transfer resulting from the movement of a heated fluid) of magma in Earth’s interior. The heat source is thought to be the decay of radioactive elements. How this convection propels the plates is poorly understood. Some geologists argue that upwelling magma at spreading centres pushes the plates, whereas others argue that the weight of a portion of a subducting plate (one that is forced beneath another) may pull the rest of the plate along.  Read more below: Principles of plate tectonicsDevelopment of tectonic theory: Driving forcesRead more about mantle convection.What is the Ring of Fire, and where is it?The Ring of Fire is a long horseshoe-shaped earthquake-prone belt of volcanoes and tectonic plate boundaries that fringes the Pacific Ocean basin. For much of its 40,000-km (24,900-mile) length, the belt follows chains of island arcs such as Tonga and Vanuatu, the Indonesian archipelago, the Philippines, Japan, the Kuril Islands, and the Aleutians, as well as other arc-shaped features, such as the western coast of North America and the Andes Mountains.Ring of FireLearn more about the Ring of Fire.Why are there tectonic plates?Earth’s hard surface (the lithosphere) can be thought of as a skin that rests and slides upon a semi-molten layer of rock called the asthenosphere. The skin has been broken into many different plates because of differences in the density of the rock and differences in subsurface heating between one region and the next. Read more below: Principles of plate tectonicsEarth: The outer shellLearn more about the layers of Earth’s surface.plate tectonics, theory dealing with the dynamics of Earth’s outer shell—the lithosphere—that revolutionized Earth sciences by providing a uniform context for understanding mountain-building processes, volcanoes, and earthquakes as well as the evolution of Earth’s surface and reconstructing its past continents and oceans.The concept of plate tectonics was formulated in the 1960s. According to the theory, Earth has a rigid outer layer, known as the lithosphere, which is typically about 100 km (60 miles) thick and overlies a plastic (moldable, partially molten) layer called the asthenosphere. The lithosphere is broken up into seven very large continental- and ocean-sized plates, six or seven medium-sized regional plates, and several small ones. These plates move relative to each other, typically at rates of 5 to 10 cm (2 to 4 inches) per year, and interact along their boundaries, where they converge, diverge, or slip past one another. Such interactions are thought to be responsible for most of Earth’s seismic and volcanic activity, although earthquakes and volcanoes can occur in plate interiors. Plate motions cause mountains to rise where plates push together, or converge, and continents to fracture and oceans to form where plates pull apart, or diverge. The continents are embedded in the plates and drift passively with them, which over millions of years results in significant changes in Earth’s geography.Discover the facts behind the theory of continental driftLearn more about the theory of continental drift.Encyclopædia Britannica, Inc.See all videos for this articleThe theory of plate tectonics is based on a broad synthesis of geologic and geophysical data. It is now almost universally accepted, and its adoption represents a true scientific revolution, analogous in its consequences to quantum mechanics in physics or the discovery of the genetic code in biology. Incorporating the much older idea of continental drift, as well as the concept of seafloor spreading, the theory of plate tectonics has provided an overarching framework in which to describe the past geography of continents and oceans, the processes controlling creation and destruction of landforms, and the evolution of Earth’s crust, atmosphere, biosphere, hydrosphere, and climates. During the late 20th and early 21st centuries, it became apparent that plate-tectonic processes profoundly influence the composition of Earth’s atmosphere and oceans, serve as a prime cause of long-term climate change, and make significant contributions to the chemical and physical environment in which life evolves.For details on the specific effects of plate tectonics, see the articles earthquake and volcano. A detailed treatment of the various land and submarine relief features associated with plate motion is provided in the articles tectonic landform and ocean. Principles of plate tectonics. In essence, plate-tectonic theory is elegantly simple. Earth’s surface layer, 50 to 100 km (30 to 60 miles) thick, is rigid and is composed of a set of large and small plates. Together, these plates constitute the lithosphere, from the Greek lithos, meaning “rock.” The lithosphere rests on and slides over an underlying partially molten (and thus weaker but generally denser) layer of plastic partially molten rock known as the asthenosphere, from the Greek asthenos, meaning “weak.” Plate movement is possible because the lithosphere-asthenosphere boundary is a zone of detachment. As the lithospheric plates move across Earth’s surface, driven by forces as yet not fully understood, they interact along their boundaries, diverging, converging, or slipping past each other. While the interiors of the plates are presumed to remain essentially undeformed, plate boundaries are the sites of many of the principal processes that shape the terrestrial surface, including earthquakes, volcanism, and orogeny (that is, formation of mountain ranges).Earth's lithosphere and upper mantleA cross section of Earth's outer layers, from the crust through the lower mantle.Encyclopædia Britannica, Inc. The process of plate tectonics may be driven by convection in Earth’s mantle, the pull of heavy old pieces of crust into the mantle, or some combination of both. For a deeper discussion of plate-driving mechanisms, see Plate-driving mechanisms and the role of the mantle. Load Next Page
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Result 17
TitlePlates on the Move | AMNH
Urlhttps://www.amnh.org/explore/ology/earth/plates-on-the-move2
DescriptionThey are floating on Earth's mantle, a really thick layer of hot flowing rock. The flow of the mantle causes tectonic plates to move in different directions ...
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Organic Position16
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H3
H2WithAnchors
Body
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Result 18
TitleWhat is Tectonic Shift?
Urlhttps://oceanservice.noaa.gov/facts/tectonics.html
DescriptionTectonic shift is the movement of the plates that make up Earth’s crust
Date26 Feb 2021
Organic Position17
H1What is Tectonic Shift?
H2Tectonic shift is the movement of the plates that make up Earth’s crust
H3
H2WithAnchorsTectonic shift is the movement of the plates that make up Earth’s crust
BodyWhat is Tectonic Shift? Tectonic shift is the movement of the plates that make up Earth’s crust. The Earth is made up of roughly a dozen major plates and several minor plates. The Earth is in a constant state of change. Earth’s crust, called the lithosphere, consists of 15 to 20 moving tectonic plates. The plates can be thought of like pieces of a cracked shell that rest on the hot, molten rock of Earth’s mantle and fit snugly against one another. The heat from radioactive processes within the planet’s interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift. Our planet looks very different from the way it did 250 million years ago, when there was only one continent, called Pangaea, and one ocean, called Panthalassa. As Earth’s mantle heated and cooled over many millennia, the outer crust broke up and commenced the plate motion that continues today. The huge continent eventually broke apart, creating new and ever-changing land masses and oceans. Have you ever noticed how the east coast of South America looks like it would fit neatly into the west coast of Africa? That’s because it did, millions of years before tectonic shift separated the two great continents. Earth’s land masses move toward and away from each other at an average rate of about 0.6 inch a year. That’s about the rate that human toenails grow! Some regions, such as coastal California, move quite fast in geological terms — almost two inches a year — relative to the more stable interior of the continental United States. At the “seams” where tectonic plates come in contact, the crustal rocks may grind violently against each other, causing earthquakes and volcano eruptions. The relatively fast movement of the tectonic plates under California explains the frequent earthquakes that occur there. Search Our Facts Get Social More Information National Geodetic Survey What is geodesy? What is the geoid? "Coping with Tectonic Shift," The American Surveyor Did you know? Measuring the motion of tectonic plates is part of the science of geodesy. To define the shape of the Earth, NOAA’s National Geodetic Survey, part of the National Ocean Service, uses a variety of techniques to measure the planet’s rate of rotation, its plate motion, and the ways that gravity affects certain scientific processes.   Learn More Last updated: 02/26/21 Author: NOAA How to cite this article Contact Us
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Result 19
TitleThere could be an extra, ancient layer of tectonic plates lurking under east Asia
Urlhttps://www.zmescience.com/science/ancient-plates-asia/
DescriptionTectonics^2
Date24 Apr 2019
Organic Position18
H1There could be an extra, ancient layer of tectonic plates lurking under east Asia
H2Tectonics^2
H3The real sunken land
Why are we only hearing about this now?
Alexandru Micu
H2WithAnchorsTectonics^2
BodyThere could be an extra, ancient layer of tectonic plates lurking under east Asia Tectonics^2. by Alexandru Micu April 24, 2019 in Geology, News, Science Reading Time: 5 mins read A A A A Reset Share on FacebookShare on TwitterSubmit to Reddit A team of researchers from the University of Houston say they’ve possibly found a deeper body of tectonic plates floating within the mantle. These plates could explain a series of mysterious, very deep earthquakes in the Pacific ocean.   ADVERTISEMENT While the theory of plate tectonics has been fought tooth and claw since its early days, it has gained widespread support in the last fifty or so years. The short of it is that the crust isn’t a single monolithic piece, but rather made up of a series of plates that bump into each other on an ocean of magma — the mantle. Continents piggyback on the plates, the ocean floor splits apart and spews magma where they drift apart, or sinks into the mantle to be recycled through subduction where the plates collide. One underlying principle of plate tectonics is that of isostasy, which basically says that a) since these plates float on a fluid, their elevation depends on how dense they are and b) you can, in broad lines, delineate an area as being ‘the crust‘, since most plates will bob around this mean elevation and there’s no free magma on top, and ‘the mantle‘ which is underneath this crust. The real sunken land. But on Tuesday, Jonny Wu from the University of Houston presented preliminary evidence at a joint conference of the Japan Geoscience Union and the American Geophysical Union in Tokyo that could blur the lines on point b) quite a lot. ADVERTISEMENT Wu and his colleagues say that they’ve identified ancient tectonic plates which subducted in the mantle millions of years ago, but instead of being recycled they stabilized in the mantle’s transition zone (a water-rich layer at around 440-660 km depth). Beyond their choice of neighborhood, these sunken plates don’t differ that much from traditional plates in behavior. They slide horizontally at about the same speeds as surface plates, and can travel thousands of kilometers from the point of subduction. They can bend the same way surface plates do, and the energy released during a break can generate earthquakes — again, pretty typical plate mannerisms. These plates could help explain the Vityaz earthquakes, a series of very deep, very powerful tremors whose hypocenters were, puzzlingly enough, traced in the mantle between Fiji and Australia. Wu and his team believe that the Vityaz earthquakes were caused by a subducted plate moving through the transition zone and hitting the sunken plate. Seismic tomographic cross-section across NE Asia. Subducted plate in white/purple. Associated earthquakesin red.Image credits Jonny Wu et al., AGU Publications (2017). Which is surprising, since subducted plates should theoretically sink right through the transition zone towards the core. But they explain that the plates subsiding under the western Pacific find themselves in a bit of a real-estate crisis. “The Pacific subduction rate is so fast that you’ve got to find space to get all the slab in there,” Wu says, “and east Asia has had such a long history of subduction it’s jammed up. So this slab is forced to slide within the upper mantle and transition zone and be thrust under China.” Why are we only hearing about this now? Well first of all you have to remember that geophysics, the field of science which allowed this discovery is really really young. Some work pertaining to geophysics is older but the bread and butter of the field — sensors that can peer into the Earth and computers who can make sense of all the data — has been around for far less than the airplane. Plate tectonics wasn’t reliably proven until the 1960s when Hess advanced his ideas of sea floor spreading. That’s just 9 years before we put a man on the Moon. So it’s very much a field still in progress. Wu’s discovery was made possible by recent technological advancements in seismological equipment, which allowed the team to model the mantle based on natural vibrations generated by earthquakes. Such snapshots into the Earth’s inner workings can be used to locate sunken plates still floating withing the mantle, and then reconstruct their likely shape and position on the planet’s surface millions of years ago. “Think of Hubble. We look out, and the further we look out the more things we discover, not just about the universe – we’re actually looking back in time. And this new seismology is like turning the Hubble to look into the Earth, because as we look deeper and get clearer images, we can see what the Earth might have looked like further and further back in time.” “We’re discovering lost oceans that we didn’t even know existed,” he added, referring to an 8,000km wide “East Asian Sea” his colleagues recently identified that likely spanned between the Pacific and Indian oceans 52 million years ago, and is now buried some 500 km to 1000 km deep in the mantle under east Asia. Still, take these findings with a grain of salt. As exciting as they are, there are still a lot of questions left to answer and, as Wu himself points out, these are just preliminary findings and yet to undergo peer review. But if they do make it past the process, I’m sure we will be hearing a lot more about these sunken plates. The preliminary paper “Philippine Sea and East Asian plate tectonics since 52 Ma constrained by new subducted slab reconstruction methods” has been published in the Journal of Geophysical Research Solid Earth. Tags: East AsiamantleTectonic Platestectonics Share1TweetShare Alexandru Micu . Stunningly charming pun connoisseur, I have been fascinated by the world around me since I first laid eyes on it. Always curious, I'm just having a little fun with some very serious science. ADVERTISEMENT ADVERTISEMENT News Environment Health Future Space Feature Post More © 2007-2019 ZME Science - Not exactly rocket science. All Rights Reserved. No Result View All Result News Environment Climate Animals Renewable Energy Eco tips Environmental Issues Green Living Health Alternative Medicine Anatomy Diseases Genetics Mind & Brain Nutrition Future Space Feature Post Pieces Feature Post Art Great Pics Fossil Friday Design AstroPicture GeoPicture Did you know? Offbeat More About The Team Advertise Contribute Our stance on climate change Privacy Policy Contact © 2007-2019 ZME Science - Not exactly rocket science. All Rights Reserved.
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Result 20
TitleIn lithospheric float what represent the plates?
Urlhttps://moviecultists.com/in-lithospheric-float-what-represent-the-plates
DescriptionLithospheric plates float on the uppermost part of the mantle called the asthenosphereasthenosphereThe asthenosphere (Ancient Greek: ἀσθενός [asthenos] meaning
Date
Organic Position19
H1In lithospheric float what represent the plates?
H2Which sphere do the plates of the lithosphere float on?
Why does lithosphere float on asthenosphere?
Why are plates floating?
What were the tectonic plates floating on?
What makes the Lithospheric Plates move? Mantle Convection, Ridge Push and Slab Pull
H3Asthenosphere - Wikipedia
Is the layer where the plates float?
Why do oceanic plates dive underneath continental plates when they collide?
How thick are tectonic plates?
How fast do tectonic plates move?
What is an interesting fact about the asthenosphere?
How does the asthenosphere affect the lithosphere?
Does the asthenosphere float on the lithosphere?
When two plates meet this is called?
What are the 3 components of lithosphere?
Which plate do we live on?
Which is the biggest tectonic plate?
How many tectonic plates are there in total?
Which part of the crust is thicker and denser?
What will happen when two continental plates collide?
What is the difference between oceanic plates and continental plates?
What causes the plates to move at a fault line?
What is plate tectonics kid friendly definition?
Do tectonic plates move?
H2WithAnchorsWhich sphere do the plates of the lithosphere float on?
Why does lithosphere float on asthenosphere?
Why are plates floating?
What were the tectonic plates floating on?
What makes the Lithospheric Plates move? Mantle Convection, Ridge Push and Slab Pull
BodyIn lithospheric float what represent the plates? Asked by: Monserrate Boyle Score: 5/5 (52 votes) Lithospheric plates float on the uppermost part of the mantle called the asthenosphere asthenosphere The asthenosphere (Ancient Greek: ἀσθενός [asthenos] meaning "without strength" and σφαίρα [sphaira] meaning "sphere") is the highly viscous, mechanically weak, and ductile region of the upper mantle of Earth. It lies below the lithosphere, between approximately 80 and 200 km (50 and 120 miles) below the surface. https://en.wikipedia.org › wiki › Asthenosphere Asthenosphere - Wikipedia. . The asthenosphere is made up of solid rocks that become... Which sphere do the plates of the lithosphere float on? In effect, the lithosphere floats on the asthenosphere "carrying" the lithospheric plates that are constantly changing position. In 1929, about the time Wegener's ideas began to be dismissed, Arthur Holmes elaborated on one of Wegener's many hypotheses; the idea that the mantle undergoes thermal convection. Why does lithosphere float on asthenosphere? Since the Lithosphere has a lower density, it floats on top of the Asthenosphere similar to the way in which an iceberg or a block of wood floats on water. The lower mantle below the Asthenosphere is more rigid and less plastic. Why are plates floating? The tectonic plates do not slowly drift over time because they are floating on a layer of liquid rock. They drift because they are sitting on a layer of solid rock (the upper mantle or "asthenosphere") that is weak and ductile enough that it can flow very slowly under heat convection, somewhat like a liquid. What were the tectonic plates floating on? Earth's thin outer shell is broken into big pieces called tectonic plates. These plates fit together like a puzzle, but they're not stuck in one place. They are floating on Earth's mantle, a really thick layer of hot flowing rock. What makes the Lithospheric Plates move? Mantle Convection, Ridge Push and Slab Pull. 23 related questions found Is the layer where the plates float? Tectonic plates float on the asthenosphere. The asthenosphere is immediately below the top layer of Earth's surface (lithosphere). Why do oceanic plates dive underneath continental plates when they collide? When an oceanic plate converges with a continental plate, the oceanic crust will always subduct under the continental crust; this is because oceanic crust is naturally denser. ... Old, dense crust tends to be subducted back into the earth. How thick are tectonic plates? Plates are on average 125km thick, reaching maximum thickness below mountain ranges. Oceanic plates (50-100km) are thinner than the continental plates (up to 200km) and even thinner at the ocean ridges where the temperatures are higher. How fast do tectonic plates move? They can move at rates of up to four inches (10 centimeters) per year, but most move much slower than that. Different parts of a plate move at different speeds. The plates move in different directions, colliding, moving away from, and sliding past one another. Most plates are made of both oceanic and continental crust. What is an interesting fact about the asthenosphere? The rock in the asthenosphere is low density and partially molten. Underneath the oceans the asthenosphere is closer to the earth's surface. When crustal plates sink into the earth's mantle deep zone earthquakes can occur in the asthenosphere. How does the asthenosphere affect the lithosphere? Convection currents also stress the lithosphere above, and the cracking that often results manifests as earthquakes. According to the theory of plate tectonics, the asthenosphere is the repository for older and denser parts of the lithosphere that are dragged downward in subduction zones. Does the asthenosphere float on the lithosphere? The lithosphere is actually broken up into several large pieces, or plates. They “float” on a softer mantle layer called the asthenosphere. Their very slow motion is the cause of plate tectonics, a process associated with continental drift, earthquakes, volcanoes, and the formation of mountains. When two plates meet this is called? When two tectonic plates meet, we get a “plate boundary.” There are three major types of plate boundaries, each associated with the formation of a variety of geologic features. ... When two plates are moving away from each other, we call this a divergent plate boundary. What are the 3 components of lithosphere? Lithosphere The solid part of the earth. It consists of three main layers: crust, mantle and core. Which plate do we live on? We live on a layer of Earth known as the lithosphere which is a collection of rigid slabs that are shifting and sliding into each other. These slabs are called tectonic plates and fit together like pieces to a puzzle. Which is the biggest tectonic plate? There are seven major plates: African, Antarctic, Eurasian, Indo-Australian, North American, Pacific and South American. The Hawaiian Islands were created by the Pacific Plate, which is the world's largest plate at 39,768,522 square miles. How many tectonic plates are there in total? Such boundaries are highly susceptible to earthquakes and volcanic eruptions. Orogeny also takes place at such boundaries. Tectonic plates are defined as major and minor plates depending on their size. There are a total of seven major tectonic plates which cover nearly 95% of the Earth's surface. Which part of the crust is thicker and denser? Earth's crust is generally divided into older, thicker continental crust and younger, denser oceanic crust. The dynamic geology of Earth's crust is informed by plate tectonics. What will happen when two continental plates collide? Plates Collide When two plates carrying continents collide, the continental crust buckles and rocks pile up, creating towering mountain ranges. ... The Himalayas are still rising today as the two plates continue to collide. The Appalachian Mountains and Alps also formed in this way. What is the difference between oceanic plates and continental plates? Oceanic plates are much thinner than the continental plates. ... At the convergent boundaries the continental plates are pushed upward and gain thickness. The rocks and geological layers are much older on continental plates than in the oceanic plates. The Continental plates are much less dense than the Oceanic plates. What causes the plates to move at a fault line? Normal faults are associated with downward movement on a sloping fault as the two plates move apart. The stretching of the Earth's crust is indicative of this type of event. ... Thrust faults are caused by plates pulling apart and colliding with continental plates. What is plate tectonics kid friendly definition? The definition of tectonic plates for kids involves thinking of the Earth's crust as large slabs that move over a liquid mantle. Mountains form and earthquakes shake at tectonic plate boundaries, where new landforms rise and fall. Do tectonic plates move? Plates at our planet's surface move because of the intense heat in the Earth's core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again.
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  • convection
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  • collide
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  • mountain
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  • earthquake
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Result 21
TitlePlate tectonics - The crust - GCSE Chemistry (Single Science) Revision - Other - BBC Bitesize
Urlhttps://www.bbc.co.uk/bitesize/guides/z2q6cwx/revision/3
DescriptionLearn about the different elements that make up the earth's crust with BBC Bitesize GCSE Chemistry
Date
Organic Position20
H1Plate tectonics
H2Accessibility links
The crust
GCSE SubjectsGCSE Subjectsupdown
H3
H2WithAnchorsAccessibility links
The crust
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BodyPlate tectonics The Earth's crust and upper part of the mantle are broken into large pieces called tectonic plates. These are constantly moving at a few centimetres each year. Although this doesn't sound like very much, over millions of years the movement allows whole continents to shift thousands of kilometres apart. This process is called continental drift. The plates move because of convection currents in the Earth’s mantle. These are driven by the heat produced by the natural decay of radioactive elements in the Earth.Where tectonic plates meet, the Earth's crust becomes unstable as the plates push against each other, or ride under or over each other. Earthquakes and volcanic eruptions happen at the boundaries between plates, and the crust may ‘crumple’ to form mountain ranges.GlossaryupdownGCSE SubjectsGCSE Subjectsupdown. Art and DesignBiology (Single Science)BusinessChemistry (Single Science)Combined ScienceComputer ScienceDesign and TechnologyDigital Technology (CCEA)DramaEnglish LanguageEnglish LiteratureFrenchGeographyGermanHistoryHome Economics: Food and Nutrition (CCEA)Hospitality (CCEA)ICTIrish – Learners (CCEA)Journalism (CCEA)Learning for Life and Work (CCEA)MandarinMathsMaths Numeracy (WJEC)Media StudiesModern Foreign LanguagesMoving Image Arts (CCEA)MusicPhysical EducationPhysics (Single Science)PSHE and CitizenshipReligious StudiesScienceSociologySpanishWelsh Second Language (WJEC)
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TitleTectonic Plates - Iceland On The Web
Urlhttps://www.icelandontheweb.com/articles-on-iceland/nature/geology/tectonic-plates
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TitleList of tectonic plates - Wikipedia
Urlhttps://en.wikipedia.org/wiki/List_of_tectonic_plates
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H1List of tectonic plates
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Current plates[edit]
Ancient continental formations[edit]
See also[edit]
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H3Major plates[edit]
Minor plates[edit]
Microplates[edit]
Ancient supercontinents[edit]
Ancient plates and cratons[edit]
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Current plates[edit]
Ancient continental formations[edit]
See also[edit]
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BodyList of tectonic plates From Wikipedia, the free encyclopedia Jump to navigation Jump to search List of the relatively moving sections of the lithosphere of Earth Map showing Earth's lithosphere divided into 15 principal tectonic plates Plate tectonics map from NASA This is a list of tectonic plates on Earth's surface. Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium). The composition of the two types of crust differs markedly, with mafic basaltic rocks dominating oceanic crust, while continental crust consists principally of lower-density felsic granitic rocks. Contents. 1 Current plates 1.1 Major plates 1.2 Minor plates 1.3 Microplates 2 Ancient continental formations 2.1 Ancient supercontinents 2.2 Ancient plates and cratons 2.2.1 African Plate 2.2.2 Antarctic Plate 2.2.3 Eurasian Plate 2.2.4 Indo-Australian Plate 2.2.5 North American Plate 2.2.6 South American Plate 3 See also 4 Notes and references 4.1 Notes 4.2 References 4.3 Bibliography 5 External links Current plates[edit]. Map showing Earth's principal tectonic plates and their boundaries in detail Geologists generally agree that the following tectonic plates currently exist on Earth's surface with roughly definable boundaries. Tectonic plates are sometimes subdivided into three fairly arbitrary categories: major (or primary) plates, minor (or secondary) plates, and microplates (or tertiary plates).[1] Major plates[edit]. These plates comprise the bulk of the continents and the Pacific Ocean. For purposes of this list, a major plate is any plate with an area greater than 20 million km2. African Plate – A major tectonic plate underlying Africa west of the East African Rift – 61,300,000 km2 Antarctic Plate – Tectonic plate containing Antarctica and the surrounding ocean floor – 60,900,000 km2 Eurasian Plate – Tectonic plate which includes most of the continent of Eurasia – 67,800,000 km2 Indo-Australian Plate – A major tectonic plate formed by the fusion of the Indian and Australian plates – 58,900,000 km2 often considered two plates: Australian Plate – Major tectonic plate, originally a part of the ancient continent of Gondwana – 47,000,000 km2 Indian Plate – A minor tectonic plate that got separated from Gondwana – 11,900,000 km2 North American Plate – Large tectonic plate including most of North America, Greenland and part of Siberia – 75,900,000 km2 Pacific Plate – Oceanic tectonic plate under the Pacific Ocean – 103,300,000 km2 South American Plate – Major tectonic plate which includes most of South America and a large part of the south Atlantic – 43,600,000 km2 Minor plates[edit]. These smaller plates are often not shown on major plate maps, as the majority do not comprise significant land area. For purposes of this list, a minor plate is any plate with an area less than 20 million km2 but greater than 1 million km2. Somali Plate – Minor tectonic plate including the east coast of Africa and the adjoining seabed – 16,700,000 km2 Nazca Plate – Oceanic tectonic plate in the eastern Pacific Ocean basin – 15,600,000 km2[note 1] Indian Plate – A minor tectonic plate that got separated from Gondwana – 11,900,000 km2 Amurian Plate – A minor tectonic plate in eastern Asia Sunda Plate – A minor tectonic plate including most of Southeast Asia Philippine Sea Plate – oceanic tectonic plate to the east of the Philippines – 5,500,000 km2 Okhotsk Plate – Minor tectonic plate in Asia Arabian Plate – Minor tectonic plate – 5,000,000 km2 Yangtze Plate – Small tectonic plate carrying the bulk of southern China Caribbean Plate – A mostly oceanic tectonic plate including part of Central America and the Caribbean Sea – 3,300,000 km2 Cocos Plate – Young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America – 2,900,000 km2 Caroline Plate – Minor oceanic tectonic plate north of New Guinea – 1,700,000 km2 Scotia Plate – Minor oceanic tectonic plate between the South American and Antarctic Plates – 1,600,000 km2 Burma Plate – Minor tectonic plate in Southeast Asia – 1,100,000 km2 New Hebrides Plate – Minor tectonic plate in the Pacific Ocean near Vanuatu – 1,100,000 km2 Microplates[edit]. These plates are often grouped with an adjacent major plate on a major plate map. For purposes of this list, a microplate is any plate with an area less than 1 million km2. Some models identify more minor plates within current orogens (events that lead to a large structural deformation of Earth's lithosphere) like the Apulian, Explorer, Gorda, and Philippine Mobile Belt plates. There may be scientific consensus as to whether such plates should be considered distinct portions of the crust; thus, new research could change this list.[2][3][4][5] African Plate Adriatic Plate, also known as Apulian Plate – A small tectonic plate in the Mediterranean Lwandle Plate – Mainly oceanic tectonic microplate off the southeast coast of Africa Madagascar Plate – Tectonic plate formerly part of the supercontinent Gondwana Rovuma Plate – One of three tectonic microplates that contribute to the Nubian Plate and the Somali Plate Victoria Microplate Seychelles microcontinent Antarctic Plate Kerguelen Plateau – Oceanic plateau in the southern Indian Ocean Shetland Plate – Tectonic microplate off the tip of the Antarctic Peninsula South Sandwich Plate – Minor tectonic plate south of the South American Plate Australian Plate Capricorn Plate – Proposed minor tectonic plate under the Indian Ocean Futuna Plate – Very small tectonic plate near the south Pacific island of Futuna Kermadec Plate – Long, narrow tectonic plate west of the Kermadec Trench Maoke Plate – Small tectonic plate in western New Guinea Niuafo'ou Plate – Small tectonic plate west of Tonga Tonga Plate – A small southwest Pacific tectonic plate Woodlark Plate – Small tectonic plate located in the eastern half of the island of New Guinea Caribbean Plate Panama Plate – Small tectonic plate in Central America Gonâve Microplate – Part of the boundary between the North American Plate and the Caribbean Plate South Jamaica Microplate North Hispaniola Microplate Puerto Rico-Virgin Islands Microplate Cocos Plate Rivera Plate – Small tectonic plate off the west coast of Mexico Eurasian Plate Aegean Sea Plate, also known as Hellenic Plate – A small tectonic plate in the eastern Mediterranean Sea Anatolian Plate – Continental tectonic plate comprising most of the Anatolia (Asia Minor) peninsula Banda Sea Plate – Minor tectonic plate underlying the Banda Sea in southeast Asia Iberian Plate – Small tectonic plate now part of the Eurasian plate Iranian Plate – Small tectonic plate including Iran and Afghanistan, and parts of Iraq and Pakistan Molucca Sea Plate – small fully subducted tectonic plate near Indonesia Halmahera Plate – small tectonic plate in the Molucca Sea Sangihe Plate – Microplate within the Molucca Sea Collision Zone of eastern Indonesia Okinawa Plate – Minor tectonic plate from the northern end of Taiwan to the southern tip of Kyūshū Pelso Plate – Small tectonic unit in the Pannonian Basin in Europe Timor Plate – Microplate in southeast Asia carrying the island of Timor and surrounding islands Tisza Plate – Tectonic microplate, in present-day Europe Nazca Plate Coiba Plate – A small tectonic plate off the coast south of Panama and northwestern Colombia Malpelo Plate – A small tectonic plate off the coast west of Ecuador and Colombia North American Plate Queen Elizabeth Islands Subplate – Small tectonic plate containing the Queen Elizabeth Islands of Northern Canada Greenland Plate – Supposed tectonic plate containing the Greenland craton Explorer Plate – oceanic tectonic plate beneath the Pacific Ocean off the west coast of Vancouver Island, Canada Gorda Plate – One of the northern remnants of the Farallon Plate Pacific Plate Balmoral Reef Plate – Small tectonic plate in the south Pacific north of Fiji Bird's Head Plate – Small tectonic plate in New Guinea Conway Reef Plate – Small tectonic plate in the south Pacific west of Fiji Easter Microplate – Very small tectonic plate to the west of Easter Island Galápagos Microplate – Very small tectonic plate at the Galapagos Triple Junction Juan de Fuca Plate – A small tectonic plate in the eastern North Pacific – 250,000 km2 Juan Fernández Plate – Very small tectonic plate in the southern Pacific Ocean Kula Plate – Oceanic tectonic plate under the northern Pacific Ocean which has been subducted under the North American Plate Manus Plate – Tiny tectonic plate northeast of New Guinea North Bismarck Plate – Small tectonic plate in the Bismarck Sea north of New Guinea North Galápagos Microplate – Small tectonic plate off the west coast of South America north of the Galapagos Islands Solomon Sea Plate – Minor tectonic plate to the northwest of the Solomon Islands in the south Pacific Ocean South Bismarck Plate – Small tectonic plate in the southern Bismarck Sea Philippine Sea Plate Mariana Plate – Small tectonic plate west of the Mariana Trench Philippine Mobile Belt, also known as Philippine Microplate – Complex portion of the tectonic boundary between the Eurasian Plate and the Philippine Sea Plate, comprising most of the country of the Philippines South American Plate Altiplano Plate Falklands Microplate North Andes Plate – Small tectonic plate in the northern Andes (mainly in Colombia, minor parts in Ecuador and Venezuela) Chibcha Terrane (Andean Region) Caribbean Terrane (Eastern Caribbean Region) Tahamí Terrane (Central Andean Region) Ancient continental formations[edit]. In the history of Earth many tectonic plates have come into existence and have over the intervening years either accreted onto other plates to form larger plates, rifted into smaller plates, or have been crushed by or subducted under other plates. Ancient supercontinents[edit]. Supercontinent – Landmass comprising more than one continental core, or craton Supercontinent cycle – Quasi-periodic aggregation and dispersal of Earth's continental crust The following list includes the supercontinents known or speculated to have existed in the Earth's past: Columbia – Ancient supercontinent of approximately 2,500 to 1,500 million years ago Euramerica Gondwana – Neoproterozoic to Cretaceous landmass Kenorland – Hypothetical Neoarchaean supercontinent from about 2.8 billion years ago Laurasia – Northern supercontinent that formed part of the Pangaea supercontinent Nena – Early Proterozoic supercontinent Pangaea – Supercontinent from the late Paleozoic to early Mesozoic eras Pannotia – Hypothesized Neoproterozoic supercontinent from the end of the Precambrian Proto-Laurasia Rodinia – Hypothetical neoproterozoic supercontinent from between about a billion to about three quarters of a billion years ago Ur – Proposed archaean supercontinent from about 3.1 billion years ago Vaalbara – Archaean supercontinent from about 3.6 to 2.7 billion years ago Ancient plates and cratons[edit]. Not all plate boundaries are easily defined, especially for ancient pieces of crust. The following list of ancient cratons, microplates, plates, shields, terranes, and zones no longer exist as separate plates. Cratons are the oldest and most stable parts of the continental lithosphere and shields are the exposed area of a craton(s). Microplates are tiny tectonic plates, terranes are fragments of crustal material formed on one tectonic plate and accreted to crust lying on another plate, and zones are bands of similar rocks on a plate formed by terrane accretion or native rock formation. Terranes may or may not have originated as independent microplates: a terrane may not contain the full thickness of the lithosphere. African Plate[edit]. Atlantica – Ancient continent formed during the Proterozoic about 2 billion years ago Bangweulu Block – Part of the Congo craton of central Africa (Zambia) Congo Craton – Precambrian craton that with four others makes up the modern continent of Africa (Angola, Cameroon, Central African Republic, Democratic Republic of Congo, Gabon, Sudan, and Zambia) Kaapvaal Craton – Archaean craton, possibly part of the Vaalbara supercontinent (South Africa) Kalahari Craton – old and stable part of the continental lithosphere, that occupies large portions of South Africa, Botswana, Namibia and Zimbabwe (South Africa) Saharan Metacraton – Large area of continental crust in the north-central part of Africa (Algeria) Sebakwe proto-Craton (Zimbabwe) Tanzania Craton – Old and stable part of the continental lithosphere in central Tanzania (Tanzania) West African Craton – One of the five cratons of the Precambrian basement rock of Africa that make up the African Plate (Algeria, Benin, Burkina Faso, Côte d'Ivoire, Gambia, Ghana, Guinea, Guinea Bissau, Liberia, Mali, Mauritania, Morocco, Nigeria, Senegal, Sierra Leone, and Togo) Zaire Craton (Congo) Zimbabwe Craton – Area in Southern Africa of ancient continental crust (Zimbabwe) Antarctic Plate[edit]. Bellingshausen Plate – Ancient tectonic plate that fused onto the Antarctic Plate Charcot Plate – Fragment of the Phoenix tectonic plate fused to the Antarctic Peninsula East Antarctic Shield, also known as East Antarctic Craton – Cratonic rock body which makes up most of the continent Antarctica Phoenix Plate – Tectonic plate that existed during the mid-Jurassc through late-Cenozoic time Eurasian Plate[edit]. Armorica – Microcontinent or group of continental fragments rifted away from Gondwana (France, Germany, Spain and Portugal) Avalonia – Microcontinent in the Paleozoic era named for the Avalon Peninsula in Newfoundland (Canada, Great Britain, and United States) Baltic Plate – Ancient tectonic plate from the Cambrian to the Carboniferous Period Belomorian Craton Central Iberian Plate Cimmerian Plate – Ancient string of microcontinents that rifted from Gondwana (Anatolia, Iran, Afghanistan, Tibet, Indochina and Malaya) East China Craton[citation needed] East European Craton – Geology of Europe Baltic Shield, also known as Fennoscandian Shield – Ancient segment of Earth's crust Junggar Plate – Geographical region in Northwest China corresponding to the northern half of Xinjiang and Eastern Kazakhstan Hunic plate Karelian Craton – Region comprising the Scandinavian Peninsula, Finland, Karelia, and the Kola Peninsula Kazakhstania – Geological region in Central Asia and the Junngar Basin in China Kola Craton Lhasa terrane – Fragment of crustal material, sutured to the Eurasian Plate during the Cretaceous that forms present-day southern Tibet Massif Central – A highland region in the middle of Southern France Moldanubian Plate – A tectonic zone in Europe formed during the Variscan or Hercynian Orogeny Moravo Silesian Plate Midlands Microcraton – Block of late Neoproterozoic crust which underlies the English Midlands North Atlantic Craton – Archaean craton exposed in southern West Greenland, the Nain Province in Labrador, and the Lewisian complex in northwestern Scotland North China Craton – continental crustal block in northeast China, Inner Mongolia, the Yellow Sea, and North Korea Ossa-Morena Plate Piemont-Liguria Plate – Former piece of oceanic crust that is seen as part of the Tethys Ocean Proto-Alps Terrane Rhenohercynian Plate – Fold belt of west and central Europe, formed during the Hercynian orogeny Sarmatian Craton – The southern part of the East European Craton or Baltica, also known as Scythian Plateau Saxothuringian Plate – Structural or tectonic zone in the Hercynian or Variscan orogen of central and western Europe Siberian Craton – Ancient craton forming the Central Siberian Plateau South Portuguese Plate Tarim Craton Teplá-Barrandian Terrane Ukrainian Shield – The southwest shield of the East European craton Valais Plate – Subducted ocean basin. Remnants found in the Alps in the North Penninic nappes. Volgo-Uralian Craton Yakutai Craton Yangtze Craton Indo-Australian Plate[edit]. Basic geological regions of Australia, by age Map of chronostratigraphic divisions of India Altjawarra Craton (Australia) Bhandara Craton, (India) Bundelkhand Craton, (India) Dharwar Craton – Part of the Indian Shield in south India Central Craton (Australia) Curnamona Craton (Australia) Gawler Craton – Province of the larger West Australian Shield in central South Australia Indian Craton Narooma Terrane – Geological structural region on the south coast of New South Wales, Australia Pilbara Craton – Old and stable part of the continental lithosphere located in Pilbara, Western Australia Singhbhum Craton (India) Yilgarn Craton – Large craton that constitutes the bulk of the Western Australian land mass Australian Shield, also known as Western Australian Shield – Large part of the continent of Australia Zealandia – Mostly submerged mass of continental crust containing New Zealand and New Caledonia. See Moa Plate and Lord Howe Rise North American Plate[edit]. North American cratons and basement rocks Avalonia – Microcontinent in the Paleozoic era named for the Avalon Peninsula in Newfoundland (Canada, Great Britain, and United States) Carolina Plate – exotic terrane from central Georgia to central Virginia in the United States Churchill Craton – Northwest section of the Canadian Shield from southern Saskatchewan and Alberta to northern Nunavut (Canada) Farallon Plate – An ancient oceanic plate that has mostly subducted under the west coast of the North American Plate (split into the Cocos, Explorer, Juan de Fuca, Gorda Plates, Nazca Plate, and Rivera Plates) Florida Plate – Overview of the geology of the U.S. state of Florida (United States) Hearne Craton – Craton in northern Canada which, together with the Rae Craton, forms the Western Churchill Province (Canada) Laurentian Craton, also known as North American Craton – A large continental craton that forms the ancient geological core of the North American continent (Canada and United States) Insular Plate – Ancient oceanic plate Intermontane Plate – Ancient oceanic tectonic plate on the west coast of North America about 195 million years ago Izanagi Plate – Ancient tectonic plate, which was subducted beneath the Okhotsk Plate Mexican Plate Nain Province – Part of the North Atlantic Craton in Labrador, Canada (Canada) Newfoundland Plate North Atlantic Craton – Archaean craton exposed in southern West Greenland, the Nain Province in Labrador, and the Lewisian complex in northwestern Scotland Nova Scotia Plate Rae Craton – Archean craton in northern Canada north of the Superior Craton (Canada) Sask Craton (Canada) Sclavia Craton – Late Archean supercraton thought to be parental to the Slave and Wyoming Cratons in North America, the Dharwar Craton in southern India, and the Zimbabwe Craton in southern Africa (Canada) Slave Craton – Archaean craton in the north-western Canadian Shield, in Northwest Territories and Nunavut (Canada) Superior Craton – Large crustal block in North America (Canada) Wyoming Craton – Craton in the west-central United States and western Canada (United States) South American Plate[edit]. Amazonian Craton – Geologic province in South America (Brazil) Guiana Shield – Precambrian geological formation in northeast South America, and one of three cratons of the South American Plate (Brazil, Colombia, French Guiana, Guyana, Suriname and Venezuela) Río de la Plata Craton – Medium-sized continental block in Uruguay, eastern Argentina and southern Brazil (Argentina and Uruguay) São Francisco Craton – An ancient craton in the eastern part of South America with outcrops in Minas Gerais and Bahia, Brazil (Brazil) Arequipa–Antofalla Craton – South American geology (Argentina, Bolivia, Chile and Peru) See also[edit]. Asthenosphere – The highly viscous, mechanically weak and ductile region of Earth's mantle Continent – Very large landmass identified by convention Craton – Old and stable part of the continental lithosphere Platform – A continental area covered by relatively flat or gently tilted, mainly sedimentary strata Shield – Large stable area of exposed Precambrian crystalline rock Earth's crust – Thin shell on the outside of Earth Continental crust – Layer of rock that forms the continents and continental shelves Oceanic crust – Uppermost layer of the oceanic portion of a tectonic plate Earth's mantle – A layer of silicate rock between Earth's crust and its outer core Lower mantle – The region from 660 to 2900 km below Earth's surface Upper mantle – A very thick layer of rock inside planet Earth Geochemistry – Science that applies chemistry to analyze geological systems Sial – Rocks rich in aluminium silicate minerals Sima – Rocks rich in magnesium silicate minerals Hydrosphere – The combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite Lithosphere – Outermost shell of a terrestrial-type planet or natural satellite Ocean – Body of salt water covering the majority of Earth Plate tectonics – Movement of Earth's lithosphere List of tectonic plate interactions – Types of plate boundaries Supercontinent – Landmass comprising more than one continental core, or craton Terrane – Fragment of crustal material formed on, or broken off from, one tectonic plate and accreted or "sutured" to crust lying on another plate Notes and references[edit]. Notes[edit]. ^ 15,600,000 km2 is the original size before the 2017 split of the Coiba and Malpelo Plates References[edit]. ^ How Many Tectonic Plates Are There? ^ Tetsuzo Seno, Taro Sakurai, and Seth Stein. 1996. Can the Okhotsk plate be discriminated from the North American plate? J. Geophys. Res., 101, 11305-11315 (abstract) ^ Bird, P. (2003). "An updated digital model of plate boundaries". Geochemistry, Geophysics, Geosystems 4 (3): 1027. doi:10.1029/2001GC000252. http://peterbird.name/publications/2003_PB2002/2003_PB2002.htm. ^ Timothy M. Kusky; Erkan Toraman & Tsilavo Raharimahefa (2006-11-20). "The Great Rift Valley of Madagascar: An extension of the Africa–Somali diffusive plate boundary?". International Association for Gondwana Research Published by Elsevier B.V. ^ Niels Henriksen; A.K. Higgins; Feiko Kalsbeek; T. Christopher R. Pulvertaft (2000). "Greenland from Archaean to Quaternary" (PDF) (185). Greenland Survey Bulletin. Archived from the original (PDF) on 2008-12-07. Retrieved 2009-10-04. Bibliography[edit]. North Andes Plate Restrepo, Jorge Julián; Oswaldo Ordóñez Carmona; Uwe Martens, and Ana María Correa. 2009. Terrenos, complejos y provincias en la Cordillera Central de Colombia (Terrains, complexes and provinces in the central cordillera of Colombia). Ingeniería Investigación y Desarrollo 9. 49–56. Fuck, Reinhardt A.; Benjamim Bley Brito Neves, and Carlos Schobbenhaus. 2008. Rodinia descendants in South America. Precambrian Research 160. 108–126. Cordani, U.G.; A. Cardona; D.M. Jiménez; L. Dunyl, and A.P. Nutman. 2003. Geochronology of Proterozoic basement from the Colombian Andes: Tectonic history of remnants from a fragmented Grenville Belt, 1–10. 10o Congreso Geológico Chileno. Restrepo, Jorge Julian, and Jean F. Toussaint. 1988. Terranes and continental accretion in the Colombian Andes. Episodes 11. 189–193. External links[edit]. Bird, Peter (2003) An updated digital model of plate boundaries also available as a large (13 Mb) PDF file vteTectonic platesMajor African Antarctic Eurasian Indo-Australian Australian Indian North American Pacific South American Minor Amurian Arabian Caribbean Caroline Cocos Indian Nazca Okhotsk Philippine Scotia Somali Sunda Yangtze Micro Adriatic Aegean Sea Anatolian Balmoral Reef Banda Sea Bird's Head Burma Capricorn Coiba Conway Reef Easter Explorer Futuna Galapagos Gonâve Gorda Greenland Halmahera Iberian Iranian Juan de Fuca Juan Fernández Kerguelen Kermadec Lwandle Madagascar Malpelo Manus Maoke Mariana Molucca Sea New Hebrides Niuafo’ou North Andes North Bismarck North Galapagos Nubian Okinawa Panama Pelso Philippine Mobile Belt Rivera Rovuma Sangihe Seychelles Shetland Solomon Sea South Bismarck South Sandwich Timor Tisza Tonga Victoria Woodlark Historical Baltic Bellingshausen Charcot Cimmeria Farallon Insular Intermontane Izanagi Kula Lhasa Malvinas Moa Phoenix Oceanic ridges Aden Ridge Cocos Ridge Explorer Ridge Galapagos Spreading Center Gorda Ridge Juan de Fuca Ridge South American–Antarctic Ridge Chile Rise East Pacific Rise Gakkel Ridge Pacific-Antarctic Ridge Central Indian Ridge Carlsberg Ridge Southeast Indian Ridge Southwest Indian Ridge Mid-Atlantic Ridge Kolbeinsey Ridge Mohns Ridge Knipovich Ridge Reykjanes Ridge Ancient oceanic ridges Aegir Ridge Alpha Ridge Kula-Farallon Ridge Mid-Labrador Ridge Pacific-Farallon Ridge Pacific-Kula Ridge Phoenix Ridge List Category Earth science Commons Retrieved from "https://en.wikipedia.org/w/index.php?title=List_of_tectonic_plates&oldid=1058160012" Categories: Geology-related listsTectonic platesHidden categories: Articles with short descriptionShort description is different from WikidataAll articles with unsourced statementsArticles with unsourced statements from May 2021 Navigation menu. 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Result 24
TitleNew origin seen for Earth's tectonic plates | Nature
Urlhttps://www.nature.com/articles/nature.2014.14993
DescriptionContinual diving of crust into mantle is sufficient to explain formation of plate boundaries
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H1New origin seen for Earth's tectonic plates
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BodyNew origin seen for Earth's tectonic plates Jessica Morrison  Nature (2014)Cite this article 3510 Accesses 127 Altmetric Metrics details Subjects. GeologyGeophysicsMathematics and computingPhysics Continual diving of crust into mantle is sufficient to explain formation of plate boundaries. Download PDF The San Andreas fault in California marks the meeting of the Pacific and North American tectonic plates. Credit: Kevin Schafer/AlamyEarth's tectonic plates may have taken as long as 1 billion years to form, researchers report today in Nature1. Increasing interest in therapy implications of epigenetics Investigation faults Japanese stem-cell researcher Calorie restriction makes monkeys live longer after all The plates — interlocking slabs of crust that float on Earth's viscous upper mantle — were created by a process similar to the subduction seen today when one plate dives below another, the report says.Starting roughly 4 billion years ago, cooler parts of Earth's crust were pulled downwards into the warmer upper mantle, damaging and weakening the surrounding crust. The process happened again and again, the authors say, until the weak areas formed plate boundaries. Other researchers have estimated that a global tectonic plate system emerged around 3 billion years ago.The finding offers a possible answer to an enduring puzzle in geology: how Earth's tectonic plates emerged. The subsequent movement of the plates has erased much of the evidence of their origin, says Paul Tackley, a geophysicist at Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland.Prior studies suggested the age of the plates, based on evidence of subduction gathered from minerals preserved in ancient rocks. The oldest such specimens are 4-billion-year-old zircons found in the Jack Hills of Australia, which appear to have formed at temperatures and pressures that are indicative of subduction. Grains of time To go a step further and investigate how the plates formed, the study's authors developed a computer model of Earth's crust as it may have existed billions of years ago, on the basis of mineral grains found in mantle rock. The model included a low-pressure zone at the base of the crust, which caused a piece of the crust to sink into the upper mantle — mimicking conditions thought to have occurred early in Earth's history.As the process repeated over time, it created a large tectonic plate with an active subduction zone. Over a much longer period, the same process could have created many tectonic plates, says co-author David Bercovici, a geophysicist at Yale University in New Haven, Connecticut. “We’ve got a physical mechanism to explain how it could have happened,” he says.This stands in contrast to conditions on Venus, where similar subduction occurs but has not produced tectonic plates. Conditions on Venus are much warmer, allowing the crust to better heal after a piece sinks down into the mantle. Bercovici's model suggests that early subduction created weak spots in Earth's crust that are now plate boundaries. Plate tectonics is defined by the idea that strong plates are separated by weak boundaries, and action at those boundaries creates geological phenomena such as volcanoes, mountains and earthquakes, he notes.“They produce a model that plausibly explains what we see,” says Michael Brown, a petrologist at the University of Maryland in College Park. It shows how to start subduction and how that could have progressed to global tectonics, and it provides an amount of time between the two — 1 billion years — that is consistent with the rock record, he adds.Robert Stern, a geologist at the University of Texas in Dallas, contends that there is no firm evidence of plate tectonics earlier than 1 billion years ago, but says that their theory of the mechanism behind plate formation is “the first interesting example of how it might have occurred”. References. 1Bercovici, D. & Yanick, R. Nature http://dx.doi.org/10.1038/nature13072 (2014).Download referencesAuthorsJessica MorrisonView author publicationsYou can also search for this author in PubMed Google ScholarRelated links. Related links. Related links in Nature Research. Minerals yield signs of early plate tectonics 2008-Nov-26 Geology: The start of the world as we know it 2006-Jul-12 Related external links. David Bercovici Paul Tackley Michael Brown Robert Stern Rights and permissions. Reprints and PermissionsAbout this article. Cite this article. Morrison, J. New origin seen for Earth's tectonic plates. Nature (2014). https://doi.org/10.1038/nature.2014.14993Download citationPublished: 06 April 2014DOI: https://doi.org/10.1038/nature.2014.14993Share this article. Anyone you share the following link with will be able to read this content:Get shareable linkSorry, a shareable link is not currently available for this article.Copy to clipboard Provided by the Springer Nature SharedIt content-sharing initiative Search. Advanced search Quick links. Explore articles by subject Find a job Guide to authors Editorial policies Close banner Close Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily. Close banner Close Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing
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TitleDo tectonic plates float on the lithosphere? – JanetPanic.com
Urlhttps://janetpanic.com/do-tectonic-plates-float-on-the-lithosphere/
Description
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Organic Position24
H1Do tectonic plates float on the lithosphere?
H2Do tectonic plates float on the lithosphere?
Where are the tectonic plates located lithosphere?
How do the lithosphere and asthenosphere play a role in plate tectonics?
What is the difference between lithospheric plates and tectonic plates?
What is the largest plate?
What really happens when plates move?
What will happen if the plates continue to move?
What type of earthquake causes the plates to move horizontally?
What are the 5 causes of earthquake?
What is the role of tectonic plates in earthquakes?
What are the relationship of plate tectonics and faults with earthquakes?
What is the relationship between locations of earthquakes and plate tectonics quizlet?
What is the relationship between volcanoes and earthquake?
Which is more dangerous a volcano or an earthquake?
Can earthquakes cause volcanoes?
Does plate tectonics cause volcanoes and earthquake?
H3JanetPanic.com
H2WithAnchorsDo tectonic plates float on the lithosphere?
Where are the tectonic plates located lithosphere?
How do the lithosphere and asthenosphere play a role in plate tectonics?
What is the difference between lithospheric plates and tectonic plates?
What is the largest plate?
What really happens when plates move?
What will happen if the plates continue to move?
What type of earthquake causes the plates to move horizontally?
What are the 5 causes of earthquake?
What is the role of tectonic plates in earthquakes?
What are the relationship of plate tectonics and faults with earthquakes?
What is the relationship between locations of earthquakes and plate tectonics quizlet?
What is the relationship between volcanoes and earthquake?
Which is more dangerous a volcano or an earthquake?
Can earthquakes cause volcanoes?
Does plate tectonics cause volcanoes and earthquake?
BodyDo tectonic plates float on the lithosphere? Table of Contents Do tectonic plates float on the lithosphere? Tectonic plates float on the asthenosphere. The asthenosphere is immediately below the top layer of Earth’s surface (lithosphere). Where are the tectonic plates located lithosphere? The lithosphere is the solid, outer part of the Earth. It includes the brittle upper portion of the mantle and the crust, the planet’s outermost layers. The lithosphere is located below the atmosphere and above the asthenosphere. How do the lithosphere and asthenosphere play a role in plate tectonics? The asthenosphere is now thought to play a critical role in the movement of plates across the face of Earth’s surface. According to plate tectonic theory, the lithosphere consists of a relatively small number of very large slabs of rocky material. What is the difference between lithospheric plates and tectonic plates? Tectonic plates are the different pieces of the Earth’s crust that move around as they float on top of the mantle. Lithospheric plates are regions of Earth’s crust and upper mantle that are fractured into plates that move across a deeper plasticine mantle. What is the largest plate? Pacific Plate What really happens when plates move? When the plates move they collide or spread apart allowing the very hot molten material called lava to escape from the mantle. When collisions occur they produce mountains, deep underwater valleys called trenches, and volcanoes. The Earth is producing “new” crust where two plates are diverging or spreading apart. What will happen if the plates continue to move? Plate tectonics moves the continents around on a scale of 100s of millions of year. Plate tectonics also has an impact on longer-term climate patterns and these will change over time. It also changes ocean current patterns, heat distribution over the planet, and the evolution and speciation of animals. What type of earthquake causes the plates to move horizontally? A transform plate boundary occurs when two plates slide past each other, horizontally. A well-known transform plate boundary is the San Andreas Fault, which is responsible for many of California’s earthquakes. A single tectonic plate can have multiple types of plate boundaries with the other plates that surround it. What are the 5 causes of earthquake? They account for most earthquakes worldwide and usually occur at the boundaries of tectonic plates. Induced Earthquakes. Induced quakes are caused by human activity, like tunnel construction, filling reservoirs and implementing geothermal or fracking projects. Volcanic Earthquakes. Collapse Earthquakes. What is the role of tectonic plates in earthquakes? Earthquakes occur along fault lines, cracks in Earth’s crust where tectonic plates meet. They occur where plates are subducting, spreading, slipping, or colliding. As the plates grind together, they get stuck and pressure builds up. Finally, the pressure between the plates is so great that they break loose. What are the relationship of plate tectonics and faults with earthquakes? Earthquakes occur on faults – strike-slip earthquakes occur on strike-slip faults, normal earthquakes occur on normal faults, and thrust earthquakes occur on thrust or reverse faults. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other. What is the relationship between locations of earthquakes and plate tectonics quizlet? What is the relationship between locations of earthquakes and plate tectonics? A. Earthquakes frequently happen where landmasses are on the boundary between two plates. What is the relationship between volcanoes and earthquake? Earth’s lithosphere is bro- ken into separate sections, or plates. When these plates move around, they collide, move apart, or slide past each other. The movement of these plates can cause vibrations known as earth- quakes and can create conditions that cause volcanoes to form. Which is more dangerous a volcano or an earthquake? Volcanoes are usually less dangerous than other natural hazards such as earthquakes, tsunamis and hurricanes. Can earthquakes cause volcanoes? Sometimes, yes. A few large regional earthquakes (greater than magnitude 6) are considered to be related to a subsequent eruption or to some type of unrest at a nearby volcano. However, volcanoes can only be triggered into eruption by nearby tectonic earthquakes if they are already poised to erupt. Does plate tectonics cause volcanoes and earthquake? As plates move, they get stuck in places, and enormous amounts of energy build up. When the plates finally get unstuck and move past each other, the energy is released in the form of earthquakes. Earthquakes and volcanoes are common features along tectonic plate boundaries, making these zones geologically very active. Back to top Copyright © | Janet Panic We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept”, you consent to the use of ALL the cookies. Do not sell my personal information.Cookie SettingsAcceptManage consent Close Privacy Overview. This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience. 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TitleEarth's mantle: what's going on deep beneath our feet? - Curious
Urlhttps://www.science.org.au/curious/earth-environment/earths-mantle-whats-going-deep-beneath-our-feet
DescriptionIt gets pretty hot and gooey down there ..
Date6 Mar 2018
Organic Position25
H1Earth's mantle: what's going on deep beneath our feet?
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BodyEarth's mantle: what's going on deep beneath our feet? We know that the ground we walk on is made of solid rock (unless we happen to wander into a patch of quicksand …). But what about the layers of Earth a bit deeper beneath our feet? Earth’s interior is made of several layers. The surface of the planet, where we live, is called the crust—it’s actually a very thin layer, just 70 kilometres deep at its thickest point. The crust and the lithosphere below (the crust plus the upper mantle) is made of several ‘tectonic plates’. These move slowly across the surface of the planet, and most of Earth’s volcanoes and earthquakes occur at the boundaries between tectonic plates. Deep in the centre of the planet is the ‘inner core’, which we think is made of solid iron and nickel. This is surrounded by the ‘outer core’, which is also made of iron and nickel, but is molten. Convection currents in the outer core create Earth’s magnetic field. And between the outer core and the crust is the mantle, which, at around 2,900 kilometres thick, accounts for the bulk (around 84 per cent by volume) of the planet. Carrying Earth’s internal heat to the surface, the convecting mantle creeps like tar on a hot day. This overturning is the ‘engine’ that drives our dynamic Earth—it’s what makes our planet’s geology so interesting, as it enables the movement of tectonic plates. Without it, we wouldn’t have volcanoes, earthquakes … and actually, Earth wouldn’t be able to sustain life.  Earth's crust is made of several tectonic plates, which slowly move around Earth's surface. Most—but not all!—tectonic activity, including volcanoes, occurs where these plates meet. The tectonic plates ‘float’ on the ‘flowing’ mantle layer. Image adapted from: Digital Tectonic Activity Map of the Earth, NASA 1998 The mysteries of mantle dynamics are what the Australian Academy of Science 2018 Anton Hales Medal winner, Dr Rhodri Davies, spends his time investigating. He uses advanced computing tools to develop models of mantle dynamics, helping us to understand the mantle’s behaviour and how it influences Earth’s surface. These models combine large-scale geophysical and geochemical datasets with knowledge of how individual minerals behave under certain temperature and pressure conditions to shed light on mantle structure, provide constraints on how the mantle flows, and demonstrate how this flow drives volcanism and other features at the surface. We know that most of Earth’s volcanoes lie at tectonic plate boundaries, where plates: move apart, as is currently occurring between Australia and Antarctica move towards each other with one sliding back into the underlying mantle, as at the northern edge of Australia’s tectonic plate beneath Papua New Guinea and Indonesia slide past each other, which is occurring at the infamous San Andreas fault in California. Some volcanoes, however, lie within tectonic plates, far away from these boundary processes. These are called intra-plate volcanoes. Many of these are caused by mantle plumes—regions of hot rock that flow upwards from Earth’s core-mantle boundary towards its surface. In doing so, they carry molten rock material containing a message from Earth’s deep mantle; a message that Dr Davies’ work allows us to decipher. This has helped solidify theories regarding the processes that create intra-plate volcanic island chains. Hot mantle plumes are regions of hot rock that flow upwards from the core-mantle boundary deep within Earth. Image adapted from: Rhodri Davies, with permission. For example, he has combined observations from several fields to show that volcanic chains within Australia formed as the Australian tectonic plate drifted to the north over several mantle plumes. This resulted in a string of volcanoes that traverse the continent from north to south, formed between 34 and 9 million years ago. Believe it or not, the now tectonically sleepy Australian continent houses one of the world’s most extensive intra-plate volcanic regions, with eruptions on the mainland as recently as around 5,000 years ago. Mantle activity has fuelled a string of volcanoes that extends from north to south eastern Australia. Image adapted from: Rhodri Davies, with permission. The Hawaiian archipelago is believed to have formed via a similar process. Hawaii sits at the south-eastern limit of a chain of volcanoes and submerged seamounts which get progressively older towards the northwest. This chain splits into two at the island of Oahu and Davies and his group recently found that this split occurred due to a shift in the Pacific Plate’s direction, roughly three million years ago. The Glasshouse Mountains in Queensland were formed by intra-plate volcanic activity. Image adapted from: Rhodri Davies, with permission Incorporating all these factors to create models of the way the mantle behaves improves our understanding of the way our planet works. This helps us explain the processes that result in Earth’s unique and spectacular geology and allows us to better understand the planet’s evolution since its formation more than 4.5 billion years ago. Back to top
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Result 27
TitleEarth Quizlet Flashcards
Urlhttps://quizlet.com/39545897/earth-quizlet-flash-cards/
DescriptionThis newly heated rocks floats to the top and creates an endless cycle. ... Hot semi-liquid zone of the mantle on which the tectonic plates float. Plates.
Date
Organic Position26
H1
H2
H3
H2WithAnchors
Body
Topics
  • Topic
  • Tf
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Result 28
TitleThe Theory of Plate Tectonics | Geology
Urlhttps://courses.lumenlearning.com/wmopen-geology/chapter/outcome-theory-of-plate-tectonics/
Description
Date
Organic Position27
H1
H2The Theory of Plate Tectonics
Critique and interpret major types of evidence supporting the Theory of Plate Tectonics
Theory of Plate Tectonics
Developing the Theory
Check Your Understanding
H3Module 5: Plate Tectonics
What You’ll Learn to Do
Earth’s Tectonic Plates
How Plates Move
Plate Boundaries
Earth’s Changing Surface
Summary
Continental Drift
Floating Continents, Paleomagnetism, and Seismicity Zones
Mid-Oceanic Ridge Spreading and Convection
Magnetic Striping
Definition and Refining of the Theory
H2WithAnchorsThe Theory of Plate Tectonics
Critique and interpret major types of evidence supporting the Theory of Plate Tectonics
Theory of Plate Tectonics
Developing the Theory
Check Your Understanding
BodySkip to main content Module 5: Plate Tectonics. The Theory of Plate Tectonics. Critique and interpret major types of evidence supporting the Theory of Plate Tectonics. Plate tectonics is the most important concept in modern geology. This section will introduce you to the concept of plate tectonics, how it works, why it is important and how it is shaping the world today. What You’ll Learn to Do. Describe and compare different types of plate motions, rates of motion and the driving mechanisms and forces involved with each. Know the role of technology in Plate Tectonics. Theory of Plate Tectonics. When the concept of seafloor spreading came along, scientists recognized that it was the mechanism to explain how continents could move around Earth’s surface. Like the scientists before us, we will now merge the ideas of continental drift and seafloor spreading into the theory of plate tectonics. Watch this video about continental drift and the mechanism of seafloor spreading create plate tectonics. Earth’s Tectonic Plates. Seafloor and continents move around on Earth’s surface, but what is actually moving? What portion of the Earth makes up the “plates” in plate tectonics? This question was also answered because of technology developed during war times – in this case, the Cold War. The plates are made up of the lithosphere. Figure 1. Earthquakes outline the plates. During the 1950s and early 1960s, scientists set up seismograph networks to see if enemy nations were testing atomic bombs. These seismographs also recorded all of the earthquakes around the planet. The seismic records could be used to locate an earthquake’s epicenter, the point on Earth’s surface directly above the place where the earthquake occurs. Earthquake epicenters outline the plates. Mid-ocean ridges, trenches, and large faults mark the edges of the plates, and this is where earthquakes occur (figure 1). The lithosphere is divided into a dozen major and several minor plates (figure 2). The plates’ edges can be drawn by connecting the dots that mark earthquakes’ epicenters. A single plate can be made of all oceanic lithosphere or all continental lithosphere, but nearly all plates are made of a combination of both. Figure 2. The lithospheric plates and their names. The arrows show whether the plates are moving apart, moving together, or sliding past each other. Movement of the plates over Earth’s surface is termed plate tectonics. Plates move at a rate of a few centimeters a year, about the same rate fingernails grow. How Plates Move. Figure 3. Mantle convection drives plate tectonics. Hot material rises at mid-ocean ridges and sinks at deep sea trenches, which keeps the plates moving along the Earth’s surface. If seafloor spreading drives the plates, what drives seafloor spreading? Picture two convection cells side-by-side in the mantle, similar to the illustration in figure 3. Hot mantle from the two adjacent cells rises at the ridge axis, creating new ocean crust. The top limb of the convection cell moves horizontally away from the ridge crest, as does the new seafloor. The outer limbs of the convection cells plunge down into the deeper mantle, dragging oceanic crust as well. This takes place at the deep sea trenches. The material sinks to the core and moves horizontally. The material heats up and reaches the zone where it rises again. Check out this animation of mantle convection and watch this video: Plate Boundaries. Plate boundaries are the edges where two plates meet. Most geologic activities, including volcanoes, earthquakes, and mountain building, take place at plate boundaries. How can two plates move relative to each other? Divergent plate boundaries: the two plates move away from each other. Convergent plate boundaries: the two plates move towards each other. Transform plate boundaries: the two plates slip past each other. The type of plate boundary and the type of crust found on each side of the boundary determines what sort of geologic activity will be found there. Divergent Plate Boundaries. Plates move apart at mid-ocean ridges where new seafloor forms. Between the two plates is a rift valley. Lava flows at the surface cool rapidly to become basalt, but deeper in the crust, magma cools more slowly to form gabbro. So the entire ridge system is made up of igneous rock that is either extrusive or intrusive. Earthquakes are common at mid-ocean ridges since the movement of magma and oceanic crust results in crustal shaking. The vast majority of mid-ocean ridges are located deep below the sea (figure 4). Figure 4. (a) Iceland is the one location where the ridge is located on land: the Mid-Atlantic Ridge separates the North American and Eurasian plates; (b) The rift valley in the Mid-Atlantic Ridge on Iceland. Figure 5. The Arabian, Indian, and African plates are rifting apart, forming the Great Rift Valley in Africa. The Dead Sea fills the rift with seawater. Check out these animations: Divergent plate boundary at mid-ocean ridge Divergent plate boundary Can divergent plate boundaries occur within a continent? What is the result? Incontinental rifting (figure 5), magma rises beneath the continent, causing it to become thinner, break, and ultimately split apart. New ocean crust erupts in the void, creating an ocean between continents. Convergent Plate Boundaries. When two plates converge, the result depends on the type of lithosphere the plates are made of. No matter what, smashing two enormous slabs of lithosphere together results in magma generation and earthquakes. Figure 6. Subduction of an oceanic plate beneath a continental plate causes earthquakes and forms a line of volcanoes known as a continental arc. Ocean-Continent When oceanic crust converges with continental crust, the denser oceanic plate plunges beneath the continental plate. This process, called subduction, occurs at the oceanic trenches (figure 6). The entire region is known as a subduction zone. Subduction zones have a lot of intense earthquakes and volcanic eruptions. The subducting plate causes melting in the mantle. The magma rises and erupts, creating volcanoes. These coastal volcanic mountains are found in a line above the subducting plate (figure 7). The volcanoes are known as a continental arc. Figure 7. (a) At the trench lining the western margin of South America, the Nazca plate is subducting beneath the South American plate, resulting in the Andes Mountains (brown and red uplands); (b) Convergence has pushed up limestone in the Andes Mountains where volcanoes are common. The movement of crust and magma causes earthquakes. Look at this map of earthquake epicenters at subduction zones. This animation shows the relationship between subduction of the lithosphere and creation of a volcanic arc. The volcanoes of northeastern California—Lassen Peak, Mount Shasta, and Medicine Lake volcano—along with the rest of the Cascade Mountains of the Pacific Northwest are the result of subduction of the Juan de Fuca plate beneath the North American plate (figure 8). The Juan de Fuca plate is created by seafloor spreading just offshore at the Juan de Fuca ridge. Figure 8. The Cascade Mountains of the Pacific Northwest are a continental arc. If the magma at a continental arc is felsic, it may be too viscous (thick) to rise through the crust. The magma will cool slowly to form granite or granodiorite. These large bodies of intrusive igneous rocks are called batholiths, which may someday be uplifted to form a mountain range (figure 9). Figure 9. The Sierra Nevada batholith cooled beneath a volcanic arc roughly 200 million years ago. The rock is well exposed here at Mount Whitney. Similar batholiths are likely forming beneath the Andes and Cascades today. Ocean-Ocean When two oceanic plates converge, the older, denser plate will subduct into the mantle. An ocean trench marks the location where the plate is pushed down into the mantle. The line of volcanoes that grows on the upper oceanic plate is an island arc. Do you think earthquakes are common in these regions (figure 10)? Figure 10. (a) Subduction of an ocean plate beneath an ocean plate results in a volcanic island arc, an ocean trench and many earthquakes. (b) Japan is an arc-shaped island arc composed of volcanoes off the Asian mainland, as seen in this satellite image. Check out this animation of an ocean continent plate boundary. Continent-Continent Continental plates are too buoyant to subduct. What happens to continental material when it collides? Since it has nowhere to go but up, this creates some of the world’s largest mountains ranges (figure 11). Magma cannot penetrate this thick crust so there are no volcanoes, although the magma stays in the crust. Metamorphic rocks are common because of the stress the continental crust experiences. With enormous slabs of crust smashing together, continent-continent collisions bring on numerous and large earthquakes. Figure 11. (a) In continent-continent convergence, the plates push upward to create a high mountain range. (b) The world’s highest mountains, the Himalayas, are the result of the collision of the Indian Plate with the Eurasian Plate, seen in this photo from the International Space Station. Check out this short animation of the Indian Plate colliding with the Eurasian Plate. Watch this animation of the Himalaya rising. The Appalachian Mountains are the remnants of a large mountain range that was created when North America rammed into Eurasia about 250 million years ago. Transform Plate Boundaries. Figure 12. At the San Andreas Fault in California, the Pacific Plate is sliding northwest relative to the North American plate, which is moving southeast. At the northern end of the picture, the transform boundary turns into a subduction zone. Transform plate boundaries are seen as transform faults, where two plates move past each other in opposite directions. Transform faults on continents bring massive earthquakes (figure 12). California is very geologically active. What are the three major plate boundaries in or near California (figure 13)? A transform plate boundary between the Pacific and North American plates creates the San Andreas Fault, the world’s most notorious transform fault. Just offshore, a divergent plate boundary, Juan de Fuca ridge, creates the Juan de Fuca plate. A convergent plate boundary between the Juan de Fuca oceanic plate and the North American continental plate creates the Cascades volcanoes. Figure 13. This map shows the three major plate boundaries in or near California. A brief review of the three types of plate boundaries and the structures that are found there is the subject of this wordless video. Earth’s Changing Surface. Geologists know that Wegener was right because the movements of continents explain so much about the geology we see. Most of the geologic activity that we see on the planet today is because of the interactions of the moving plates. Figure 14. Mountain ranges of North America. In the map of North America (figure 14), where are the mountain ranges located? Using what you have learned about plate tectonics, try to answer the following questions: What is the geologic origin of the Cascades Range? The Cascades are a chain of volcanoes in the Pacific Northwest. They are not labelled on the diagram but they lie between the Sierra Nevada and the Coastal Range. What is the geologic origin of the Sierra Nevada? (Hint: These mountains are made of granitic intrusions.) What is the geologic origin of the Appalachian Mountains along the Eastern US? Figure 15. About 200 million years ago, the Appalachian Mountains of eastern North America were probably once as high as the Himalaya, but they have been weathered and eroded significantly since the breakup of Pangaea. Remember that Wegener used the similarity of the mountains on the west and east sides of the Atlantic as evidence for his continental drift hypothesis. The Appalachian mountains formed at a convergent plate boundary as Pangaea came together (figure 15). Before Pangaea came together, the continents were separated by an ocean where the Atlantic is now. The proto-Atlantic ocean shrank as the Pacific ocean grew. Currently, the Pacific is shrinking as the Atlantic is growing. This supercontinent cycle is responsible for most of the geologic features that we see and many more that are long gone (figure 16). Figure 16. Scientists think that the creation and breakup of a supercontinent takes place about every 500 million years. The supercontinent before Pangaea was Rodinia. A new continent will form as the Pacific ocean disappears. This animation shows the movement of continents over the past 600 million years beginning with the breakup of Rodinia. Summary. Plates of lithosphere move because of convection currents in the mantle. One type of motion is produced by seafloor spreading. Plate boundaries can be located by outlining earthquake epicenters. Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth’s geologic activity takes place at plate boundaries. At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes. At a convergent boundary with at least one oceanic plate, an ocean trench, a chain of volcanoes develops and many earthquakes occur. At a convergent boundary where both plates are continental, mountain ranges grow and earthquakes are common. At a transform boundary, there is a transform fault and massive earthquakes occur but there are no volcanoes. Processes acting over long periods of time create Earth’s geographic features. Developing the Theory. In line with other previous and contemporaneous proposals, in 1912 the meteorologist Alfred Wegener amply described what he called continental drift, expanded in his 1915 book The Origin of Continents and Oceans[1], and the scientific debate started that would end up fifty years later in the theory of plate tectonics. Starting from the idea (also expressed by his forerunners) that the present continents once formed a single land mass (which was called Pangea later on) that drifted apart, thus releasing the continents from the Earth’s mantle and likening them to “icebergs” of low density granite floating on a sea of denser basalt. Supporting evidence for the idea came from the dove-tailing outlines of South America’s east coast and Africa’s west coast, and from the matching of the rock formations along these edges. Confirmation of their previous contiguous nature also came from the fossil plants Glossopteris and Gangamopteris, and the therapsid or mammal-like reptile Lystrosaurus, all widely distributed over South America, Africa, Antarctica, India and Australia. The evidence for such an erstwhile joining of these continents was patent to field geologists working in the southern hemisphere. The South African Alex du Toit put together a mass of such information in his 1937 publication Our Wandering Continents, and went further than Wegener in recognising the strong links between the Gondwana fragments. Figure 17. Detailed map showing the tectonic plates with their movement vectors. (Click on the image to open a larger version of the map.) But without detailed evidence and a force sufficient to drive the movement, the theory was not generally accepted: the Earth might have a solid crust and mantle and a liquid core, but there seemed to be no way that portions of the crust could move around. Distinguished scientists, such as Harold Jeffreys and Charles Schuchert, were outspoken critics of continental drift. Despite much opposition, the view of continental drift gained support and a lively debate started between “drifters” or “mobilists” (proponents of the theory) and “fixists” (opponents). During the 1920s, 1930s and 1940s, the former reached important milestones proposing that convection currents might have driven the plate movements, and that spreading may have occurred below the sea within the oceanic crust. Concepts close to the elements now incorporated in plate tectonics were proposed by geophysicists and geologists (both fixists and mobilists) like Vening-Meinesz, Holmes, and Umbgrove. One of the first pieces of geophysical evidence that was used to support the movement of lithospheric plates came from paleomagnetism. This is based on the fact that rocks of different ages show a variable magnetic field direction, evidenced by studies since the mid–nineteenth century. The magnetic north and south poles reverse through time, and, especially important in paleotectonic studies, the relative position of the magnetic north pole varies through time. Initially, during the first half of the twentieth century, the latter phenomenon was explained by introducing what was called “polar wander” (see apparent polar wander), i.e., it was assumed that the north pole location had been shifting through time. An alternative explanation, though, was that the continents had moved (shifted and rotated) relative to the north pole, and each continent, in fact, shows its own “polar wander path”. During the late 1950s it was successfully shown on two occasions that these data could show the validity of continental drift: by Keith Runcorn in a paper in 1956,[2] and by Warren Carey in a symposium held in March 1956.[3] The second piece of evidence in support of continental drift came during the late 1950s and early 60s from data on the bathymetry of the deep ocean floors and the nature of the oceanic crust such as magnetic properties and, more generally, with the development of marine geology which gave evidence for the association of seafloor spreading along the mid-oceanic ridges and magnetic field reversals, published between 1959 and 1963 by Heezen, Dietz, Hess, Mason, Vine & Matthews, and Morley. Simultaneous advances in early seismic imaging techniques in and around Wadati-Benioff zones along the trenches bounding many continental margins, together with many other geophysical (e.g. gravimetric) and geological observations, showed how the oceanic crust could disappear into the mantle, providing the mechanism to balance the extension of the ocean basins with shortening along its margins. All this evidence, both from the ocean floor and from the continental margins, made it clear around 1965 that continental drift was feasible and the theory of plate tectonics, which was defined in a series of papers between 1965 and 1967, was born, with all its extraordinary explanatory and predictive power. The theory revolutionized the Earth sciences, explaining a diverse range of geological phenomena and their implications in other studies such as paleogeography and paleobiology. Continental Drift. Figure 18. Alfred Wegener in Greenland in the winter of 1912-13. In the late nineteenth and early twentieth centuries, geologists assumed that the Earth’s major features were fixed, and that most geologic features such as basin development and mountain ranges could be explained by vertical crustal movement, described in what is called the geosynclinal theory. Generally, this was placed in the context of a contracting planet Earth due to heat loss in the course of a relatively short geological time. It was observed as early as 1596 that the opposite coasts of the Atlantic Ocean—or, more precisely, the edges of the continental shelves—have similar shapes and seem to have once fitted together. Since that time many theories were proposed to explain this apparent complementarity, but the assumption of a solid Earth made these various proposals difficult to accept.[ The discovery of radioactivity and its associated heating properties in 1895 prompted a re-examination of the apparent age of the Earth. This had previously been estimated by its cooling rate and assumption the Earth’s surface radiated like a black body. Those calculations had implied that, even if it started at red heat, the Earth would have dropped to its present temperature in a few tens of millions of years. Armed with the knowledge of a new heat source, scientists realized that the Earth would be much older, and that its core was still sufficiently hot to be liquid. By 1915, after having published a first article in 1912, Alfred Wegener was making serious arguments for the idea of continental drift in the first edition of The Origin of Continents and Oceans. In that book (re-issued in four successive editions up to the final one in 1936), he noted how the east coast of South America and the west coast of Africa looked as if they were once attached. Wegener was not the first to note this (Abraham Ortelius, Antonio Snider-Pellegrini, Eduard Suess, Roberto Mantovani and Frank Bursley Taylor preceded him just to mention a few), but he was the first to marshal significant fossil and paleo-topographical and climatological evidence to support this simple observation (and was supported in this by researchers such as Alex du Toit). Furthermore, when the rock strata of the margins of separate continents are very similar it suggests that these rocks were formed in the same way, implying that they were joined initially. For instance, parts of Scotland and Ireland contain rocks very similar to those found in Newfoundland and New Brunswick. Furthermore, the Caledonian Mountains of Europe and parts of the Appalachian Mountainsof North America are very similar in structure and lithology. However, his ideas were not taken seriously by many geologists, who pointed out that there was no apparent mechanism for continental drift. Specifically, they did not see how continental rock could plow through the much denser rock that makes up oceanic crust. Wegener could not explain the force that drove continental drift, and his vindication did not come until after his death in 1930. Floating Continents, Paleomagnetism, and Seismicity Zones. As it was observed early that although granite existed on continents, seafloor seemed to be composed of denser basalt, the prevailing concept during the first half of the twentieth century was that there were two types of crust, named “sial” (continental type crust) and “sima” (oceanic type crust). Furthermore, it was supposed that a static shell of strata was present under the continents. It therefore looked apparent that a layer of basalt (sial) underlies the continental rocks. Figure 19. Global earthquake epicenters, 1963–1998 However, based on abnormalities in plumb line deflection by the Andes in Peru, Pierre Bouguer had deduced that less-dense mountains must have a downward projection into the denser layer underneath. The concept that mountains had “roots” was confirmed by George B. Airy a hundred years later, during study of Himalayan gravitation, and seismic studies detected corresponding density variations. Therefore, by the mid-1950s, the question remained unresolved as to whether mountain roots were clenched in surrounding basalt or were floating on it like an iceberg. During the 20th century, improvements in and greater use of seismic instruments such as seismographs enabled scientists to learn that earthquakes tend to be concentrated in specific areas, most notably along the oceanic trenches and spreading ridges. By the late 1920s, seismologists were beginning to identify several prominent earthquake zones parallel to the trenches that typically were inclined 40–60° from the horizontal and extended several hundred kilometers into the Earth. These zones later became known as Wadati-Benioff zones, or simply Benioff zones, in honor of the seismologists who first recognized them, Kiyoo Wadati of Japan and Hugo Benioff of the United States. The study of global seismicity greatly advanced in the 1960s with the establishment of the Worldwide Standardized Seismograph Network (WWSSN) to monitor the compliance of the 1963 treaty banning above-ground testing of nuclear weapons. The much improved data from the WWSSN instruments allowed seismologists to map precisely the zones of earthquake concentration worldwide. Meanwhile, debates developed around the phenomena of polar wander. Since the early debates of continental drift, scientists had discussed and used evidence that polar drift had occurred because continents seemed to have moved through different climatic zones during the past. Furthermore, paleomagnetic data had shown that the magnetic pole had also shifted during time. Reasoning in an opposite way, the continents might have shifted and rotated, while the pole remained relatively fixed. The first time the evidence of magnetic polar wander was used to support the movements of continents was in a paper by Keith Runcorn in 1956, and successive papers by him and his students Ted Irving (who was actually the first to be convinced of the fact that paleomagnetism supported continental drift) and Ken Creer. This was immediately followed by a symposium in Tasmania in March 1956. In this symposium, the evidence was used in the theory of an expansion of the global crust. In this hypothesis the shifting of the continents can be simply explained by a large increase in size of the Earth since its formation. However, this was unsatisfactory because its supporters could offer no convincing mechanism to produce a significant expansion of the Earth. Certainly there is no evidence that the moon has expanded in the past 3 billion years; other work would soon show that the evidence was equally in support of continental drift on a globe with a stable radius. During the thirties up to the late fifties, works by Vening-Meinesz, Holmes, Umbgrove, and numerous others outlined concepts that were close or nearly identical to modern plate tectonics theory. In particular, the English geologist Arthur Holmes proposed in 1920 that plate junctions might lie beneath the sea, and in 1928 that convection currents within the mantle might be the driving force. Often, these contributions are forgotten because: At the time, continental drift was not accepted. Some of these ideas were discussed in the context of abandoned fixistic ideas of a deforming globe without continental drift or an expanding Earth. They were published during an episode of extreme political and economic instability that hampered scientific communication. Many were published by European scientists and at first not mentioned or given little credit in the papers on sea floor spreading published by the American researchers in the 1960s. Mid-Oceanic Ridge Spreading and Convection. In 1947, a team of scientists led by Maurice Ewing utilizing the Woods Hole Oceanographic Institution’s research vessel Atlantis and an array of instruments, confirmed the existence of a rise in the central Atlantic Ocean, and found that the floor of the seabed beneath the layer of sediments consisted of basalt, not the granite which is the main constituent of continents. They also found that the oceanic crust was much thinner than continental crust. All these new findings raised important and intriguing questions. The new data that had been collected on the ocean basins also showed particular characteristics regarding the bathymetry. One of the major outcomes of these datasets was that all along the globe, a system of mid-oceanic ridges was detected. An important conclusion was that along this system, new ocean floor was being created, which led to the concept of the “Great Global Rift.” This was described in the crucial paper of Bruce Heezen (1960),[4] which would trigger a real revolution in thinking. A profound consequence of seafloor spreading is that new crust was, and still is, being continually created along the oceanic ridges. Therefore, Heezen advocated the so-called “expanding Earth” hypothesis of S. Warren Carey (see above). So, still the question remained: how can new crust be continuously added along the oceanic ridges without increasing the size of the Earth? In reality, this question had been solved already by numerous scientists during the forties and the fifties, like Arthur Holmes, Vening-Meinesz, Coates and many others: The crust in excess disappeared along what were called the oceanic trenches, where so-called “subduction” occurred. Therefore, when various scientists during the early sixties started to reason on the data at their disposal regarding the ocean floor, the pieces of the theory quickly fell into place. The question particularly intrigued Harry Hammond Hess, a Princeton University geologist and a Naval Reserve Rear Admiral, and Robert S. Dietz, a scientist with the U.S. Coast and Geodetic Survey who first coined the term seafloor spreading. Dietz and Hess (the former published the same idea one year earlier in Nature,[5] but priority belongs to Hess who had already distributed an unpublished manuscript of his 1962 article by 1960)[6] were among the small handful who really understood the broad implications of sea floor spreading and how it would eventually agree with the, at that time, unconventional and unaccepted ideas of continental drift and the elegant and mobilistic models proposed by previous workers like Holmes. In the same year, Robert R. Coats of the U.S. Geological Survey described the main features of island arc subduction in the Aleutian Islands. His paper, though little noted (and even ridiculed) at the time, has since been called “seminal” and “prescient.” In reality, it actually shows that the work by the European scientists on island arcs and mountain belts performed and published during the 1930s up until the 1950s was applied and appreciated also in the United States. If the Earth’s crust was expanding along the oceanic ridges, Hess and Dietz reasoned like Holmes and others before them, it must be shrinking elsewhere. Hess followed Heezen, suggesting that new oceanic crust continuously spreads away from the ridges in a conveyor belt–like motion. And, using the mobilistic concepts developed before, he correctly concluded that many millions of years later, the oceanic crust eventually descends along the continental margins where oceanic trenches—very deep, narrow canyons—are formed, e.g. along the rim of the Pacific Ocean basin. The important step Hess made was that convection currents would be the driving force in this process, arriving at the same conclusions as Holmes had decades before with the only difference that the thinning of the ocean crust was performed using Heezen’s mechanism of spreading along the ridges. Hess therefore concluded that the Atlantic Ocean was expanding while the Pacific Ocean was shrinking. As old oceanic crust is “consumed” in the trenches (like Holmes and others, he thought this was done by thickening of the continental lithosphere, not, as now understood, by underthrusting at a larger scale of the oceanic crust itself into the mantle), new magma rises and erupts along the spreading ridges to form new crust. In effect, the ocean basins are perpetually being “recycled,” with the creation of new crust and the destruction of old oceanic lithosphere occurring simultaneously. Thus, the new mobilistic concepts neatly explained why the Earth does not get bigger with sea floor spreading, why there is so little sediment accumulation on the ocean floor, and why oceanic rocks are much younger than continental rocks. Magnetic Striping. Figure 20. Seafloor magnetic striping Beginning in the 1950s, scientists like Victor Vacquier, using magnetic instruments (magnetometers) adapted from airborne devices developed during World War II to detect submarines, began recognizing odd magnetic variations across the ocean floor. This finding, though unexpected, was not entirely surprising because it was known that basalt—the iron-rich, volcanic rock making up the ocean floor—contains a strongly magnetic mineral (magnetite) and can locally distort compass readings. This distortion was recognized by Icelandic mariners as early as the late eighteenth century. More important, because the presence of magnetite gives the basalt measurable magnetic properties, these newly discovered magnetic variations provided another means to study the deep ocean floor. When newly formed rock cools, such magnetic materials recorded the Earth’s magnetic field at the time. Figure 21. A demonstration of magnetic striping. (The darker the color is, the closer it is to normal polarity) As more and more of the seafloor was mapped during the 1950s, the magnetic variations turned out not to be random or isolated occurrences, but instead revealed recognizable patterns. When these magnetic patterns were mapped over a wide region, the ocean floor showed a zebra-like pattern: one stripe with normal polarity and the adjoining stripe with reversed polarity. The overall pattern, defined by these alternating bands of normally and reversely polarized rock, became known as magnetic striping, and was published by Ron G. Mason and co-workers in 1961, who did not find, though, an explanation for these data in terms of sea floor spreading, like Vine, Matthews and Morley a few years later. The discovery of magnetic striping called for an explanation. In the early 1960s scientists such as Heezen, Hess and Dietz had begun to theorise that mid-ocean ridges mark structurally weak zones where the ocean floor was being ripped in two lengthwise along the ridge crest (see the previous paragraph). New magma from deep within the Earth rises easily through these weak zones and eventually erupts along the crest of the ridges to create new oceanic crust. This process, at first denominated the “conveyer belt hypothesis” and later called seafloor spreading, operating over many millions of years continues to form new ocean floor all across the 50,000 km-long system of mid-ocean ridges. Only four years after the maps with the “zebra pattern” of magnetic stripes were published, the link between sea floor spreading and these patterns was correctly placed, independently by Lawrence Morley, and by Fred Vine and Drummond Matthews, in 1963, now called the Vine-Matthews-Morley hypothesis. This hypothesis linked these patterns to geomagnetic reversals and was supported by several lines of evidence: the stripes are symmetrical around the crests of the mid-ocean ridges; at or near the crest of the ridge, the rocks are very young, and they become progressively older away from the ridge crest; the youngest rocks at the ridge crest always have present-day (normal) polarity; stripes of rock parallel to the ridge crest alternate in magnetic polarity (normal-reversed-normal, etc.), suggesting that they were formed during different epochs documenting the (already known from independent studies) normal and reversal episodes of the Earth’s magnetic field. By explaining both the zebra-like magnetic striping and the construction of the mid-ocean ridge system, the seafloor spreading hypothesis (SFS) quickly gained converts and represented another major advance in the development of the plate-tectonics theory. Furthermore, the oceanic crust now came to be appreciated as a natural “tape recording” of the history of the geomagnetic field reversals (GMFR) of the Earth’s magnetic field. Today, extensive studies are dedicated to the calibration of the normal-reversal patterns in the oceanic crust on one hand and known timescales derived from the dating of basalt layers in sedimentary sequences (magnetostratigraphy) on the other, to arrive at estimates of past spreading rates and plate reconstructions. Definition and Refining of the Theory. After all these considerations, Plate Tectonics (or, as it was initially called “New Global Tectonics”) became quickly accepted in the scientific world, and numerous papers followed that defined the concepts: In 1965, Tuzo Wilson who had been a promotor of the sea floor spreading hypothesis and continental drift from the very beginning added the concept of transform faults to the model, completing the classes of fault types necessary to make the mobility of the plates on the globe work out. A symposium on continental drift was held at the Royal Society of London in 1965 which must be regarded as the official start of the acceptance of plate tectonics by the scientific community, and which abstracts are issued as Blacket, Bullard & Runcorn (1965). In this symposium, Edward Bullard and co-workers showed with a computer calculation how the continents along both sides of the Atlantic would best fit to close the ocean, which became known as the famous “Bullard’s Fit”. In 1966 Wilson published the paper that referred to previous plate tectonic reconstructions, introducing the concept of what is now known as the “Wilson Cycle.” In 1967, at the American Geophysical Union’s meeting, W. Jason Morgan proposed that the Earth’s surface consists of 12 rigid plates that move relative to each other. Two months later, Xavier Le Pichon published a complete model based on 6 major plates with their relative motions, which marked the final acceptance by the scientific community of plate tectonics. In the same year, McKenzie and Parker independently presented a model similar to Morgan’s using translations and rotations on a sphere to define the plate motions. Check Your Understanding. Answer the question(s) below to see how well you understand the topics covered in the previous section. This short quiz does not count toward your grade in the class, and you can retake it an unlimited number of times. Use this quiz to check your understanding and decide whether to (1) study the previous section further or (2) move on to the next section. Wegener, Alfred (1929). Die Entstehung der Kontinente und Ozeane (4 ed.). Braunschweig: Friedrich Vieweg & Sohn Akt. Ges. ↵Runcorn, S.K. (1956). "Paleomagnetic comparisons between Europe and North America". Proceedings, Geological Association of Canada 8 (1088): 7785. ↵Carey, S. W. (1958). "The tectonic approach to continental drift." In Carey, S.W. Continental Drift—A symposium, held in March 1956. Hobart: Univ. of Tasmania. pp. 177–363. Expanding Earth from p. 311 to p. 349. ↵Heezen, B. (1960). "The rift in the ocean floor." Scientific American 203 (4): 98–110. doi: 10.1038/scientificamerican1060-98. ↵Dietz, Robert S. (June 1961). "Continent and Ocean Basin Evolution by Spreading of the Sea Floor". Nature 190 (4779): 854–857. ↵Hess, H. H. (November 1962). "History of Ocean Basins" (PDF). In A. E. J. Engel, Harold L. James, and B. F. Leonard. Petrologic studies: a volume to honor of A. F. Buddington. Boulder, CO: Geological Society of America. pp. 599–620. ↵ Licenses and Attributions CC licensed content, OriginalIntroduction to The Theory of Plate Tectonics. Authored by: Kimberly Schulte and Lumen Learning. Provided by: Lumen Learning. License: CC BY: AttributionCC licensed content, Shared previously6.4: Theory of Plate Tectonics. Provided by: CK-12. Located at: http://www.ck12.org/book/CK-12-Earth-Science-For-High-School/section/6.4/. License: CC BY-NC: Attribution-NonCommercialPlate tectonics. Provided by: Wikipedia. Located at: https://en.wikipedia.org/wiki/Plate_tectonics#Development_of_the_theory. License: CC BY-SA: Attribution-ShareAlikeAll rights reserved contentPlate Tectonics. Authored by: Bozeman Science. Located at: https://www.youtube.com/watch?v=JmC-vjQGSNM. License: All Rights Reserved Privacy Policy
Topics
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Result 29
Titlestructure of the earth
Urlhttp://www.geography.learnontheinternet.co.uk/topics/structureofearth.html
Description
Date
Organic Position28
H1Structure of Earth
H2
H3
H2WithAnchors
BodyStructure of Earth Structure of the earth Continental Drift and Plate tectonics Why do plates move? Plate boundaries Hotspots         Online Activities [Online activities]: n Activities related to this topic Volcanoes - Fling the teacher game Tectonics Grade or No Grade Game This activity is provided by our sister site www.interactivegeography.co.uk and will pop up in a new window Podcast [Podcast]: n Audio file for playback on mobile devices and personal computers   Structure of the earth When studying plate-tectonics the best starting point is examining the structure of the earth. The earth is very similar to a peach in its structure. In the centre is a solid core. Surrounding the core is the inner core, then the mantle, which is covered in the earths 'skin' or crust. figure 1. Cross section of the earth (source: Wikipedia) The inner core is the centre of the earth and is the hottest part of the earth. It is a solid mass of iron and nickel. The temperature of the core is around 5500°C The outer core is the layer around the inner core. It is also made up of iron and nickel though it is in liquid form. The next layer is the matle.This layer is made up of semi molten rock, known as magma. The final layer is the earth's crust. This layer is between 0-60km thick. Continental Drift and Plate Tectonics In 1912 Alfred Wegener published a theory to explain why the Earth looked like a huge jigsaw. He believed the continents were once joined forming a supercontinent he called Pangaea. Over 180 million years ago this supercontinent began to "break up" due to continental drift. During the 20th Century, scientists developed the theory of Plate Tectonics. The theory suggested that the crust of the Earth is split up into seven large plates (see map below) and a few smaller ones, all of which are able to slowly move around on the Earth's surface. They float on the semi-molten mantle rocks, and are moved around by convection currents within the very hot rock. See why do plates move? for more details. The are two types of tectonic plates - continental plates and oceanic plates. Continental plates are lighter (less dense) than oceanic plates. Oceanic crust is much younger in geologic age than continental crust. Continental crust is on average thicker than oceanic crust. figure 2. The Earth's main plates Why do plates move?  The earth's tectonic plates are in constantly moving like giant 'rafts' on top of the semi-molten mantle below. However this movement is slow and rates vary from less than 2.5cm /yr to over 15cm/yr. The movement of the earth's crustal plates is believed to be due to convection currents which occur in the semi-molten mantle. These convection currents are created by heat from within the earth - much of which is generated by radioactive decay in the core. So how do convection currents cause plate movements? As semi-molten rock in the mantle is heated it becomes less dense than its surroundings and rises. As it reaches the crust above, it spreads out carrying the plates above with it. As the semi-molten rock then cools, it gradually sinks back down to be re-heated. (see diagram above) Plate Boundaries   The point where two or more plates meet is known as a plate boundary. It is at these locations where earthquakes, volcanoes and fold mountain form. There are four main types of plate boundary. These are constructive, destructive, conservative and collision margins. Plate Boundary Diagram Description Landforms Example Tensional / Constructive (divergent ) plate boundaries Constructive plate boundaries occur when two plates move away from each other. Ocean ridge and volcanic islands North American and Eurasian Plate Compressional / Destructive (subduction zones) plate boundaries Destructive plate boundaries occur when an oceanic plate is forced under (or subducts) a continental plate. Fold Mountains and Oceanic trenches Pacific Plate and the Eurasian Plate Conservative (transform faults) plate boundaries Conservative plate boundaries occur when two plates slide past each other.   North American Plate and the Pacific Plate Collision plate boundaries Collision plate boundaries occur when two continental plates move towards each other. Fold Mountains Indo-Australian and the Eurasian Plate Hotspots You should be aware that whilst most volcanoes / earthquakes occur along plate boundaries, there are exceptions. For example the volcanic Hawaiian islands which can be found in the middle of the Pacific Plate are formed due to a Hotspot. Hotspots are plumes of molten rock which rise underneath a plate causing localised melting and the creation of magma resulting in volcanic activity. See this animation for further explanation of hotspot activity. Key Terms Constructive Boundary (Divergent) - where two plates move away from each other resulting in new crust being formed. Destructive Boundary (Convergent) - where two plates move towards each other - in the case of a plate consisting of continental crust meeting a plate consisting of oceanic crust, the oceanic crust will be subducted and destroyed as it is less dense. Conservative Boundary - where two plates move alongside each other - although crust is neither created or destroyed here, earthquakes usually occur here. Collision Boundary - where two plates of continental crust move towards each other creating fold mountains. Volcano - a vent through which lava, ash etc. is erupted (often, but not always cone-shaped) Earthquake - a sudden movement of the earth's surface       Internet Geography © 2012
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Result 30
TitlePlate Tectonics on the Earth II
Urlhttp://homework.uoregon.edu/pub/emj/121/lectures/earthd121.html
Description
Date
Organic Position29
H1The Drivers of Plate Tectonics
H2Would these exist on other planets?
H3
H2WithAnchorsWould these exist on other planets?
BodyThe Drivers of Plate Tectonics: Would these exist on other planets? . The composition of the earth's interior can be determined as well as distinguishing liquid from solid layers by analyzing the propogation of seismic waves. The size of the liquid core is measured by seeing where the S-waves disappear, while the nature of the core (liquid or solid) can be studied by seeing how the P-waves are refracted as they enter and pass through it. The inner, solid core is deduced from refraction of P-waves due to their much higher velocity in the solid than in the liquid. The amount of refraction depends on the density of the material. The driving mechanism of plate tectonics is a network of convective heat currents, generated by the hot core of the earth and which circulate in the mantle. The heat is provided from the decay of Uranium-238 which is an R-process Supernova element meaning that is a neutron heavy isotope of uranium. The overall transport of heat from the core through the mantle is quite inefficient so it takes a long time for these convective heat currents to become established. Hence, plate movements are something which occurs late (i.e. now) in the geological history of the earth. The earth's crust is actually a two-component layer. The lithosphere is a thin layer of rock (average density of 2.7 grams per cc) and "floats" on top of a plastic-like layer called the asthenosphere. Plastic-like materials are weird - they deform under stress but don't really break. A glacier is a good example of a material that moves and flows plastically. The convective heat currents in the mantle impinge on the asthenosphere causing deformation and subsequent movement of the lithospheric plates. This process can be simulated in your kitchen by putting some jello in a bowl and putting some peebles on top of the jello. As you shake the bottom of the bowl, the jello deforms but doesn't break and the rocks that float on the jello collide. (apologies to real geologists for this analogy). The resulting pulling apart or crustal separation results in large scale surface features like the Mid-Atlantic Ridge: In cross section, the atlantic ocean looks as shown below. Note that broadly similar features are seen on the surface of Venus. The current structure of the earth, as mapped by seismic waves is fairly complex as shown below. Note that the D" layer, recently discovered, seems to represent some interface between the outer molten core and the lower mantle. It has been speculated that the intense pressures here have produced a new kind of crystalline rock that has unusual properties. This helps to explain why the D" layer doesn't occur at constant depth since the pressure won't be a constant function of depth. As a result of plate movements, interesting things occur at plate boundaries. In general you don't want to live near a plate boundary as the earth is active there. About 75% of the world's population does live near these boundaries. There are three types of plate boundaries: A divergence boundary crustal separation two plates are moving apart in opposite directions A convergence boundary collision of two plates. A collision of a less dense continental plate with a more dense oceanic plate creates a subduction zone where the denser plate dives (subducts) beneath the less dense plate. A collision between two continental plates results in general uplift. ( animation of Pacific Northwest ) A transform plate boundary here two plates slide by one another in opposite directions. The San Andreas Fault is the most well-known (and potentially most deadly) translational interface. ( animation of southern california ) Local Manifestations of Plate Tectonics: Find The Fault Lines The Pacific Northwest is an active tectonic zone. If your interested in monitoring this on a daily basis then bookmark this page One of the prime hazards of active volcanoes is the heavy mudflows which can result from the sudden melting of their heavily glaciated slopes. Some examples of Northwest Hazards are shown below: Volcanoes all in a Line Recent Lava Intrusions Basalt Flows in the Pacific Northwest Mudflows from Mt. Rainier And of course, Mt. St. Helens The Next Cascade Volcano?
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  • convective
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Result 31
TitleWhat do you call the part of the mantle where the tectonic plates float? – SidmartinBio
Urlhttps://www.sidmartinbio.org/what-do-you-call-the-part-of-the-mantle-where-the-tectonic-plates-float/
Description
Date4 Mar 2019
Organic Position30
H1What do you call the part of the mantle where the tectonic plates float?
H2What do you call the part of the mantle where the tectonic plates float?
What is the layer of the mantle called?
What is the layer just below the plates called?
How is the mantle related to tectonic plate boundaries?
How are the materials in the upper mantle brought to the surface?
What is the division between the crust and the mantle called?
What are the fundamental units of plate tectonics?
H3
H2WithAnchorsWhat do you call the part of the mantle where the tectonic plates float?
What is the layer of the mantle called?
What is the layer just below the plates called?
How is the mantle related to tectonic plate boundaries?
How are the materials in the upper mantle brought to the surface?
What is the division between the crust and the mantle called?
What are the fundamental units of plate tectonics?
BodyWhat do you call the part of the mantle where the tectonic plates float? Esther FlemingMarch 4, 2019 Table of Contents What do you call the part of the mantle where the tectonic plates float? The tectonic plates do not slowly drift over time because they are floating on a layer of liquid rock. They drift because they are sitting on a layer of solid rock (the upper mantle or “asthenosphere”) that is weak and ductile enough that it can flow very slowly under heat convection, somewhat like a liquid. What is the layer of the mantle called? lithosphere Earth’s mantle is divided into two major rheological layers: the rigid lithosphere comprising the uppermost mantle, and the more ductile asthenosphere, separated by the lithosphere-asthenosphere boundary. What is the layer just below the plates called? asthenosphere The crust is made up of hard rock and is the outer layer of the Earth. Together, these solid parts are known as the lithosphere. Above the lithosphere is the atmosphere, which is the air that surrounds the planet. Below the lithosphere is the asthenosphere. How is the mantle related to tectonic plate boundaries? 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 transfer of heat and material in the mantle helps determine the landscape of Earth. How are the materials in the upper mantle brought to the surface? Most of the materials in the upper mantle exist in a semi-molten state (magma) and are brought to the Earth’s surface through tectonic movements such as volcanicity. The pressure in the upper mantle is responsible for different chemical and physical properties. What is the division between the crust and the mantle called? 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. What are the fundamental units of plate tectonics? The fundamental units of plate tectonics are large pieces of Earth’s lithosphere, the outermost rocky layer of the planet that is composed of the Earth’s crust and the upper 50 to 80 miles of the next-lower layer, the mantle. The lithosphere is not a uniform mass of rocks. Begin typing your search term above and press enter to search. Press ESC to cancel. Back To Top We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.Ok
Topics
  • Topic
  • Tf
  • Position
  • mantle
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  • earth
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  • lithosphere
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  • tectonic
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  • plate
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  • layer
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  • rock
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  • tectonic plate
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  • crust
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  • upper
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  • asthenosphere
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  • upper mantle
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  • called
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  • mantle called
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  • part
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  • solid
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  • boundary
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  • material
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