The Structure of the Earth and Chapter 13 - Belmont...
Transcript of The Structure of the Earth and Chapter 13 - Belmont...
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Chapter 13The Structure of the Earth and
Plate Tectonics
Structure of the Earth3 main layers:• Core (inner + outer)
• Mantle• Crust Inner core
Outer core
Mantle
Crust
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Continental Crust- thick (10-70km)- buoyant (less dense) - mostly old
Oceanic Crust- thin (~7 km)- dense (sinks under continental crust)- young
The Crust
More details to follow in Chapter 15S.3
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How do we know what the Earth is made of?
• Geophysical surveys: seismic, gravity, magnetic, electrical, geodesy
• Acquisition: land, air, sea and satellite• Geological surveys: fieldwork, boreholes, mines
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What is Plate Tectonics?
If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle.
Plate Tectonics• The Earth’s crust is divided into 12 major plates
which are moved in various directions.• This plate motion causes them to collide, pull
apart, or scrape against each other.• Each type of interaction causes a characteristic
set of Earth structures or “tectonic” features.• The word, tectonic, refers to the deformation of
the crust as a consequence of plate interaction.
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World Plates What are tectonic plates made of?
Plates are made of rigid lithosphere.
The lithosphere is made up of the crust and the solid upper part of the mantle.
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What lies beneath tectonic plates?Below the lithosphere is the asthenosphere.
The asthenosphere, is the molten part of the upper mantle.
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Plate Movement“Plates” of lithosphere are moved around by the underlying hot mantle convection cells.
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Exercise 1
Supercontinents!The Pangaea Puzzle
Note: DO NOT overlap edges.
What happens at tectonic plate boundaries?
• Divergent
• Convergent
• Transform
Three Types of Plate Boundaries
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• Spreading Ridges– As plates move apart new material is erupted to
fill the gap.
Divergent Boundaries
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Age of Oceanic Crust
Courtesy of www.ngdc.noaa.gov
Age of Oceanic Crust
Courtesy of www.ngdc.noaa.gov
Seafloor Spreading and Magnetic Reversals
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There are three styles of convergent plate boundaries• Continent-Continent collision• Continent-Oceanic Crust collision• Oceanic-Oceanic Crust collision
Convergent Boundaries
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• FORMS MOUNTAIN RANGES(e.g. European Alps, Himalayas)
Continent-Continent Collisions
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India + Eurasia = The Himalayas
• Results in SUBDUCTION ZONES
Continent-Oceanic Crust Collisions
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• Oceanic lithosphere subductsunderneath the continental lithosphere
• Oceanic lithosphere heats and dehydrates as it subsides
• The melt rises forming volcanoes
• e.g. Andes, Cascades
Subduction
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• one plate runs over the other which causes it to sink into the mantle forming a subduction zone.
• subducting plate is bent downward to form a very deep depression in the ocean floor called a trench.
• deepest parts of the ocean found along trenches. – Mariana Trench is 11 km deep– Mount Everest is only 8 km high.
Ocean-Ocean Plate Collision
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Ocean-Ocean Plate Collision
Mariana Trench vsMt. Everest
• Where plates slide past each otherTransform Boundaries
Above: View of the San Andreastransform fault
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Exercise 1
Supercontinents!The Pangaea Puzzle
Note: DO NOT overlap edges.
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Exercise 2
Plate Motion!• Label the Tectonic Plates Map• Show the relative motion of each plate.
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UNIT TEST - Chapters 13-16
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Assignments:Chapter 13 – Plate Tectonics Notes & Vocab √Chapter 14 – Plate Tectonics & Volcanoes Notes & VocabChapter 15 – Plate Tectonics & Earthquakes Notes & VocabChapter 16 – Plate Tectonics & Mountain Building Notes & Vocab
For Review and Test Prep:Go to esc11.weebly.com
• Flashcard Library (home page)• volcano photo review• link to practice quizzes and review PowerPoints• Quizlab – Chapters 13-16 Practice Test