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Plate Tectonics

Ch. 16. Plate Tectonics. Layers of the Earth. Thickness: 5 – 40 km Composition: Oxygen, Silicon, Aluminum, Calcium, Iron, Sodium, Potassium, Magnesium Temperature: Up to 1,600 degrees F. Crust. Thickness: 2,900 km

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Plate Tectonics

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  1. Ch. 16 Plate Tectonics

  2. Layers of the Earth

  3. Thickness: 5 – 40 km Composition: Oxygen, Silicon, Aluminum, Calcium, Iron, Sodium, Potassium, Magnesium Temperature: Up to 1,600 degrees F Crust

  4. Thickness: 2,900 km • Composition: Silicon, Oxygen, Iron, Magnesium • Temperature: 1,600 F to 8,000 F Mantle

  5. The uppermost part of the mantle is the lithosphere. • Lithos means “stone”. • The soft layer of the mantle, beneath the lithosphere, is the asthenosphere. Asthenes means “weak”.

  6. Thickness: 2,250 km Composition: Iron, Nickel Temperature: 2,200 F to 11,000 F Outer Core

  7. Thickness: 1,200 km Composition: Iron, Nickel Temperature: 9,032 F to 13,000 F Inner Core

  8. Layers of the Earth • Skin of the peach is the crust • Meat of the peach is the mantle • Pit of the peach is the core

  9. TYPES OF ROCKS • Igneous • Sedimentary • Metamorphic

  10. IGNEOUS ROCKS • Formed from molten material including volcanic lava, ash, or bombs as well as magma below Earth’s surface.

  11. TYPES OF IGNEOUS ROCKS BASALT GRANITE

  12. SEDIMENTARY ROCKS • Made of layers that have been pressed or cemented together • Pebbles, sand, silt, or clay are sediments • Shells and bones can also be sediments

  13. TYPES OF SEDIMENTARY ROCKS LIMESTONE SHALE COAL

  14. METAMORPHIC ROCKS • Rocks that are changed by intense heat and pressure while inside Earth’s surface • Igneous, sedimentary, and even metamorphic rocks can be changed into different metamorphic rocks.

  15. TYPES OF METAMORPHIC ROCKS SLATE MARBLE

  16. ROCK CYCLE • The rock cycle is a never-ending process of rocks forming, weathering, and changing into other rocks

  17. ROCK CYCLE

  18. Faults occur because forces inside Earth cause Earth’s plates to move, placing stress on or near the plate edge.

  19. When rocks break, they move along faults. • Applied forces cause rocks to undergo elastic deformation. • When elastic limits are passed, rocks break.

  20. Rocks on one side of a fault can move up, down, or sideways in relation to the rocks around them.

  21. Rocks will bend, compress, stretch, and possibly break.

  22. Rocks break, move along the fault, return to original shapes. Rock on one side of a fault can move over, under, or past each other along fault lines. Earthquake - vibrations produced by breaking rock.

  23. Are waves generated by an earthquake; can move the ground forward, backward, up & down, side to side. Focus - an earthquake’s point of energy release. Seismic waves

  24. A seismic wave’s speed and direction change as the wave moves through different layers with changes in densities.

  25. Seismograph - measures seismic waves. • Consists of a rotating drum of paper + a pendulum with an attached pen. • Makes a paper record of a seismic event called a seismogram.

  26. Shadow zones do not receive seismic waves because the waves are bent or stopped by materials of different density. Generally increases with depth as pressure increases. Density

  27. Changes in seismic wave speed allowed detection of boundaries between Earth’s layers.

  28. Although earthquakes are natural events, they kill many people and cause a lot of damage. • Seismologists are scientists who study earthquakes.

  29. Most earthquakes are of a magnitude too low to be felt by humans - 3.0 to 4.9 on the scale.

  30. Divergent Plate Boundary • A place where two plates move apart, or diverge • Most occur along the mid-ocean ridge where sea-floor spreading occurs.

  31. Mid-ocean ridge • Mountains that lie mostly hidden under the ocean • Iceland is a part of the mid-ocean ridge that rises above the surface.

  32. Mid-Ocean Ridge

  33. Sea floor spreading • The sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added. • As a result, the ocean floors move like conveyor belts, carrying the continents along with them.

  34. Sea floor spreading

  35. Rift valley • Forms along the divergent boundary, only it forms on land

  36. Rift Valley

  37. Convergent plate boundary • The place where two plates come together, or converge • When two plates collide, the density of the plates determines which one comes out on top.

  38. Transform Boundary • A place where two plates slip past each other, moving in opposite directions • Earthquakes often occur along these boundaries.

  39. Transform Boundary

  40. Subduction • A process in which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.

  41. Subduction

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