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Composition of the Earth. Earth Layers  The earth isn’t a solid sphere  It is made of 4 major layers - Crust - Mantle - Outer core - Inner core.

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Presentation on theme: "Composition of the Earth. Earth Layers  The earth isn’t a solid sphere  It is made of 4 major layers - Crust - Mantle - Outer core - Inner core."— Presentation transcript:

1 Composition of the Earth

2 Earth Layers  The earth isn’t a solid sphere  It is made of 4 major layers - Crust - Mantle - Outer core - Inner core

3 Crust  “outer skin”  Continental crust is about 70km thick  Oceanic crust is about 10 km thick  (this is why so much ocean drilling occurs)

4 Mantle  About 2900 km thick  Made of mostly Iron, Silicon and Magnesium  Asthenosphere is the upper part of the mantle  Very viscous

5 Outer Core  Approx 2100 km thick  Made of molten Iron and Nickel

6 Inner Core  Approx 1300 km radius  Solid ball of Iron and Nickel  Extremely hot  Stays a solid due to very high pressure

7 Quick check  T/F – all layers are made of solid rock  T/F – thickest layer is the mantle  T/F – Inner core is made of liquid Iron and nickel  T/F – Outer core is made of silicon and oxygen

8 Answers  F – all layers are made of solid rock  T – thickest layer is the mantle  F – Inner core is made of liquid Iron and nickel  F – Outer core is made of silicon and oxygen

9 Plate Movement  Caused by convection currents in the mantle

10 Definitions  Trench – steep walled valley where 2 plates meet  Slab pull – plates subducting pulls the rest of the plate with it  Ridge Push – new forming rock pushes plate away from spreading centre

11 Definitions  Spreading Centre – area where plates move apart from each other  Rift Valley – a spreading centre that occurs on land

12 Types of Movement

13 Collisions at Plate Boundaries  Divergent - Pulling apart (spreading) - New rock is often formed here

14 Collisions at Plate Boundaries  Convergent - Plates come together - Often subduction occurs (one slides under the other) **More on this in a moment**

15 Collisions at Plate Boundaries  Transform - Plates slide past each other - Produces earthquakes - Eg. San Andreas Fault

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17 Convergent Boundaries  There are three different types of convergent boundaries  These depend on what type of plates come together  Oceanic-continental  Oceanic-oceanic  Continental-continental

18 Oceanic-Continental  The oceanic plate subducts beneath the continental plate  Eg. Coastal BC  The Juan de Fuca (oceanic) plate subducts under the North American (continental) plate  This causes coastal mountains and land volcanoes

19 Oceanic-Oceanic  One plate will subduct beneath another  Volcanic activity and possible islands form

20 Continental-Continental  Plates are not likely to subduct  They push on each other and form mountains

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