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Composition of the Earth

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Presentation on theme: "Composition of the Earth"— 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


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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