The Restless Earth

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The Restless Earth

• Lesson 1 Structure of the Earth

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Why is the Earths Crust Unstable?

• Key Idea 1 The Earths crust is unstable,
  especially at plate margins
• Key words crust, plate, plate margin/boundary,
  mantle, convection currents.

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The Structure of the Earth
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The Structure of the Earth
Layer of the Earth Characteristics
Crust This is 0-70km thick and can be divided into two types continental and oceanic (explained later). It is solid and made out of granite and basalt with an average temperature of 10?C.
Mantle This layer is 2900km thick and is liquid. The temperature is 375?C.
Core (Inner and Outer) This is the hottest part of the Earth at 3000?C. The outer part is liquid but the inner is solid and it is made from iron and nickel ore. It is in total 3500km thick.
Then copy diagram A from p8 Then copy diagram A from p8
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The Structure of the Earth
A B C D
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What is the evidence for this?
Continental Drift Theory
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What is the evidence for this?
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Why do the plates move?
Crust
Convention Currents
Mantle
The plates move due to convection currents in the
mantle
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Convection Currents
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Convection Currents

• The crust is not one large shell around the
  earth. In fact it is made up of lots of smaller
  pieces called plates. These plates float on top
  of the mantle and move around due to convection
  currents. The liquid rock in the mantle gets
  heated from the core. The warm material has more
  energy and so it rises towards the surface.
  Eventually when it cools down the material will
  start to sink as it has less energy than the
  warmer material around it. This up-down motion is
  called a convection current.

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The Plate boundaries
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What have we learned?

• Why is the Earths crust unstable?
• Because it is made up of plates, which crash into
  each other due to the convection currents in the
  mantle moving them around
• 2. What are the 4 parts of the Earths crust
• Crust, Mantle, Outer Core, Inner Core
• 3. What is a convection current?
• When hot liquid rock from the core rises, then
  cools and flows outwards and downwards back
  towards the core, where it is re-heated
• Homework Learn plate names for mini-test next
  lesson