Plate Movements

Question 1

What is the driving force for plate-tectonic movement?

Answer 1

Earth’s internal heating

Question 2

Outline convection currents within the Earth

Answer 2

1) Mantle reaches core, temp increases, density lowers and begins to rise
2) Mesosphere heated by convection from core
3) It’s temp decreases as mantle moves away from core
4) Cooling mantle cannot sink due to continual rising
5) Mantle moves laterally along boundary between asthenosphere and lithosphere
6) Friction causes plates to ‘drag’ in direction of convection current
7) Mantle cools and sinks due to increasing density
8) Cycle continues

Question 3

Who proposed the concept of ‘Continental Drift’?

Answer 3

Alfred Wegener, 1912

Question 4

What is the ‘Continental Drift’ theory?

Answer 4

• Continental landmasses changed over time

- 200 million years ago all continents joined, forming supercontinent ‘Pangea’

Question 5

Give the timeline of ‘Continental Drift’

Answer 5

• Permian (225 million years ago): Pangea
• Triassic (200 million years ago): Splits in two, Laurasia and Gondwondaland
• Jurassic (135 million years ago): First sign of modern day continents
• Cretaceous (65 million years ago): Africa and S. America drift apart, India drift to Asia

Question 6

Give 5 pieces of evidence that support ‘Continental Drift’

Answer 6

• Continental shapes match
• Rock and fossil records
• Glacial record (Similar glacial landforms very far apart)
• Palaeomagnetism (Magnetic traces reveal intensity and direction of Earth’s magnetic field)
• Sea floor spreading (Discovered oceans much newer than continents)