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Yr12: Natural Hazards
The Evolution of Plate tectonics theory
A. The structure of the Earth.
Exercise 1: Import a diagram that shows the Earth’s structure. Annotate it to explain the
characteristic features of each of the layers. (Remember to consider structure according the physical
and chemical characteristics)
Exercise 2: Complete the table to summarise the differences between the two types of crust.
Oceanic Crust
Continental Crust
Age
Thickness
Composition
Weight
Why is knowledge of the crustal characteristics important to your understanding of what happens at
plate boundaries? Explain.
B. Continental Drift
Exercise 3: Define what the theory of continental drift is and explain why the theory was not initially
accepted.
Exercise 4: Describe and explain the evidence for the movement of continents over time
using the following 4 categories:
a) Continental jigsaw puzzle
b) Geological evidence
c) Biological evidence
d) Climatological evidence
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c. Theory of plate tectonics
Exercise 5: What is the theory of plate tectonics? Describe and explain the key elements
associated with the theory of plate tectonics.
a) Define ‘Plate tectonic theory’
b) Label the major tectonic plates on the map below.
c) Import a map of the world which shows a record of known earthquake and volcanic
eruptions. Describe and explain the relationship between the occurrence of
earthquakes and volcanoes and tectonic plate boundaries.
d) Using a diagram, explain the theory behind the mechanism that causes crustal plates
to move.
Exercise 6: Describe and explain (using annotated diagrams) how the discovery of sea-floor
spreading and Palaeomagnetism provided evidence to support the theory of continental
drift, subsequently termed plate tectonics.
(Hint: include a diagram showing the magnetic stripes in oceanic crust and explain how
magnetism is recorded in the rocks)
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