2. Gateway 1: Why are some areas more
prone to tectonic hazards
• Natural hazard: naturally occurring event that threatens
human lives and causes damages to property.
5. Tectonic Plate
Oceanic Crust Continental Crust
Beneath deep oceans Beneath earth’s continental
land masses and under
shallow sea
Between 5-8km Between 30-70km
Consist mainly basalt
Rocks of less than 200
million years old
Consist of lighter rocks
Rocks ranges from young to
nearly 4 billion years
6. Why do tectonic plates move?
• Convection
currents
• Slab-pull
force
7. Why do tectonic plates move?
• Convection currents are movements of heat within
the mantle
• Material in the mantle is heated by the core,
causing the mantle material to expand, rise and
spread out beneath the plates
• This causes plates to be dragged along and to
move away from each other
• Then the hot mantle material cools slightly and
sinks, pulling the plate along
8. Different types of plate movements
• Divergent plate boundaries
• Convergent plate boundaries
• Transform plate boundaries
9. Pairwork
• Each pair choose 1 plate movement and draw the
formation of the landform.
• The pair is to explain their diagram to the class.
13. • Magma rises from the mantle to fill the gap
between the plates as they diverge.
• New sea floor is formed when the magma cools
and solidifies. This process is called sea-floor
spreading.
• New sea floor is formed when the magma cools
and solidifies. This process is called sea-floor
spreading.
• At various points along the ridge, magma builds
up above the ocean to form volcanic islands.
15. Rift valleys and Block mountains
• A fault
▫ Fracture in the rocks along which the rocks are
displaced
▫ Due to tensional forces
• Rift Valley
▫ Is a valley with steep sides that is formed when the
sections of the crust extend along fault lines
• Block Mountain
▫ A block of land with steep sides
15
18. Oceanic- Oceanic Convergence
Denser Plate Subducts
Oceanic Trench
Crust of subducted plate
melts and forms magma
Magma rises through crust
and forms volcanoes
29. Transform plates
• Plates slide past each other along transform
plate boundaries.
• The plate movement cause the slow build up of
stress on the rocks found on either side of the
fault.
• When the rocks can no longer withstand the
increasing stress, they can suddenly slip many
metres, causing an earthquake.
Notas do Editor
Explain to students the difference between a fold mountain and a block mountain.
Block mountains are formed by the downward movement of masses of land along lines of weakness while fold mountains are formed from the sideways motion of land being compressed.
Suggested activity:
Let students watch a video on continental-continental plate convergence: http://www.youtube.com/watch?v=ngV66m00UvU&feature=related
