Plate Tectonics

1. List and describe the layers of the
Earth in order from the interior out.
Inner core – hot, solid iron and nickel
Outer core – hot, molten iron and
Mantle – hot rock
Crust – solid outer layer of the Earth
2. Temperature and pressure both
______________ with depth.
 Both Increase
3. How do scientists study the
interior of the Earth?
Seismic Waves from earthquakes
4. What technology gave us the first
look at the ocean floor?
5. What makes up the inner core and
outer core?
6. What 3 types of evidence did Alfred
Wegener use to support his theory of
continental drift?
Evidence from Landforms
Evidence from Fossils
Evidence from Climate
7. What is Pangaea?
Alfred Wegener’s supercontinent
8. What is subduction? When and
why does subduction take place
 Subduction is the process by which old oceanic crust
is pushed back down into the mantle melting rock
and turning it back into molten material.
 Subduction takes place at deep ocean trenches where
convection currents are causing two lithospheric
plates to move/push together.
9. What is the mid-ocean ridge
Longest chain of mountains located on
the ocean floor
10. Explain the process of sea-floor
spreading and where does it take place.
Process by which new material is
continually added to the ocean floor and
happens at the mid-ocean ridge
11. The movement of the plates is
caused by ________________.
Convection currents
12. Explain the Theory of Plate
Tectonics and Continental Drift.
Plate Tectonics – pieces of Earth’s
lithosphere are in constant slow
motion, driven by convection currents
in the mantle.
Continental Drift – all continents were
once joined together in a single
landmass and has since drifted apart.
13. List and describe the 3 types of
plate boundaries
Transform boundary – 2 plates slip
past each other causing earthquakes
13. Plate boundaries continued…..
 Divergent boundary – 2
plates move apart
 Convergent boundary –
2 plates come together
14. A rift valley forms where two
plates do what?
 A rift valley forms where two continental and
continental plate move away from each other.
15. What is the lithosphere?
Uppermost part of the mantle and the
crust together form a rigid layer of rock
16. What is the asthenosphere?
Layer beneath the lithosphere that is
less rigid then the rock above it
17. Explain how convection currents in
the mantle cause the lithospheric plates
to move
The warm less dense material rises and
the cool more dense material sink causes
movement of the plates
18. Where is new ocean crust
At the mid-ocean ridge through seafloor spreading
19. Explain the 3 types of convergent
boundaries and what each produces.
 Convergent oceanic and oceanic plates – 1 plate is
subducted (the more dense plate) through a trench
and forms a chain of volcanic islands
 Convergent oceanic and continental plates – oceanic
is more dense and is subducted under the
continental plate. Volcanoes on land are produced.
 Convergent continental and continental plate – 2
continental plates collide, crust buckles and
mountain ranges are formed.
20. The Earth has a magnetic field
because of the
21. What is the difference between
continental and oceanic crust? Why is
ocean crust younger than continental crust?
Oceanic crust is more dense than
continental crust. It also moves through
the rock cycle faster than continental
crust. New ocean crust is created at the
mid-ocean ridge and old ocean crust is
subducted at a trench.
22. What happens at trenches on the
ocean floor?
Oceanic crust is pushed back into the
mantle and forms molten material
23. What is density?
The amount of matter in a given
amount of space.
Density = mass/volume
24. What type of boundaries form at
the mid-ocean ridge?
Divergent boundary
25. Which layer do the Earth’s plates
float on?
26. Explain why oceanic crust is
subducted at an oceanic and continental
convergent boundary
Oceanic crust is more dense than

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