Chapter 9: Plate Tectonics Review
1. Layers of the Earth: crust >>> mantle >>> outer core >>> inner core
2. From the Earth’s Crust to the Inner Core: Depth Increases, Pressure Increases, Temperature
Increases
3. Lithosphere: This layer is broken down into several large tectonic plates
4. Asthenosphere: The asthenosphere is the semi-rigid part of the middle mantle that flows like
hot asphalt under a heavy weight. The tectonic plates float on this semi-liquid layer.
5. Lithosphere Vs. Asthenosphere: Lithosphere= rigid; Asthenosphere= semi-soft
6. Convection Currents in the Mantle: According to scientists, convection currents is the driving
force behind the movement of the Earth’s plates
7. Convection: Heated water is less dense therefore rises while Cooled water is more dense, which
sinks. This is also true with air
8. Continental Drift: Evidence of continental drift is the matching coastline shapes of South
America and Africa Also, South America and Africa where once joined because:
i. they fit together like a puzzle
ii. A mountain range lines up between Argentina and South Africa.
9. Alfred Wegener’s hypothesis on Continental Drift: All the continents had once been joined in a
single landmass, called Pangaea, and have since drifted apart. Evidence from Landform,
Evidence from Fossils, Evidence from Climate
10. Continental Coastlines: Why don’t the continents look like they did millions of years ago?
Coastlines change over time due to beach erosion.
11. Pangaea: A supercontinent, meaning “all lands”, that existed about 300 million years ago.
12. Scientists Reject Wegener’s Hypothesis: Wegener could not provide a satisfactory explanation
for the force that pushes or pull the continents.
13. Earthquakes: Occur usually when 2 plates slide past each other, however, can happen at all
plate boundaries. Release of energy when the lithosphere suddenly breaks and slides
14. Sea-Floor Spreading: Molten material rises from the mantle and erupts along the mid-ocean
ridge
15. Subduction: Process by which the ocean floor sinks beneath a deep-ocean trench and back into
the mantle.
16. Plate Tectonics: Geological theory that states that pieces of Earth's lithosphere are in constant,
slow motion
17. Forming Mountains: When 2 continental plates collide, folding mountains occur
18. Divergent Boundaries: Plate boundary where 2 plates move away from each other. Is the result
of new ocean floor, such as the mid-ocean ridge and valley’s on land.
19. Transform Boundaries: Plate boundary where two plates slip past each other, moving in
opposite directions. Earthquakes frequently occur along these boundaries.
20. Cause of Deep Ocean Trenches: When an ocean plate collides with a continental plate, the plate
is subducted under the continent.
21. Ring of Fire: Volcanoes form where tectonic plates meet other plates.