Chapter 9: Plate Tectonics Review

1. Chapter 9: Plate Tectonics Review

2. Layers of the Earth

3. From the Earth’s Crust to the Inner Core: • Depth Increases • Pressure Increases • Temperature Increases

4. Lithosphere • The cool, rigid layer of the crust and upper most solid mantle. • This layer is broken down into several large tectonic plates.

5. 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.

6. Lithosphere vs. Asthenosphere Lithosphere= rigid Asthenosphere= semi-soft

7. Convection Currents in the Mantle • According to scientists, convection currents is the driving force behind the movement of the Earth’s plates.

8. Convection • Heated water is less dense therefore rises whilecooled water is more dense, which sinks. • This is also true with air and other fluids.

9. Alfred Wegener’s hypothesis on Continental Drift • Evidence from Landform • Evidence from Fossils • Evidence from Climate All the continents had once been joined in a single landmass, called Pangaea, and have since drifted apart.

10. Evidence of Continental Drift • A mountain range lines up between Argentina in South America and Africa. • Fossils of the reptiles Mesosaurus and Lystrosaurus have been found in places now separated by oceans. • Fossils of the fernlike plant, Glossopteris, have been found in rocks in Africa, South America, Australia, India, & Antarctica. • Deep scratches in rocks show that continental glaciers once covered South Africa.

11. Pangaea • A supercontinent, meaning “all lands”, that existed about 300 million years ago.

12. Plate Tectonics • Geological theory that states that pieces of Earth's lithosphere are in constant, slow motion

13. 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 rift valley’s on land.

14. Sea-Floor Spreading Molten material rises from the mantle and erupts along the Mid-Atlantic ridge Image: A diver swims between the Eurasian and North American plates in Thingvellir lake, Thingvellir National Park, Iceland. Iceland is one place where a mid-ocean ridge can be seen on land and in shallow waters.(credit: Wild Wonders of Europe/Lundgre http://www.bbc.co.uk/science/earth/surface_and_interior/mid_ocean_ridge

15. Convergent Boundaries • Two plates move towards each other and collide. • The result can be an ocean trench, island arc, volcanoes, and mountain ranges.

16. Cause of Deep Ocean Trenches • When an ocean plate collides with a continental plate, the plate is subducted under the continent. • Subduction - Process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.

17. Folded Mountains • When 2 continental plates collide, folding mountains occur Himalayans from space

18. Transform Boundaries • Plate boundary where two plates slip past each other, moving in opposite directions. • Earthquakes frequently occur along these boundaries. • Creates a fault

19. 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

20. Ring of Fire • Volcanoes form where tectonic plates meet other plates.