1. Good Afternoon!
Please get your science notebook and get out your plate boundaries map and worksheet from Friday.

2. Chapter 9: Plate Tectonics Review

3. Layers of the Earth

4. From the Earth’s Crust to the Inner Core:
Depth Increases
Pressure Increases
Temperature Increases
Layers of the Earth
Temp.
(°C)
Elements
Crust
0- 860
Oxygen, silicon
Mantle
870
Iron, magnesium
Outer
Core
2200
Iron, nickel
Inner
5000
iron

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

6. 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.

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

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

9. Convection
Heated water is less dense therefore rises while cooled water is more dense, which sinks.
This is also true with air and other fluids.

10. 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

11. 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.

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

13. Sea-Floor Spreading Theory
As the plates diverge, molten material rises from the mantle and erupts along the mid-ocean 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

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

15. 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.

16. Convergent Boundaries
Two plates move towards each other and collide.
The result can be an ocean trench, volcanic island arc, volcanoes, and folded mountains.

17. Cause of Deep Ocean Trenches
When an ocean plate collides with a continental plate, the plate is subducted under the continent.
Subduction – when one tectonic plate (oceanic) is pushed underneath another tectonic plate.

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

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

20. 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

21. Ring of Fire
Volcanoes form where tectonic plates meet other plates.