1. Theory of Plate Tectonics
Oceans 11

2. But first…a little about the internal structure of the Earth
A Brief look Earth’s 2 major layers

3. Earth’s Internal Structure
Earth can be divided into 3 main layers:
Crust (outside of Earth)
Mantle
Core (very inside)

4. Earth’s Crust Crust is the outermost layer. Two Parts of Crust:
Continental crust
Mainly granite
Up to 75km thick
Density 2.6g/cm3
Oceanic crust
Made up of basalt rock (type of volcanic rock)
Up to 8 km thick
Density 3.0g/cm3

5. The Mantle The mantle is the next layer.
This zone is about 2900km thick and makes up great 82% of Earth’s volume.
Fragments of the mantle have been brought to the surface by volcanic eruptions.

6. Earth’s Core Earth’s core is extremely hot – hot as the sun!
Divided into two parts.
Outer Core
Liquid iron and nickel
Inner Core
Solid iron

7. Now let’s look at the Theory of Plate Tectonics…

8. Plate Tectonics – brief history
1912
Alfred Wegener, German geophysicist and meteorologist
Wegener thought that all landmasses formed one supercontinent approximately 225 mya “Pangaea” meaning all earth.

9. Wegener’s research: Geologic record (rock strata) Fossil record
Climatic record of continents
A KEY FINDINGS:
Southern America & Africa have many similarities
Large coal deposits

10. Resistance…
Wegener was met with a lot of skepticism from other scientists and the church.
1950 to 1960’s
Geologic Discoveries:
Similar fossils on each continent
Same age rock on coast lines
It wasn’t until the 1960’s that Wegener’s theory was accepted and coined Theory Plate Tectonics

11. Animation of Continental Drift

12. PANGEA

15. Definition of Plate Tectonics
Tectonic – Greek meaning “building” or “construction”
Refers to the configuration of Earth’s crust as a result of internal forces.

16. Plate Tectonic Processes
Include:
Upwelling of magma
Crustal plate movements
Sea-floor spreading
Subduction of crust
Earthquakes
Volcanic activity
Warping, folding and faulting of crust.

17. Earth’s Plates Plates are made up of:
Continental crust
Oceanic crust
These plates float upon the moving asthenosphere.
Plates move 1 to 19 cm per year
Movement of plates are a result of convection currents in the asthenosphere

18. Earth’s Plates

19. What do you notice about the relationship between volcanoes(red), earthquakes (yellow) and location of plate boundaries?

20. 3 Main types of Plate Boundaries
Divergent plate boundary
Convergent plate boundary
Transform plate boundary

21. Divergent Plate Boundaries
Plates separate (move away from each other)
Almost always occurs between two ocean plates.
When ocean plates separate, new crust is formed through the upwelling of magma. This is called sea-floor spreading.
Mid-oceanic ridges

22. Iceland, "the land of fire and ice", is being split by an oceanic ridge that surfaces to create an oceanic island (left and below) in the North Atlantic Ocean.
Red triangles show Iceland's active volcanoes, including Krafla. Reykjavik is Iceland's capital.

23. Divergent Plate Boundaries
Something interesting!!!
Great Rift Valley in Africa
A continental plate is breaking up!
Convection currents under the crust are pulling this area apart!

24. Convergent Plate Boundaries
These plate boundaries can occur between:
Oceanic and Continental plates
“Subduction Zones”
Continental and Continental plates
Mountain building

25. Transform Plate Boundaries
These are where plates move side-to-side.
Trigger earthquakes

26. Your Task
Complete the “checking your understanding” questions and hand in.
Complete the Plate Tectonic Map Activity