1. Earth’s Surface and Tectonic Processes: Part 2

2. Continental Drift
Wegener proposed the idea of supercontinent called Pangaea

3. Evidence of Pangaea 1) Coastline fit : Puzzle
2) Geologic fit: Rocks are same on matching coasts
3) Paleoclimatology: (past climates)
- Coal formation in polar regions...coal only forms in tropical regions
4) Fossil Correlation: Matching fossils of dead animals on matching coast lines

5. Theory of Plate Tectonics
Idea put forward by Alfred Wegener in 1912
For a long time scientists debated Wegener’s ideas. Nowadays they are generally considered to be correct
Plates travelling on the asthenosphere
Convection currents move these plates 2-3 cm per year

7. Plate Movement 1) Divergence
Plates move apart due to convection in the asthenosphere
Creates either: Mid Ocean Ridges / Rift Zones
Examples: Mid-Atlantic Ridge or African Rift Valley
Sea floor spreads, new magma rises and fills the crack
Creates Transform Faults, as this does not happen in a straight line.

11. 2) Convergence
Plates come together and one goes under the other.
a) Ocean plates are more dense, so they go under continental plates.
Where this happens is called subduction zone
Plate goes back to mantle

13. B) Two ocean plates come together, neither want to go down
Eventually one does, and creating Shield Cone volcanoes and Island Arcs
Philippines for example

14. Convergence c) Two continental plates.
These plates “fold up”, creating fold mountains
Himalayas, Rockies.

16. 3) Horizontal Movement Plates sliding past each other
Tear or Strike-slip fault or Transform
Example: San Andreas fault in California AND Mid-Atlantic Ridge
Sometimes the plates get stuck, tension builds, when released can cause earthquakes