1. Continental Drift Theory
Alfred Wegener
Early 1900’s
Examined and compiled data of fossil, rock, glacier and design of earth’s continents
The ‘what’ of earth change,
not the why nor how

2. Puzzle Pieces
South America and Africa
North America and Europe

3. Rock Evidence
Different continents with same age, type, design of form

4. Glacier and Mineral Deposits
Same deposits on different continents
all over the world.

5. Fossil Evidence
Glossopteris- plant
Mesosaurus- animal

6. Ocean Floor? Entirely unknown Too difficult to study
Environment studied during WWII
WHY?

7. Ocean Floor Revealed!
Necessity is the mother of invention- author unknown
Ocean floor mapping for submarine offense and defense during WWII
Data compiled after war in the late 40’s and 50’s

8. Mid Ocean Ridges Mid Ocean Ridges made visible
Mountain Ranges on all ocean floors
Continuous crust of Earth includes basaltic oceanic crust

9. SO…. Fissures in ocean floor and other features led to new ideas
New information, new ideas
New data, new theories

10. Theory of Plate Tectonics
Plates moving in 3 basic directions
Motion displayed in earthquake and volcanic data
EQ and Volcanic data outline plates

11. Plate Motions
Subduction
Transform Boundary
Ocean floor spreading

12. EQ and Volcano Data Earthquake data plotted Volcano data plotted
Earth shows patterns of plate boundaries not visible nor known prior to ocean floor topography or data plotted

13. Why do plates move? Asthenosphere
Properties of asthenosphere are semi-solid
Flowable material

14. Energy transfer Energy is transferred in 3 ways: Conduction Convection
Radiation

15. Convection Currents in Mantle
Material moves from heated, more energetic region due to heat, to cooler region, where molecules condense, become less active, more dense and sink.
Cycle continues

16. YOUR TURN…
Use resources to diagram the motions of the plates and identify at least one place on the Earth where each motion occurs.