1. The Theory of Plate Tectonics

2. Plates Separate sections of Earth’s outer shell, the lithosphere
Plates have jagged edges but fit closely together
Some plates carry the continents or parts of the ocean floor or both

3. Scientific Theory
A well tested concept that explains a wide range of observations

4. J. Tuzo Wilson Canadian scientist
Observed cracks in continents similar to those in ocean floor

5. The Theory of Plate Tectonics
The theory of plate tectonics is the geological theory that states that the pieces of Earth’s lithosphere are in constant slow motion being driven by the convection currents in the mantle.

6. The theory of plate tectonics explains the formation, movement and subduction of earth’s plates.

7. Plate Boundaries - where 2 plates meet, they extend deep into the lithosphere
Fault – breaks in Earth’s crust where rocks have slipped past each other

8. 3 Types of Plate Boundaries
Transform
Divergent
Convergent

9. Transform Boundary
Where 2 plates slip past each other moving in opposite directions
Earthquakes occur frequently along transform boundaries

10. Divergent Boundary Where 2 plates move apart or diverge
Most occur at the mid-ocean ridge
Rift Valley – a deep valley that forms along a divergent boundary on land

11. Convergent Boundary Where 2 plates come together or collide
The density of the plate determines which one comes out on top

12. Collisions at Convergent Boundaries and their Results:
Oceanic crust + Oceanic crust = deep ocean trench
Continental crust = Continental crust = mountains
Oceanic crust + Continental crust = deep ocean trench and mountains

13. The Continents Slow Dance
The plates move at a slow, steady pace of about 1-10 cm/year
Compare to the rate of fingernail growth
The rate of plate movement is slow, but multiply it over millions of years to understand how Pangaea became Earth’s continents today.