1. Plate Tectonics

2. Boundary Types Divergent: plates move apart
Convergent: plates move toward each other
Transform: plates move horizontally past each other

3. Boundary Movement

4. Associated with earthquakes and volcanoes
Divergent
Plates move apart
Most on sea-floor at rift valley
Sea floor spreading begins
New ocean floor formed
Associated with earthquakes and volcanoes
Divergent boundary on continents creates a rift valley.
i.e. East African Rift Valley
a.k.a.
Constructive boundary

5. East African Rift Valley

6. Convergent Boundaries
Oceanic to Continental
Example:
Cascade Mountain Range
Oceanic crust dense
therefore
Subduction
occurs
a.k.a. Destructive boundary

7. Convergent Boundaries (cont)
Oceanic to Oceanic
Oldest crust is the most dense and will subduct.
The Marianas Trench, for example, is a deep trench created as the result of the Phillipine Plate subducting under the Pacific Plate.

8. Convergent Boundaries (cont)
Continental to Continental
Relatively light and resist downward motions so the land buckles up or sideways.
Example:
Himalayas
and
Appalachian

9. Transform Boundary Plates slide horizontally past each other
Most occur along mid-ocean ridges
San Andreas Fault in CA is transform boundary found on land
Associated with EARTHQUAKES

10. San Andreas Fault

11. Causes of plate motion