1. Plate Boundaries

2. Plate Boundaries
Why do we care about plate boundaries?

3. Plate Boundaries
Volcanoes and earthquakes most often occur where tectonic plates come together.
At plate boundaries, many other geologic features, such as mountains and rift valleys, can also occur.

4. Plate Boundaries 1. Divergent 2. Convergent
There are three basic types of plate boundaries:
1. Divergent
2. Convergent
3. Transform Fault Boundary

5. Divergent Boundary
A divergent boundary occurs where two plates move apart and create a gap between them.

6. Divergent Boundary
Hot rock rises from asthenosphere and cools to form new lithospheric rock.
Diverging plates then pull newly formed lithosphere away from gap.
New lithospheric (oceanic crust) is formed.

7. Divergent Boundary
Mid-oceanic ridges are mountain ranges at divergent boundaries in oceanic crust.

8. Divergent Boundary Real Life Example: Mid-Atlantic Ridge
Mid-Atlantic Ridge runs through Atlantic Ocean from Arctic Ocean to an area off the southern tip of South America.

9. Convergent Boundary
A convergent boundary occurs where two plates move toward one another.

10. Convergent Boundaries
There are two types of convergent boundaries:
1. Subduction
2. Collision

11. Convergent Boundary - Subduction
Subduction is the process by which one lithospheric plate moves beneath another plate.

12. Convergent Boundary - Subduction
Ocean – Ocean
Two oceanic plates collide
Generates volcanoes
Generates island chains
Real World Example
Japan

13. Convergent Boundary - Subduction
Ocean – Continent
Oceanic and continental plate collide
A thin, dense oceanic plate collides with a relatively light, thick continental plate, the oceanic plate is forced under the continental plate
Real World Example
Andes Mountains

14. Convergent Boundary - Collision
Continental – Continental
Two continental plates collide
Real World Example
Himalayas

15. Transform Fault Boundary
A transform fault boundary occurs where two plates slide past one another.

16. Transform Fault Boundary
Plate movement at transform fault boundaries is one cause of earthquakes.
Real World Example
San Andreas Fault