2. Plate Boundaries Where two plates meet.

3. Recall: The lithosphere is broken into plates that “float” or “ride” on the asthenosphere. Convection in the mantle is the driving force for this movement.

4. There are 3 Types of Plate Boundaries…

5. I. Convergent Boundaries
Two plates move towards each other
3 Types:
Oceanic-Oceanic
Oceanic-Continental
Continental-Continental

6. Complete the Table for Convergent Boundaries:
Type of Boundary
Convergent:
Sketch of Boundary/ Direction of movement
Description of boundary
Deformation Formed
Oceanic - Oceanic
Oceanic-Continental
Continental- Continental

7. 1. Oceanic – Oceanic Convergence:
One plate subducts under the other
Forms Volcanoes and Volcanic Island Arches.
Ex.: Japan, Philippines, West Indies

8. Oceanic - Oceanic Boundary:

9. Oceanic – Oceanic convergence
Convergent Type
Sketch/ Direction
Description
Deformation Produced
Oceanic - Oceanic
Oceanic plate melts as it sinks under another oceanic plate into mantle
New magma rises
Forms volcanoes on ocean floor
May form volcanic island arc
Produce earthquakes & tsunamis
One oceanic plate descends beneath the other
Volcanoes form on the ocean floor
May eventually form volcanic island arc

10. 2. Oceanic- Continental Convergence:
Oceanic crust is denser, so it is forced under the continental crust, creating a SUBDUCTION ZONE
Oceanic always subducts under continental
Example: Andes Mountains in western South America

11. Oceanic-Continental Boundary

12. Oceanic – Continental convergence
Convergent:
Sketch/ Direction
Description
Deformation Produced
Oceanic - Continental
Oceanic plate melts as it sinks under continental plate into the mantle
New magma rises
Produce earthquakes & tsunamis
Can form volcanic arc and/or mountains onshore
Forms deep-sea trenches offshore

13. 3. Continental - Continental convergence:
Colliding edges are crumpled and uplifted
Neither will Subduct
Deformation: mountain ranges. (Non-Volcanic)
Ex. N. America + Africa Plates = Appalachian Mtns.
India + Eurasia Plates = Himalayas

14. Continental/Continental Boundary

15. Continental-Continental convergence
Convergent:
Sketch/ Direction
Description
Deformation Produced
Continental - Continental
Continental plates collide
Earthquakes common
Forms NON-VOLCANIC mountain ranges

16. Fill in the Table for Divergent Boundaries
Type of Boundary
Divergent:
Sketch of Boundary/ Direction of movement
Description of boundary
Example
Oceanic
Continental

17. II. Divergent boundaries:
2 plates moving apart from each other

18. 1. Oceanic Ridge Sea floor spreading produces new lithosphere
Magma rises to fill the gap as the plates separate, pushing-up on the plates, and forming a mid-oceanic ridge
Example: Mid-Atlantic Ridge (Atlantic Ocean)

19. Oceanic Ridge (seafloor spreading)

20. Oceanic Ridges
Ocean
Elevated seafloor separating along the plate boundary
Mid-Ocean Ridges
1. Mid-Atlantic Ridge

21. Rift Valley
Magma close to the surface sinks the crust as it tries to pull it apart.
Examples:

22. Rift Valley Divergent Continental
Sketch
Description
Deformation:
Continental
Lowered area of continental crust due to magma close to the surface
Continental Rift – occurs on land & eventually splits the landmass

23. Rift Valley

24. III. Transform Fault Boundaries
Most located within ocean basins
Some cut through continental crust
Example: San Andreas Fault in California.

25. Transform Fault Boundaries
Type of boundary
Sketch/ Direction
Description
Deformation
Transform Fault
Two plates scrape past each other
No production or destruction of the lithosphere
Earthquakes or Tsunamis
Fault Line

26. Transform Fault Boundaries ex.

27. Convection in the Mantle