1. The Big Crack Up!

2. Explain the causes of earthquakes and volcanic eruptions.
LEARNING TARGET 4:
Describe plate movements that cause ocean basins, ocean trenches, and mountains to form;
Explain the causes of earthquakes and volcanic eruptions.

3. EARTH: A GIGANTIC RECYCLING CENTER!

4. Plate Tectonics
The theory of plate tectonics is based on the evaluation of scientific evidence and observation- The Scientific Method
Continental Drift hypothesis
Seafloor Spreading hypothesis

5. Convergent Divergent Transform
Plate Boundaries
Convergent
Divergent
Transform

6. Plate Tectonics
Explains the configuration of topographic features of the Earth- mountains, valleys, volcanoes, islands, oceanic trenches, faults

7. Tectonic plates Are composed of the lithosphere
Move as a coherent mass
May contain oceanic crust and continental crust

8. Plate Boundaries Where does the energy come from to move plates?
Where does it go?
Topographic features on the Earth’s surface reflects what is happening in the mantle.

10. Convergent Plate Boundary
Volcanic arc
Oceanic crust subducts under continental crust
Melting occurs at about 100 miles down
Hot more buoyant material rises

11. Volcanic Arc Oceanic and continental crust
Cascade Range, Andes, Alaska
Characteristics: large volcanoes; subduction zone; trench; oceanic crust subducts under continental crust

12. Convergent Plate Boundary  
Convergent Plate Boundary
Map and cross-section views of the subduction zone
The oceanic Juan de Fuca plate subducts under the continental North American Plate

13. Convergent Plate Boundary
Two oceanic crusts
Oceanic crust subducts under opposing oceanic crust
Oldest oceanic crust subducts

14. Island Arc
Japan, Indonesia, Philippines, Caribbean, Aleutian Islands

15. Convergent Plate Boundary
Earthquakes trace the SUBDUCTING SLAB to about 500 miles or 650 kilometers
Gold dots represent earthquake hypocenters

16. Sketch a cross-section of a convergent plate boundary that contains an oceanic crust.
Label with the following terms:
Subduction zone
Trench
Area of melting
Area of volcanism
Arrows indicating direction of plate movement

17. Convergent Plate Boundaries
Two continental crusts
Neither subduct due to buoyancy of crusts
Mountains form

18. India collided with Asia about 40 million years ago
Mt. Everest, 29,000 feet

19. Divergent Plate Boundary
Two plates move apart
Run through ocean basins

20. Divergent Plate Boundaries
New crust forms at mid-oceanic ridges. The seafloor spreads out. This is Seafloor Spreading.

21. In most locations, mid-ocean ridges are 6,500 feet (1,980 m) or more below the surface of the oceans.
In a few places, they reach above sea level and form islands. Iceland (North Atlantic), the Azores (west of Portugal), and Tristan de Cunha (south Atlantic between southern Africa and South America)

22. How Does Seafloor Spreading Affect Neighboring Plates?

23. East Africa Rift Zone
Continental crust is beginning to pull-apart forming a rift valley

24. Process of Ocean Basin Formation

25. Sketch a cross section of a divergent plate boundary.
Label with the following terms:
rift valley;
oceanic ridge;
oceanic crust;
location of melting and volcanism;
and arrows indicating direction of plate movement .

26. Transform Plate Boundary

27. Transform Plate Boundary
The tectonic plates pass by each other
Connected to other plate boundaries
San Andreas Fault
Label the plates, their movement directions, and the San Andreas Fault

28. Hot Spots Animation of Formation
Stationary plumes of hot material that initiate at the core/mantle interface
Hawaii: the plume is beneath oceanic crust

29. Hot Spots

30. Hot Spots
Yellowstone is associated with a hot spot under continental crust

31. Name the landform associated with oceanic crust subducting under continental crust. Oceanic crust?