1. Chapter 9

2. Earth’s surface consists of a number of rigid, but moving pieces called plates
Theory of Plate Tectonics:
Theory that helps explain the formation and movements of these plates

4. Continental Drift

5. Evidence of Continental Drift
Fossil
Climatic
Geological
Paleomagnetic
Seafloor Spreading

6. Fossil

7. Identical fossil remains of Mesosaurus, a small, extinct land reptile that lived 270 million years ago, has been found in both eastern South America and western Africa. These reptiles could not have swum across the Atlantic Ocean.

8. Climatic
Ancient Glaciers grooves (shown by arrows) in present day structures)

9. Gondwana Reconstruction of Southern hemisphere super continent
Gondwana Reconstruction of Southern hemisphere super continent. Notice how ring of glaciers match the patterns of a polar ice

10. Geological

11. Paleomagnetic

14. Lithosphere This outer shell of the Earth Made of crust and mantle
Rigid but broken into plates that move with respect to one another

15. Types of Earth’s Crust Oceanic Crust –
Made up of material on the ocean floor
Continental Crust –
Made up of continental landmasses.

16. Asthenosphere
Layer within mantle that lithospheric plates rest on

18. Where convection currents are rising…
New material moves to Earth’s surface
Pushes older material aside
Lithospheric plates move apart

19. Where cooler, denser currents are sinking
Lithospheric plates are pulled together!

21. Plate Boundaries
Place where one plate is moving relative to another plate
Belts where earthquakes and volcanoes are located – stress builds up along boundary

22. When stress is too great – fractures form and earthquakes occur
Boundaries are also area of high heat flow, magma moves upward to surface and forms a volcano

23. Kinds of Plate Boundaries…

24. Divergent boundaries
Places where two lithospheric plates are moving apart (spreading centers)
Contain mid-ocean ridges which have deep valleys along entire length called rift valleys
As plates move apart, molten rock rises and fills space between plates – cools and hardens

27. Transform Fault Boundaries
Lithospheric plates are sliding past one another
Transform fault – break or crack in the Earth’s crust along which movements have occurred

29. Example: San Andreas Fault

31. Converging Boundaries
Places where two plates come together
There are 3 types….

32. SUBDUCTION Zone When an ocean plate and continental plate collide
Ocean plate slides under continental plate
Forms deep-ocean trench

35. CONT. to CONT. Convergence
Two continental plates collide
Become crumpled and uplifted
Form mountain ranges

40. OCEANIC TO OCEANIC Crust Convergence
One plate is subducted, forms trench
Subducted plate melts
Molten rock rises to surface along trench
Forms island chain called an ISLAND ARC

42. Can you pick out the types
Here it is – all in one big picture…
Can you pick out the types
of Plate Boundaries?

43. Were you right?

44. fault: break or crack along which rocks move
caused by stress

45. faulted rocks have two blocks:
hanging wall: block of rock above fault
foot wall: block of rock below fault

46. Types of Faults
normal fault: formed when hanging wall moves down relative to the foot wall

47. reverse fault: formed when hanging wall moves up relative to the foot wall

48. strike-slip fault: rocks on either side of fault are moving past each other

49. fold: bend in the rock (rock deformed but doesn’t break)
anticline: upward fold in the rock (forms ridges)
syncline: downward fold in the rock (forms valleys)