1. Chapter 7 Section 1: Continental Drift Section 2 : Sea Floor Spreading
Section 3: Plate Tectonics

2. Section 1 Continental Drift
Alfred Wegener
( )
Proposed hypothesis of continental drift
Pangaea

3. Evidence to support C.D.
Continents appear to fit together like a puzzle
Similar fossils have been found on different continents
Remains of warm climate plants in arctic zones and Arctic clues in tropical zones
Similar rock structures found on different continents

4. Section 2: Seafloor Spreading
Magma below Oceanic crust pushes upward and outward forcing the crust into large underwater mountain ranges.
Mid Ocean Ridges

5. Evidence for S.F.S A theory Has been proven to occur
Rocks increase in age as one moves away from the mid-ocean ridges.
Continents are measure farther apart by 1 or 2 inches per year
old
new

6. Section 3: Theory of Plate Tectonics
Combines the hypothesis of continental drift with the theory of sea floor spreading.
Earth’s crust and upper mantle broken into plates.
Shift on layer of molten rock.

7. Earth’s plates Lithosphere Asthenosphere
Earth’s crust and upper mantle
Layer that shifts
Asthenosphere
-like layer
of mantle.

8. Earth’s crust Continental crust Oceanic crust Thick Less dense Older
Forms land
Oceanic crust
Thin
Dense
Younger
Forms ocean bottom

9. Plate Boundaries Divergent Where 2 plates move apart
Sea floor spreading!
Mid-Atlantic ridge
Rift Valley

10. Plate Boundaries contd.
Convergent Boundary
Where 2 plates move together.
Oceanic / Continental plate collision
Subduction
zone.
Volcanic
Mtns.
Trench

11. Convergent Boundaries contd.
Continental / Continental crust collision
Forms mountains
India plate moving north / Eurasian plate moving south.
Himalayan Mountains

12. Himalayan Mountains

13. Oceanic/Oceanic convergent collision.
Creates a trench
Both subducted, but one more than the other

14. Transform Boundaries 2 plates sliding past each other
Strike-slip faults
Can move in different directions or the same direction at different rates.
San Andreas Fault in California.
Earthquake zone

15. Transform Boundary

16. Causes of Plate movement.
Convection Currents
The heating, rising, cooling, and falling cycle of molten rock in the earth’s mantle.

17. Earth’s Plates and movement.

18. Tectonic Plates and Land Forms.