1. Theory of Continental Drift
Cornell Notes
Pg. 95

2. The Theory of Continental Drift
Alfred Wegener (1910)
Formed a hypothesis that all the continents were once joined together and have drifted apart

3. What was Wegener’s evidence?
Evidence from:
Landforms—the continents fit together
Fossils—ancient plants and animals found in many different continents
Climate—Antarctica has plant fossils. Tropics have rocks with ice scratches from glaciers.
Rock Types- similar rocks found were continents may have once been joined together.

4. Wegener’s DATA

5. Pangaea Continents were joined together in one land mass
“The super continent” 245 mya

8. Which way are the continents moving today?

9. Plate Tectonics Timeline
page 98

10. The Theory of Sea Floor Spreading
Page 99

11. Sea Floor Spreading Harry Hess (1960)
as the ocean floor spreads apart, new crust material rises from the mantle and creates new sea floor to fill the “hole.”

13. HESS (1960) Sea floor spreading
Continents were moving (as Wegener had proposed)
Evidence 1. 2. 3.

14. 1. The discovery of the Mid-ocean Ridge
Scientists mapped 47,000 miles of underwater volcanic ridges by using sonar

15. Map of Mid-ocean Ridges

16. 2. Ocean floor shows Magnetic Poles reversing

17. 3. Ocean floor samples—older crust is further away from ridges