1. Drifting Continents
Chapter 5 Section 3

2. Continental Drift Alfred Wegener (1910) hypothesized that all the
continents were once joined
together as one landmass
(Pangaea) and have since drifted apart.
Many scientists did not agree with him, so Wegener went out to find support for his hypothesis.

3. Evidence of Continental Drift
What Alfred Wegener found

4. Continents looked like they fit together

5. Mesosaurus fossils found on S. America and Africa
Mesosaurus fossils found on S. America and Africa. Fresh water reptile not likely to have swum across ocean.

6. Glossopteris fossils found in Africa, Australia, India, S
Glossopteris fossils found in Africa, Australia, India, S. America, and Antarctica. Not likely to find this fern in so many different climates

7. Warm weather plant fossils found in Greenland
Glacial deposits and grooved bedrock found in S. America, Africa, India, and Australia

8. Similar rock structures found in U.S., Greenland, and W. Europe

9. Even though Wegener had all this information, scientists did not accept his theory

10. Sea Floor Spreading
Chapter 5 Section 4

11. What we found out after Wegener died
Sea floor spreading
- Ocean floor rocks are no older than 200 million years old
- Continental rocks are as much as 3 billion years old
- Rocks nearest the mid-ocean ridges are the youngest

12. Sea-floor spreading

13. Rock record shows reversed polarity in iron containing minerals

14. Subduction
When one plate moves beneath another plate