The Theory of Continental Drift

1. The Theory of Continental Drift

2. Continental Drift Theory • Proposed by Alfred Wegener in 1912 • 250 million years ago, all of the continents were combined into one super-continent called “Pangaea” • The continents gradually drifted apart to where they are today

3. Video Link • Alfred Wegener clip

4. Evidence of Continental Drift Puzzle Pieces • Continents look like they could be part of a giant jigsaw puzzle • Continental shelves of Africa and South America fit together almost perfectly

5. Distribution of Fossils • The Fossil Record • Glossopteris remains found in SA, Australia, Asia, and Africa, & Antarctica • Fossils of deciduous trees found near North Pole • Coal formation in many parts of the world, but needed to be swampy marshes with lots of rain near the equator

6. The Evidence • Fossil Evidence

7. The Evidence • Fossil Evidence

8. Sequence of Rock Types • The Rock Record • Rocks in Argentina identical to ones in Africa • Diamond rich rocks in South Africa match rocks in Brazil • Coal beds in NA, Britain, and Belgium same • Red sandstone same in NA, Greenland, Britain, Norway

9. The Evidence Mountain Ranges

10. Ancient Climates • Tropical plant remains (coal deposits) found in Antarctica • Glaciation in Africa, South America, India, and Australia during the same time

11. The Evidence • Climatic Evidence • Glacial evidence

12. Theory of Continental Drift • Vocabulary • Continental shelf – part of a continent that extends under shallow water from the ocean’s edge to the steeper sea floor slope. • Pangaea- all land • Panthalassa – all seas • Theory of Continental Drift – continents were once one landmass that broke apart and moved to present locations.

13. Evidence of Continental Drift • 1. • 2. • 3. • 4.

14. Evidence of Continental Drift • 1. Puzzle Pieces – continents fit together like a giant puzzle – esp. SA and Africa • 2. Fossil Record – the same plants, trees, and animals and coal beds occur in different continents • 3. Rock Record – same sequence of rock occurs on different continents, same mountain ranges occur on different continents • 4. Climate – same glaciation marks on different continents some now warm, fossil indicate tropical climates where now cold.

15. Pangaea