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. “Puzzle Pieces”
Continents look like they could be part of a giant jigsaw puzzle

4. Evidence to Support the Theory

5. Distribution of Fossils
Plant and animal fossils found on the coastlines of different continents

6. Sequence of Rocks
Same rock patterns found in South America, India, Africa, Antarctica and Australia

7. Ancient Climates
coal deposits(Tropical plant remains) found in Antarctica
Glaciers leave behind deposits and marks that show where they were located in Africa, South America, India, and Australia during the same time

8. Ancient Mountains
Mountain ranges on five continents fit together on the jigsaw map

9. Problems With The Theory
No mechanism for movement of continents
Wind and currents could possibly move fossils
Theory was not accepted by scientists

10. Continental Drift with Years

11. Plate Tectonics explain how continents move.
                                                                                                                    
Plate Tectonics explain how continents move.

12. The plate movements cause earthquakes.

13. Volcanic eruptions,

14. And mountain formation.
Before and After
And mountain formation.
                                             

15. These events are most common along plate boundaries
These events are most common along plate boundaries. A ring of active volcanoes called the ring of fire is found along parts of the Pacific Plate boundary.

16. Convergent boundaries
The size of the Earth has not changed significantly during the past 600 million years, and very likely not since shortly after its formation 4.6 billion years ago.
The Earth's unchanging size implies that the crust must be destroyed at about the same rate as it is being created, as Harry Hess surmised.

17. The Floor of the Earth's Ocean Basins
                                                                                                                  
The Floor of the Earth's Ocean Basins