Lesson 20 What is the theory of Continental Drift?

1. Lesson 20 What is the theory of Continental Drift?

2. What is a continent? A continent is a very large land mass. There are 7 continents on earth. Scientists believe that at one time, the earth had only one giant continent.

3. The continents are always moving. Only 2.5 cm a year, but moving. Scientists believe that about 200 million years ago, the giant continent, called Pangaea, began to move apart.

5. Pangaea moved very slowly.

6. And kept moving.

7. And moving.

8. Even today, the continents continue to move. Continental Drift is the theory that the continents were once one giant land mass.

9. Continental Drift was first stated in 1912 by Alfred Wegener, a German scientist. He based the idea on his study of the coastlines of the continents. They seemed to fit together, like a jigsaw puzzle.

10. There is other evidence of Wegener’s theory. Fossils are remains of things that lived long ago. Similar plant and animal fossils have been found in places that are far apart, in matching coastlines on different continents.

11. Mountains: Some mountain ranges on different continents seem to match. For example, a mountain range in eastern Canada seems to match one found in Norway and Sweden. The mountains would have separated with the continents.

12. Rocks: The age and kind of rocks and minerals along the edge of one continent match rocks and minerals along the edge of another continent.

13. Most scientists support the idea of continental drift. Some however, are not convinced. They point to evidence and questions that this theory cannot explain.