Essay on Evidence for Plate Tectonics

Submitted By lanaaatw
Words: 470
Pages: 2

Evidence for plate tectonics

Some of the evidence that suggests that the continents have shifted to their present positions is:

1. A number of continents have coastlines that appear to fit together like a jigsaw. These are remnants of the super-continents Pangaea and Gondwana

2. Fossils of an animal called Mesosaurus have been found in only two places – South America and Africa. Thus, this suggests that these continents must have been joined at some time. Other fossils, like a certain type of gum tree, have been found in India, Africa and Australia. Fossils of an animal the size of a sheep, called Lystrosaurus, have been found in India, Africa and Antarctica. This was a land animal and would not have been able to swim between the continents

3. Mapping the ages of the rocks on either side of the Mid-Atlantic Ridge showed that the rocks get older as you move away from the ridge on either side. This suggests that the ridge is where the new rock is forming and causing the older rock, carrying the continents of Africa and South America, to move apart

4. Similar volcanic rock outcrops have been found on two continents now separated by ocean. This suggests that they came from the same volcano, indicating that they must have been once close

5. Coal has been discovered in Antarctica. Coal comes from large forests which would have been formed in the tropical climates

6. Africa, Australia and South America all have glaciation markings which match up

7. The ocean floors have been found to be quite young (200 to 400 billion years old) compared to the continental land masses which are over 4.5 billion years old. This means the ocean floors must be getting renewed every few hundred million years.

8. Several sites of ancient marine life and sea shells have