1. Continental drift – what is it?

2. Continental drift is the theory that continents can drift apart from one another

3. The History and development of the continental drift theory
In 1915 Alfred Wegner
developed the theory
of “Continental Drift”.
Alfred didn’t come up
with this theory all by
himself. He combined
evidence from several
different scientists.

4. Sir Francis Bacon In 1620 Sir Francis Bacon noticed by
looking at a map
that there was a
“very good fit”
between some of
the continents

5. Antonio Snider Pellegrini
In 1858 French Scientist Antonio Pellegrini cited that fossils of
the same plant
and animal species
were found on both
sides of the Atlantic
Ocean.

6. Other research Other research indicated that glacial grooves don’t
match as the continents
are positioned today but
they would match if the
continents had been put
together in their proposed
original arrangement

7. Alfred Wegner’s theory of Continental drift was not accepted!
Even though Alfred Wegner had combined evidence from many different sources to show that the continents had once been connected and then drifted apart his theory was not accepted because he did not explain “HOW” the continents moved.

8. Later … Frank Taylor
In 1958 An American Geologist named Frank Taylor pointed out geologic similarities between South America and Africa.
Similar Rocks found on both sides of the Atlantic
Evidence of the same climate
Frank Taylor could not explain how the plates moved either and so his observations were also “dismissed”

9. Harry Hess gets the job done!
In the 1960’s Harry Hess, an American Geologist and an armed service veteran from World War II, discovered that the sea floor splits apart in the center
of the Atlantic ocean at
areas called mid ocean
ridges. He used sonar to
map the ocean floor, and
to identify German U boats!

10. Mapping the ocean floor!

11. Sea Floor Spreading explains “continental drift”

12. Continental drift explains Pangea and the moving continents

13. All of this leads to the “Theory of Plate Tectonics”

14. Picture citations http://universe-review.ca/I09-03-drift.jpg