1. Continental Drift- The Theory

2. The Earth’s crust is broken into about 12 rigid plates, which slide over a semi-molten plastic layer of the mantle.

3. Tectonic Plates on Modern Earth

4. The material making up the plates can be divided in two types:
i. Oceanic crust
ii. Continental crust

5. The History of the Theory of Continental Drift

6. 1600 - development of a comprehensive world map (missing details of some continents such as
Australia and Antarctica). .

7. Francis Bacon noted the similarity of the shape of the continents on either side of the Southern Atlantic – Africa and South America

8. Antonio Snider developed a theory that when the Earth cooled from a molten mass continents formed only on one side. This created instability causing the Americas to be pulled away from the rest of the continents.

9. 1879 – Sir George Darwin said that the Pacific Ocean was the scar left behind when the Moon
pulled away from the Earth. After this happened, the continents moved to create a
balanced planet. .

10. 1924 - Alfred Wegener developed the theory of Continental Drift to explain the similarities of
rocks, fossils and other geological structures on either side of the Atlantic. At this time it
was accepted that the continents sat like icebergs on the mantle. Wegener suggested as well as moving up and down in the mantle, continents could move sideways in the mantle.
-Wegener was a meteorologist and his theory was not well accepted. (He died on an
expedition in Greenland collecting ice samples).

11. Continental Puzzle Time

15. End of Day 1

16. Continental Drift: Evidence
Geographic fit of South America and Africa
Fossils match across oceans
Rock types and structures match across oceans
Ancient glacial features

17. the continents, especially using
Continental
Drift:
Evidence
Tight fit of
the continents, especially using
continental shelves.

18. Continental Drift: Evidence
Fossil critters and plants

19. Continental Drift: Evidence
Correlation of mountains with nearly
identical rocks and structures

20. Continental Drift: Evidence Glacial features of the same age
restore to a
tight polar
distribution.

21. Earth ~200 million years ago