1. CONTINENTAL DRIFT THEORY

2. Today’s Goals  be able to describe the Continental Drift Theory
 be able to describe the evidence for the Continental Drift Theory including:
 jigsaw puzzle fit of continents
geological structures
fossils
climatic evidence

3. Continental Drift Theory
continents were not always where they are today
continents have drifted apart over millions of years

4. Continental Drift Theory
the continents are still moving today!

5. Who proposed the Continental Drift Theory?
proposed by Alfred Wegener (1915)
German Scientist
based his proposal on 4 lines of evidence:
1. jigsaw puzzle fit of continents
2. geological structures
3. fossils
4. climatic evidence

6. 1. Jigsaw puzzle fit of the continents
coast lines of continents appear to roughly fit together like jigsaw puzzle pieces
led Wegener to propose that continents once fit together and formed a supercontinent called Pangaea
pan = all
gaea = Earth

7. 2. Matching geological structures
mountain ranges begin on one continent, end at the coast and then appear to continue on another continent across the ocean
similar findings exist with rock types and patterns across the Earth’s surface
Giant’s Causeway
(Ireland and Scotland)

8. 3. Fossils
similar fossils are found on different continents despite the continents being separated by vast oceans
How did the creatures get between the continents?
creatures could not swim or fly that great of distance
most likely explanation = continents were closer together at some point in time 8

10. 4. Climatic Evidence 4A. Paleoglaciation
rock markings left behind from ancient glaciers
suggest tropical regions may have once been more polar (allowing for the formation of glaciers)
and suggests continents were once closer together
Ancient Glacial Rock Markings Proposed Location of Continents
(Paleoglaciation) and Ancient Glacier 10

11. 4. Climatic Evidence 4B. Coal deposits
coal is formed from decay of tropical plants
coal deposits are found in Antarctica
suggests Antarctica was once a tropical climate that was closer to the equator
Penguins during Pangaea Penguins Today 11

12. Summary of Evidence for Continental Drift Theory12

13. Continental Drift Theory – A Theory Ridiculed!
Continents move!?! – As if!
further evidence would be needed
was found after Wegner died (1930)
= discovery of plate tectonics and the fact that the Earth is not solid rock at its core 13