CONTINENTAL DRIFT THEORY
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
Continental Drift Theory continents were not always where they are today continents have drifted apart over millions of years http://www.youtube.com/watch?v=CFCP8l0vNTU&feature=related
Continental Drift Theory the continents are still moving today!
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
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
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)
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
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
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
Summary of Evidence for Continental Drift Theory 12
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