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Published byCurtis Doyle Modified over 6 years ago
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Aim: Have the continents always been where they are?
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- You will have 5 minutes for this task.
Do Now: - Take the “Continental Drift Theory” reading from the back of the room. - After reading the short article on your own, answer the questions on the back with your partner. - You will have 5 minutes for this task.
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The Continental Drift Theory
1. Wegener believed the landmasses could all fit together. 2. Wegener did not have enough hard evidence or proof to support his ideas. 3. It took until the 1960’s for new evidence to emerge. 4. Fossils of Glossopteris (a fern plant) are found on many continents. Scientists think the seeds were too large to be carried by wind, and therefore, could not explain how it traveled the great distances between the continents today. This indicates the continents must have been closer. 5. Fossils of Lystrosaurus (swamp-dwelling hippo-like creature) are found on many continents. Scientists do not believe this creature could have swam the great distances between the continents today. This indicates the continents must have been closer.
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I. The Continental Drift Theory
- theorized that the continents floated around the planet through the oceans. Alfred Wegener around 300mya, all the continents were together in one land mass he called Pangea.
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Formation of Pangaea (~300mya)
What do you notice about the shapes of the continents on this animation?
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II. Evidence for Continental Drift
The Continental Puzzle - continents fit together like a giant puzzle.
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Fern Fossil Alexander Island, Antarctica
2. Matching Fossils - Fossils of the same organisms (plants and animals) are found on different continents. What significance does finding the fossil of a fern plant on Antarctica have for Wegener's Continental Drift Theory? Fern Fossil Alexander Island, Antarctica
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3. Rock Types and Structures
Present (2015) 250 Million Years ago - different mountain ranges across oceans have the same rock composition and age.
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III. Rejecting a Hypothesis
After hearing and reading about Wegener’s theory, what questions would you have for Alfred Wegener if he were here? Do you think he is missing any important information or facts to support his idea? - Most scientists rejected Wegener’s hypothesis because he could not explain what causes the continents to move.
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IV. A New Theory Emerges The Theory of Plate Tectonics
the continents are attached to the lithosphere, and that the lithosphere moves carrying these continents. (still uses Wegner’s evidence)
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Closure What will most likely happen to the continents over the next 300MY?
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