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Wegener's Hypothesis Rejection: Lack of Explanation for Continental Movement

This text discusses why Wegener's hypothesis was rejected, highlighting his inability to explain the forces driving continental movement. It also introduces the concept of sea-floor spreading and the role of Harry Hess in proposing this theory.

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Wegener's Hypothesis Rejection: Lack of Explanation for Continental Movement

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  1. Warm Up! Why was Wegener´s hypothesis rejected?

  2. Warm Up! Why was Wegener´s hypothesis rejected? He could not explain what was pushing or pulling the continents

  3. S4 - Sea-Floor SpreadingBig book pgs. 141-147Small book pgs. 23-29

  4. Was Wegener Right? • In the 1950s, scientists used sonar to find the mid-ocean ridge.

  5. Was Wegener Right? • In the 1950s, scientists used sonar to find the mid-ocean ridge.

  6. Was Wegener Right? • In the 1950s, scientists used sonar to find the mid-ocean ridge.

  7. Sonar

  8. Mid-Ocean Ridge

  9. Harry Hess • American Scientist, studied Mid Ocean Ridge • Said ocean floors move like conveyor belts. • As the ocean floor moves, they carry the continents with them

  10. Harry Hess • American Scientist, studied Mid Ocean Ridge • Said ocean floors move like conveyor belts. • As the ocean floor moves, they carry the continents with them

  11. Mid-Ocean Ridge

  12. TO DO From Section 4: Sea-Floor Spreading • define the following key terms: • Mid-ocean ridge • Sonar • Sea-floor spreading • Deep-ocean trench • Subduction *Use glossary in back of book to help you

  13. Warm Up! • Continue defining the following key terms: • Mid-ocean ridge • Sonar • Sea-floor spreading • Deep-ocean trench • Subduction *Use glossary in back of book to help you

  14. What is Sea Floor Spreading? • Magma rises from the mantle and erupts through the Mid Ocean Ridge. • The magma pushes older rocks away on both sides of the ridge.

  15. What is Sea Floor Spreading? • New crust is being created at the Mid Ocean Ridge

  16. The new crust pushes older crust away on both sides of the ridge.

  17. Evidence • 1. Evidence from molten material (magma) • 2. Evidence from magnetic stripes • 3. Evidence from drilling samples • Not necessary to copy

  18. 1. Evidence from Molten Material • Rocks found that form when magma and water mix

  19. 1. Evidence from Molten Material • Rocks found that form when magma and water mix

  20. 2. Evidence from Magnetic Stripes • Pattern in rock shows that iron faces different directions

  21. 2. Evidence from Magnetic Stripes • Pattern in rock shows that iron faces different directions

  22. Evidence from Magnetic Stripes • When Earth’s magnetic field pointed north, the iron in the magma that erupted into the ocean faced north as it hardened. • When Earth’s magnetic field reversed, the iron faced south. • The magnetic field reversed again. This formed stripes.

  23. 3. Evidence from Drilling Samples • Newer rock is found near the Mid Ocean Ridge.

  24. 3. Evidence form Drilling Samples • Newer rock is found near the Mid Ocean Ridge.

  25. To do • S4 Assessment • Big Book pg. 147 #1,2 • Small book pg. 29 #1,2

  26. Warm Up! • Who proposed the idea of Sea Floor Spreading?

  27. Warm Up! • Who proposed the idea of Sea Floor Spreading? • Harry Hess, an American scientist purposed the idea in 1960

  28. What is Sea Floor Spreading?

  29. What is Sea Floor Spreading? The new crust pushes older crust away on both sides of the ridge.

  30. What is Sea Floor Spreading? The new crust pushes older crust away on both sides of the ridge.

  31. Subduction Part of the ocean floor sinks back to the mantle at the deep ocean trench

  32. Subduction Part of the ocean floor sinks back to the mantle at the deep ocean trench

  33. Open Textbooks to: Big book, pg. 148 Small book pg. 30

  34. Modeling Sea Floor Spreading Big book, pg. 148 -149 Small book pg. 30 -31 • Can work alone or with a partner (group of 2 for 1 model max) • Follow directions under Procedure • 3. When finished, Put your names on the model and turn in to back table • 5. Complete Section 4 Assessment in Science notebook (Due Friday) • 6. Work on Math Packet (Fractions)

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