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

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

3. S4 - Sea-Floor Spreading Big book pgs. 141-147 Small 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

23. 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.

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

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

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

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

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

30. What is Sea Floor Spreading?

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

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

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

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

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

38. Modeling Sea Floor Spreading
Big book, pg
Small book pg
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
Complete Section 4 Assessment in Science notebook (Due Friday)
Work on Math Packet (Fractions)