1. Agenda Roll PowerPoint “Restless Continents”
September 25, 2013
Agenda
Roll
PowerPoint “Restless Continents”
Welcome to Science!

2. Subject Area: Restless Continents
EQ: How does the fit of the continents provide evidence for plate tectonics?
Questions:
Why was Wegner’s theory of continental drift not accepted at first?
How does sea floor spreading provides a way to explain how continents move?
How does new oceanic crust forms at mid-oceanic ridges?
How does magnetic reversals provide evidence for sea-floor spreading?

3. Restless Continents Wegener’s Theory of Continental Drift
The Breakup of Pangaea
Sea-Floor Spreading
Magnetic Reversal
Untold tragedies of Continental Drift.

4. Restless Continents
If you look at the continents they would fit together. It is possible that the continents were actually together sometime in the past.

5. Wegner’s Theory of Continental Drift
In the Early 1900’s Alfred Wegner wrote about the theory of continental drift. Continental Drift is the theory that continents can drift apart from one another and have done so in the past. Some fossils were found on both sides of an ocean, there is no way the ancient animal could have crossed the ocean.
Partner Question:
What is the theory of Continental Drift?

6. Wegner’s Theory of Continental Drift
Continental drift also explained the evidence left by glaciers. The glaciers cut grooves that can be matched in their original arrangement. The Glacial grooves fit together.

7. The Breakup of Pangaea
Wegener thought the separate continents of today were once joined in a single landmass. This landmass he called Pangaea. Pangaea is the Greek word for “all earth” where all the continents were once joined together.
Partner Question:
What does Pangaea mean?

8. Sea-Floor Spreading
Wegner could not explain how the continents moved. Later scientists discovered Mid-oceanic ridges. This is where sea-floor spreading takes place. Sea-floor spreading is the process by which new oceanic lithosphere is created as older materials are pulled away.
Partner Question:
What is Sea-Floor spreading?

9. Magnetic Reversals
In Earth’s history, the north and south magnetic poles have changed places many times. When the magnetic poles change it is called magnetic reversal. Minerals record the magnetic signal in stone. Then it moves with the moving material across the ocean floor. This is just more proof that sea-floor spreading does occur.
Partner Question:
What is magnetic reversal?

10. Intro to Continental Drift
What did I know? 1. 2. 3.
What did I learn?
What do I want to know
more about?

11. Pangaea Puzzle
You are only coloring today. Do not cut any out today. We will do that tomorrow!!!

12. Workbook Chapter 6 section 2 on pages 40 – 42.
Class work
Workbook Chapter 6 section 2 on pages – 42.
Science Rules!