1. Development of a Theory
Chapter 6 Lesson 2

2. Mapping the Ocean Floor
Echo Sounder – tool helped scientists mapping the depths of the ocean floor.
Found MOUNTAIN RANGES called Mid-ocean Ridges.

3. Seafloor Spreading
This is process by which new oceanic crust forms along a mid-ocean ridge and older oceanic crust moves away.
Short video for you guys!!  Pretty cool and it has Bill Nye

4. Seafloor Spreading Continued
Floor spreads apart at plates, it spews out lava. Creates basalt.
Pillow lava…
Older basalt away from center. Newer is close to ridge.
This helped Wegener’s theory (of course he is frozen in Antarctica, so he has no idea… no we may not go there and dig him up!!!!!)

5. Pillow Lava.. Cools super quick

6. Topography of the Seafloor
Remember that topography means the shape of the land…. And the seafloor!!!!
Rugged mountains on seafloor can form 2 ways…
Lava build up creating mountains
Lava cools and cracks, moves and creates the ranges.

7. Topography of the Seafloor Cont’d
Abyssal plains – when the sediment accumulates and creates flat surfaces on the ocean floor.

8. Supporting Wegener
So…. If the floor is spreading and crust is getting bigger…. The continents are MOVING when new lava comes out!
Being PUSHED by new lava!

9. Normal Polarity Compass needle will point North.
This picture shows the
Everything going to the North.

10. Magnetic Reversal
When the magnetic field changes direction!

11. Reversed Polarity
When the needle points South on a compass.

12. Rocks show Magnetic Reversal
Basalt is iron rich.
Iron is magnetic.
It will point in different directions based on the polarity of the Earth.

13. Video So now that you are completely confused by the magnetic stuff….
Watch a video. 

14. Last Video