1. Plate Tectonic Notes
2/7/19

2. Alfred Wegner
Came up with idea that at one point in our history our continents were all one giant land mass, called Pangea.
He then concluded that the large mass of land separated into two continents, Gondwanaland and Laurasia.
His theory that continents shift overtime is called CONTINENTAL DRIFT.
He had several pieces of evidence to show that the continents moved.

3. Alfred Wegner’s 4 Clues to Continental Drift
He had 4 clues that he used to explain continental drift!
Puzzle Pieces
Fossils
Rock Strata
Coal

4. 1. Puzzle Pieces
It fits like a puzzle! Different continents appear to be able to fit together like a puzzle. When they are all pushed together it forms PANGEA

5. 2.Distribution of Fossils
Fossils of the same exact reptile were found on different continents. When the continents split different life forms developed on each continent. That is why we don’t notice similarities in today’s animals!

6. 3. Rock Strata Correlation
The age and layering of the rock strata is identical in specific areas suggesting that at one time they were touching.
The distribution of rocks in Earth’s crust is a direct result of tectonic activity.

7. 4. Coal Formations
Coal formations have been found in cold and dry climates when coal can only form in warm wet climates.
Like wise fossil remains of oceanic life have been found in the very top of mountain peaks.

8. Why didn’t they believe him?
Looking at all of the evidence surely they would believe him!
No! The greater scientific community didn’t because he couldn’t fully explain his WHY these things happened.
He had evidence that it was happening, but he didn’t know exactly how the plates were moving.

9. Harry Hess
Harry was using sonar to research for the U.S. Navy when he realized that the ocean was shallowest in the center.
This doesn’t make much sense that it is shallowest in the center and deepest right off our coasts, so
He concluded that the crust must be created from the center, but how?
So he got in a submarine and started researching.
He found that hot less dense material below the Earth’s crust rises toward the surface at mid-ocean ridges
Hess named this idea, SEAFLOOR SPREADING.

10. Tectonic Boundaries
Boundaries are where two tectonic plates meet.

11. Divergent Boundary Where two plates are moving apart Creates new land
Mid-Atlantic Ridge

12. Seafloor Spreading
New seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge
Can only occur at a divergent boundary

13. Tension
Forces that pull rocks apart
Causes a NORMAL Fault

14. Convergent Boundary Where two plates come together and collide
Mountains and volcanoes

15. Convergent Boundaries
Ocean meets Continent: Ocean goes below Continent
Continent meets Continent: Collide make a mountain
Ocean meets Ocean: Collide one breaks

16. Subduction Zone
SUBduction Zone occurs when a plate SUBmerges under another plate
Can only occur at a convergent boundary

17. Compression Forces that push or squeeze rocks together
Causes a REVERSE Fault

18. Transform Boundary Where two plates slide past each other Earthquakes
San Andreas Fault

19. Shearing
Forces that cause rocks on either side of the faults to push in
Causes a STRIKE SLIP Fault

20. How do we know plate tectonics are real?
Distribution of fossils (aka Alfred Wegner)
Earthquakes
Continental and Ocean Floor Features
Mountains
Volcanoes
Faults
Trenches

21. Ring of Fire
An area in the Pacific Ocean where there is a lot of volcanic and earthquake activity happening.

22. Volcano
The vent as well as the mountain that forms around it from cooled lava, ash, cinders, and rock

23. Vent
Magma is released through these in Earth’s crust