1. Welcome! Please get out:
Rates of Plates Part 2 (blue) and your Sinking Slabs worksheet (yellow)
Get a BSCS textbook
Biology Journal
A writing utensil
Your brain…activate it!
50,000,000 years

2. Warm-Up:
#1 A plate is moving at a rate of 2 cm/ year. How many years would it take the plate to move 1,600,000,000 cm?
#2 How many centimeters are in 5,400 meters?

3. Warm up Review
#1 1 year x 1,600,000,000 cm = 800,000,000 yrs 2 cm #2 100 cm x 5,400 m = 540,000 cm 1 m

4. Let’s review our past work…
Have both Mountainous changes part 1 and part 2 in front of you

5. Homework Review Scaling up to Mt. Change Pts I & II
Big Take Homes:
Do tectonic plates move quickly? Slowly?
How can such a slow process lead to such great changes?
Can you think of an analogy of something else that moves very slowly, but can lead to great changes?
How does coral end up in places that aren’t under water?
Do all the locations change at the same rate?
What might lead to differing rates of change in the mountain heights?
Why are some mountains jagged, and other mountains more rounded?
What makes mountains? What makes them smaller?

6. Let’s take some notes…
Open up your Biology Journal to the Class Notes Section.
If you fall behind you can always review my presentation on my SWIFT site.

7. Principle of Superposition
In a set of layered (sedimentary) rocks, the oldest must be at the bottom and the youngest at the top.

8. Example!

9. Youngest Rocks
Oldest Rocks

10. You don’t make an ice cream cone from the top down!

11. Principle of Original Horizontality
Sediment is deposited in horizontal layers… (thus sedimentary rock layers are initially horizontal).
So if layered rocks are tilted, they probably didn’t start that way – something changed.
Not original position

12. What’s Inside the Earth?

13. Theory of Continental Drift
Continents were formed from the drifting apart of one super continent Pangaea
Found evidence of similar fossils and geological formations on different continents
The shape of continents also seemed to “fit” together

14. Fossil & Geologic Evidence
Big flaw with theory: How did the continents actually move?

15. Theory of Plate Tectonics
Outer “shell” of Earth is broken into plates
Plates are carried by convection cells in mantle
Moving plates collide, diverge, or slide by each other

16. Convection cells in (upper mantle) cause sea floor spreading

18. Ocean and Continental Crust
OCEAN crust
Denser
Thinner
Eventually subducted
Relatively young
CONTINENTAL crust
Less dense
Thicker
Rarely/never subducted
Oldest crust on Earth

19. How do tectonic plates interact?
Three Major Ways:
Convergent – Come Together
Divergent – Drift Apart
Transform – Slide side by side

20. Convergent Two plates collide together.
The faster they move, the stronger the seismic events will be (stronger earthquakes, taller mountains, etc).
This is the way huge mountains are made.

21. Convergent Boundaries
1. Continental/Oceanic
Denser ocean crust is subducted (pulled) under
Deep trenches, mountains, strong earthquakes
Melting oceanic plates turn into magma
Examples:
Andes Mts.
Cascade Mts.

22. Convergent Boundaries
2. Oceanic/Oceanic
Slower plate is subducted (pulled under)
Outcome = volcanic islands, strong earthquakes, tsunamis, deep trenches
Ex: Aleutian islands (Alaska), Hawaiian Islands, Japan, Southeast Asia

23. Himalayan Formation

24. Divergent Boundary, Seafloor Spreading-Magnetic Reversals
This kind of plate boundary usually results in ocean spreading ridges (underwater mountains that expand)

25. Divergent Boundary Normal Fault Mostly below the ocean
Sea Floor Spreading - Forms new crust
Example: Mid
Atlantic Ridge, Rift
Valley in Africa

26. Great Rift Valley- Africa

27. Age of Seafloor

28. Transform Boundaries Transform Boundary
Description: Two plates slide by each other.
Creates: Earthquakes and underwater Mountains Ranges
Where: San Andreas and Turkey
Connection: Rubbing your hands together or Sneakers on the gym floor.

29. Transform Plate Boundaries
2 plates sliding in opposite directions
E.g. San Andreas Fault

30. Faults Fractures in crust
Occur along plate boundaries, but occasionally occur in the middle of a plate
Rigidity of crust builds up tension; eventually slippage occurs to release tension  this is an earthquake

32. Rates of Plates Packet Part 1 and 2 & Sinking Slabs WS
Complete both packets.
Both packets are due at the beginning of the next class.
QUIZ on Tuesday, Sept. 26 (Blue) or Sept. 27 (Gold)
Make sure you know the following for the QUIZ:
Convert from cm to m
Calculate rates (ex. 3cm/year…how many years to move 1,200, cm?)
Calculate slope
Vocabulary definitions
Boundary types and events that occur there.
Difference between rifts and trenches