1. Plate Tectonics Earth’s Interior Convection Currents
Sea Floor Spreading
Plate Boundaries
Hot Spots

2. Objective(s):
List the layers and properties of the interior of the Earth
Relate plate tectonic evidence to Continental Drift
List and describe plate movements and interactions

3. DO NOW How many mm are in a cm? 10!
So, 1 cm is the same as __________mm.
If from my room to the library is 20 meters and from the library to Mr. Doyle’s room is 50 meters, how many meters do I have to walk to get to Mr. Dolye?

4. Earth’s Interior Includes the crust to the center of the Earth

5. Crust UPPER MANTLE Coolest in Temperature Least Dense Two Parts:
Continental
Thicker
Mostly Granite
Less Dense
2.7 g/cm3
Oceanic
Thinner
Mostly Basalt
More Dense
3.0 g/cm3
Crust
LITHOSPHERE
UPPER MANTLE

6. Mantle Upper Mantle (Rigid) Asthenosphere (Plastic Mantle)
Part of the lithosphere
Asthenosphere (Plastic Mantle)
Mushy
Allows the lithosphere to move
Lower Mantle (Rigid)

7. Outer Core Liquid! Composed of Iron (Fe) and Nickel (Ni)
Not under enough pressure to be solid
Composed of Iron (Fe) and Nickel (Ni)
Believed to be the source of Earth’s Magnetic Field
Protects us from Solar Winds which would destroy our atmosphere and make us as lifeless as Mars

8. Inner Core Solid Composed of Iron (Fe) and Nickel (Ni) Most Dense
Increased pressure causes this layer to be solid unlike the outer core
Composed of Iron (Fe) and Nickel (Ni)
Most Dense
Greatest in Temperature

9. DO NOW What happens to the density of a material when you heat it?
Density decrease
What causes the lithospheric plates to move?
Convection currents
Which part of the mantle does this occur?
aesthenosphere

10. DO NOW What are the four layers inside the Earth ?
Crust, mantle, outer core, inner core
Which layer is responsible for the plates moving?
Asthenosphere
Why?
This layer is “mushy” therefore allowing movement called convection currents

11. DO NOW What are the two types of crust? Continental and oceanic
Which is thicker, which is more dense?
Continental thicker and less dense
Which layer is liquid?
Outer core
Why isn’t the inner liquid if it is the hottest?
Too much pressure pushes the molecules together

12. The Theory of Plate Tectonics
Convection cells occur inside the Earth’s mantle cause crustal movement.
These convection cells are thought to be like conveyor belts, which would cause the rock above to move and shift.
It solves Alfred Wegener’s biggest flaw!!

13. Convection Currents
Currents in the mantle are thought to be responsible for the movement of the lithospheric plates
Movement of heat in mantle due to differences in density
HOT = Less dense and RISES
COOL = More dense and SINKS

14. Sea Floor Spreading
The ocean floors are spreading apart as new rock material is added to the crust in the regions of mid-ocean ridges

15. Continental Drift – Seafloor Spreading Connection!!
Alfred Wegener’s missing evidence:
Seafloor spreading explains how the continents move (in addition to convection currents)
The continents are on plates, which move over the asthenosphere

16. Where’s the Evidence? Age of Igneous Rock on Ocean Floor
The sea floor is younger at the ridges and gets older as you move towards the continents
Reversal of Magnetic Polarity
Igneous rocks at the mid-ocean ridge show magnetic orientation of Earth’s magnetic poles when the rock solidifies

17. Magnetic Polarity Normal Polarity Reverse Polarity
The compass needle would point to north
This is the magnetic orientation of Earth today
Reverse Polarity
The compass needle would point to south
Not today’s magnetic field, but has occurred in the past many times

18. Plate Boundaries Where the edges of plates meet Three types Divergent
Convergent
Transform

19. Types of Plate Boundaries
1. Divergent Plate Boundary
Where plates move apart
Geologic Features Found Here:
Rift Valley
Volcanoes
Earthquakes
Examples:
Mid-Atlantic Ridge
Great Rift Valley in Africa

20. Mid-Atlantic Ridge

21. 2. Convergent Plate Boundary
Where plates move towards each other
Oceanic – Continental
Oceanic – Oceanic
Continental – Continental
Geologic Features and Activities Found Here:
Mountains
On Continents
Volcanoes
Earthquakes
Trench
Deepest part of the ocean
Example:
Tonga Trench

22. Subduction Zones
The area where two plates collide together (Converge) and one of the plates (Subducting Plate) is forced down into the mantle where it will be destroyed
Subducting Plate
The plate that is being forced down
This creates volcanoes
EX: Andes mountains in South America contains many volcanoes

23. Oceanic – Continental

24. Oceanic – Oceanic
Islands of Japan were formed this way

25. Continental – Continental
No subduction – Plates crumple up forming mountains.

26. Himalayan Mountains

27. Transform (Sliding) Boundaries
Where plates slide past one another
Geologic Activity Found Here:
Earthquakes
Example:
San Andreas Fault

28. San Andreas Fault https://www.youtube.com/watch?v=Kg_UBLFUpYQ
Plate tectonics 14 min

29. EARTHQUAKES

30. Elastic Limit
When rock reaches its elastic limit an earthquake occurs.
When rock breaks they move along surfaces called faults.
This movement creates vibrations in the ground.

31. earthquakes Occur at plate boundaries Convergent: Plates move together
Divergent: Plates move apart
Transform: Plates are sliding