1. Environmental Science
Plate Tectonics
Environmental Science

2. Plate Tectonics The Earth Inside Out The Theory of Continental Drift
Bathymetry and Seafloor Mapping
The Theory of Continental Drift
Lab continental drift
Seafloor Spreading
Lab seafloor spreading
Plate Tectonics
Lab plate tectonics

3. Earth’s Internal Layers
How do we classify the Earth’s internal layers?
How is the lithosphere different from the crust?

4. Layers of the Earth

5. Composition, Density and Temp.
Core: Nickel (Ni), Iron (Fe) and other heavy elements
Inner core and outer core same temperature however massive pressure and density keeps inner core solid
Mantle: mostly Silicon (Si) and Oxygen (O)
Lower density than core
Lower mantle is solid, upper mantle is “plasticy”

6. Lithosphere and Asthenosphere

7. Lithosphere and Asthenosphere
Lithosphere = Crust and upper part of upper mantle
Asthenosphere = lower part of upper mantle
Lithosphere “floats” on asthenosphere

8. Rock Cycle
What are the three types of rock? How does the rock cycle account for their formation?

11. Isostatic Equilibrium
How does Archimedes Principle relate to the structure of the Earth?
What is isostatic equilibrium?
What links some earthquakes with isostatic equilibrium? Where do such earthquakes occur?

12. Archimedes Principle

13. Archimedes Principle

14. Isostatic Equilibrium

15. Isostasy The lithosphere floats on the asthenosphere
The various portions of the Earth’s crust reach gravitational equilibrium
Due to variations in thickness and density, some crustal blocks ride higher than others
Isostasy explains the vertical distribution of Earth’s crust. George Bedell Airy proposed that the density of the crust is everywhere the same and the thickness of crustal material varies. Higher mountains are compensated by deeper roots. This explains the high elevations of most major mountain chains, such as the Himalayas. G H Pratt hypothesized that the density of the crust varies, allowing the base of the crust to be the same everywhere. Sections of crust with high mountains, therefore, would be less dense than sections of crust where there are lowlands. This applies to instances where density varies, such as the difference between continental and oceanic crust. Condition of gravitational equilibrium of all parts of the Earth’s crust. The crust is in isostatic equilibrium if, below a certain depth, the weight and thus pressure of rocks above is the same everywhere. The idea is that the lithosphere floats on the asthenosphere as a piece of wood floats on water. A thick piece of wood floats lower than a thin piece, and a denser piece of wood floats lower than a less dense piece. There are two theories of the mechanism of isostasy, the Airy hypothesis and the Pratt hypothesis, both of which have validity. In the Airy hypothesis crustal blocks have the same density but different thicknesses; like ice cubes floating in water, higher mountains have deeper roots. In the Pratt hypothesis, crustal blocks have different densities allowing the depth of crustal material to be the same. In practice, both mechanisms are at work.

16. Isostatic Rebound
Isostatic Equilibrium is the balance between the weight of the lithosphere and the buoyant force of the asthenosphere
Isostatic Rebound is when compensation occurs from an increase or decrease of lithospheric weight…causing earthquakes along weak areas called - faults

18. Onto the Festivities!!!

19. Alfred Wegner and Continental Drift
What is Pangea and Panthalassa?
What is the theory of continental drift?
What evidence did Wegner use to support his theory?
Why didn’t scientists support his theory? What further evidence could have strengthened his theory?

20. Pangea
Panthalassa

21. Wegner’s Theory Pangea: big supercontinent
Panthalassa – Ocean surrounding Pangea
Wegner theorized that because the less dense continents floated on the more dense matle, Pangea broke apart into separate pieces.
Theory of Continental Drift

22. The Evidence
Pieces fit together like a puzzle

24. Fossil Distribution

25. Accepted Theory? I Think Not!
Good evidence but no go for public acceptance.
Possibly because Alfred was a meteorologist not a geologist
To many gaps between continents
He disappeared on an expedition in 1930 in Greenland
Later on, plate tectonics theory described how the gaps between the continents were continental shelves

26. O.k. Let’s Check It Out
Pangea Lab!!!!
Oooooh Yeah Baby!