1. Liz LaRosa http://www.middleschoolscience.com 2009
Plate Tectonics
Liz LaRosa

2. Earth’s Layers
The Earth's rocky outer crust solidified billions of years ago.
This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle. It is less dense than the mantle, so it floats on top of it.

3. difference in thickness between the Oceanic & the Continental crust!
The Crust
Look at the
difference in thickness
between the Oceanic & the Continental crust!
Outermost layer
5 – 100 km thick
Made of Oxygen, Silicon, Aluminum

4. The Mantle Lies between the crust and the core
Contains most of the Earth’s mass
Has more Mg and less Al and Si than the crust
Crust + upper mantle=Lithosphere

5. The Core Below the mantle and to the center of the Earth
Believed to be mostly Iron, smaller amounts of Nickel, almost no Oxygen, Silicon, Aluminum, or Magnesium

6. Tectonic Plates

7. Plate Tectonics Greek – “tektonikos” =“of a builder”
Pieces of the lithosphere that move around
Each plate has a name
Fit together like jigsaw puzzles
Float on top of mantle similar to ice cubes in a bowl of water

8. Alfred Wegener Born in Berlin 1880 Died in Greenland 1930
In 1915 he argued that there had once been a huge super continent, which he named 'Pangaea', made up of all the land masses on the planet. He chose the name Pangaea because it means 'all earth'.

9. Continental Drift Theory
Alfred Wegener’s theory
Continents were once a single land mass that drifted apart.
Fossils of the same plants and animals are found on different continents
245 Million years ago 1st split
Split again – Laurasia & Gondwana 180 million years ago

10. Evidence of Pangea

11. Sea Floor Spreading

12. Mid-Ocean Ridge: topographical section

13. Sea Floor Spreading
Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins
Magma rises to the surface and solidifies and new crust forms
Older Crust is pushed
farther away from the ridge

14. Sea Floor Spreading

15. Subduction Oceanic crust is pushed down into the mantle.

16. How Plates Move

17. Notes for Plate Tectonics – Part 1
Set up your notes page like this one.
2.5” column on the left. This space is for main ideas or questions.
6” column on the right. This space is for notes and details.
2” space at the bottom. This space is for summarizing the notes.

18. What are the layers of the Earth?
Crust: outermost layer; 5 – 100 km thick. Broken into many plates.
Mantle: layer between the crust and the core. Most of the Earth’s mass. Asthenosphere layer is flowing rock.
Core: center of the Earth.
Pieces of the Earth’s crust that move around over the flowing mantle.
Plates fit together like a puzzle.
The moving plates of the lithosphere provide evidence that the continents were once a single mass and have moved over time.
What are Tectonic Plates?
How do tectonic plates relate to Continental Drift Theory?

19. How do the plates move around?
Sea Floor Spreading: magma pushes up through the crust forming underwater mountain chains – Mid Ocean Ridges.
Subduction: in some areas convergent boundaries push some of the crust into the mantle, forming ocean trenches.
Convection Currents: the flowing mantle circulates due to differences in density.

20. Different Types of Boundaries

21. Divergent Boundary – Arabian and African Plates
Arabian Plate
Red Sea
African Plate

22. Divergent Boundary – Iceland

23. Divergent Boundary - Oceanic

24. Divergent Boundary - Continental

25. Convergent Boundary – Indian and Eurasian Plates
Indian Plate

26. Convergent Boundary – Oceanic & Continental
&

27. Convergent Boundary – Oceanic & Oceanic
Note – plates are reversed
&

28. Convergent Boundaries - Continental
&

29. Transform Boundary – San Andreas Fault

30. Plate Tectonics Notes Part 2 – Plate Boundaries
What happens when the tectonic plates move?
Tectonic plates have boundaries between them.
Plate boundaries form mountains, trenches and valleys.
Earthquakes and volcanoes are also caused by plate boundaries.

31. Overview of Divergent Boundaries
Oceanic divergent boundary
Continental divergent boundary
Divergent Boundaries:
Plates pull apart.

32. Convergent Boundaries:
Plates push together.
Convergent boundary: oceanic and continental.
Convergent boundary: oceanic and oceanic.
Convergent boundary: continental

33. Transform Boundaries:
Plates slide together horizontally. Also called a strike-slip boundary.

34. The End