1. Plate Tectonics

2. Earth’s Layers
The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed.
This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle.

3. The Crust Outermost layer 5 – 100 km thick
The solid part of earth is called the lithosphere

4. The Mantle Layer of Earth between the crust and the core
Contains most of the Earth’s mass
Has more magnesium and less aluminum and silicon than the crust
Is denser than the crust
The liquid part of the Earth is called the asthenosphere

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
Gravity draws everything to the core.

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. Plate Tectonics The plates move around on the asthenosphere
The theory that the Earth’s crust is broken into sections.
Causes earthquakes, volcanoes, trenches and mountains on Earth

9. Continental Drift Pangaea
Alfred Wegener suggested that all the continents were once joined together in the past and broke apart about 200 million years ago. He thought this because of the apparent way that the continents fit together like pieces of a puzzle. The large landmass was called Pangaea.

10. Continental Drift Alfred Wegener 1900’s
Continents were once a single land mass that drifted apart.
Fossils of the same plants and animals are found on different continents
Called this supercontinent Pangea, Greek for “all Earth”
245 Million years ago
Split again – Laurasia & Gondwana 180 million years ago

11. Evidence of Pangea

12. Evidence of Pangaea
Fossils
Rock formations
Continent shape

13. Sea Floor Spreading

15. 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

16. How Plates Move

17. Different Types of Boundaries

18. Divergent Plate Boundaries Plates move apart Ex: Mid Ocean Ridges, Continential rifts

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

20. Divergent Boundary Iceland

21. Divergent Boundary - Oceanic

23. Divergent Boundary - Continental

24. African Rift

25. Convergent Boundaries Plates collide EX: Mountains, trenches, and island arcs

26. Convergent Boundaries - Continental
&

27. Convergent Boundary – Indian and Eurasian Plates
Indian Plate

29. Subduction When an ocean plate sinks beneath a continental plate
Subduction When an ocean plate sinks beneath a continental plate. EX: Trenches, volcanoes

30. Convergent Boundary – Oceanic & Continental
&

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

35. Island Arcs Aleutian Islands Northeastern Japan arc
Japan and Ryukyu Islands
Mariana Islands
Philippines

38. Transform boundaries Plates slide past each other
Transform boundaries Plates slide past each other. EX: San Andreas Fault, earthquakes are common on transform boundaries.

39. Transform Boundary – San Andreas Fault

40. Review Name the 3 main layers of the Earth What is a tectonic plate?
What was Pangea?
What is Sea-Floor spreading?
Name the three different types of plate boundaries and one location on Earth for each one

41. Convergent boundaries
Transform boundaries
Divergent boundaries