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. How Plates Move

4. The Lithosphere & The Asthenosphere
The lithosphere floats on top of the asthenosphere. Convection currents that occur in the asthenosphere, cause the lithosphere to move. This creates/destroys landforms on Earth’s crust.

5. Tectonic Plates

6. Continental Drift

7. Continental Drift
Geologist Alfred Wegener-first to propose evidence that continents were once connected.
He called this “super” continent Pangaea, meaning “All Earth”

8. Pangaea

9. Political Pangaea

10. Support for Continental Drift
Shape of the continents
They fit together like jigsaw puzzle pieces.

11. Support for Continental Drift
2. Fossil Correlation SAME FOSSILS : DIFFERENT CONTINENTS

12. Support for Continental Drift
3. Rock and Mountain Correlation
SAME ROCK : DIFFERENT RANGE
Existing mountain ranges separated by vast oceans contain rocks of identical mineral content.
Ex: Appalachian Mtns in the eastern US and Caledonian Mtns in the British Isles

14. Support for Continental Drift
4. Past Climate Data (Paleoclimates)
Glacial Scars
SAME SCARS : DIFFERENT CONTINENTS
Coal Deposits
Have been found in temperate and polar regions, however coal is formed in tropical regions.

15. Glacial Scars

16. Coal Deposits

17. Continental Drift in Doubt
Why didn’t people believe in continental drift?
People couldn’t imagine how the Earth could be millions of years ago.
People couldn’t imagine a force great enough to move the continents.
BUT…by the 1960s, evidence would prove continental drift is TRUE!

18. Sea Floor Spreading

19. Sea Floor Spreading Harry Hess-1960s
Discovered the Mid-Atlantic Ridge while mapping the ocean floor.
Mid-Ocean Ridges-underwater mountain chains
Magma rises to the surface and solidifies to form new oceanic crust.
Older crust is pushed farther away from the ridge

20. Sea Floor Spreading

21. Plate Tectonics
The theory that Earth’s crust and upper mantle (lithosphere) are broken into sections, called plates, that slowly move around on the rest of the mantle (asthenosphere) due to convection currents.

22. Types of Crust
The type of crust present and the direction of the convection current determines how Earth’s surface will be effected.
Oceanic: made primarily of basalt; more dense
Continental: made primarily of granite; less dense

23. Different Types of Boundaries

24. Divergent Boundary - Oceanic

25. Divergent Boundary - Oceanic
Effects on Earth:
Submarine Mountain range
Mid-Atlantic Ridge
Volcanic Activity
Fissure Eruptions
Shallow Earthquake Activity
New sea-floor & a widening ocean basin

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

27. Divergent Boundary – Iceland Mid – Atlantic Ridge

28. Divergent Boundary - Continental

29. Divergent Boundary - Continental
Effects on Earth
Rive Valley with long linear lakes or a shallow arm of the ocean
Normal faults
Shallow earthquake activity
Sometimes volcanic activity

30. Divergent Boundary - Continental

31. Convergent Boundary – Indian and Eurasian Plates
Indian Plate

32. Convergent Boundary – Oceanic & Continental
&

33. Convergent Boundary – Oceanic &Continental
Effects on Earth
Zone of earth quack activity along continent margin
Trench immediately off shore of the continent
Line of volcanic eruptions a few hundred mils inland from shoreline
Destruction of Oceanic Lithosphere

34. Convergent Boundary – Oceanic &Continental
Real World Example(s)
Cascade Mountain Range along the coast of Washington-Oregon
Andes Mountain Range of Western South America

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

36. Convergent Boundary – Oceanic & Oceanic
Effects on Earth
Oceanic Trench
Chain of Volcanic Islands
Deeper Earthquakes
Destruction of Oceanic Lithosphere

37. Convergent Boundary – Oceanic & Oceanic
Real World Examples
Aleutian Islands
Eastern Caribbean Islands of Martinique
St. Lucia and St. Vincent

38. Convergent Boundaries - Continental
&

39. Convergent Boundary – Continent & Continent
Effects on Earth
Intense folding and faulting
Broad Folded Mountain Range
Shallow Earthquake activity
Shortening and thickening of plates in the collision zone

40. Convergent Boundary – Continent & Continent
Real World Examples
Himalaya Mountain Range

41. Transform Boundary – San Andreas Fault

42. Transform Boundary – San Andreas Fault
Effects on Earth
Earthquake Activity
Shallow because they occur within and between the plates that are not involved in subduction
NO volcanic activity

43. Transform Boundary – San Andreas Fault
Real World
San Andreas Fault Zone on Western North America