1. Plate Tectonics

2. The word “tectonic” means
“to build.”

5. So the evidence is 1. Coastlines seem to fit like a puzzle.
2. Matching mountain chains on separate continents.
3. Matching rock formations on separate continents.
4. Fossils of plants and animals on separate continents.

6. Plate tectonics is a relatively new scientific concept, introduced
50 years
ago
Geez… 50 is SOOOOO OLD!!!

8. Most scientists say there are about 17 plates.
How do we know where the plate edges are?

9. What makes these plates move?
Giant lithospheric ants?
A funky beat?
How ‘bout CONVECTION?
Click on the lamp.

11. Plate Tectonics

12. The plates consist of an outer layer of the Earth, the lithosphere,
which is cool enough to behave as a rigid shell.
Occasionally the hot asthenosphere of the Earth finds a weak place in the lithosphere to rise as a plume
PLATE BOUNDARIES!!!
Oh Behave

13. DIVERGENT Boundaries There are THREE types of plate boundaries:
where new crust is generated as the plates pull away from each other.
These occur mostly in the ocean
Rocks of crust feel tension stress

14. Click below for an animation of divergent boundaries.

15. DIVERGENT Boundaries Results in the following: Volcanoes
a. mafic magma and lava
b. islands are made
2. Earthquakes
3. Mountain chains
4. Rift zones or Valleys
5. Geothermal activity

16. DIVERGENT Boundaries Examples include: Mid-Atlantic Ridge Iceland
East African Rift Valley
East Pacific Rise

17. DIVERGENT Boundaries The Evidence is that the Sea Floor is spreading
Earth’s magnetic field reverses every million years
New magnetic rock in the ocean floor looks different.

18. So the sea floor must be spreading!
Click here for an animation online.

19. Evidence of sea floor spreading
Click here for an animation, explaining how scientists know the sea floor is spreading.
SO WHAT?!?
So what is slowly happening to the Atlantic Ocean????
That’s right…it’s getting BIGGER!

22. Another animation here!

23. mmm… hot syrup

26. 2. CONVERGENT boundaries -- where crust is destroyed as one plate dives under another.
This is also known as a
SUBDUCTION BOUNDARY!

27. Convergent Boundaries
Boundary in which two plates meet
Rocks of crust feel compression stress
Types of Convergent boundaries are shown in the table
All can result in earthquakes

28. Ocean meets _continent_
Plates Involved
Description
Picture
Example
Ocean
meets
_continent_
The denser ocean plate subducts and melts under the continental plate.
Andes Mtns
_Mt. St. Helens_
Vesuvius
_ocean__
The denser ocean plate _subducts__.
Japan
Marianas _Trench_
Continent
The continental plates do not subduct, they _collide__ and push up on each other.
_Himalayas_

29. SO WHAT?!? So what is slowly happening to the Pacific Ocean????
That’s right…it’s getting SMALLER!

30. Animation!
L I Q U I D H O T M A G M A

31. a number of long narrow, curving trenches thousands of kilometers long and 8 to 10 km deep cutting into the ocean floor. Trenches are the deepest parts of the ocean floor and are created by subduction.
Animation!

32. Burn baby burn,
Disco inferno!!!

34. Let’s see an animation! Wouldn’t that be grand?!

35. 3. TRANSFORM boundaries -- where crust is neither produced (created) nor destroyed

36. TRANSFORM boundaries
A boundary in which two plates slide laterally past one another.
Most are found on the ocean floor but some are on coastlines.
Rocks of crust feel a lot of stress

37. TRANSFORM boundaries Results in: Earthquakes
No volcanoes (volcanoes DO NOT form along transform boundaries)

38. TRANSFORM boundaries Examples include: Haiti
Haiti is situated to the north of the Caribbean Plate, on a transform (slip/conservative) plate boundary with the North American Plate. The North American plate is moving west. This movement is not smooth and there is friction between the North American Plate and the Caribbean Plate. Pressure builds between the two plates until it is released as an earthquake.

39. TRANSFORM boundaries Examples include:
2. San Andreas Fault in California
SO WHAT?!?
So what is really going to happen to western California?
Part of California will end up in the Pacific Ocean

40. zone between two plates sliding horizontally past one another is called a transform-fault boundary
Most transform faults are found on the ocean floor. They commonly offset the active spreading ridges, producing zig-zag plate margins
San Andreas fault zone in California

42. 4. Hot Spot Not a plate boundary!
This is a place where there is a plume of magma under the middle of a plate. It can push up through the plate as the plate moves across the stationary hot spot

43. Results in any or all of the following: Geothermal geysers Volcanoes
4. Hot Spot
Results in any or all of the following:
Geothermal geysers
Volcanoes
Earthquakes

44. 4. Hot Spot
Examples include:
Hawaiian Islands
Yellowstone

46. Volcanoes and the Hawaiian Islands

47. Animation!

48. Visualizing Eruptions

49. Disco Stu is tellin’ YOU… This is the last Hawaiian Island above water, all the rest are DOWN LOW!!!

50. A Review of Plate Boundaries
Click here!