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1. Plate Tectonics
Notes

2. When I think of
plate tectonics, I
think of...

3. Volcanoes!!!

4. Let’s go back
into history!

5. Alfred Wegener
● German scientist
● Noticed in the early 1900’s that
some continents seemed to fit
together as a puzzle
● Wegener hypothesized that
these continents were once a
great land mass or
supercontinent called Pangea

8. Theory of Plate Tectonics
● Earth’s plates are in
constant, slow motion
● Between 2.5 and 15 cm
per year!
● Explains how plates
move and form
Since you’ve been alive, plates have moved
more than 180 centimeters!!!

9. Theory of Plate Tectonics continued...
Geologists came to the conclusion in the 1960’s that the Earth’s
lithosphere was broken up into about 12 large pieces called
plates that are moving relative to one another.

10. The lithosphere floats upon the asthenosphere (upper mantle).

11. The crust and upper layer of
the mantle together make up a
zone of rigid, brittle rock called
the lithosphere.
Continental crust is less dense
than oceanic crust.
Continental crust is composed of granite.
Oceanic crust is composed of basalt.

12. Plate Movement
● Plate motion is the result of
the movement of material in
the upper mantle, which
drags the overlying plates
above.
● Convection currents take
place in the mantle

13. Convection Currents
● the transfer of heat by movements within a
fluid
○ hot rises, cool sinks
● Convection currents within the mantle cause
the plates to move

14. Continental Drift
The process
continues as the
current
earth/volcano hot
spots of the world
reflect the edges
of the moving
plates atop which
the continents sit.

15. Plate Boundary Rap

16. 3 Types of Stress
a force that acts on a rock to change its shape or volume
tension compression shearing

17. Now let’s move on to the
three types of plate boundaries!

18. Plate Boundaries
Convergent Plate Boundary
two plates
moving
together
stress = compression
mountain building, trenches, volcanoes

19. Subduction Zone
A subduction zone is a
convergent boundary where
two tectonic plates collide.
The Atlantic Ocean is getting larger
as the Western Hemisphere moves
away from Europe and Asia. The
Pacific Ocean, on the other hand, is
becoming smaller.

20. Subduction zones appear as deep oceanic trenches.
Most of the continental mountain belts occur where plates are
pressing against one another.

21. In the cross section of the Earth in the Southern Hemisphere, the
map shows a subduction zone that has created the Peru-Chile
Trench at the western edge of South American and the Andes
Mountains along the west coast of South America.

23. CONVERGENT
COLLIDE

24. Plate Boundaries
Divergent Plate Boundary
two plates
moving apart
stress = tension

25. The Earth is producing “new” crust where two plates are
diverging.

26. Mid-Atlantic Ridge
The Atlantic Ocean is getting larger as the
Western Hemisphere moves away from
Europe and Asia while the Pacific Ocean is
becoming smaller. This is occurring
because the North and South American
plates are moving westward.

27. A satellite view of the Sinai
Peninsula shows two arms of
the Red Sea spreading ridge,
exposed on land.
This is the northern extension
of Africa’s Great Rift Valley.
Divergent Plate Boundary

28. DIVERGENT
DIVIDE

29. Plate Boundaries
Transform Plate Boundary
when two
plates slide
past one
another
stress = shearing

30. Meeting of the Plates
An aerial view shows probably the
most familiar meeting of two plates
in the United States, the San
Andreas fault slicing through the
Carrizo Plain in the Temblor Range
east of the city of San Luiz Obispo,
CA.
Photograph by Robert E. Wallace, USGS

31. EARTHQUAKES!!!

32. TRANSFORM
TECTONIC PLATES
SLIDE

33. Why do volcanoes occur?
● magma rises to the surface where
the earth’s plates pull apart
(divergent zones)
● “holes” in the plates called hotspots
● cooler oceanic crust dives
underneath continental crust
(convergent boundary) forcing
magma to rise to the surface

34. Where do volcanoes occur?
● mostly where plates meet
● middle of tectonic plates at hotspots
A lot of volcanoes occur around the edge of the pacific ocean
called the Pacific Ring of Fire.

35. Trench Forms
When the less
dense, lighter
continental plate
overrides the
oceanic plate a
subduction zone
forms.

36. DIVERGENT, DIVIDE
CONVERGENT, COLLIDE
TRANSFORM TECTONIC PLATES, SLIDE

37. Plate Boundary Rap

38. Quiz Time!
1. The plates move along the top of the
A. core
B. asthenosphere
C. crust
D. inner core

39. Quiz Time!
2. Plate movement occurs because of
A. conduction currents in the mantle
B. convection currents in the mantle
C. convection currents in the crust
D. conduction currents in the crust

40. Quiz Time!
3. Earth’s lithosphere is broken into a number
of large pieces called…
A. faults
B. volcanoes
C. plates
D. folds

41. Quiz Time!
4. Plate boundary where new crust is being
formed
A. convergent
B. divergent
C. transform

42. Quiz Time!
5. Two plates sliding next to each other
A. convergent
B. divergent
C. transform

43. Quiz Time!
6. Where mountain building occurs
A. convergent
B. divergent
C. transform

44. Quiz Time!
7.
A. shearing
B. tension
C. compression

45. Quiz Time!
8.
A. shearing
B. tension
C. compression

46. Quiz Time!
9.
A. shearing
B. tension
C. compression

47. Quiz Time!
10. Subduction occurs at a
A. transform plate boundary
B. convergent plate boundary
C. divergent plate boundary