2. Theory of Plate Tectonics
1. Continents appear to “drift” with time
2. Lithosphere is broken up into rigid
“plates”, that are moving
3. There are three types of plate boundaries:
1. Divergent
2. Convergent
3. Transform
3. 3 types of plate boundaries:
1. Divergent – such as a mid ocean ridge where
sea floor spreading occurs
2. Transform boundary – where 2 plates slide
along side of one another
3. Convergent – where 2 plates collide
9. There are 3 types of convergent plate boundaries
1. Ocean plate and another ocean plate
2. Ocean plate and a continental plate
3. Continental plate and another continental plate
Example: the Aleutian trench
Example: Peru-Chile Trench
Himalayan Mountains
19. Name this plate boundary
Continental crust Mantle
The oceanic crust
melts and rises
Explosive volcanoes
Oceanic plate The oceanic crust sinks under
the less dense continental crust
Match the labels to the letters
A
B
C
D
E
F
24. In Summary:
1. The Earth’s surface is broken up into plates
2. The plates move a few centimeters per
year in different directions
3. The plate boundaries may be
classified into convergent or divergent
or transform
4. Divergent plate boundaries are rift
zones usually associated with a mid
ocean ridge
25. Convergent Plate Boundaries may
be the following types
1. Two oceanic plates- resulting in a subduction zone
and an island arc. Ex. Aleutian Islands and trench
2. An oceanic plate and a continental plate –
resulting in a subduction zone and coastal mountains
– ex. Andes Mtns.
3. Two continental plates – resulting in severe
uplifting of the earth’s crust and a very large
mountains like the Himalayas, or the Alps
