1. Plate Tectonic Notes

2. I. Continental Drift Theory
A. proposed by Alfred Wegener in 1912
B. states that all continents were once one supercontinent (Pangaea) and have since “floated” apart over time
C. Evidence to support theory
1. fossil records are similar on different continents
2. land forms such as mt. ranges and mineral deposits line up
3. coastlines of current continents appear to “fit together” like a puzzle

3. II. Theory of Plate Tectonics
A. states that the earth’s crust is broken into large moving pieces (plates) to which the continents are attached.
B. Why Change the Theory?
1. new technology allows
scientists to discover new
information
a) sonar
b) SCUBA
c) submarine improvements
C. New Evidence
1. sea-floor spreading
2. earthquakes and volcanoes
3. actual recorded movement

4. C. 16 plates (* means major plate)
1. N. American* 6. Arabian Indo-Australia*
2. Eurasian* 7. Phillippine* 12. Fiji
3. Juan De Fuca 8. S. American* 13. Nazca*
4. Caribbean 9. Caroline Pacific*
5. Cocos African* 15. Scotia
16. Antarctic*

5. III. Plate Boundaries
A. locations where two plates meet
B. where the forces that shape the earth’s surface occur
1. Constructive forces – create landforms
2. Destructive forces – destroy landforms
C. three different types

6. 1. Divergent
a) plates move away from each other
b) sea-floor spreading & ridges
c) new crust is formed at this boundary type
d) mid-Atlantic Ridge in Atlantic Ocean
2. Convergent
a) plate move toward one another
b) subduction- one plate forced underneath another
> deep trenches, coastal mt. ranges, volcanoes
> Andes Mts on west coast of S. America
c) collision – both plates push upward
> large mt ranges, earthquakes
> Himalaya mt range in northern India
3. Transform
a) plates move past one another in different directions
b) faults visible at surface, large earthquakes
c) San Andres Fault in California

7. Landform(s) & Examples
Boundary
Movement
Picture
Landform(s) & Examples
Divergent
Plates move AWAY from one another
Landforms:
Mid-ocean ridges & rift valleys
Example:
Mid-Atlantic Ridge
Convergent
Collision
Plates move TOWARD each other and BOTH push upwards
Large mountain ranges w/ lots of earthquakes
Himalayan Mts in India
Subduction
Plates move TOWARD each other and one plate gets pushed under the other
Deep ocean trenches, coastal mt. ranges & volcanoes
Andes Mts in South America
Transform
Plates move past one another in opposite directions
Faults that are visible on land
San Andres Fault in California

8. divergent boundary transform boundary convergent / subduction boundary
convergent / collision