this ppt contains all details about Plate Tectonics.

1. Theory of Plate
Tectonics – an
overview
Geo 100N
Spring 2005

2. Plate Tectonics -Overview
1. The Lithosphere and Crust
2. Basic Concepts of Plate Tectonics
3. Plate Movements and Boundaries
4. Summary

3. Inside the Earth
USGS

4. The Lithosphere
http://volcano.und.edu/vwdocs/vwlessons/plate_tectonics/part1.html

5. Basic Concepts of Plate
Tectonics

6. The Earth’s surface is covered by
about 12 lithospheric plates
USGS

7. The plates move slowly (a few
cm/year).
USGS

8. Most endogenic geological activity
occurs at or near plate boundaries.
Endogenic = process that originates
within the Earth’s interior
Mt St Helens, 1980

9. Plate interiors are relatively quiet
geologically

10. Plate Movements and
Boundaries

11. Divergent boundaries
Plates move apart
Volcanic activity is always present
Earthquakes are shallow
Two types of boundaries:
1. Oceanic
2. Continental

12. Oceanic Divergent Boundary
 Sea-floor spreading of oceanic lithosphere
 examples: Mid Atlantic Ridge, East Pacific
Ridge
USGS

13. Sea-floor spreading of oceanic
lithosphere
USGS, Digital elevation model

14. Mid Atlantic Rift at Iceland
Þingvellir (Thingvellir), Iceland

15. Continental Divergent Boundary
Continental rifting
Eventually, oceanic crust is formed and
divergence becomes oceanic type
Modern Example: East Africa

16. East African Rift Zone
Oldoinyo Lengai, Kenya

17. Convergent boundaries
Plates move toward each other
Volcanic activity common
Deep, medium, and shallow
earthquakes
Three types of Convergent Boundaries
1. Ocean-ocean
2. Ocean-continent
3. Continent-continent

18. Ocean-ocean convergence
 Subduction – one oceanic plate subducts
(dives) beneath the other
 Volcanic island arc is formed
 Example: Aleutian Islands

19. Aleutian Islands, Alaska
Kanaga

20. Ocean-continent convergence
During ocean-continent convergence,
oceanic lithosphere always subducts
beneath continental lithosphere
Continental volcanic arc formed
Example: Andes mountains

23. Continent-continent convergence
Subduction does not occur (continental crust
is too buoyant to be subducted)
Mountain building occurs without volcanism
Example: Himalayas, Alps

24. India-Asia Collision
 Collision of India
with Eurasian plate
caused uplift of the
Himalaya, the
highest mountains
on Earth.

25. Transform boundaries
Plates slide past each
other
Little or no volcanic
activity
Shallow earthquakes
Example: oceanic
transform faults;
San Andreas Fault

26. San Andreas Fault
Pacific plate is
moving NW relative
to the North
American Plate
As plates move,
transform fault
slips, and
earthquakes occur

27. Summary
1. Earth’s surface is covered by about
12 lithospheric plates.
2. The plates move slowly (2.5-15
cm/year).
3. Most volcanism and earthquake
activity occurs at or near plate
boundaries.
4. Plate interiors are relatively quiet
geologically (some exceptions).

28. Geo 100- Useful Information
Course Homepage:
http://mercury.atmos.albany.edu/geo10
For SKN, email your name to
instructor at
arnason@albany.edu