04.plate tectonics
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1. The Earth's surface is covered by about 12 lithospheric plates that move slowly at rates of a few centimeters per year. 2. Most endogenous geological activity such as volcanism and earthquakes occurs at or near plate boundaries, where the plates converge, diverge, or move past one another. 3. Plate interiors are generally geologically quiet, with exceptions in some areas.
04.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