1. Plate Boundaries

2. Boundaries-Geologically Active Regions Three Main Classes of Plate Boundaries 1. Convergent 2. Divergent 3. Transform

3. Convergent Plate Boundaries 1. Converging - Ocean to Ocean plate

4. Subduction, volcanic island arc (andesite - conversion of oceanic crust), deep ocean trench Subduction, volcanic island arc (andesite - conversion of oceanic crust), deep ocean trench Unstable geologically Unstable geologically Examples - West Indies, Japan, Aleutian Islands, Philippine Islands, Indonesia, Central America Examples - West Indies, Japan, Aleutian Islands, Philippine Islands, Indonesia, Central America

5. Volcanic Island Arc-Aleutians, Japan, Indonesia

6. Converging plate boundary composite volcanoes, Fuego and Acatenango, as seen from the flanks of the Volcan de Agua, near Antigua Guatemala August, 2000, Nikon FE2, 200 mm Nikon AIS f4 lens. Converging plate boundary composite volcanoes, Fuego and Acatenango, as seen from the flanks of the Volcan de Agua, near Antigua Guatemala August, 2000, Nikon FE2, 200 mm Nikon AIS f4 lens.

7. First stage in conversion of oceanic crust to continental crust

8. 2. Convergent Plate Boundary - Continent to Ocean

9. Volcanic alpine chain, subduction, deep ocean trench Examples - Andes Mtns., West coast of Mexico, Cascades - Pacific Northwest of United States

10. Andes Mountains South America

11. 3. Convergent - Continent to Continent

12. Shallow focus earthquakes, granitic mountain range Shallow focus earthquakes, granitic mountain range Himalayan Mtns. - India/Australian plate collides with Asian plate - creates Himalayan Mtns. Himalayan Mtns. - India/Australian plate collides with Asian plate - creates Himalayan Mtns. Destructive earthquakes in China - 2,000 miles from plate boundary Destructive earthquakes in China - 2,000 miles from plate boundary

13. Nepal/China/India Himalayas

14. 1. Continent-Continent Rifting (Diverging) 1. Continent-Continent Rifting (Diverging) Divergent (Rifting) Plates

15. Rift Valley, block faulted mountain ranges, basaltic volcanic activity, shallow focus earthquakes Rift Valley, block faulted mountain ranges, basaltic volcanic activity, shallow focus earthquakes East African Rift Valley Lake Region Extends to Jordan River Valley Sinai Peninsula - Asia and Africa Rift apart Dead Sea - between Israel/Jordan - 300 m below sea level Lowest point on continental crust Djibouti - Red Sea trickles into Africa *First stage in the development of an ocean basin East African Rift Valley Lake Region Extends to Jordan River Valley Sinai Peninsula - Asia and Africa Rift apart Dead Sea - between Israel/Jordan - 300 m below sea level Lowest point on continental crust Djibouti - Red Sea trickles into Africa *First stage in the development of an ocean basin

16. Great Rift Valley Kenya

17. 2. Ocean - Ocean Divergent 2. Ocean - Ocean Divergent

18. Sea floor spreading, pillow basalts, shallow focus earthquakes, oceanic ridge Sea floor spreading, pillow basalts, shallow focus earthquakes, oceanic ridge Growth of an ocean basin Growth of an ocean basin Red Sea - early stage Atlantic Ocean - advanced Iceland Mid-Ocean Ridge present in all ocean basins East Pacific Rise Red Sea - early stage Atlantic Ocean - advanced Iceland Mid-Ocean Ridge present in all ocean basins East Pacific Rise

19. Mid Atlantic RidgeMAR in Iceland

20. Sliding plates One plate grinds past another - friction Sliding plates One plate grinds past another - friction Shallow focus earthquakes Only contact without volcanic activity Shallow focus earthquakes Only contact without volcanic activity San Andreas Fault, Anatolian Fault, Motagua Fault San Andreas Fault, Anatolian Fault, Motagua Fault Transform Boundary

21. San Andreas Fault

22. North Anatolian Fault, Turkey

24. Convection - Heat Flow Heat (convection) cells in mantle/asthenosphere Lithosphere rests on asthenosphere Rising heat cells - plates separate Sinking heat cells - plates pushed down into mantle

25. Convection Currents

26. Measured heat flow Highest at ridge Lowest at trench Deep heat - from convection, highest under ocean crust

27. Area of concentrated heat flow from deep mantle Hawaii - not on plate boundary Pacific plate passing over thermal plume New Hawaiian Island Loihi Thermal Plume-Mantle Hot Spots

30. Other thermal plumes Afar Triangle - numerous thermal plumes intra African plate Yellowstone Pacific Plate contains numerous thermal plumes Reunion Islands - similar to Hawaii

31. Afar Triangle Africa

32. San Andreas Fault - 5.5 cm/yr San Andreas Fault - 5.5 cm/yr Mid-Atlantic Ridge Iceland - 1.8 cm/yr; South Atlantic (Ascension Island) - 3.9 cm/yr Mid-Atlantic Ridge Iceland - 1.8 cm/yr; South Atlantic (Ascension Island) - 3.9 cm/yr East Pacific Rise - off South America Most rapid movement - 17.1 cm/yr East Pacific Rise - off South America Most rapid movement - 17.1 cm/yr Rate of Plate Movement

33. Lost Continents Lost Continents Micro-continent Seychelles Bank in Indian Ocean Granitic crust "floating" over oceanic crust Broke away from Africa, has not subducted Beaches of Seychelles Is. - pink sand - indicative of granite Seychelles Micro-continent Seychelles Bank in Indian Ocean Granitic crust "floating" over oceanic crust Broke away from Africa, has not subducted Beaches of Seychelles Is. - pink sand - indicative of granite SeychellesSeychelles