plate tectonics chap. 17 continental driftcontinental drift seafloor spreading theory of plate...
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Plate TectonicsPlate TectonicsChap. 17Chap. 17Chap. 17Chap. 17
Continental Drift
Seafloor Spreading
Theory of Plate Tectonics
Causes of Plate Motion
Continental Drift
The End
Seafloor Spreading – 17.2
ObjectivesObjectives
• Summarize the evidence that led to the discovery of seafloor spreading.• Explain the significance of magnetic patterns on the seafloor.• Explain the process of seafloor spreading.
I.I. Seeing the ocean floorSeeing the ocean floor
I.I. Seeing the ocean floorSeeing the ocean floorA.A. SonarSonar
I.I. Seeing the ocean floorSeeing the ocean floorA.A. SonarSonar
B.B. MagnetometerMagnetometer
II.II. Topography of Ocean FloorTopography of Ocean Floor
*See map on p. 912*See map on p. 912
II.II. Topography of Ocean FloorTopography of Ocean FloorA.A. Mountain ranges (oceanic Mountain ranges (oceanic
ridges)ridges)
These are associated with earthquakes These are associated with earthquakes and volcanosand volcanos
II.II. Topography of Ocean FloorTopography of Ocean FloorA.A. Mountain ranges (oceanic Mountain ranges (oceanic
ridges)ridges)
B.B. Canyons (deep-sea trenches)Canyons (deep-sea trenches)
*See map on p. 912*See map on p. 912
III.III. Rock StudiesRock StudiesA.A. Youngest rocks near ridgesYoungest rocks near ridges
III.III. Rock StudiesRock StudiesB.B. Old rocks (over 180 million Old rocks (over 180 million
years) cannot be found on years) cannot be found on seafloor. seafloor.
Continental rocks have been dates up to Continental rocks have been dates up to 3.8 billion years old.3.8 billion years old.
III.III. Rock StudiesRock StudiesC.C. Thin layer of sediment present Thin layer of sediment present
(thickness increases further (thickness increases further away from ridge).away from ridge).
III.III. Rock StudiesRock StudiesD.D. MagnetismMagnetism
Paleomagnetism is the study of the Paleomagnetism is the study of the Earth’s magnetic record.Earth’s magnetic record.
III.III. Rock StudiesRock StudiesD.D. MagnetismMagnetism
1. Magnetic reversals have occurred.
A change in the Earth’s A change in the Earth’s magnetic fieldmagnetic field
III.III. Rock StudiesRock StudiesD.D. MagnetismMagnetism
1. Magnetic reversals have occurred.
2. Basaltic rocks show these reversed fields.
III.III. Rock StudiesRock StudiesD.D. MagnetismMagnetism
3. Reversals are records in the seafloor.
III.III. Rock StudiesRock StudiesD.D. MagnetismMagnetism
4. Scientists created isochrons.
A line on a map that connects points of A line on a map that connects points of equal equal ..
III.III. Rock StudiesRock StudiesD.D. MagnetismMagnetism
4. Scientists created isochrons.
A line on a map that connects points of A line on a map that connects points of equal equal ageage..
IV.IV. Seafloor SpreadingSeafloor Spreading
IV.IV. Seafloor SpreadingSeafloor SpreadingA.A. Theory developed by Harry HessTheory developed by Harry Hess
IV.IV. Seafloor SpreadingSeafloor SpreadingA.A. Theory developed by Harry HessTheory developed by Harry Hess
B.B. Magma surfaces at ocean ridges, Magma surfaces at ocean ridges, forming new crust.forming new crust.
IV.IV. Seafloor SpreadingSeafloor SpreadingA.A. Theory developed by Harry HessTheory developed by Harry Hess
B.B. Magma surfaces at ocean ridges, Magma surfaces at ocean ridges, forming new crust.forming new crust.
C.C. Crust is destroyedCrust is destroyedat deep-sea at deep-sea trenchestrenches
The End
Theory of Plate Tectonics
I.I. Plates and BoundariesPlates and Boundaries
I.I. Plates and BoundariesPlates and BoundariesA.A. Tectonic plates are named Tectonic plates are named
(*diagram)(*diagram)
1. Pacific plate
2. North American Plate
3. Eurasian Plate
4. African Plate
5. South American Plate
6. Indian-Australian Plate
7. Antarctic Plate
8. Arabian Plate
9. Philipine Plate
10. Caribbean Plate
11. Nazca Plate
12. Cocos Plate
I.I. Plates and BoundariesPlates and BoundariesA.A. Tectonic plates are named Tectonic plates are named
(*diagram)(*diagram)
B.B. BoundariesBoundaries
Location where tectonic plates interactLocation where tectonic plates interact
I.I. Plates and BoundariesPlates and BoundariesA.A. Tectonic plates are named Tectonic plates are named
(*diagram)(*diagram)
B.B. BoundariesBoundaries1. Divergent
Divergent Boundaries
Divergent BoundariesPlates are moving apart
Divergent Boundaries Plates are moving apart Causes thinning of the lithosphere
Divergent Boundaries Plates are moving apart Causes thinning of the lithosphere Often form on ocean floor
Divergent Boundaries Plates are moving apart Causes thinning of the lithosphere Often form on ocean floor Ex. Rift Valley in East Africa
I.I. Plates and BoundariesPlates and BoundariesA.A. Tectonic plates are named Tectonic plates are named
(*diagram)(*diagram)
B.B. BoundariesBoundaries1. Divergent
2. Convergent
Convergent Boundaries
Convergent Boundaries Plates are moving together
Convergent Boundaries Plates are moving together Three types:
Convergent Boundaries Plates are moving together Three types:
1. Oceanic-oceanic- one of the plates
undergoes subduction
SubductionSubduction
Process where one tectonic plate slides below another.
Convergent Boundaries Plates are moving together Three types:
1. Oceanic-oceanic- one of the plates
undergoes subduction
- some of the magma returns to the surface forming volcanic islands and a trench
Convergent Boundaries Plates are moving together Three types:
2. Oceanic-continental
- Denser oceanic crust goes under continental crust.
Convergent Boundaries Plates are moving together Three types:
2. Oceanic-continental
- Denser oceanic crust goes under continental crust.
- Produces a trench and volcanoes
Convergent Boundaries Plates are moving together Three types:
3. Continental-continental- two continental plates
collide, forming a mountain range.
Convergent Boundaries Plates are moving together Three types:
3. Continental-continental- two continental plates
collide, forming a mountain range.
- Ex. Himalayas
I.I. Plates and BoundariesPlates and BoundariesA.A. Tectonic plates are named Tectonic plates are named
(*diagram)(*diagram)
B.B. BoundariesBoundaries1. Divergent
2. Convergent
3. Transform
Transform Boundaries
Transform Boundaries Plates are sliding past each
other.
Transform Boundaries Plates are sliding past each
other. No new crust formed, nor is
crust destroyed.
Transform Boundaries Plates are sliding past each
other. No new crust formed, nor is
crust destroyed. Characterized by shallow
earthquakes.
Transform Boundaries Plates are sliding past each
other. No new crust formed, nor is
crust destroyed. Characterized by shallow
earthquakes. Ex. San Andreas, California.
The End
Causes of Plate Motion
I.I. Mantle ConvectionMantle Convection
I.I. Mantle ConvectionMantle ConvectionA.A. Warmer materials move _____.Warmer materials move _____.
I.I. Mantle ConvectionMantle ConvectionA.A. Warmer materials move _____.Warmer materials move _____.
B.B. Cooler materials move _____.Cooler materials move _____.
I.I. Mantle ConvectionMantle ConvectionA.A. Warmer materials move _____.Warmer materials move _____.
B.B. Cooler materials move _____.Cooler materials move _____.
C.C. This creates a circular This creates a circular movement.movement.
II.II. Slab motionSlab motion
II.II. Slab motionSlab motionA.A. At a ______ boundary new rock At a ______ boundary new rock
causes the plate to be pushed. causes the plate to be pushed. (This is (This is ridge pushridge push))
II.II. Slab motionSlab motionA.A. At a ______ boundary new rock At a ______ boundary new rock
causes the plate to be pushed. causes the plate to be pushed. (This is (This is ridge pushridge push))
B.B. At a ______ boundary the old At a ______ boundary the old rock is pulled underneath rock is pulled underneath another layer. (This is another layer. (This is slab pullslab pull). ).
III.III. Other questionsOther questions
III.III. Other questionsOther questionsA.A. How do mantle convection currents How do mantle convection currents
originate?originate?
III.III. Other questionsOther questionsA.A. How do mantle convection currents How do mantle convection currents
originate?originate?
B.B. Are these currents permanent?Are these currents permanent?
III.III. Other questionsOther questionsA.A. How do mantle convection currents How do mantle convection currents
originate?originate?
B.B. Are these currents permanent?Are these currents permanent?
C.C. How deep do these currents reach?How deep do these currents reach?
III.III. Other questionsOther questionsA.A. How do mantle convection currents How do mantle convection currents
originate?originate?
B.B. Are these currents permanent?Are these currents permanent?
C.C. How deep do these currents reach?How deep do these currents reach?
D.D. Does a downward convection cause a Does a downward convection cause a subduction zone, or does a subduction zone, or does a subduction zone cause a downward subduction zone cause a downward current?current?
The End
Image SourcesImage SourcesA. http://www.manatee.k12.fl.us/sites/elementary/
palmasola/pshwgif4con1.htm
Image SourcesImage SourcesG. Dead Sea. http://jan.ucc.nau.edu/~shand/image_archive.htmH. http://www.gc.maricopa.edu/earthsci/imagearchive/I. White Cliffs of Dover, England.
http://www.calstatela.edu/faculty/acolvil/geo_time.htmlJ. Bituminous coal, Pittsburg mine.
http://www.appaltree.net/aba/coalspecs.htmK. Gneiss. http://geology.csupomona.edu/alert/metamorphic/metaclass.htmL. Schist.
http://gaia.busanedu.net/~creative/2002/cyber/rock/pages/30313_schist_central_museum.htm
M. Biotite Gneiss. http://gaia.busanedu.net/~creative/2002/cyber/rock/pages/30469_biotie_gneiss_kbise.htm
N. Quartzite. http://www.gc.maricopa.edu/earthsci/imagearchive/quartzite.htmO. Quartzite. http://www.dragonlogic.com/Presentations/Slide_35.htmlP. Marble.
http://gaia.busanedu.net/~creative/2002/cyber/rock/pages/30615_marble_kbise.htm
Q. Kyanite with garnet. http://www.millenniumminerals.com/gemstones/kyanite.html