• Save
GEOG 100--Lecture 12--Plate Tectonics
Upcoming SlideShare
Loading in...5
×

Like this? Share it with your network

Share
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads

Views

Total Views
1,385
On Slideshare
1,135
From Embeds
250
Number of Embeds
8

Actions

Shares
Downloads
0
Comments
0
Likes
0

Embeds 250

http://csmgeography.blogspot.com 238
http://csmgeography.blogspot.co.uk 3
http://csmgeography.blogspot.de 3
http://csmgeography.blogspot.com.au 2
http://csmgeography.blogspot.se 1
http://csmgeography.blogspot.ru 1
http://csmgeography.blogspot.in 1
http://csmgeography.blogspot.mx 1

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n

Transcript

  • 1. Plate Tectonics Chapter 9
  • 2. Rigid Earth Theory
  • 3. Rigid Earth Theory• It was once believed that Earth’s crust was hard and brittle and could not bend
  • 4. Rigid Earth Theory• It was once believed that Earth’s crust was hard and brittle and could not bend
  • 5. Rigid Earth Theory• It was once believed that Earth’s crust was hard and brittle and could not bend• Plasticity
  • 6. Rigid Earth Theory• It was once believed that Earth’s crust was hard and brittle and could not bend• Plasticity – We now know that Earth’s crust can bend (like a tough plastic) before breaking
  • 7. Isostacy• “The maintenance of hydrostatic equilibrium in the crust” – hydrostatics—branch of physics related to the pressure and equilibrium of liquids (hydro) • statics—bodies not active; at rest; in equilibrium; as opposed to dynamics
  • 8. Isostacy
  • 9. Isostacy• Addition or removal of crustal material causes a sinking or rebounding of crust
  • 10. Isostacy• Addition or removal of crustal material causes a sinking or rebounding of crust – Add or remove continental mass and the crust will sink or rise to accommodate the added/removed weight
  • 11. Isostacy• Addition or removal of crustal material causes a sinking or rebounding of crust – Add or remove continental mass and the crust will sink or rise to accommodate the added/removed weight • a glacier growing or remelting, crust eroding off the surface, sediment deposits, water bodies on land, esp. those created by dams
  • 12. Alfred Wegener andHis Continental Drift Theory
  • 13. Alfred Wegener and His Continental Drift Theory• German meteorologist, 1920s “The present continents were originally connected as one enormous landmass that has broken up and drifted apart over the last few 100 million years. The drifting continues….”
  • 14. Alfred Wegener and His Continental Drift Theory• German meteorologist, 1920s “The present continents were originally connected as one enormous landmass that has broken up and drifted apart over the last few 100 million years. The drifting continues….”• Pangaea (Gk. “whole land”)
  • 15. Alfred Wegener and His Continental Drift Theory• German meteorologist, 1920s “The present continents were originally connected as one enormous landmass that has broken up and drifted apart over the last few 100 million years. The drifting continues….”• Pangaea (Gk. “whole land”)
  • 16. Wegener’s Lines of Evidence
  • 17. Wegener’s Lines of Evidence• Similar geology (rocks and rock structures)…
  • 18. Wegener’s Lines of Evidence• Similar geology (rocks and rock structures)…• …petrology (rock chemistry),
  • 19. Wegener’s Lines of Evidence• Similar geology (rocks and rock structures)…• …petrology (rock chemistry),• …paleontology (fossilized plants and animals),
  • 20. Wegener’s Lines of Evidence• Similar geology (rocks and rock structures)…• …petrology (rock chemistry),• …paleontology (fossilized plants and animals),• …matching glacial features (U-shaped valleys, glacial deposits, etc.) on continents separated by oceans
  • 21. Wegener’s Lines of Evidence• Similar geology (rocks and rock structures)…• …petrology (rock chemistry),• …paleontology (fossilized plants and animals),• …matching glacial features (U-shaped valleys, glacial deposits, etc.) on continents separated by oceans• …continent shapes that seem to fit together,
  • 22. Wegener’s Lines of Evidence• Similar geology (rocks and rock structures)…• …petrology (rock chemistry),• …paleontology (fossilized plants and animals),• …matching glacial features (U-shaped valleys, glacial deposits, etc.) on continents separated by oceans• …continent shapes that seem to fit together,• …patterns in the locations of volcanoes
  • 23. Wegener’s Lines of Evidence• Similar geology (rocks and rock structures)…• …petrology (rock chemistry),• …paleontology (fossilized plants and animals),• …matching glacial features (U-shaped valleys, glacial deposits, etc.) on continents separated by oceans• …continent shapes that seem to fit together,• …patterns in the locations of volcanoes
  • 24. Wegener’s Lines of Evidence• Similar geology (rocks and rock structures)…• …petrology (rock chemistry),• …paleontology (fossilized plants and animals),• …matching glacial features (U-shaped valleys, glacial deposits, etc.) on continents separated by oceans• …continent shapes that seem to fit together,• …patterns in the locations of volcanoesEx.: S. America/Africa, Madagascar/India, Australia/Antarctica
  • 25. …but no one bought it.
  • 26. …but no one bought it. Thecrust is too rigid!
  • 27. …but no one bought it. The So why don’t wecrust is see the crust too ripping apart rigid! right now?
  • 28. …but no one bought it. The So why don’t wecrust is see the crust too ripping apart rigid! right now? What do you mean, “Thecontinents are floating???”
  • 29. …but no one bought it. The So why don’t wecrust is see the crust too ripping apart rigid! right now? And hey, what’s the What do you power source driving mean, “The these movements of allcontinents are the land masses, floating???” anyway???
  • 30. …but no one bought it. The So why don’t wecrust is see the crust too ripping apart rigid! right now? And hey, what’s the What do you power source driving mean, “The these movements of allcontinents are the land masses, floating???” anyway??? What a knucklehead.
  • 31. Then along came OceanographerHarry Hess in the 1960s…
  • 32. Then along came OceanographerHarry Hess in the 1960s…
  • 33. The evidence continued to mount…
  • 34. The evidence continued to mount…• Military seafloor mapping: Seafloor geology— structure, chemistry, and age
  • 35. The evidence continued to mount…• Military seafloor mapping: Seafloor geology— structure, chemistry, and age – Oceanic crust: only 100 m.y.o
  • 36. The evidence continued to mount…• Military seafloor mapping: Seafloor geology— structure, chemistry, and age – Oceanic crust: only 100 m.y.o – Continental crust: 4.1 b.y.o.
  • 37. The evidence continued to mount…• Military seafloor mapping: Seafloor geology— structure, chemistry, and age – Oceanic crust: only 100 m.y.o – Continental crust: 4.1 b.y.o.• Core sampling
  • 38. The evidence continued to mount…• Military seafloor mapping: Seafloor geology— structure, chemistry, and age – Oceanic crust: only 100 m.y.o – Continental crust: 4.1 b.y.o.• Core sampling• Seafloor sediment
  • 39. The evidence continued to mount…• Military seafloor mapping: Seafloor geology— structure, chemistry, and age – Oceanic crust: only 100 m.y.o – Continental crust: 4.1 b.y.o.• Core sampling• Seafloor sediment• Rigid Earth folks retired—paradigm shift to plasticity
  • 40. The evidence continued to mount…• Military seafloor mapping: Seafloor geology— structure, chemistry, and age – Oceanic crust: only 100 m.y.o – Continental crust: 4.1 b.y.o.• Core sampling• Seafloor sediment• Rigid Earth folks retired—paradigm shift to plasticity• Convection currents as mechanism/power source
  • 41. The evidence continued to mount…• Military seafloor mapping: Seafloor geology— structure, chemistry, and age – Oceanic crust: only 100 m.y.o – Continental crust: 4.1 b.y.o.• Core sampling• Seafloor sediment• Rigid Earth folks retired—paradigm shift to plasticity• Convection currents as mechanism/power source• Geologists, geophysicists, seismologists, oceanographers, physicists, and paleontologists all agree the theory fits the evidence gathered within their respective fields
  • 42. The Theory of Plate TectonicsTectonic (crustal) plates• Pulling apart (spreading/diverging)• Slamming together and sinking (subducting/converging)• Sliding laterally (sideways)
  • 43. Divergent Plate Boundaries• Spreading centers – Crust pulling apart, magma rising to the surface
  • 44. Convergent Plate Boundaries
  • 45. Convergent Plate Boundaries• Subduction zones
  • 46. Convergent Plate Boundaries• Subduction zones – Crust being forced together
  • 47. Convergent Plate Boundaries• Subduction zones – Crust being forced together – Lightest material rises (mountain-building) while the heaviest stuff sinks (pushed back into the mantle)
  • 48. Convergent Plate Boundaries• Subduction zones – Crust being forced together – Lightest material rises (mountain-building) while the heaviest stuff sinks (pushed back into the mantle) – Remelting (mostly from friction) creates volcanoes
  • 49. Convergent Plate Boundaries• Subduction zones – Crust being forced together – Lightest material rises (mountain-building) while the heaviest stuff sinks (pushed back into the mantle) – Remelting (mostly from friction) creates volcanoes – Intense, deep-focus earthquakes
  • 50. Three Types of Subduction Zones
  • 51. Three Types of Subduction Zones1. Continental crust meets oceanic crust
  • 52. Three Types of Subduction Zones1. Continental crust meets oceanic crust – Oceanic crust sinks
  • 53. Three Types of Subduction Zones1. Continental crust meets oceanic crust – Oceanic crust sinks – Big trench offshore
  • 54. Three Types of Subduction Zones1. Continental crust meets oceanic crust – Oceanic crust sinks – Big trench offshore – Volcanoes on the continental margin
  • 55. Three Types of Subduction Zones1. Continental crust meets oceanic crust – Oceanic crust sinks – Big trench offshore – Volcanoes on the continental margin – Big earthquakes (potential for tsunamis)
  • 56. Continental-Oceanic Subduction
  • 57. Three Types of Subduction Zones
  • 58. Three Types of Subduction Zones2. Oceanic crust meets oceanic crust
  • 59. Three Types of Subduction Zones2. Oceanic crust meets oceanic crust – The older and colder crust will probably sink
  • 60. Three Types of Subduction Zones2. Oceanic crust meets oceanic crust – The older and colder crust will probably sink – Big earthquakes and volcanic islands (called “island arcs”)
  • 61. Three Types of Subduction Zones2. Oceanic crust meets oceanic crust – The older and colder crust will probably sink – Big earthquakes and volcanic islands (called “island arcs”) – Deep ocean trench
  • 62. Three Types of Subduction Zones2. Oceanic crust meets oceanic crust – The older and colder crust will probably sink – Big earthquakes and volcanic islands (called “island arcs”) – Deep ocean trench – Potential for tsunamis
  • 63. Oceanic-Oceanic Subduction
  • 64. Three Types of Subduction Zones
  • 65. Three Types of Subduction Zones3. Continental crust meets continental crust
  • 66. Three Types of Subduction Zones3. Continental crust meets continental crust – Too light to subduct
  • 67. Three Types of Subduction Zones3. Continental crust meets continental crust – Too light to subduct – Mountain-building
  • 68. Three Types of Subduction Zones3. Continental crust meets continental crust – Too light to subduct – Mountain-building – Big earthquakes
  • 69. Three Types of Subduction Zones3. Continental crust meets continental crust – Too light to subduct – Mountain-building – Big earthquakes – Little if any volcanism (mostly intrusive)
  • 70. Continental-Continental Subduction
  • 71. Transform Fault Boundaries
  • 72. Transform Fault Boundaries• Tectonic plates slide past one another
  • 73. Transform Fault Boundaries• Tectonic plates slide past one another – Earthquakes are less intense than subduction
  • 74. Transform Fault Boundaries• Tectonic plates slide past one another – Earthquakes are less intense than subduction – No volcanoes
  • 75. Transform Fault Boundaries• Tectonic plates slide past one another – Earthquakes are less intense than subduction – No volcanoes – Little or no mountain-building
  • 76. “Hot spots”
  • 77. “Hot spots”• Also called magma plumes
  • 78. “Hot spots”• Also called magma plumes• Generally occur some distance from any other type of plate boundary
  • 79. “Hot spots”• Also called magma plumes• Generally occur some distance from any other type of plate boundary• Unrelated to convergent, divergent, or transform boundaries
  • 80. “Hot spots”• Also called magma plumes• Generally occur some distance from any other type of plate boundary• Unrelated to convergent, divergent, or transform boundaries• Anomalous (odd) “balloons” of rising magma
  • 81. “Hot spots”• Also called magma plumes• Generally occur some distance from any other type of plate boundary• Unrelated to convergent, divergent, or transform boundaries• Anomalous (odd) “balloons” of rising magma – Hot spot stays in one position as the moving, island-covered crustal plate rides away from it
  • 82. Accreted Terranes• A moving continent may pick up new land material as lighter (felsic) material scrapes off of a subducting plate
  • 83. Accreted Terranes• A moving continent may pick up new land material as lighter (felsic) material scrapes off of a subducting plate
  • 84. Craton• These terranes were added to the original material first formed from magma that rose out of Earth’s earliest crust – Craton--the name given to these ancient proto- continents cratons 29
  • 85. Continental Shields• More magma material was added to the cratons, forming continents. – Continental shields: Where the earliest continental material still exists intact and is exposed at the surface. 30
  • 86. 31
  • 87. Topography• Right from the very beginning, the crust was affected by stresses and strains that caused crustal deformations• Over time, the crust has continued to be folded, faulted, broken, eroded and further built upon, creating the topography, the ups and downs of land relief, that we see today 32