Plate Tectonics

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Plate Tectonics
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Plate Tectonic Vocabulary

• Continental drift
• Continental Crust
• Convection
• Convection Current
• Convergent Boundary
• Divergent Boundary
• Mid-Ocean Ridge
• Ocean Trench

• Pangaea
• Plate Tectonics
• Seafloor Spreading
• Subduction Zone
• Mid-Atlantic Ridge

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Crust

• a. What are the two types of crust?
• b. Each type of crust is composed of what kind
  of rock?
• c. Which type of crust is denser?

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Shorelines are not true boundaries

• Continental margin
• where the ocean water
• covers the continental
• crust
• Deep ocean basin-
• where the ocean water
• covers oceanic crust

water
Continental margin
Oceanic basin
Continental crust
Oceanic crust

• The ocean water may cover miles of the
  continental crust

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Earths Tectonic Plates
dpc.ucar.edu
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Crust

• The crust is broken into separate plates.
• How many plates are there?
• T or F Plates are stationary.

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Plate Movement

• Convection currents produced in the mantle cause
  the plates to move.
• As the plates move, everything on them moves
  along with them.
• Examples
• The North American plate moves west at a rate of
  4 cm per year (1.6 in./yr)
• The Pacific Ocean plate moves northward at the
  same rate.

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• PLATE TECTONICS
• The continental oceanic plates on the earths
  surface are constantly moving.
• Many geologists believe that at one time all
  landmasses were together supercontinent.
• Also called?

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Pangaea
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uni-graz.at

• Alfred Wegener
• He was a leading scientist in providing
• evidence that continents were moving.
• CONTINENTAL DRIFT THEORY
• Continents are drifting or moving.
• Break-up of Pangaea occurred around 240 million
  yrs ago
• Over time continents broke up into smaller
  pieces and have drifted to their current location
  
• The continents are currently still moving

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Alfred Wegener Continental Drift
EvidenceEvidence 1. Similarities in
coastlines2. Similarities in fossil records3.
Similarities in rock
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• Continental Drift Evidence
• 180 million years ago, Pangaea began to break up
  into separate continents.
• Provided evidence of ancient animal and plant
  remains from South America, Africa, India, and
  Australia that were very similar.

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Wegeners Continental Drift Theory

• What problem or concern do you think other
  geologist had with Wegners theory?
• Could not provide direct evidence that the
  continents were moving.

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Continental Drift Theory Conclusive Evidence

• Where? Under the Atlantic Ocean
• What? Mountain Range
• Mid Atlantic Ridge
• the ridge looks like a mountain with a valley
  running down the center
• Who? Harry Hess

velikovsky.info
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Aerial picture of the Mid-Atlantic Ridge
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Harry Hess Important Observations

• Studied rock data from the Mid Atlantic Ridge
• Found in the center of the ridge is a crack or
  rift.
• Magma would flow up through this rift

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• Harry Hess Conclusion
• The ocean floor was moving away from the ridge on
  both sides.
• As it moved away, it was replaced by rising magma
  that cooled and solidified into new rock.
• He called this process Sea Floor Spreading

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Sea Floor Spreading
Thingvellir, the spreading zone in Iceland
between the North American (left side) and
Eurasian (right side) tectonic plates. January
2003.
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Bell Ringer Plate Tectonics

• 1. What layer of the earth is the plates located?
• 2.What indirect evidence did Wegener have to
  hypothesize his continental drift theory?
• 3.What direct evidence did Hess have to conclude
  from his research seafloor spreading?
• 4. From the article Plate Tectonics Earths
  Lucky Geologyidentify three interesting facts
  from the article about plate tectonics.

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• Hess Later Observations and Conclusions
• Continued to support sea floor spreading.
• Evidence by further studying the structure,
  properties, and age of the rock around the
  Mid-Atlantic ridge.

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Scientific Evidence is Dynamic

• Scientific evidence presented to the public is
  only established after years of sound research in
  the hands of many scientists. Despite this truth,
  scientists continue to test these facts as
  technology advances.
• Homework Read and annotate the article UCLA
  scientist discovers plate tectonics on Mars.
  Explain with three supporting facts from this
  article why the statement above is necessary for
  science to remain beneficial to humanity.

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Plate Tectonics

• Homework due Wednesday
• Annotate article and answer question related to
  article.
• Complete sea floor spreading questions.
• Complete questions from plate tectonic worksheet.
• Continue to record seismic activity.
• Quiz Wednesday
• Test Friday

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Plate Boundaries

• Plate boundaries are where two plates meet.
• What type of plates can meet?
• There are 3 types of plate boundaries
• 1. divergent boundaries
• 2. convergent boundaries
• 3. transform boundaries

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Divergent Boundaries
What are divergent boundaries?
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Divergent Boundaries

• Iceland is above a divergent boundary.
• The North American Plate the Eurasian Plate

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Thingvellier,Iceland
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Divergent Boundaries
Mid-Atlantic Ridge Extends from the Arctic Ocean
to beyond the southern tip of Africa moves
2.5cm per year.
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Divergent Boundaries
African Rift Valley east African Plate is
spreading has torn Saudi Arabia away from the
rest of the African continent forming the Red Sea
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Convergent Boundaries

• What is convergent boundaries?

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Convergent Boundaries
What are the three types of convergent boundaries?
1. Oceanic-oceanic
2. oceanic-continental
3. continental-continental
nature.nps.gov
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Convergent Boundaries Continental
Convergence

• Continental convergence form mountain ranges
• Example Himalayan Mountains formed by the
  convergence of the Indian and Eurasian Plates.

nature.nps.gov
nature.nps.gov
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Himalayan Mountain Range
destination360.com
geography.howstuffworks.com
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• Convergence Boundaries
• Continental and Oceanic Convergence
• Create trenches and volcanic mountains
• One crust subducts under another.

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Aleutian Islands

• Pacific Plate North American Plate form the
  Aleutian Islands in the Pacific Ocean off the
  northeast coast of Siberia

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Andes Mountains
Nazca Plate South American Plate form the Andes
Mountains on the western border of the South
American continent
geo1202peru.blogspot.com
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• Convergent Boundaries
• Oceanic Convergence
• Creates trenches, volcanic islands, and
  volcanic island arcs
• Subduction zone

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Mariana Trench

• Located in the Pacific Ocean near Japan.
• Created by ocean-to-ocean subduction.
  -Phillipine Plate is subducting under the
  Pacific Plate

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Plate Tectonics

• Homework due Wednesday
• Annotate article and answer question related to
  article.
• Complete sea floor spreading questions.
• Continue to record seismic activity.
• Complete questions from plate tectonic worksheet.
• Quiz Wednesday
• Test Friday

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Sea Floor Spreading Model

• Use the picture below to help understand the sea
  floor
• spreading model you made last week.
• What kind of boundary is represented at 1?
  (slit?)
• What kind of boundary is represented at 2?
  (slit?)

1.
2.
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Transform Boundaries
What is a transform boundary?
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Transform Boundaries
Create Earthquakes

The Pacific Plate and the North American Plate
slide past each other.
San Andreas Fault By Robert E. Wallace, USGS
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Plate Tectonics

• How does it affect climate?
• Changed the climate over the last 250 million
  years by constantly creating geological processes
  (volcanoesearthquakes) that produced heat and
  chemicals in the atmosphere that would promote
  and support life. Climate keeps most water from
  freezing.
• How does it affect life?
• Plate tectonics promotes diversity among animals
  by causing isolation due to geographical
  formations (mountains).

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Earths Tectonic Plates
dpc.ucar.edu