Earth

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Earths Interior and Plate Tectonics

• Physical Science
• Section 17.1

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This is how the continents formed.

• http//www.youtube.com/watch?vTzzGPfVx32MlistPL
  ABDC7B24FAFE33FD

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The Earth is like a parfait, it has layers

• If you cut the earth in half, it would look very
  much like a parfait, with different layers and
  compositions based on density
• The earth has three main layers, the crust, the
  mantle, and the core

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The Crust

• We live on this layer
• Its is cool, and made of solid rock
• Oceanic crust is thinner and denser than
  continental crust.
• The crust is the least dense portion of the earth
  and only about 12-25 miles thick

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The Mantle

• Layer of rock that is denser than the crust
• About 1800 miles thick
• Outer mantle is solid rock
• Inner mantle the rocks are extremely hot and
  bendable like gum (plastic)

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The Core

• The center of the earth
• Made mostly of iron and nickel
• The inner core is solid metal while the outer
  core is liquid metal

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The Earth heats up with depth

• At only 2 miles down the temperature increase to
  120 F
• The core is much hotter than the mantle
• In the core, temperatures reach over 10,000 F

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The earth heats up with depth

• The earth gets warmer towards the core because it
  contains so many radioactive isotopes
• These unstable isotopes are constantly breaking
  down, releasing huge amounts of energy, which in
  turn heat the earth

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How do plates move?
http//www.youtube.com/watch?vryrXAGY1dmE
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Evidence 1 The Pangea Puzzle

• In the 20th century, Alfred Wegener noticed that
  eastern S.America fits into western Africa
• He also noticed that several of the other
  continents fit together like puzzle pieces
• He also found that fossil evidence showed that
  several of the same organisms are found on
  continents now separated by oceans
• He theorized that 250 million years ago all the
  continents combined to form the giant land mass
  he named pangea

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How did this happen?

• The earths outer shell, called the lithosphere
  is made of the crust and upper portion of the
  mantle.
• This lithosphere is very rigid and consists of 7
  large pieces and a few small ones that fit
  together like a puzzle
• These large pieces are called tectonic plates

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Plate Tectonics

• These plates fit together like puzzle pieces and
  move in relation to each other
• these plates move away, towards, or alongside
  each other
• Tectonic plates move about 6 inches per year

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Divergent ? ? Plate Boundaries

• In some areas, the plates move away from each
  other
• When this occurs, hot liquid rock called magma
  rises and cools, forming new lithospheric rock

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Convergent ? ?Plate Boundaries

• Less dense continental plate floats over more
  dense oceanic plate
• This process is called subduction
• As this more dense rock goes down into the
  mantle, it heats up and melts
• The magma rises and pushes up the crust, forming
  volcanic mountains also earthquakes

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• Subduction - two plates meet, the more dense
  plate (oceanic crust), dives beneath the less
  dense plate (continental crust)

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Continental vs. Continetal

• Same density so no subduction
• Builds non-volcanic mts.
• Earthquakes

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Oceanic vs. Oceanic

• Similar density, but subduction anyway
• Earthquakes, trenches,
• volcanic island arcs

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Transform Fault Boundaries

• These are areas where plates move along side one
  another
• As plates move, they can cause cracks in the
  lithosphere called faults
• As plates move along side each other at these
  faults, the plates cause a great deal of force
  and create earthquakes

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RECAP ?

• Divergent ? ? Plate Boundaries
• Divergent means plates MOVE AWAY? ? from each
  other
• Convergent ? ? Plate Boundaries
• Convergent means plates MOVE TOWARD ? ? each
  other
• Transform Fault Boundaries
• areas where plates move along side one another
• like this ? or this ?
• ? ?

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• Earth is made of 3 main layers
• Crust- cool, thin, made of rock, 10-25 miles
  thick
• Mantle, denser than crust, 2500 miles thick, 80
  of earths volume inner mantle solid rock, outer
  mantle bendable gummy rock
• Core- center of earth, made of iron and nickel,
  made of 2 layers inner solid metal, outer liquid
  metal

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• Pangea- 250 million years ago all the continents
  combined to form the giant land mass called
  Pangea
• Lithosphere (earths outer shell) is made of the
  crust and upper portion of the mantle.
• lithosphere -very rigid and consists of 7 large
  pieces (called tectonic plates) and a few small
  ones that fit together like a puzzle

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• Plate Tectonics
• These plates fit together like puzzle pieces and
  move in relation to each other
• these plates move away, towards, or alongside
  each other
• Tectonic plates move 6 inches per year

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Evidence 2 Biogeographical
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Final views

• http//www.youtube.com/watch?vQrQDXnnXOo4feature
  player_embedded!