CH 5 Plate Tectonics Section 51 Earths Interior

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CH 5 Plate Tectonics Section 5-1 Earths Interior

• Earth is made up of 3 main layers
• Crust, Mantle, and Core, (Inner Outer Core)
• Two types of evidence of the Earths interior
• Rock Samples (direct) - drilled holes as deep as
  12 km for samples.
• Seismic Waves (indirect) shock waves produced
  by an earthquake. We look at the speed and path
  they take for info. (pg 126)
• As you go towards the core the temperature and
  pressure will increase.

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• Crust think outer layer of the Earth, made of
  solid rock, that includes both dry land and ocean
  floor. (about 40 km thick)
• Oceanic crust is made of Basalt.
• Continental crust is made of Granite.
• Mantle made up of very hot semi-solid rock,
  divided into layers based on physical properties.
  (about 3000 km thick)(80 total volume of the
  Earth)
• Lithosphere very upper part of the mantle,
  basically the crust.
• Asthenosphere below the lithosphere, where rock
  bends like a plastic (plasticity).
• Lower Mantle bottom section extending to the
  core.

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• Core made mostly of metals nickel and iron
• Outer core liquid part of the core.
• Inner core dense ball on solid metal due to
  pressure.
• Magnetic Field like a bar magnet through the
  middle of the Earth. Protects us from certain
  things in space (Radiation, Meteors).
• Due to the molten outer core.
• Page 131.
• Causes compasses to work on the Earth.

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Sec 5-2 Convection and the Mantle

• Heat moves three ways on the Earth
• Radiation transfer of heat energy through empty
  space (sunlight)
• Conduction transfer of heat directly through
  touching (through a piece of metal)
• Convection transfer of heat through a fluid
  like a liquid or a gas (water, air)
• Movement occurs because of differences in density
  of the liquids as they heat up and cool down.
• Hot goes up, and cold goes down.
• - Heat from the core and the mantle itself
  causes convection currents in the mantle

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Sec 5-3 Drifting Continents

• Continental Drift states that all the continents
  were once joined together in a single landmass
  and have since drifted apart.
• Alfred Wegener 1910 german scientist who
  discovered this. Called the supercontinent
  Pangea (all land)
• Evidence that supports this continental drift
• Land features like shape of coastlines, mineral
  deposits (coal), and glacial erosion.
• Fossils like Glossopteris (fernlike plant) are
  found in rocks on Africa, South America, India,
  Australia, and Antarctica (page138-139). Also
  reptile fossils helped.
• Climatic change also helped by showing some
  plants and animals could not live on the current
  land masses today because of temperature
  differences.

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Sec 5-4 Ocean Floor Spreading

• Mid-ocean ridges are where the plates pull apart
  under the oceans. They form under water mountain
  chains.
• Sonar uses sound waves under water to map out
  objects echoes as they bounce back.
• Sea-floor spreading occurs when both sides of the
  mid-ocean ridges pull apart and new crust is made
  between them.
• They move like conveyor belts carrying the
  continents along with them.
• Evidence for this include molten material,
  magnetic stripes on the ocean floor, and the age
  of the rocks.

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• Subduction Zones areas where ocean plates are
  pushed down into the mantle. Rock is recycled
  from Ch 4. Oceanic Crust (Basalt) is younger
  then Continental Crust (Granite)
• - creates trenches along the edges of the
  oceans. (Mariana Trench 11033 meters)
• Pacific ocean is shrinking due to subduction
  zones.
• Atlantic ocean is growing due to ocean-floor
  spreading.

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Sec 5-5 Theories

• Theory of Plate Tectonics explains the formation,
  movement, and subduction of the Earths plates.
• There are 3 different types of plate boundaries
  where movement occurs. (pg. 152-153)
• Divergent Boundary two plates move apart from
  each other, or diverge.
• Convergent Boundary two plates come together,
  or converge.
• Transform Boundaries two plates slide past each
  other in opposite directions
• History of the plates movement show a
  supercontinent called Pangea, (225 mya) which
  later split into two major landmasses called
  Laurasia (north) and Gondwannaland (south) (190
  mya)