Structure of the Earth

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Structure of the Earth
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Compositional (Chemical) Layers

• Crust Low density
• High in silicon (Si) and oxygen (O)
• Moho Density boundary between crust and
  mantle
• Mantle Higher density
• High in Magnesium (Mg) and Iron (Fe)
• Core High in Nickel (Ni) and Iron (Fe)

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Earth The Giant Magnet

• Magnetic field created by liquid iron convecting
  in outer core.

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• Magnetic field directs solar winds (ionized
  particles) around the Earth or to the poles.

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Aurora Borealis
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Heat Flow in the Earth

• Heat sources
• latent heat from the formation of the Earth
• Radioactive decay in the core and mantle
• Temperature at core 3000-5000 C
• Cooling processes
• Convection currents
• Plate tectonics (volcanoes)

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Mechanical (Physical) Layers of the Earth
Lithosphere Crust and upper, solid part of the
mantle plates in plate tectonics Asthenosphere
Partially molten part of mantle location of
convection current that drive plates Outer core
Liquid Inner core Solid
Greatest temperatures, solid due to intense
pressure
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Evidence for Structure of the Earth

• Seismic (earthquake) waves
• P waves (Primary) Longitudinal (compressional)
  waves faster, can move through any matter
• S waves (Secondary) Transverse waves. Can only
  travel through solid matter.

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Evidence for Structure of the Earth Cont.

• S waves can not travel through the outer core.

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Rock Types

• Igneous Solidified molten magma
• 2 types of Igneous
• Extrusive (volcanic) erupted lava
• Cools more quickly, so only small crystals
  form.
• Intrusive (plutonic) never erupted magma
• Cools more slowly within the earth, so larger
  crystals can form.

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• Quartz Silica (SiO2), light color. Magma high
  in silica is viscous.
• High silica magma found in more explosive
  volcanoes due to build up of pressure with more
  viscous magma.
• Forms stratovolcano (cone shape)
• Low silica magma found in less explosive
  volcanoes.
• Form shield shape.

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Extrusive Igneous Rock
Basalt Andesite Rhyolite
Low in silica High in Silica
Black Pale pink, grey
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Intrusive Igneous Rock

Gabbro Dacite Granite
Low in Silica High in Silica
Black Pale Grey, pink
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Sedimentary Rock

• Sedimentary rock formed by compaction of
  sediments. Classified by particle size.

Shale
Sandstone
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Sedimentary Rock cont.

• Almost all fossils found in sedimentary rock
• Almost all fossil fuels (coal, oil, gas) found in
  sedimentary rock.

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Metamorphic Rock

• Metamorphic rock is rocked that has been
  changed by heat and/or pressure.
• Caused by burial and proximity to volcanic
  areas.
• Dense, often streaks/folds
• Many gemstones are metamorphic.

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Rock Cycle