The Earth

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The Earth

• Remember from vocabulary
• Hydrosphere (water)
• Atmosphere (gases)
• Geosphere
• We will focus this unit on the geosphere (the
  solid earth)

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The Earth's Interior
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Layers of the Earth

• 3 major zones/layers
• Core
• Mantle
• Crust

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The Earths Core
THE EARTH'S CORE
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Core

• Broken into 2 parts Inner Core outer Core
• Made of iron and nickel

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• 2. Inner core
• 1300 km thick
• up to 5000 deg. C
• Solid due to high pressure
• Solid in core explains magnetic field

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• 3. Outer Core
• 2250 km thick
• 2200- 5000 deg. C
• Liquid iron nickel
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How do we know?

• Seismic waves vibrations that travel through the
  earth
• Come from explosion or earthquakes _at_ Earths
  surface
• Scientists study how they travel through the Earth

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• Seismic Wave Paths
• P waves slow and bend as they move from solids
  to liquids speed up and bend as they move from
  liquids to solids
• S waves disappear as they enter the outer core
  (liquid)
• Shadow Zone- region with no P or S waves
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http//www.pbs.org/wnet/savageearth/animations/ear
thquakes/
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• Above the outer core
• 2900 km thick
• 80 of Earths volume
• 68 of Earths mass

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• Broken into 2 parts
• 1. Lithosphere (uppermost part of mantle)-solid,
  rigid layer 65-100km thick

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• 2. Asthenosphere 200 km thick Solid Rock can flow
  slowly and change shape- due to extreme heat
  pressure

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Elements in the mantle

• Silicon, oxygen, iron magnesium

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• Determined by looking at ocean floor and volcanic
  rocks

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• Greater percentage of iron in lower mantle than
  upper mantle

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• Density, temperature (870- 220 deg. C), and
  pressure increases with depth

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• Boundary between crust and the mantle is the Moho

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Moho
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The Earth's Crust
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• Thin, outermost layer
• All life lives on or within a few hundred meters
  of surface

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• 3. Made up of three types of rocks

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• Igneous rock- formed by cooling/hardening of
  magma

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b. Sedimentary rock- formed by hardening of
layers of sediment
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c. Metamorphic rock- formed by changing of
existing rock
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4. Thickness of crust varies

• Average of 8 km on the ocean floor
• Average of 32 km beneath the continents

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5. Ocean crust made up mostly of silicon,
oxygen, iron, magnesium
The largest ophiolite is in Oman near the Persian
Gulf. Photo by Peter Kelemen.
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6. Continental crust made up mostly of silicon,
oxygen, aluminum, calcium, sodium potassium