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Earth: the home planet

Earth: the home planet. Earth’s Interior. Earth’s Layered Structure. Earth’s interior consists of layers Layers are arranged according to density Most dense material is at the center – core Density decreases outward Density layering includes the hydrosphere (oceans) and atmosphere.

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Earth: the home planet

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  1. Earth: the home planet

  2. Earth’s Interior

  3. Earth’s Layered Structure • Earth’s interior consists of layers • Layers are arranged according to density • Most dense material is at the center – core • Density decreases outward • Density layering includes the hydrosphere (oceans) and atmosphere

  4. Thickness and Composition of Earth’s Layers

  5. Earth’s Temperature Structure

  6. How Do We Know?

  7. Refraction of Seismic Waves

  8. Seismic Waves • Refraction – change in speed and direction when passing through a material of different density.

  9. Other Evidence • Refraction of seismic waves • Density of the entire planet • Gravity (mass) of entire planet • Composition of meteorites • Existence of magnetic field

  10. Earth’s Magnetic Dynamo

  11. Earth’s Magnetic Field

  12. Was it always this way? • Accretion of the protoplanet • Homogeneous structure • Density differentiation

  13. Density Differentiation • Gravitational effects vary with density of material • Materials must be free to move • Requires plastic flow or fluid flow • Requires heat

  14. Earth: The Unfinished Planet • Earth continues to lose heat • Volcanism brings material to Earth’s surface • Other processes (subduction) return more dense material to interior • Conclusion: Earth is still under construction!

  15. Implications of anUnfinished Planet • Volcanism • Earthquakes • Atmospheric and climate change • Effects on life

  16. Theory of Plate Tectonics • Earth’s lithosphere (crust +uppermost mantle) is divided into plates • Plates move as a result of heat inside the Earth • Plates interact to cause: • Earthquakes • Volcanos • Mountain systems

  17. What makes the plates move? • Uneven distribution of heat in the upper mantle (Asthenosphere) causes heat to rise in some places • Differences in density cause colder, more dense Lithosphere to sink back into the asthenosphere • This Convection drives the motion of the plates

  18. Interactions between Plates cause: • Earthquakes • Volcanos • Formation of mountains • Formation of ocean basins • Increase amount of continental lithosphere

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