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Earth

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... Lithosphere: cool, outer ridge (Crust and outer most Mantle 2) Asthenosphere: hot, ... Outer Layers The Core Keeping the Continents Afloat ... – PowerPoint PPT presentation

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Title: Earth


1
Earths Structure and Movement
  • Earths Composition and Plate Tectonics

2
Density Stratification
3
Evidence of Composition
  • Earthquakes
  • Seismic Waves Travel through earth, bend and
    reflect while travelling back to the surface.
    This can tell us about the Earths composition.
    (2 types)
  • 1) Surface Waves move on surface, property
    damage
  • 2) Body Waves Primary (P) Waves and
    Secondary (S) Waves
  • Seismograph Measures P waves which travel faster
    then S waves

4
Important Events
  • 1900 Richard Oldham Waves travelled at
    different speeds as they moves through the earth
    due to density differences.
  • 1906 Oldham - S waves are absorbed when they hit
    the earths core. (Shadow Zone portion of earth
    where S waves do not exist.)
  • 1935 Lehmann P waves speed up at the core due
    to increased density

5
Confirmation of Layers
  • 1964 Near Anchorage, Alaska earthquake with
    magnitude of 9.2.
  • Seismographs all over the world monitored the P
    and S waves, data confirmed the existing
    knowledge of the earths density stratification.

6
Also called Mantle
7
The Layers (Outer to Inner)
  • Crust 0.4 of Earths Total Mass
  • Less then 1 of its volume
  • Oceanic Mostly Basalt (Heavy)
  • Continental Mostly Granite (Lighter)
  • Mantle 68 of Earths Total Mass
  • 83 of its volume
  • Mostly Silicon and Oxygen
  • Core Mostly Iron and Nickel
  • 31.5 of Earths Total Mass
  • 15 of its volume

8
Outer Layers
  • Crust and upper Mantle float (2 Parts) over the
    warmers inner MantleCrust and Upper Mantle
  • 1) Lithosphere cool, outer ridge (Crust and
    outer most Mantle
  • 2) Asthenosphere hot, partially melted upper
    Mantle
  • Lower Mantle
  • Hotter then upper but does not melt due to
    pressure

9
The Core
  • Outer Core Dense Liquid
  • Inner Core Solid

10
Keeping the Continents Afloat
  • Buoyancy Thicker continental crust and
    lithosphere floats on the flowing layers below.
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