The Earth

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The Earths Interior
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Write down the things that are in yellowOther
terms in this PowerPoint are helpful but do not
need to be included in your notes.
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Plate tectonics- describes movement of the crust
(theory)

1. Continental Drift- the continents have drifted
   from one location to another
2. Continents used to be in one mass called Pangea
   (250 mill. Years ago)

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Earthquakes

• Seismic Waves
• generated waves traveling through the Earths
  interior
• These waves give us clues to the composition of
  the Earth

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(No Transcript)
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Types of waves

• P-waves (primary waves)
• Compress and expand rock
• Are the fastest
• First waves to register on seismograph

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Types of waves (cont.)

• S-waves (secondary waves)
• Vibrate up and down or side to side
• 2nd waves to register on a seismograph

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IV. Measuring Earthquakes

• Seismograph
• Device which measures seismic waves
• Clicker ?s 1-9

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Movement along a fault boundary

• Transform-fault boundary
• plates are sliding past one another
• EX. San Andreas
• fault in California
• ? Earthquakes caused by shearing forces

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Movement (cont.)

• B. Divergent Boundary
• 1. two plates are moving apart
• ? Plate A Plate B ?
• 2. Forms rift valleys - large spreading
  valleys
• or
• 3. Creates sea floor spreading- a rift valley
  on sea floor
• 4. Caused by tensional forces

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Divergent Boundaries
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Divergent Boundaries- can observe reverse polarity
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Movement (cont.)

• Convergent Boundaries
• 2 plates move towards each other
• Plate A ? ? Plate B
• Leads to subduction- one plate
• (usually oceanic crust)
• goes beneath the other
• (continental crust).
• Caused by compressional forces

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Convergent Boundaries
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Convergent Boundaries

• Ex Andes Mountains in S. America
• (Still growing because of subduction)
• 3. ?Common place to find volcanoes
• Ex Cascade Range
• (Mt. St. Helens Mt. Rainier)

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Earths internal layers

• Geologists did research with seismic waves
• Concluded that the Earths
• interior is layered.

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Earths internal layersSKETCH THIS!
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Earths internal layers

• A. Core-
• 1. Composed mostly of iron and nickel
• 2. Inner Core
• very hot
• solid Fe Ni due to high pressure of the Earth

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The Core (continued)

• 3. Outer Core
• less pressure from the earth
• liquid Fe Ni
• Flow in the outer core generates an electric
  current that powers the Earths magnetic field.

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B. The Mantle

1. Rocky layer
2. About 3000 km thick

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Mantle (cont.)

• a. Lower mantle
• b. Upper mantle
• two sections

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Upper mantle (cont.)

• 1. Asthenosphere - behaves in a semi-fluid manner
  

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Upper mantle (cont.)
Source http//www.uwsp.edu/geo/faculty/ritter/ima
ges/lithosphere/tectonics/earth_structure.jpg

• Lithosphere- rigid and brittle

Legend Lithosphere Crust Mantle
Asthenosphere Outer Core Inner
Core
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Thickness of layers.
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C. The Crust

• Uppermost portion of the lithosphere
• Two types of crust
• a. Oceanic crust below ocean, dense
• about 10 km thick

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The Crust (cont.)

• b. Continental crust below land, less dense
• about 20-60 km thick

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• Evidence that supports the theory of Continental
  Drift
• 1. Geologic (rock)
• 2. Biologic (life)
• 3. Climatological (past weather)
• 4. Continental Shelves fit together well

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Tectonic Plates

• moving sections of the lithosphere
• on which continents lie

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Major Tectonic Plates
Clicker ?s 1-9 (Continental Drift and Faults)