Crustal Motion

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Dynamic Earth
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Earth has 3 rock layers

• Crust (solid rigid outer rock layer)
• Moho separates crust from mantle
• Mantle (beneath the crust, not so solid)
• 80 of Earth is mantle
• Core (outer core liquid, inner core solid)
• made of nickel and iron (magnetic)
• very dense!

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Layered Earth
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Lithosphere Crust upper mantleAsthenosphere
partly molten part of upper mantle below the
lithosphere
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• There are two types of CRUST
• Oceanic Crust basalt rock, dense, thin layer
• Continental Crust granitic rock, less dense,
• thicker layer

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Upper portion of Earth
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The crust of the Earth appears to be moving!
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Evidence for motion of the crustOriginal
HorizontalitySedimentary rocks are always
deposited in horizontal layers called
strata.Now we see sedimentary rocks that are
messed up.
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Horizontal rock strata.
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Tilted Strata
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Folded Strata
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Faulted Strata
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Another Fault
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Other Evidence of Crustal Motion.Marine
(ocean) fossils found high atop mountains
(uplift).
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Jigsaw Continents (Wegner)
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Mountain Belts
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Wegener proposed the Theory of Continental Drift
But no one believed it!
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World War II and after Studies of Mid-ocean Ridge
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Age around mid ocean ridge
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Magnetic Stripes
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Theory of Seafloor Spreading
(no one believed it.!)
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Lithosphere cracked into separate plates.
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Earthquake/Volcano Zones
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Recent evidence led to theory of Plate
Tectonics Most motion of lithosphere related
to motion at plate boundaries/edges.