Stage 1

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Stage 1

• Red dots represent volcanoes on advancing edges
• Teeth are on the upper side of subduction zone
• All sections begin to move away from center.

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Phase 2

• Rifting continues along two of the three rifts
  the third fails or peters out
• New ocean crust is formed in active rift
• Old ocean crust is subducted along opposite edge.

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Phase 3

• New rifts may form over time
• New crust continues to be produced in center
  rift
• Volcanoes continue to erupt along outer margins.

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Phase 4

• Continents continue to advance, rotate, or slow
  as other convection cells become active
• Volcanoes continue to erupt on advancing edge
• Continental plates converge on advancing edges.

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What good is a theory?

• Generalizes a series of observations from the
  testing of hypotheses
• Provides explanatory power for characterizing
  future observations
• Provides predictive value when generating new
  hypotheses.

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Dark Sucker Theory

• Light is not emitted - it is sucked in
• The process of sucking generates frictional heat
  from darkons
• Dark is heavier than light
• Dark sucker storage devices must be emptied or
  discarded when full of dark
• There is an infinite supply of dark.

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The Rifting Model
Hot Spot
Mantle Plume
Convection Cell
Convection Cell
Rifting events and the formation of divergent
plate boundaries are driven by mantle convection
cells. Where a mantle plume or convection cell
rises toward the lithosphere (red zones in the
diagram above) heat is transferred to the
lithosphere causing it to swell upward into a hot
spot. The surface rocks at the hotspot as they
stretch upward crack and form normal faults, that
develop into a horst and graben system, the
beginning of a rifting event.
http//fti.neep.wisc.edu/neep602/FALL97/LEC15/lect
ure15.html
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A continental crustal block

• Why is this thicker than the ocean crust?
• What are the general properties of this material?
• What is the generalized rock type for this block?

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A crack in the world

• Why does this pull apart?
• What is Rock A?
• I/S/M?
• Felsic/Interm/Mafic?
• What is Rock B?
• I/S/M?
• Mature/Immature?

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The Rifting Model
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An ocean runs through it

• What is Rock C?
• I/S/M?
• Felsic/Interm/Mafic?
• What happened to the rocks from the previous
  slide?

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A quiet little cove somewhere

• What kind of rock is Rock D?
• I/S/M?
• Fine, coarse, or mixed grained?
• What kind of rock is Rock E?
• How is this different than Rock C?

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Somethings gotta give...

• Rock F?
• Rock G?
• Difference between F G?
• Rock H?
• Rock I?
• Difference between H I?

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Volcanic (Island) Arc Orogeny
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There once were only two cars in Kansas

• What is rock J?
• How is this different than rock B?
• What rocks would you expect on the right?

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And they just keep coming

• What is Rock K?
• I/S/M?
• What happened to the mountains on the left?

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Cordilleran (Andean-type) Orogeny
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Thats gotta hurt!

• What is rock L?
• I/M/S?
• Does this rock have any internal structure?

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Barrovian Metamorphism
Collision between two continents
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Stuck in the middle of nowhere

• What is likely to be rock M?
• What happened to the mountains?
• How many separate pieces have now joined?

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Werent we here before?

• Is this new continent the same size as the
  starting continent?
• If bigger, where did the extra material come
  from?
• What is likely to happen to this continent in the
  future?

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