Igneous

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Igneous Systems Plutons Such
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Extrusive Rock Bodies

• Form of extrusive bodies influenced by magma
  properties
• Composition
• Silica content
• Viscosity
• Volatile content
• Temperature

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Intrusive Rock Bodies

• Less dense magmas rise through the crust
• Rising magmas slowly cool
• Viscosity increases
• Density increases
• Intrusions form as magma solidifies beneath the
  surface

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Intrusive Rock Bodies

• Intrusions are classified by their size, shape
  and relative age
• Large intrusions
• Batholiths
• Stocks
• Small intrusions
• Dikes
• Sills
• Laccoliths

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Types of magmatic intrusions
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Igneous Dikes
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Dike cross-cutting a granite in Yosemite Natl
Park. -note the smaller dikes cut by the larger
one
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Igneous Sill Big Bend Natl Park, TX
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