Unit 3: Geology

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Unit 3 Geology
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Unit 3 Geology

• Mapping the World
• Geologic Time
• Composition of the Earth
• Plate Tectonics
• Volcanoes
• Earthquakes

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E. Volcanoes

• Magma
• Intrusive Activity
• Volcanoes

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1. Magma

• There are 3 types of magma
• Basaltic magma
• When rocks in upper mantle melt, little viscosity
• Volcanoes erupt quietly
• Andesitic magma
• Composed of oceanic crust or oceanic sediments
• 60 silica
• Intermediate eruptions
• Rhyolithic magma
• Very viscous
• Violent, explosive eruptions

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2. Intrusive Activity

• Uprising magma can affect the crust in several
  ways by intruding into it.

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3. Volcanoes

• Volcanoes produce various features that alter
  Earths landscape.
• There are thousands of volcanoes on Earth, many
  are still active today.

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Worlds Active Volcanoes
Mt. Shasta (41N, 122W)
Fuji (35N, 139E)
Colima (19N, 104W)
Kilimanjaro (3S, 37E)
Copahue (38S, 71W)
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Anatomy of a Volcano

• Regardless of the type, all volcanoes have the
  following characteristics in common
• Vent
• At the surface of Earth, where lava erupts.
• Crater
• Bowl-shaped depression around the vent.
• Volcanic craters are usually less than ½ mile in
  diameter. Larger craters are called calderas.
• Magma Chamber
• Crater connected to magma chamber by the vent.

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Types of Volcanoes

• There are 3 types of volcanoes
• Shield volcano
• Cinder-Cone volcano
• Composite volcano

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Shield Volcano

• Broad slopes
• Nearly circular base
• They form when layer upon layer of basaltic lava
  accumulates during non-explosive eruptions.

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Cinder-Cone Volcano

• Lava gets ejected high into the air and falls
  back and piles up around the vent
• Steep slopes
• Very explosive
• Generally small (500 meters high)

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Composite Volcano

• Forms when layers of volcanic fragments alternate
  with lava
• Much larger than cinder-cone
• Violent explosions

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Composite
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Cinder-Cone
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Shield
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Volcano Project (30 pts.)

• Make a model of a volcano and include the
  following
• Volcano anatomy
• Vent, crater, magma chamber
• Volcano type
• Composite, shield, cinder-cone
• Magma type
• Basaltic, andesitic, rhyolithic
• Must show the inside of the volcano
  (cross-section)
• Volcano must erupt!

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Materials you can use for volcano