Chapter 11: Mountain Building

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Chapter 11 Mountain Building

• 11.1 Where Mountains Form
• 11.2 How Mountains Form
• 11.3 Types of Mountains

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11.1 Where Mountains Form

• Mountain Belts
• Mountain-A large mass of rock that rises a great
  distance above its base.
• Most mountains are found along convergent plate
  boundaries. Why?

Because of the collision of the plates.
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11.1 Where Mountains Form

• B. Continental Margin- A boundary between
  continental crust and oceanic crust.
• Two Types Active and Passive. Active occur near
  plate boundaries and passive do not.
• Mountain building takes place at active
  boundaries.
• Passive continental margins are the material used
  for mountain building.

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11-2 How Mountains Form

• Types of Stress
• Stress- A measure of the amount of force applied
  over a given area.
• Compression-Rocks are being squeezed inward.
  Bows upward.
• Tension- Rocks are being stretched. Creates a
  valley.
• Shear Stress- Rock layers are being pushed in two
  different directions.

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11-2 How Mountains Form

• B. Folds
• Occurs underground and then is exposed by erosion
  and weathering.
• Anticline- An upfold of rock layers. P. 239
• Syncline- A downfold of rock layers.

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11-2 How Mountains Form
Hanging wall

• Faults
• Normal Fault- When hanging wall moves down with
  respect to the footwall.
• Reverse Fault- Hanging wall moves up with respect
  to the footwall.
• Thrust Fault- Is a reverse fault in which the
  fault plane dips 45 (or less from horizontal.
• Strike-slip- The rocks on opposite sides of the
  fault plane move horizontally.

Foot Wall
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11-2 How Mountains Form

• D. Joints
• Joints- Are breaks in bedrock along which no
  apparent movement has occurred.
• 2. Provide an avenue for groundwater and magma
  flow. This allows for large deposits of
  minerals.

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11-3 Types of Mountains

• Folded Mountains- When two plates carrying
  continental crust collide, rocks can fold and
  crumple. examples The Alps, Himalayas and Rocky
  Mountains.
• Oceanic crust subducts until there is a
  continent-to-continent collision.
• See Himalayan example pg. 243. Why are there
  ocean sediments at the top of Mt. Everest?

Uplift of Sea Floor Sediments
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11-3 Types of Mountains

• B. Dome Mountain- A nearly circular folded
  mountain. They are individual, isolated
  structures that occur in flat lying sedimentary
  rocks.
• Bent upwards by uplifting forces.
• Two Types Plutonic and Tectonic. Plutonic is
  created by rising magma. Tectonic is created by
  uplifting forces.

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11-3 Types of Mountains

• C. Volcanic Mountains
• These mountains are created by rising magma that
  forms volcanoes.
• 2. They are a result of a subducting plate
  boundary.

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11-3 Types of Mountains

• D. Fault-Block Mountains
• These mountains are created by tension in the
  crust as it is slowly being up lifted.
• E. Horst and Grabens
• As the earth's crust uplifts, some blocks of rock
  are thrust upward (Horst) and some are dropped
  (Graben). See page 245!