UNIT 3: DYNAMIC EARTH Chapter 11: Mountain Building

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UNIT 3 DYNAMIC EARTHChapter 11 Mountain
Building

• C/S 11.1 Where Mountains Form
• C/S 11.2 How Mountains Form
• C/S 11.3 Types of Mountains

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C/S 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?
• Continental Margins
• 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
  mountain building.

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C/S 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.
• 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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C/S 11-2 How Mountains Form (cont)

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

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C/S 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?
• Dome Mountains
• 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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C/S 11-3 Types of Mountains (cont)

• Volcanic Mountains
• These mountains are created by rising magma that
  forms volcanoes.
• They are a result of a subducting plate boundary.
• Fault-Block Mountains
• These mountains are created by tension in the
  crust as it is slowly being up lifted.
• 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!