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Mountain Building


Used to determine elevation of earth's crust ... Isostasy. Isostasy displacement of mantle by continental and oceanic crusts ... Isostasy & Erosion. Erosion ... – PowerPoint PPT presentation

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Title: Mountain Building

Chapter 20
  • Mountain Building

Crust-Mantle Relationship
  • Topography change in elevation
  • Used to determine elevation of earths crust
  • 70 below sea level
  • Density
  • More dense (oceanic crust) surface will sink
    less dense (continental crust) surface will float

  • Isostasy displacement of mantle by continental
    and oceanic crusts
  • Crust are in equilibrium because of gravity
    pushing downward and buoyancy pushing upward
  • Getting into and out of a boat

Isostasy Erosion
  • Erosion
  • As mountains are eroded ? mass decreases roots
    become smaller because they are pushing upward to
    make up for the loss of mass
  • Isostatic rebound slow process of earths crust
    rising as the result of the removal of mass from
    the crust
  • Seamounts individual volcanic mountains formed
    from plates moving over hot spots

  • Orogeny process that forms mountain ranges
  • Orogenic belts broad, linear regions of
    deformation associated with plate boundaries
  • Convergent boundaries
  • Oceanic-oceanic convergence
  • Crust of island arc forms roots
  • Displacement of mantle by roots that provides
    buoyancy for a mountain peak

  • Oceanic-continental
  • As continental plate pushes upward, orogeny
  • Roots form to support mountains formed
  • Magma forms and pushes up sediments causing
    metamorphosed rocks to form
  • Continental-continental
  • Magma that forms due to collision results in
  • Marine sedimentary rock forms

Appalachian Mts.
  • Divided into regions based on rocks
  • Early formation
  • 700-800 million years ago due to convergence
  • Figure 20-11 on page 533

Divergent-Boundary Mts.
  • Magma rising from ocean ridges is forced upward
    causing an upward push in the lithosphere forming
    a gently sloping mountain range
  • Ocean-ridge rocks
  • Igneous rocks
  • Pillow basalts formed from magma rising and
    pushing through dikes and erupting on seafloor

Nonboundary Mts.
  • Uplifted mountains
  • Large regions of earth slowly forced upward
  • Uplift is not well understood
  • Adirondack Mts plateaus
  • Fault-block mountains
  • Large pieces of crust are tilted, uplifted, or
    dropped downward between large faults
  • Grand Tetons Basin Range Province
  • Volcanic Peaks
  • Formed by hot spots
  • Hawaii

  • Use the following terms to create a concept map
    that contrasts the mountain types discussed in
    this section
  • uplifted mountains
  • solitary volcanoes
  • form as a result of hot spots
  • result from tension
  • form at divergent boundaries
  • show little structural deformation
  • ocean ridges
  • fault-block mountains

Answer to Closure
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