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INTRO by qingyunliuliu

VIEWS: 7 PAGES: 28

									   Intro to Geology
EARTH’S CRUST         Summer 2008

     and
  INTERIOR
                                            Earth
• 4.55 Billion years old
• „Average‟ diameter
  12,742 km
                                                               You are here

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                  a still-active planet
                       significant heat-driven motions
                       above and below the surface




a long inactive moon
     615
Lecture 1: Density and Gravity

    MOUNTAINS: A VIRTUAL TOUR

 • A geologist’s view of mountains
Earth‟s Crust and Interior



     Purpose
  • to explain Earth‟s surface form
  • to teach scientific method and logic
  • physical geology
  • rocks and minerals


    Img_0179
Sugarloaf Peak, Box Springs Mountains

an ancient “magma chamber”
molten rock reservoir beneath a volcano
i.e. must have solidified and been uplifted many kilometers
Sierra Nevada and Owens Valley

a chain of ancient magma chambers

originally below a line of volcanoes like the Cascade Range
i.e. volcanoes can be turned off and worn off the face of Earth
Hawaiian Islands




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Hawaii cont



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Mt. Ruapehu
1995




                                          Ruapehu

                              Ngauruhoe


 eruptions not
 always good
                  Tongariro
    for conical
         shape

                  active volcanoes in a line
Mt. St. Helens, WA
May 17, 1980




                     Sept 10, 1980
Mt. Ngauruhoe, New Zealand
Mt. Ngauruhoe, New Zealand




 i.e. young, not yet worn away
      active? dormant?
Mt. Doom, Mordor




       volcano with conical shape
Other Volcano Shapes         small dome of viscous lava

Hawaii




                                                    Pu’u He’ewa




         tiny cinder cones                             explosions
                                                     build cones;
                                                       lava builds
                                                      shields and
                                                           domes
Shape is a clue to eruptive style
There are chains of volcanoes on the ocean floor too!
    granite



                   skirt of young debris




Marble Mountains, Mojave Desert        (old Route 66)

ancient sea-floor deposits, resting on
rocks of ancient magma chamber
      granite



                       skirt of young debris




 Marble Mountains, Mojave Desert           (old Route 66)

 ancient sea-floor deposits, resting on
 rocks of ancient magma chamber
i.e. oceans may expand and contract
     ocean floor may be tilted and uplifted onto continent
                                    The French Alps




                                 more layered
                             oceanic sediment

i.e. many mountains are constructed from ocean floors
Mt Everest, Himalaya Mountains
more layered oceanic rocks
i.e. uplift may reach nearly 9 kilometers above sea level
Monument Valley, Arizona/Utah




 Sandstone (hard)




 Shale (soft)




 horizontal layered sediments

 i.e. requires huge volumes to be worn away (eroded)
      requires long-term stability
The white cliffs of Dover



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Just a Place
   to Ski
 and Climb?
The Steinplatte, Austria




 An “exhumed coral reef”
i.e. sea floor was uplifted, then the soft mud-rocks
around the reef were worn away
                                                   Glacier
                                             National Park




 a “pyramidal peak” or “horn”

faces of peak carved by ice of glaciers flowing by
     i.e. evidence of recent climate change
Earth‟s Crust and Interior




Patterns for mountain formation?
• observations: mountains form
    – at volcanoes (on land and at sea)      “heat from
    – from the uplifted roots of volcanoes   below”
    – by pushing rocks up above sea level
                                             “tectonics”
    – by folding/compressing rocks
    – by erosion of soft rocks by rivers     “surface
    – by erosion of hard rocks by glaciers   processes”

• these factors are interrelated, as we shall see…
Earth‟s Crust and Interior




          Next up:           Density

								
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