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Essentials of Geology (PDF)

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					 Essentials of Geology
               David Sallee                                                             An
                                                                                   Introduction
                                                                                        To
                                                                                     Geology
Chapter 1




           What is Geology?                                       How Does Geology Affect
 Specialties of Geology related to the                              our Everyday Lives?
 subsystems of Earth include:                                    Natural Events
 Geochronology
                                                                 Economics and
 Geochemistry
 Mineralogy
                         Jobs / Career Preparation
                                                                 Politics
 Planetary Geology                                               Our role as
 Environmental Geology
 Hydrogeology                                                    Decision-
                                                                 Decision-makers
 Geophysics              - Earth Sciences Jobs
                                                                 Consumers and
                         - Earth Sciences Organizations
 Structural geology
 Stratigraphy
                         - Reading Science for Comprehension
                         - Geology Schools
                                                                 Citizens
 Seismology                                                      Sustainable
 Oceanography
 Paleontology
                                                                 Development




Global Geologic and Environmental                              Global Geologic and Environmental
    Issues Facing Humankind                                        Issues Facing Humankind
                                           From a
                                      population of
                                      one billion at
                                      the beginning
                                        of the 19th
                                       century, our
                                       species now
                                         numbers
                                      more than six
                                      billion people.
     Overpopulation ?                                                          Global warming ?




                                                                                                   1
        The Origin of the Solar                       The Differentiation of Early
               System                                            Earth
  Solar Nebula
   Hypothesis

•Condensation
and collapse of
interstellar
material
•Flattening and                                   Perhaps the most significant event in Earth history,
rotation of cloud                                the ‘settling’ of material according to density resulted
•Accretion of                                      in a layered Earth. This concentric arrangement of
planetesimals                                     material led to the formation of continents, oceans,
•Birth of Sun                                                       and the atmosphere.




                                                 The Core
                                                                            Why is Earth a
           A View of Earth                         •solid inner
                                                   •liquid outer
                                                   •density of 10-13
                                                                10-
                                                                           Dynamic Planet?
                                     self-
 Earth is a planet that is small and self-         gm/cm³
 contained                                       The Mantle
                                                   •surrounds the core
 Earth’
 Earth’s four spheres                                           3.3-
                                                   •density of 3.3-
     Hydrosphere                                   5.7gm/cm³
                                                   •three distinct zones
     Atmosphere                                  The Crust
     Biosphere                                     •oceanic - 3 gm/cm³
                                                   •continental - 2.7
     Solid Earth                                   gm/cm³
                                                  Plate Tectonic Theory
                                                         explains
                                                 the interactions of these
                                                           zones




       Geology and the                                    Plate                      The
                                                                                     Formulation
    Formulation of Theories
                                                        Tectonic                     of Plate
  Plate Tectonic Theory                                                              Tectonic
  The Rock Cycle
                                                         Theory                      Theory
                                                                                      • Divergent
  Organic Evolution                                                                     boundaries
  Geologic Time and                                                                   • Convergent
                                                                                        boundaries
  Uniformitarianism                                                                   • Transform
                                                                                        boundaries
    These theories, supported by extensive
   research, are the cornerstones of the study                                        • convection
       of geology, and help explain many                                                cells
       seemingly unrelated observations.                                              • subduction
                                                                                        zones




                                                                                                            2
        Plate Tectonic Theory                                                   The Rock Cycle
                                                                                                             Provides a way to
                                                                                                             examine the
                                                                                                             relationships
                                                                                                             between internal
                                                                                                             and external
                                                                                                             processes
                                                                                                             Relates Igneous,
                                                                                                             Metamorphic, and
                                                                                                             Sedimentary rocks
                                                                                                             to one another and
                                                                                                             to the processes
                                                                                                             which ‘recycle’
 The Earth’s lithosphere is divided into rigid plates of                                                     earth materials
                                     asthenosphere.
  various sizes that move over the asthenosphere.




                                                                   Geologic Time and
            The Rock Cycle
                                                                   Uniformitarianism
                                                                  The perspective of geologic
                                                                  time requires a shift in our
                                                                  usual way of thinking.
                                                                  The geologic time scale is the result of
                                                                  the collaboration of many earth
                                                                  scientists
                                                                  working together to construct a
                                                                  chronology
                                                                  of events on Earth.
                                                                  The Principle of Uniformity holds that
                                                                  present day processes have operated
 Igneous rocks                               Metamorphic rocks
                                                                  throughout Earth’s history, therefore we
                      Sedimentary rocks
 basalt, granite   limestone, conglomerate    gneiss, quartzite   can better understand past events by
                                                                  studying modern processes.




       How Does the Study of
                                                                  The nature of scientific inquiry
        Geology Benefit Us?
An understanding of
the dynamic nature of                                                 Science assumes the natural world is
the planet allows us to:                                              consistent and predictable
•Appreciate the balance                                               Goal of science is to discover
in delicate systems
•Make appropriate                                                     patterns in nature and use the
choices about our                                                     knowledge to make predictions
interaction with the
environment                                                                               facts”
                                                                      Scientists collect “facts” through
•Ensure that a quality
future will be left to our
                                                                      observation and measurements
children as we make
                              Santa
difficult decisions          Tecla-
                             Tecla-El
regarding natural            Salvador
resource consumption          2000




                                                                                                                                  3
The nature of scientific inquiry             The nature of scientific inquiry
                                             Scientific methods
 How or why things happen are                     Scientific method
                                                  involves
 explained using a                                gathering facts
    Hypothesis – a tentative (or untested)        through
    explanation                                   observations and
                                                  formulation of
               well-
    Theory – a well-tested and widely             hypotheses and
    accepted view that the scientific             theories
    community agrees best explains
    certain observable facts                  There is no fixed path that
                                             scientists follow that leads
                                               to scientific knowledge




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