WELCOME TO GG 101 PHYSICAL GEOLOGY

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WELCOME TO GG 101PHYSICAL GEOLOGY

• My name is Patty Lee.
• We meet Monday , Wednesday and Friday from 1030
  to 1120.
• SHOW UP!

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We will study the PHYSICAL characteristics or the
GEOLOGY of our planet, EARTH.

• WHAT IS GEOLOGY?
• logia (study) of the geo (earth)
• HOW DO WE STUDY IT?
• directly indirectly using the scientific method
• WHY DO WE STUDY IT?

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To figure out how Earth works!

• resources

• environment

• hazards

• RESOURCES
• HAZARDS
• ENVIRONMENT
• BEAUTY

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2 MAJOR CONCERNS

• GEOLOGIC TIME
• ENERGY

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GEOLOGIC TIMEARISTOTLE

• FAST TIME
• BISHOP USSHER
• CATASTROPHISM
• WORLD-WIDE SUDDEN DISASTERS

• SLOW TIME
• JAMES HUTTON
• UNIFORMITARIANISM
• THE PRESENT IS THE KEY TO PAST

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Siccar Point, Scotland
Fig. 1.3
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Geologic Time Scale
Geologic Time Scale
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ENERGY

• GIANT MACHINE (EARTH) DRIVEN BY
• 2 ENGINES -gt HEAT ENGINES
• EXTERNAL ENGINE
• INTERNAL ENGINE

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EXTERNAL ENGINE - SUN

• 60 OF SOLAR ENERGY IS USED TO DRIVE WEATHER
  SYSTEM BY VARIABLE HEATING
• HYDROLOGIC CYCLE
• -gt EVAPORATION
• JOB IS TO FLATTEN THE SURFACE OF EARTH BY
  WEATHERING, EROSION DEPOSITION!

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INTERNAL ENGINE

• HEAT FLOWS FROM HIGH TO LOW TEMPERATURE
• FROM INSIDE TO OUTSIDE OF EARTH
• JOB IS TO BUILD VOLCANOES, MOUNTAINS, MOVES
  PLATES -gt PLATE TECTONICS

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HOW HEAT WORKS

• WORKS IN 2 WAYS -gt CONDUCTION CONVECTION
• ROCKS BEHAVE PLASTICALLY (wax, soft tar)
• GEOTHERMAL GRADIENT -gt 1deg.C/40M

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THE UNIVERSE

• Hubble DEEP FIELD
• ltorigins.jpl.nasa.gov/poster/
• deepfield.htmlgt

BIG BANG

• UNIVERSE COMPOSED OF
• HYDROGEN (76)
• HELIUM (23)
• ALL ELSE (1)

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THE SOLAR SYSTEM

• SOLAR NEBULAR FORMED 4.55 BILLION YEARS AGO AS
• PLANETESIMALS COALESCED INTO PLANETS
• 4 INNER ROCKY PLANERS AND 4 GAS GIANTS PLUTO
• HEATED BY IMPACTS OF NUBULAR DEBRIS
• CAUSING PLANETS TO DIFFERENTIATE

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The origin of the solar system.
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A catastrophic impact between the proto-Earth and
a Mars-sized impactor.
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Heating and differentiation of the early Earth.
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EARTH - OUR ISLAND HOME
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The Three States of Water(Why Earth is so
special)
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A model of the Earths interior.
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OK!

• SO WHAT?
• WE HAVE ALL THIS INFORMATION
• BUT
• WHAT DOES IT MEAN?
• WHAT IS PLATE TECTONICS?
• LETS FIND OUT!

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PLATE TECTONICS

• UNIFYING THEORY of plate motion
• PLATES - 7 major plates many minor plates
• MOVE with respect to each other as fast as finger
  nails grow
• remember that crust rides in lithosphere over
  the asthenosphere
• Three (3) kinds of PLATE MARGINS

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DIVERGENT MARGIN lt-SPREADING-gt

• Plates move apart leaving a gap that is filled by
  magma/lava making new sea floor new plate
• Occurs at Divergent Margins (MOR)
• Mid-Ocean Ridges (MOR) are elevated sub-marine
  volcanic mountains

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CONVERGENT MARGIN-gtSUBDUCTION OR COLLISIONlt-

• Deep sea trenches where subducting plates move
  into Earths interior
• Oceanic crust is SUBDUCTED, destroyed
• Continental crust COLLIDES and builds mountains

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TRANSFORM MARGINS

• Plates slide horizontally past each other at
  great vertical faults
• Plates scrape deform margins as they move
• Crust is neither created nor destroyed

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Earthquakes Plate Margins
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WHY ALL THIS ACTIVITY?Just what drives the
plates?

• CONVECTION CURRENTS - transfers heat from inside
  to surface - plates ride the currents
• RIDGE-PUSH - upwelling pressure so great at MOR
  that forces plates to split
• SLAB-PULL - cooled slabs are so heavy that drag
  plate down a subduction zone-gravity assisted
• RIDGE MASS - mass is so great _at_ MOR that forces
  plates to move away
• MANTLE PLUMES - locally concentrated upwellings,
  lateral flow, slow downwelling

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SYSTEMS - Run by energy made of matter

• 1. Definition ANY PORTION OF THE UNIVERSE
  SEPERATED FROM THE REST OF THE UNIVERSE FOR THE
  PURPOSE OF OBSERVING CHANGES
• It is implied that all systems have boundaries
• The amount of matter in a closed system is fixed!
• Systems are composed of SUBSYSTEMS which are in
  DYNAMIC BALANCE

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Kinds of Systems
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The Earth is a Closed System
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CYCLES - Group of processes that move matter and
energy between subsystems

• HYDROLOGIC CYCLE - driven by Sun and works on
  surface
• ROCK CYCLE - 3 families defined by formation
  processes
• IGNEOUS ROCKS - born of fire melted rock-gt
  MAGMA
• SEDIMENTARY ROCKS - formed at surface from rock
  fragments
• METAMORPHIC ROCKS - altered preexisting rock
  material
• TECTONIC CYCLE - moves rock material between
  surface Earths interior by interaction of
  tectonic plates run by internal heat

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The 3 Major Cycles
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IRON CATASTROPHY
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STRUCTURE OF EARTH