Geology of Planet Earth GEOL - 101

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Geology of Planet EarthGEOL - 101
Picture of Earth taken from Apollo 17

• Text Physical Geology, by Plummer, McGeary
  Carlson

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Physical Geology Concepts
Earths Systems Atmosphere the gases that
envelop the Earth Hydrosphere water on or near
the Earths surface Biosphere all living or
once-living materials Geosphere the solid rocky
Earth
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Geology in Todays World

• Geology - The scientific study of the Earth
• Physical Geology is the study of Earths
  materials, changes of the surface and interior of
  the Earth, and the forces that cause those
  changes
• Practical Aspects of Geology
• Natural resources
• Geological hazards
• Environmental protection

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Chino Hills Earthquake July 29 (Tuesday), 2008,
1142 am
Magnitude 5.4 Depth was 8.5 miles Felt in
Las Vegas, NV Produced 40 aftershocks
near the intersection of 3 faults 1.
Whittier Fault (strike-slip) 2. Chino Hills
Fault (dips soutj) 3. Peralta Fault (dips
north) Main shock most likely produced by
oblique slip (part thrust, strike-slip)
3-D animation movie was produced by undergraduate
interns at SCEC. Caltech animation (blue is
downward motion of Earth's surface)
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Chino Hills Earthquake
Rupture animation Caltech
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Southern California SHAKEOUT Drill November 13,
2008, 1000 am
Animation For a potential 7.8 Eq along locked
zone of the San Andreas -ground velocity
Millions of people in homes, schools, businesses
public places will Drop,
Cover, and Hold To prepare for a possible large
earthquake expected for southern Ca. Go to
http//www.shakeout.org/drill/ to be counted in
drill and learn about safety.
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Practical Aspects of Geology

• Natural Resources
• All manufactured objects depend on Earths
  resources
• Useful geological resources are mined or
  extracted
• If it cant be grown, it must be
  mined
• Most resources are limited in quantity and
  non-renewable

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Resource Extraction and Environmental Protection

• Coal Mining
• Careless mining can release acids into
  groundwater
• Petroleum Resources
• Removal, transportation and waste disposal can
  damage the environment

Alaska pipeline

• Dwindling resources can encourage disregard for
• ecological damage caused by extraction
  activities

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Geologic Hazards

• Earthquakes
• Shaking can damage buildings and break utility
  lines large undersea quakes may generate
  tsunamis
• Volcanoes
• Ash flows and mudflows can overwhelm populated
  areas

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Move Mount St. Helens
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Mt Pinatubo, Philippines, 1991
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Geologic Hazards

• Landslides, floods, and wave erosion

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Movie Banda Aceh Tsunami
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Sumatra Earthquake Seafloor Rupture
Coastline offshore Sumatra at earthquake
epicenter. Green region center shows slide.
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Theory of Plate Tectonics

• Continental Drift Hypothesis
• Originally proposed (early 20th cent.) to explain
  the fit of continents, matching rock types and
  fossils.
• Insufficient evidence found for driving force
  hypothesis initially rejected
• Plate Tectonics Theory
• Included new understanding of the seafloor and
  explanation of driving force
• Describes lithosphere as being broken into plates
  that are in motion
• Explains origin and distribution of volcanoes,
  fault zones and mountain belts

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Tectonic Plates Plate Boundaries

• Divergent boundaries
• Plates move apart
• Transform boundaries
• Plates slide past one another
• Convergent boundaries
• Plates move toards each other

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Earths Interior and Tectonic Plates

• Mechanical Layers
• Lithosphere (100 km thick)
• Rigid/brittle outer shell of Earth
• Composed of both crust and uppermost mantle
• Makes up Earths tectonic plates
• Asthenosphere
• Plastic (capable of flow) zone on which the
  lithosphere floats

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Tectonic Plate Boundaries

• Divergent boundaries
• Plates move apart
• Magma rises, cools and forms new lithosphere
• Typically expressed as mid-oceanic ridges

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The Earth's Interior

• Earths Heat Engines
• External (energy from the Sun)
• Primary driver of atmospheric (weather) and
  hydrospheric (ocean currents) circulation
• Controls weathering of rocks at Earths surface
  
  
• Internal (heat moving from the hot interior
  to the cooler exterior)
• Primary driver of most geospheric phenomena
  (volcanism, magmatism, tectonism)

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Earths Interior

• Compositional Layers
• Crust (7-70m thick)
• Very thin outer rocky shell of Earth
• Mantle (2900 km thick)
• Solid interior that flows slowly over
  time
• Core (3400 km radius)
• Outer core liquid iron
• Inner core - solid iron

mantle
The Earth's total radius is 6480 km
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Geology at Macro and Micro Scales
Geologists study tectonic activity at plate
boundaries using surface observables such as
- Rock and mineral formation Three types of
rocks - Sedimentary rocks -
Igneous rocks - Metamorphic rocks Each
rock is made up of minerals, atoms and elements
with an atomic structure.
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