Introduction to Geology

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Introduction to Geology
Geology Knowlege or study of the
Earth." Physical geology examines the
materials and processes of the Earth. Historical
geology examines the origin and evolution of our
planet through time.
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USES OF ROCK

• Source of power
• Source of minerals
• Source of soil
• Source of building and road making materials
• Source of industrial raw materials
• Source of gems and precious metals

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Geology in the News
http//news.nationalgeographic.com/news/2003
San Andreas Fault
Geologic Hazards

• Two die in 6.5 magnitude Earthquake near San Lois
  Obispo California
• Earthquake triggers mudslides

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Geology in the News 2
Major Quake Likely to Strike San Francisco Bay
Region Between 2003 and 2032
Dealing with Geologic Hazards

• Assessing Risks
• Avoiding Risks
• Preventing Damage
• Predicting Impact

http//quake.wr.usgs.gov/research/seismology/wg02/
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Earthquake Bam, Iran
Photos from AP

• A Magnitude 6.5 Earthquake hits a stone- and
  mud-house city of 100,000 in Iran 12-26-03
• 30,000 Dead
• 30,000 Refugees
• US sends aid and releases sanctions
• Relations improved

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Geological Hazards
Volcanoes
Landslides
Earthquakes
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Geology in Engineering
Slope Failure Risk Assessment and Control
To prevent slope failure engineers must
understand the geology that forms and controls
the slope
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Geology in Engineering
The Leaning Tower Straightens Up
In Pisa the tilted one is back in business after an 11-year effort to keep it from collapsing

Committee member John Burland, an engineer,
promoted soil extraction as the best way to save
the tower.
Engineers use knowledge of geology to design,
protect and correct structures
www.smithsonianmag.si.edu
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ESS

What's the first thing that you notice about our
planet when you see this image?
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The Earth System
What are some of the interactions between these
spheres?
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ESS
The Earth System
Hydrosphere The oceans cover 71 of our planet
and represent 97 of all the water on our planet.
Atmosphere The thin blanket of air that
covers our planet. It is not only the air we
breathe, but protects us from harmful radiation
from the sun.
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ESS
The Earth System
Biosphere includes all life on Earth -
concentrated at the surface. Plants and animals
don't only respond the their environment but also
influence it. Solid Earth (Lithosphere) The
majority of the Earth system.
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The Origin of the Earth

• Nebular Hypothesis The Earth, the other 8
  planets and the Sun accreted from a vast cloud of
  dust and gas (nebula).
• Gravitational contraction (5 BYA)
• Rotates and flattens.
• Solar fusion (4BYA)
• Newly formed planets begin to differentiate
• heavier elements and chemical components sink to
  the center and rocky material formed the crust.

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Earth's Internal Structure
The Earth's interior is characterized by a
gradual increase in temperature, pressure and
density with depth. At only 100 km depth, the
temp is 1300C. At the Earth's center, the
temperature is gt6700C. The pressure in the
crust increases 280 bars for every kilometer
depth.
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Earth's Internal Structure

• The Earth consists of 3 major regions marked by
  differences in chemical composition.
• Crust (Lithosphere) rigid outermost layer of
  the Earth. Consists of two types
• 1. oceanic - 3-15 km thick and is composed of
  basalt (igneous). Young (lt180 million years old).
• 2. continental - up to 70 km thick and composed
  of a wide variety of rock types (ave.
  granodiorite). Ranges from young to old (gt3.8
  billion years old).

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Earth's Internal Structure

• Mohorovicic Discontinuity The slip surface
  boundary between the crust and the mantle.
• Mantle comprises 82 of the Earth by volume
  and is 2900 km thick.
• Change in composition occurs.
• Asthenosphere is the soft, solid but ductile
  region just below the lithosphere.
• The mantle is able to flow (plasticity) at very
  slow rates.

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Earth's Internal Structure

• Core composed of iron, nickel and other minor
  elements.
• Outer core is liquid, capable of flow and source
  of the Earth's magnetic field.
• Inner core is solid Fe-Ni. There is no major
  chemical difference between the outer and inner
  core.