Earths Dynamic Systems Hamblin

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Class website www.sci.uidaho.edu/coslab/ -follow
Teaching link to Geology 101
Textbook Earth An Introduction to Physical
Geology by Tarbuck Lutgens
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Tests and Grading   3 Exams 600 pts (200
pts each) Final Exam 350 pts
(cumulative) Email Quizzes 50 pts 1000
pts First Exam 7 February Wed.
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The Earth in Space
You will be here.
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What makes Geology different from Physics or
Chemistry? Geology is Postdictive.as opposed to
Predictive like Chemistry. Postdictive science
is historical in nature. -it is science with a
story
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Age of the Earth 4.5 Billion years 4,600,000,00
0 years Age of the Universe 14 Billion years
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• Time is measured by change
• -Deep time
• -millions billions of years
• -James Hutton (1726-1797) considered the
  father of geological science.
• -postulated a very old Earth
• -formulated concept of Uniformitarianism

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Uniformitarianism

• Laws of nature dont change with time
• Past events explained by modern processes
• Uniformity of Process not Rate
• Assumes vast amounts Deep Time

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Earth Compared to Other Planets

• The Solar System
• The inner planets
• Rocky planets near the Sun
• Mercury, Venus, Earth Mars
• The outer planets
• Giant gaseous planets
• Jupiter, Saturn, Uranus, Neptune
• Pluto, a small icy minor planet

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Origin of the Solar System

• Gravitational collapse of gas dust cloud
  nebula
• Rotation around a central mass
• Disk shaped cloud
• Temperature variations segregated matter
• Small particles accreted into larger
  planetesimals, planets

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How do we Know this?
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Ordinary Chondritic Meteorite -composition of
asteroids and the early solar system
-pyroxene chondrule in thinsection
-chondrules
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Iron Meteorites -actually mixture of Fe and
Ni -planetary cores?
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• Differences between inner and outer planets
• Density
• The rocky inner planetsdensities of
• 3 g/cm3 more
• The gaseous outer
• Planetsdensities
• of 1.6 g/cm3 or less

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Earth

• Internal Heat
• Produces changes in the Earths features
• Sources of internal heat
• Radioactive decay
• Decay releases heat energy
• Accretionary heat
• from Earths formation

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Earths Outermost Layers

• The most dynamic portion of the Earth
• Atmosphere
• Thin gaseous envelope surrounding Earth
• Hydrosphere
• Water layer dominated by the oceans
• Biosphere
• All living things on the planet
• Lithosphere
• Rocky outer shell

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The Atmosphere

• Composition is unique in solar system
• 78 nitrogen
• 21 oxygen (not present in early atmosphere)
• Minor amounts of carbon dioxide, argon and water
  vapor

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The Hydrosphere

• Total mass of water on or near the Earths
  surface
• Covers 71 of Earths surface
• 98 in oceans
• 2 in glaciers, groundwater, lakes and streams
  (fresh water)

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The Biosphere

• All life on Earth
• Animals plants on land, in the sea and air
• Microorganisms-the most common form of life
• Evolved within narrow zone near the Earths
  surface

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Earths Internal Structure

• Solid Earth has a layered structure
• Layers defined by composition and physical
  properties
• Compositional layers
• crust - mantle - core
• Physical layers
• lithosphere - asthenosphere - mesosphere - outer
  core - inner core

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Compositional Layers

• Crust
• Outermost compositional layer
• Definite change in composition at the base of the
  crust
• 2 types
• Continental crust
• Oceanic crust

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Compositional Layers

• Mantle
• Largest layer in the Earth
• 2900 km thick
• 82 by volume
• 68 by mass
• Composed of silicate rocks with abundant iron and
  magnesium
• Density ranges from 3.2 to 5 g/cm3

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Compositional Layers

• Core
• Central mass about 7000km in diameter
• Average density of 10.8 g/cm3
• 16 by volume, 32 of mass
• Indirect evidence of composition
• Metallic iron

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Physical Layers

• Lithosphere
• Crust upper portion of the mantle
• Solid rigid
• Thickness ranges from 10 km beneath oceans to 300
  km in continental areas

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• Crust
• Continental crust
• Thick - up to 75 km
• Lower density - 2.7 g/cm3
• Strongly deformed
• Much older - may be billions of years old

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• Crust
• Oceanic crust
• Thinner - about 8 km
• More dense - 3.0 g/cm3
• Comparatively undeformed
• Much younger - lt 200 million years old

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Majors Features of the Continents

• Shields
• Stable platforms
• Folded Mountains

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Continental Margin San Francisco Monterey Bay
Area