GEOLOGIC TIME - Earth is 4.65 Ga old

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GEOLOGIC TIME - Earth is 4.65 Ga old

• A diagrammatic representation of the last 3.8
  billion years of the geological time scale of the
  Earth showing the different groups of organisms
  that evolved through time. Note that man's
  presence on earth represents just an extremely
  small fraction of the 3.8 billion year history of
  life on Earth. On a 24 hour clock, our species,
  Homo sapiens, appeared at 2 seconds before
  midnight.

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GEOLOGIC TIME SCALE

• Geologic time terms
• Eon
• Era
• Period
• Epoch
• Age
• Two Eons
• Precambrian
• (4.7 Ga - 544 Ma)
• Phanerozoic
• (since 544 Ma)
• Ma million years
• Ga billion years

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GEOLOGIC TIME SCALE

• Be aware of the Geologic Time Scale in general.
• What is the Jurassic Period?
• When did it begin?
• Why is it important to oceanography?
• What is the Pleistocene Epoch?
• When did it begin and end?
• Why is it important to oceanography?

Hadean
4.65
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SEDIMENT DISTRIBUTION PROCESSES(continued)

• transportation agents
• ice (glaciers)
• wind (e. g., coastal sand dunes)

• Water
• rivers
• oceans
• waves
• tides
• currents
• storms
• review water cycle (lesson 1)

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• Roter Kamm crater, Namibia (27.7S
  16.3E) Recent High altitude oblique photograph
  from the Space Shuttle (November 1990). One of
  the world's clearest craters formed by the impact
  of an extraterrestrial bolide stands out in this
  arid landscape. Note the raised rim of the
  crater, a common feature of both volcanic and
  bolide craters. This is a moderate sized impact
  crater, 2.5 kilometers (1.5 miles) in diameter
  rim to rim, and is 130 meters (400 feet) deep.
  However, its original floor is covered by sand
  deposits at least 100 m (300 ft) thick. It is
  thought that this crater was formed only about 5
  million years ago. Because of rapid erosion on
  Earth, older craters are much more difficult to
  recognize. Many scientists believe, however,
  that bolide impacts have had a significant
  "impact" on the evolution and partial extinctions
  of life on earth.

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• Clearwater Lakes, northwestern Quebec, Canada.
  Modern High altitude oblique photograph from the
  Space Shuttle (October-November 1985). Strongly
  eroded craters in Precambrian rocks of the
  Canadian Shield. The craters were formed by
  meteorite impacts dated at about 300 myBP.

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• Stanley Miller's experimental apparatus for
  producing organic molecules from a mixture of
  gases believed to be similar to the Earth's
  primitive atmosphere.

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• Chancet Cliffs, Ward Beach, NE corner of South
  Island, New Zealand Modern Kelp beds and tidal
  pools along a rocky coastline. Some scientists
  have proposed that life on Earth could have
  originated in such settings although others feel
  that oceanic vents are more likely sites.

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• East Pacific Rise (21N), North Pacific Ocean.
  Recent. From joint US-French-Mexican RISE
  expedition (1979). Top of black smoker chimney
  in an ocean-ridge axial valley. Such sites have
  been proposed as the potential environments in
  which life on earth began.

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• Channel north of Lee Stocking Island, Exuma
  Islands, Bahamas. Modern. Giant stromatolites
  exposed showing the different growth forms on
  their tops and sides. The nature of the
  encrusting sessile plants and organisms forming
  the microbial mats changes throughout the year
  and depends on the time of their exposure. If
  exposed in the summer an entirely different type
  of plant and animal community colonizes the
  surface than if exposed in the colder winter
  months.

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• Northwest Territories, Canada Precambrian, ca.
  1.8 Ga Pethei Group Mid-Precambrian reef Facies
  Strongly elongate stromatolites formed as part of
  prograding reefal rim. The domes are remarkably
  similar in morphology to modern forms from Shark
  Bay, Australia. Hammer

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• Carbla Point, Shark Bay, Western Australia,
  Australia Recent Large head-shaped
  algal/cyanobacterial stromatolites in the upper
  intertidal zone of a hypersaline, tidal basin.
  Note elongate club shape of many of the algal
  heads -- this is produced by strong tidal current
  action. Structures similar to these are common
  in Precambrian rocks, indicating that this may
  have been what much of the coastal world looked
  like for about two to three billion years.

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• A diagrammatic representation of the buildup of
  atmospheric oxygen through geological time on
  Earth. Oxygen was probably generated largely
  though the metabolism of simple plants, mainly
  photosynthetic algae and/or cyanobacteria.
  During early history, production was consumed by
  the large volume of reactive, unoxidized
  inorganic materials at the Earth's surface. The
  long-term rise of oxygen was slowed and
  eventually balanced through animal respiration
  and biomass burning.

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