Geology Test 2

Last update by Shanal on 11/01/2013
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What is normal Polarity?

Answer:
Today's magnetic field

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  • erober92
    Answered in Geology Test 2
    Reversed polarity

    180 degrees from todays field.

  • erober92
    Answered in Geology Test 2
    Does the polarity of the earth ever change?
    Yes-- The polarity of Earth's magnetic field flops back and forth on an irregular basis, with intervals ranging from a few tens of thousands of years, to millions of years.
  • erober92
    Answered in Geology Test 2
    What is denclination?
    Denclination is the angle between magnetic north (the direction the north end of a compass needle points) and true north.
  • erober92
    Answered in Geology Test 2
    How does Remnant Magnetism work?

    When hot rocks cool through the Curie Point (550 degrees centigrade) they lock in the Earth's magnetic field (polarity and declination).
  • erober92
    Answered in Geology Test 2
    What are the paths of apparent polar wandering?
    1. Declination of ancient rocks do not point to the modern pole position.
    2. Layered rocks of different ages at the same location have changing magnetic declinations.
    3. Rocks of the same age on different continents have magnetic declinations that do not point to the same location.
  • erober92
    Answered in Geology Test 2
    What causes this? Do the MAGNETIC POLES wander?

    No! The continents wander! Wegener was on to something!

  • erober92
    Answered in Geology Test 2
    What was used to map the bathymetry of the sea floor?
    Sonar
  • erober92
    Answered in Geology Test 2
    What was discovered on the sea floor?
    1. Long continuous mountain chains- ridges
    2. Trenches-- deep valleys on the sea floor
    3. Continental Shelves
    4. Abyssal Plains
  • erober92
    Answered in Geology Test 2
    How does the theory of sea floor spreading work?
    1. The sea floor moves laterally away from the ocean ridges
    2. Magma rises up to the sea floor ridges
    3. The magma hardens to form new seafloor
    4. The ridges crack in half and move apart from each other.
  • erober92
    Answered in Geology Test 2
    What evidence supports sea floor spreading?

    1. The age of the sea floor
    2. Seafloor sediment thickens away from the ridge
    3. Valleys (tensional features) run down the center of the ridges
    4. Paleomagnetism- Magnetic stripes on the seafloor

  • erober92
    Answered in Geology Test 2
    What is the age of the oldest seafloor?
    180 million year ago