Sea-floor spreading, Paleomagnetism and Convection Currents

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  • Created by: OctaviaL
  • Created on: 31-05-16 18:40
What provides evidence for sea-floor spreading?
Alternating magnetic polarity of ocean crust either side of Mid-Atlantic Ridge and the crust gets older with distance from the ridge.
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What is paleomagnetism?
Iron particle in lava erupted on the ocean floor are aligned with Earth's magnetic field. As the lavas solidify, these particles provide a permanent record of Earth's polarity at the time of eruption.
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Approximately how often does Earth's polarity reverse?
Every 400,000 years.
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What gave evidence of plates being destroyed to counteract sea-floor spreading?
Huge ocean trenches where large areas of ocean floor have been pulled down.
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What forms hot spots in the mantle?
Radioactive decay of elements around the core.
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What creates convection currents?
Lower parts of the asthenosphere heat up so become less dense and slowly rise. As they move up the diverge before cooling again, becoming more dense and sinking.
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How do the convection currents move the plates?
They create drag along the base of the tectonic plates.
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Other cards in this set

Card 2

Front

What is paleomagnetism?

Back

Iron particle in lava erupted on the ocean floor are aligned with Earth's magnetic field. As the lavas solidify, these particles provide a permanent record of Earth's polarity at the time of eruption.

Card 3

Front

Approximately how often does Earth's polarity reverse?

Back

Preview of the front of card 3

Card 4

Front

What gave evidence of plates being destroyed to counteract sea-floor spreading?

Back

Preview of the front of card 4

Card 5

Front

What forms hot spots in the mantle?

Back

Preview of the front of card 5
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