The age of the rocks on the floor of the Atlantic Ocean, in which the youngest rocks were in the middle.
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What is the concept in which the plates are moving in the ocean?
Sea-floor spreading- By Harry Hess
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What is the rate of spreading estimated at for a year?
5cm
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What is the study of magnetic field in rocks called?
Palaeomagnetism
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How many years roughly does the magnetic field change?
400,000 Years
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What in rocks records the magnetic orientation of the Earth's magnetic field?
Magnetite (Iron Oxide)
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What two types of plate material is there?
Continental- over 1500 Ma, Oceanic- less than 200 Ma
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Which of the two types of plates is denser?
The Oceanic plate
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What plate often gets subducted?
Oceanic
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What are the varying rates at which plates move relative to each other?
Between 2 and 16cm
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What creates convectional currents?
Hot spots that heat the lower mantle, causing magma to rise, which becomes denser as it cools, causing it to sink again
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What is Gravitational sliding?
The lithosphere thickens with distance away from an MOR, this is because the crust begins to cool, however due to gravity, at some plates the crust gets pushed down at subduction zones.
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What is Ridge Push?
Gravity acting on the weight of the lithosphere near the ridge pushing the older part of the plate in front.
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What is Slab Pull?
The weight of the lithosphere going down a subduction zone causes the rest of the plate to go with it
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Other cards in this set
Card 2
Front
Who updated continental drift?
Back
Harry Hess
Card 3
Front
What did Hess study?
Back
Card 4
Front
What is the concept in which the plates are moving in the ocean?
Back
Card 5
Front
What is the rate of spreading estimated at for a year?
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