Geography exam-style question 1: Structure of the Earth and Covection Currents

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Is the crust a high or low density?
Low density.
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Why is the crust of this density?
So it can float on the more fluid, flexible mantle.
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What is the lithosphere?
The upper mantle and the crust.
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Is the mantle solid or liquid?
Solid.
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Where are convection currents?
In the mantle.
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Is the lower mantle solid or liquid?
Liquid.
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What is the asthenosphere?
The upper mantle.
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Is the lower mantle dense or not?
Dense
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How can the lower mantle be described?
Sticky, viscous, dense rock, slowly moving in great convection currents?
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Describe the movement of the mantle.
It is like soup. When heated, it rises to the surface, spreads and begins to cool, then sinks to the bottom, reheats and rises again.
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How does the flowing action in the asthenosphere affect the lithosphere?
It causes volcanoes and earthquakes.
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Is the outer core solid or liquid?
Liquid
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What are plate tectonics?
The constant pressure building up beneath the surface, breaking the crust up.
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What happens as a result of a constructive plate margin?
Deep cracks in the crust allows magma to rise to the surface and cool to form a new crust in a ridge shape.
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What are the largest plates?
Pacific and Atlantic.
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What type of rock is the continental crust made of?
Granite.
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What type of rock is the oceanic crust made of?
Basalt.
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Why do the plates vary in thickness?
To compensate for the imbalance in density.
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Why don't the massive slabs of solid rock remain on Earth's surface?
The rocks are of a different density, so the more dense, oceanic crust is subducted.
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What drives convection currents?
Heat of core.
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What causes the core to be so hot?
Partly the pressure of the overlying material, but also the radioactivity of the core itself.
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What causes the constant cycle of rising and sinking?
The difference in temperature with depth.
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How does the temperature of the core compare to that of the Sun?
They are the same temperature.
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In what part of the Earth do the currents generate Earth's magnetic field?
Outer core.
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What are convection currents?
Circulating movements of magma in mantle (which are driven by heat in the core).
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Describe the state of the asthenosphere.
Semi-molten.
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Describe the motion of convection currents.
They cool, spread out, rise and sink again.
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What is a hotspot?
A spot on the mantle that is anomalously hot causing lots of volcanic activity.
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What is direct evidence?
Evidence from exploring inside the Earth.
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What is indirect evidence?
Earthqakes and material from space.
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What is the purpose of the asthenosphere?
To act as a layer of lubrication. It is mostly solid so the plates don't sink in and is like very very dense hot porridge.
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What are plate boundaries/ margins?
Areas where plates meet.
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Other cards in this set

Card 2

Front

Why is the crust of this density?

Back

So it can float on the more fluid, flexible mantle.

Card 3

Front

What is the lithosphere?

Back

Preview of the front of card 3

Card 4

Front

Is the mantle solid or liquid?

Back

Preview of the front of card 4

Card 5

Front

Where are convection currents?

Back

Preview of the front of card 5
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