Chemistry C1 7.2 The restless Earth.

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What is the Earth's crust and upper mantle cracked into?
Tectonic plates which are constantly moving.
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Why do the tectonic plates move?
Because of convection currents in the mantle that are caused by radioactive decay.
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Where do Earthquakes and volcanoes happen?
Where tectonic plates meet, but it is difficult to predict accurately when and where earthquakes will happen.
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What is Wegener's theory?
Theory of continental drift, which was not accepted for many years.
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How much do tectonic plates move?
A few centimetres a year.
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What are convection currents caused by?
Energy released by the decay of radioactive elements heating up the mantle.
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What happens where the tectonic plates meet?
Huge forces build up, eventually the rocks give way, changing shape or moving suddenly causing earthquakes, volcanoes or mountains to form.
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Who was the scientist that put forward the idea of continental drift and when?
Alfred Wegener in 1915.
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Why didn't other scientist accept Alfred Wegener's theory of continental drift at the time?
Because he could not explain why the continents moved.
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What did other scientist believe?
That the Earth was shrinking as it cooled.
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When was Wagener's theory accepted?
In the 1960's scientists found new evidence and the theory of plate tectonics was developed.
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What causes tectonic plates to move?
Convection currents caused by heating of the mantle by energy from radioactivity or decay of radioactive elements.
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Why can scientist not predict when and where earthquakes will happen?
We do not know enough about what is happening inside the Earth/we do not have good enough data or models to make accurate predictions.
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Why were Wegener's ideas not accepted for many years?
He could not explain why the continents moved and they had their own/different/established ideas about the Earth.
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Other cards in this set

Card 2

Front

Why do the tectonic plates move?

Back

Because of convection currents in the mantle that are caused by radioactive decay.

Card 3

Front

Where do Earthquakes and volcanoes happen?

Back

Preview of the front of card 3

Card 4

Front

What is Wegener's theory?

Back

Preview of the front of card 4

Card 5

Front

How much do tectonic plates move?

Back

Preview of the front of card 5
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