Plate Tectonics

Continental drift

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What was Wegener's theory of continental drift?
Approximately 300 million years ago, there was just one supercontinent. This land mass, Pangaea, broke into smaller chunks which moved apart. He claimed that these chunks - our modern-day continents - were still slowing drifting apart.
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Name on piece of evidence that supports Wegener's theory of continental drift and explain why.
There were fossils of very similar plants and animals that were found on opposite sides of the Atlantic Ocean, which suggested that there had once been land bridges linking the continents, and these bridges had sunk/covered since.
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Name another piece of evidence that supports Wegener's theory of continental drift and explain why.
The coastlines of nearby continents seemed to match like pieces of a jigsaw, e.g. the coastlines of Africa and South America. These continents may have been one continent that split. There were matching layers in the rocks in different continents.
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What were the fossils found in the matching layers of rock like and why did this support the theory?
The fossils were in the 'wrong' environments. Fossils of tropical plants had been discovered on Arctic islands where the present climate would have killed them off. Therefore, the continents must have split for this to be possible.
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What was Wegener's theory for how the land masses 'drifted' away from one another?
Wegener thought that the continents were 'ploughing through' the sea bed, and that their movement was caused by tidal forces and the Earth's rotation.
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Why was this idea about how the continents drifted treated with hostility?
Other geologists said this was impossible because one scientist calculated that the forces needed to move the continents like this would also have stopped the Earth rotating.
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Why were Wegener's predictions irrational?
He had used inaccurate data in his calculations.
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What was one of the reasons why Wegener himself was not trusted by other scientists?
He wanted a professional geologist; he was an astronomer.
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What evidence was later found to support Wegener's theory?
Scientists were able to investigate the ocean floor and found new evidence to support the theory. This proved that his main idea was correct.
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By the 1960s, what conclusion had geologists made about the Earth as a result of the continental drift theory?
The Earth's crust is made of several chunks called tectonic plates which move about, and that colliding chunks push the land up to create mountains.
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Other cards in this set

Card 2

Front

Name on piece of evidence that supports Wegener's theory of continental drift and explain why.

Back

There were fossils of very similar plants and animals that were found on opposite sides of the Atlantic Ocean, which suggested that there had once been land bridges linking the continents, and these bridges had sunk/covered since.

Card 3

Front

Name another piece of evidence that supports Wegener's theory of continental drift and explain why.

Back

Preview of the front of card 3

Card 4

Front

What were the fossils found in the matching layers of rock like and why did this support the theory?

Back

Preview of the front of card 4

Card 5

Front

What was Wegener's theory for how the land masses 'drifted' away from one another?

Back

Preview of the front of card 5
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