Plate tectonics Flashcards
What was Wegener’s theory
Continental drift
What was the evidence for Wegener’s theory
He found fossils of very similar plants and animals were on opposite sides of oceans
What concept did people accept to explain the animals and plants on different sides of the oceans
That there had once been land bridges linking the continents so animals had been able to cross and that the bridges had sunk since then
What else did Wegener notice that led him to believe differently to everyone else (2)
That the coastlines on Africa and South America seemed to match - like a jigsaw.
There was matching layers in the rocks in different continents
What happened in 1915
Wegener felt he had enough evidence and published his theory of continental drift
What did Wegeners theory officially state
That there had once been one supercontinent 300 million years ago and that it had broke into smaller chunks and moved apart; he said that these chunks were still slowly moving apart.
What was the name of the supercontinent
Pangea
Why wasn’t Wegener’s theory accepted
His explanation wasn’t very convincing
He used inaccurate data in his calculations
Geologists said it was impossible
Why did people think Wegener’s theory was unconvincing
He said that the plates ploughed through the sea bed and that their movement was caused by tidal forces
What did Wegener actually study that discredited him
Astronomy
What happened in the 1950’s
Scientists discovered new evidence on the ocean floor to support Wegener’s theory
