Alfred Wegener's Theory of Continental Drift

Wasn't excepted because...
1. Movement wasn't detectable.
2. He wasn't a geologist, he was a meteorologist.
3. It was just after the war and Wegener was German.
4. His possible explanations on why drifting happened were deemed impossible.
  1. Movement could be caused by...
    1. The Earth's rotation.
    2. Tidal forces.
It explained...
1. Why similar fossils of plants and animals had been found on opposite sides of the Earth.
2. Mountain building which happened when continents smashed together.
Instead it was believed...
1. Continents used to be linked by land bridges.
His theory...
1. Africa and South America had been one continent which then split.
2. 300 years ago there was a supercontinent called Pangaea.
3. The continents are moving apart.
It was proven correct in the end because...
1. In the 1950's, scientists investigated the Mid-Atlantic Ridge.
  1. Evidence that magma rises up through the sea floor, solidifies and forms underwater mountains that are roughly symmetrical either side of the ridge was found.
    1. This suggested that the sea floor was spreading.
2. Magnetic orientation of the rocks.
  1. As liquid magma erupts out of the gap, iron particles in the rocks tend to align themselves with the Earth's magnetic field.

Resumo de Recurso

	Criado por Jessica Phillips mais de 10 anos atrás