The Earth in the Universe (1)

Gap-fill exercise

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Arthur presented his theory of drift in 1912. He did provide evidence that the continents were once together. He noted that the of the continents seemed to match, like a jigsaw. He also found identical plants in both South Africa and South . He also found evidence of similar zones millions of years ago. Coal deposits of the same age have been found in Europe and in North America. Evidence of the same ice age millions of years ago has been provided from geological studies in Australia, South Africa, Brazil and Antartica. This suggests that these continents were once close together near the Pole

In the 1920's Arthur was able to explain the formation and destruction of continental plates. The behaves as a thick liquid. It is forced, under pressure, to move in a current. This movement should provide the force necessary to move the continents. Also, in the 1020's. a Japanese geoplogist, Monotori Mutayami noticed that the particles in rocks reversed direction over long periods of time. They recorded the direction of the Earth's magnetic field. Further evidence of the reversal of magnetism in rocks was discovered in 1960's. As the distance from oceanic ridges increases, the magnetism changed direction again and again. This happened on sides of an oceanic ridge. This provided evidence that the magma was being forced up and outwards forming new rock. The newest rocks were being found nearest the oceanic ridge.

In 1967 a new theory, based on the evidence of the spreading of the sea floor, was introduced. This theory is call plate . In this theory the is made up of a collection of plates. These plates constantly move very slowly over a year. Sometimes the pressure can become very high as they collide, move apart, or against each other. occur when the pressure is released suddenly.