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This is cited from Cambridge International A and AS level Geography book by Garrett Nagle and Paul Guinness. "In 1912 Alfred Wegener proposed the idea of continental drift. Others, such as Francis Bacon in 1620, had commented on how the shape of the coast of Africa was similar to that of South America. Wegener proposed that the continents were slowly drifting about the Earth. He suggested that, starting in the Carboniferous period, some 250 million years ago, a large single continent, Pangaea, broke up and began to drift apart, forming the continents we know today. Wegener's theory provoked widespread debate initially, but with the lack of a mechanism to cause continental drift, his theory failed to receive widespread support. In the mid-twentieth centrury the American Harry Hess suggested that convection currents would force molten rocks (magma) to well up in the interior and crack the crust above and alternate directions in a series of identical bands on both sides of the ridge. This suggested that fresh magma had come up through the centre and forced the rocks apart. In addition, with increasing distance from the ridge the rocks were older. This supported the idea that new rocks were being pushed apart. In 1965 a Canadian geologist J. Wilson linked together the ideas of continental drift and seafloor spreading into a concept of mobile belts and rigid plates, which formed the basis of plate tectonics. The evidence of plate tectonics includes: 1. The past and present distribution of earthquakes 2. changes in the Earth's magnetic field. 3. the 'fit' of the continents: in 1620 Francis Bacon noted how the continents of either side of the Atlantic could be fitted together like a jigsaw 4. glacial deposits in Brazil match those in West Africa 5. the fossil remains in India match those of Australia 6. the geological sequence of sedimentary and igneous rocks in parts of Scotland match thouse found in Newfoundland 7. Ancient mountains can be traced from east Brazil to west Africa, and from Scandanavia through Scotland to Newfoundland and the Appalachians 8. fossil remains of a small aquatic reptile, Mesosaurus, which lived about 270 million years ago, are found only in a restricted part of Brazil and in south-west Africa. It is believed to be a poor swimmer!"