Oceans have been created, and oceans have been destroyed many times in the Earth’s history by plate tectonics. In this chapter we shall meet Alfred Wegner and learn about his early theory of continental drift and its problems. Rivals to Wegner’s theory were the shrinking Earth theory and the expanding Earth theory, but they had problems of their own. We will meet Marie Tharp and her discovery of the great rift valley that encircles the globe. The “Rosetta Stone” for plate tectonic theory was the discovery of magnetic “stripes” on the ocean floor created by episodic reversals of the Earth’s magnetic field. The disintegration of Pangea 170 million years ago and the rise and fall of the Tethys Ocean 6 million years ago are merely brief stages of the cycle of the birth and death of oceans.
KeywordsAlfred Wegener Pangea Continental drift Plate tectonics Marie Tharp Bruce Heezen Harry Hess Seafloor spreading Paleomagnetism Magnetic north pole Panthalassa Ocean Tethys Ocean
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