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The British geophysicist, Sir Edward Bullard, 1907-1980. After serving in naval research during World War II, he became director of the National Physical Laboratory in England. Bullard first successfully measured geothermal heat flow through the oceanic crust, establishing that it is similar in magnitude to continental crust heat flow. Then independently of Elsasser he proposed the "dynamo" theory of the Earth's magnetic field: in which the field is generated by the motion of the Earth's liquid iron core undergoing convection. In 1965, Bullard used computer modelling (another first) to study continental drift and found an excellent fit in contour between Africa and South America.
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