Plate Tectonics. Search for:. Theory of Continental Drift The continental drift hypothesis was developed in the early part of the 20th century, mostly by Alfred Wegener. Scientists used magnetometers, devices capable of measuring the magnetic field intensity, to look at the magnetic properties of rocks in many locations.
Geologists noted important things about the magnetic polarity of different aged rocks on the same continent. Magnetite crystals in fresh volcanic rocks point to the current magnetic north pole no matter what continent or where on the continent the rocks are located.
Older rocks that are the same age and are located on the same continent point to the same location, but that location is not the current north magnetic pole. Older rock that are of different ages do not point to the same locations or to the current magnetic north pole. In other words, although the magnetite crystals were pointing to the magnetic north pole, the location of the pole seemed to wander.
Scientists were amazed to find that the north magnetic pole changed location through time. There are three possible explanations for this: 1 The continents remained fixed and the north magnetic pole moved. Geologists noted that for rocks of the same age but on different continents, the little magnets pointed to different magnetic north poles.
For example, million-year-old magnetite in Europe pointed to a different north magnetic pole than the same-aged magnetite in North America. Around million years ago, the north poles were also different for the two continents.
The scientists looked again at the three possible explanations. Only one can be correct. The most poignant attack came from a father-son duo. Chamberlin had launched his career with an iconoclastic attack on establishment thinking. He went on to define a distinctly democratic and American way of doing science, according to historian Naomi Oreskes. By the s, Chamberlin was the dean of American science and his colleagues fawned that his originality put him on a par with Newton and Galileo.
Rollin T. For decades afterward, older geologists warned newcomers that any hint of an interest in continental drift would doom their careers. Wegener took the assault as an opportunity to refine his ideas and address valid criticisms. When critics said he had not presented a plausible mechanism for the drift, he provided six of them including one that foreshadowed the idea of plate tectonics.
When they pointed out mistakes—his timeline for continental drift was far too short—he corrected himself in subsequent editions of his work. But even he would have been astonished by the charges against the Italians for failing to turn continental drift into a predictive device; that trial is expected to continue for months.
The turnabout on his theory came relatively quickly, in the mids, as older geologists died off and younger ones began to accumulate proof of seafloor spreading and vast tectonic plates grinding across one another deep within the earth. Today we have all learned at school—or even before, in cartoons—the theory of continental drift. But Wegener died in , long before his success was recognised.
During an expedition in Greenland, he left the camp for supplies and was found frozen months later. He was buried there and is still there, although he is now about two metres further away from his birthplace in Berlin.
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