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Abraham Ortelius
In 1596, Abraham Ortelius first mentions how some continents seem to fit together. He was the first to propose the idea of continental drift. -
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Plate Tectonics
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Sonar Is Invented
In 1906, SONAR is invented to detect icebergs. This technology would help map out the ocean floor,contributing to the theory of sea floor spreading. -
Alfred Wegener's Theory of Continental Drift
Alfred Wegener first proposed the hypothesis that Earth's continents once formed a massive supercontinent he named Pangaea. He also hypothesized that around 200 million years ago the continents began to move apart,slowly coming into their present positions. He had evidence in the form of the same fossils on the coasts of Africa and South America,matching rock types in different parts of the world, and evidence of glaciers where they couldn't have existed, -
Wegener's Hypothesis Is Rejected
Wegener's hypothesis had one major flaw. He couldn't explain what made the continents move. This detail is what made most of his contemporaries reject his hypothesis. Some however, continued to search for evidence of continental drift. -
Harry Hess & Sea Floor Spreading
In 1963, Harry Hess published his hypothesis on sea-floor spreading. He described the process of sea-floor spreading as occuring when new ocean floor appears along mid-ocean ridges,then slowly move outward across ocean basins,and then finally sinking back into the mantle. Evidence to prove his hypothesis include magnetic stripes in ocean floor rock, the age of ocean floor rocks,and earthquake patterns. -
Wilson & The Theory of Plate Tectonics
In the early '60s, J. Tuzo Wilson and a few others developed the Theory of Plate Tectonics. Developed from Wegener's and Hess's hypotheses, Wilson proposed that the lithosphere was broken into several massive pieces called plates. The plates move slowly relative to each other,powered by convection currents in the mantle. Wilson finally explained why the plates moved,and they moved because of convection currents.