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Alfred Wegener proposes the idea of Pangaea
Alfred Wegener had an idea that the continents were once one. He called this super continent Pangaea. He had wondered as many school children do why South America and Africa fit together like a jigsaw puzzle. Except unlike them he wasn't afraid to ask why. He had evidence from fossils, climate, and land features; but he lacked the most important thing. That was "What caused the continents to move?". -
Arthur Holmes proposes the idea of convection currents
Arthur Holmes, a British geologist, proposes the idea that convection currents moved the continents. These currents were in the Earth's mantle. His idea did not get much attention until the 1960's. He got more attention because more was known about the ocean floor. Later, other scientists had a similar idea but had more evidence to support them. -
Alexander Du Toit suggests that Pangaea seperated into two continents.
Alexander Du Toit, who was a South African geologist, modified Wegener's hypothesis. He suggested that there were two continents: Gandwana in the south and Laurasia in the north. Du Toit had more evidence than Wegener had, but the hypothesis was still rejected. Du Toit's modification shows that Pangaea seperated into two continents. -
Harry Hess suggests sea-floor spreading
Harry Hess,who was a Princeton University geologist,was in the U.S. Navy during World War II. While moving between battles he would perform echo-sounding surveys in the Pacific Ocean. He discovered that in the middle of every ocean was a mid ocean ridge. This research led him to a hypothesis called sea-floor spreading. This was the evidence that Wegener needed to support his hypothesis, a moving sea floor.