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In 1915, Alfred Wegener published the first edition of "The Origin of Continents and Oceans," in which he laid out his Continental Drift hypothesis and the evidence that he had amassed to support it. Wegener proposed that continents were not only capable of moving across ocean basins, but they had in fact done so, merging to form the supercontinent of Pangea approximately 250 million years ago. Pangea subsequently broke apart and the continents slowy made their way to their present positions. Wegener presented arguments based on geodesy, geophysics, geological relationships, paleontology and climate. The most often cited is the match of the coastlines of Africa and South America, Europe and North America. Reconstruction of these continents also explained the unusual distribution of terrestrial fossils--organisms which otherwise would have had to cross thousands of miles of open ocean, or else rely on hypothetical "land bridges" that some scientists envisioned spanning the Atlantic Ocean.
As anyone working on a jigsaw puzzle knows, its not enough to match up the shape of the pieces; the illustration must match also. In the case of continental drift the geological, paleontological and climatic features preserved on the continents represent the illustration. In the case of geological and climatic features, the matches are quite compelling. The paleontology was more difficult to interpret, and Wegener made several mistakes in his biological arguments which caused many scientists to discount his entire hypothesis. By far the biggest objection to Continental Drift, however, came from the geophysical community, who balked at the complete lack of any plausible mechanism by which massive continents could actually move intact through ocean basins. It wasn't until the 1950's and the development of instrumentation enabling geophysicists to explore the ocean floor that a new way of looking at Wegener's arguments was conceived.
In this activity, students are asked to use an interactive
map to attempt their own reconstruction of Pangea.
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Tectonics 1.0 To use this interactive puzzle, move the continents around by clicking on and dragging them to the desired location. They can also be rotated with the rotation wheel. The Pangea On button turns on an underlayer that outlines the ancient continent of Pangea. The Reset to Modern Day will reset all the continents to their present day locations. |
