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What observations led Alfred Wegener to propose continental drift?
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Pangea
Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins near the end of the Permian Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.
Alfred Wegener proposed the theory of continental drift in 1912, suggesting that the continents were once joined in a single supercontinent he named Pangea before slowly moving apart over geologic time.123
His hypothesis was based on several key observations:
- Jigsaw-fit coastlines: Wegener was struck by the visual similarity between the coastlines of eastern South America and western Africa, suggesting they were once connected.124
- Geological evidence: He identified matching rock strata and mountain ranges across widely separated continents, particularly between the Americas and Africa.14
- Paleontological evidence: He noted that identical fossil organisms were found on continents now separated by vast oceans, arguing these species could not have crossed such distances while alive.24
- Climate data: Wegener observed that ancient climate belts and glacial deposits matched across continents when they were reconstructed as a single landmass, supporting the idea that they had drifted from different positions.52
While his observations were later vindicated, his theory was initially rejected because he could not provide a plausible mechanism for how continents moved.123