Alfred Wegener's original theory of continental drift, proposed in 1912, was based on several lines of evidence, including:
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Fit of the Continents: The coastlines of continents such as South America and Africa appeared to fit together like pieces of a jigsaw puzzle.
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Fossil Evidence: Identical fossils of plants and animals were found on continents that are now widely separated by oceans. For example, fossils of the reptile Mesosaurus were found in both South America and Africa, which were not able to swim across the Atlantic Ocean.
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Geological Similarities: There were similarities in rock formations and mountain ranges across continents. For example, the Appalachian Mountains in North America were geologically similar to the Caledonian Mountains in Scotland, suggesting that these land masses were once connected.
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Paleoclimate Evidence: Wegener noted that certain regions now located in temperate or polar climates had evidence of ancient tropical climates, like coal deposits found in Antarctica or glacial deposits in present-day India and Africa.
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Distribution of Glacial Deposits: Patterns of glacial deposits and striations indicated that they once extended over much of the southern hemisphere continents, suggesting those continents were once closer together in a warmer climate.
These pieces of evidence collectively supported Wegener's hypothesis, although it was not widely accepted during his time due in part to the lack of a mechanism explaining how continents could drift. The theory of plate tectonics, developed later, provided the necessary framework to understand this movement.
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