What Five Factors Did Wegener Use to Support His Theory?
In proposing the theory of continental drift, Alfred Wegener relied on evidence from the shape of the continents, the distribution of plants and animals, similarities between landscapes, contiguous veins of ore that ran between continents, and the distribution of glacial deposits. Though the evidence for his hypothesis was strong, the theory lacked a mechanism and was not generally accepted during Wegener's lifetime.
Wegener's first line of evidence that the continents once formed a single landmass was the shape of the continents themselves. By ignoring the changeable coastlines and focusing instead on the continental shelves, Wegener showed that Africa and South America could fit together nearly seamlessly. In addition, the landscape of South Africa's Great Karoo is very similar to the Santa Catarina formation in Brazil. Wegener argued that they were once a single contiguous feature.
Wegener also discounted the then-popular land bridge theory as an explanation for the distribution of plants and animals. An ancient network of land bridges would also not be able to explain why certain veins of ore run across Africa, stop at the ocean and then pick up again in South America. Finally, Wegener tallied the locations of glacial deposits from ancient ice ages and showed that their orientation only made sense if the southern continents had once been joined in a single landmass.