Final answer:
Alfred Wegener proposed the theory of continental drift, suggesting that continents were once connected in a supercontinent called Pangaea, based on evidence such as the fit of South America and Africa, fossil correlations, and paleoclimate data.
Step-by-step explanation:
Alfred Wegener proposed the theory of continental drift after noticing that the coasts of South America and Africa appeared to fit together like two interlocking puzzle pieces. This observation was one of the cornerstones of his hypothesis, which he initially conceived in 1910 and later published in 1915. Wegener's theory was supported by several types of evidence: the jigsaw puzzle-like fit of the continents, the presence of matching fossils on widely separated continents, the alignment of mountain ranges, and paleoclimate evidence indicating past positions of continents relative to the polar regions and the equator. He theorized that all continents were once joined together in a supercontinent named Pangaea. Despite the compelling nature of his evidence, Wegener could not provide a convincing mechanism to explain how the continents moved, and his ideas were not widely accepted until the development of the plate tectonics theory in the 1960s.