Read an Academic Passage

[1]In 1912, the German scientist Alfred Wegener proposed that the continents had once been joined in a single landmass and had slowly moved apart. He pointed to several kinds of evidence. The coastlines of South America and Africa fit together like puzzle pieces, and fossils of the same land animals and plants had been found on continents that are now separated by oceans.

[2]Most geologists rejected the idea. Their main objection was not to the evidence of a shared past but to the lack of a convincing mechanism. Wegener could not explain what force was strong enough to push entire continents through the solid rock of the ocean floor, and the forces he suggested were shown to be far too weak.

[3]Opinion changed only in the 1960s. Studies of the seafloor revealed long underwater mountain ranges where new crust forms and spreads outward, and the magnetic patterns in the rock on either side of these ridges matched each other. These findings supplied the missing mechanism: continents do not plow through the ocean floor but are carried on moving plates. Decades after his death, Wegener's central idea was accepted as part of the theory of plate tectonics.