Anyone who looks carefully at a map of the Atlantic Ocean is likely to be struck by an interesting point. The eastern coastline of South America bears a striking similarity to the western coastline of Africa. Indeed, it looks almost as if the two continents could somehow fit together--provided, of course, one could find a way to slide the land masses across the ocean floor.

The match of coastlines was noticed by scholars almost as soon as good maps were first available in the late fifteenth century. In 1620, for example, the English philosopher Sir Francis Bacon commented on this fact and argued that the match was "no mere accidental occurrence."

One obvious explanation for the South America-Africa fit was that the two continents had once been connected and had somehow become separated in the past. A few early scientists tried to use the Biblical story of...