The division of the world into land and sea seems so
natural and timeless that it is hard to imagine it any other
way. Yet the very existence of continents and oceans is unique to
planet Earth, and their behaviour is even more remarkable.
Early in the 20th century, a German meteorologist named
Alfred Wegener noted the extraordinary way coastlines of
continents seemed to match across the oceans, like the separated
pieces of a vast jigsaw. He suggested that this was because the
continents were once joined together and the oceans between
them opened up as they split apart and drifted around the
world over many millions of years.
