The Origin of Continents and Oceans
The continents fit together like the torn halves of a map — they were once one.
Look at a world map: the eastern hump of South America fits the western dent of Africa like two pieces of a torn page. Wegener said that is no accident — they were once joined.
The idea, unpacked
Wegener proposed that the continents are not nailed in place. Long ago they were packed together into one giant landmass; since then they have slowly drifted apart to where they are now.
He didn't rest the case on the coastlines alone — that could be a fluke — but on the way the rocks and fossils on either side of the Atlantic continue each other, as if you had torn a printed page in two and found the sentences still running straight across the rip.
A meteorologist out of his lane
Wegener was a meteorologist and polar explorer, not a geologist. On 6 January 1912, in Frankfurt, he stood before the Geological Association and argued that continents move — and published the idea that same year. He spent the next two decades gathering evidence and expanding it into a book, The Origin of Continents and Oceans, through four editions. Most geologists rejected it: partly because he could not say what force could shove a continent across the globe, and partly because he was an outsider. He died in 1930 on the Greenland ice cap, still unvindicated.
Why it mattered
Wegener was right, and almost everyone else was wrong — a rare, clean case in science. He saw the single fact (the continents move) that ties together coastlines, mountain ranges, fossils and ancient climates, and he saw it forty years before anyone could explain how. When the explanation finally came — the seafloor itself spreads — it confirmed him and reorganized all of geology around moving plates. The ground under your feet is part of a slab gliding a few centimetres a year, about as fast as your fingernails grow.
The torn newspaper
Wegener's own image: imagine tearing a sheet of newspaper in two. You can tell whether two scraps were once joined not just by matching the ragged edges, but by checking whether the printed lines run straight across the tear. The coastlines are the ragged edges; the rock layers and fossil beds are the lines of print — and they line up.
Before and after
The matching Atlantic coasts had been noticed for centuries — the mapmaker Abraham Ortelius suggested as early as 1596 that the Americas had been “torn away” from Europe and Africa — but the resemblance was waved away, or explained by land bridges that had conveniently sunk. After Wegener came the missing engine: in the 1960s, seafloor spreading and the magnetic stripes of the ocean floor turned “continental drift” into “plate tectonics”, the framework that now explains earthquakes, volcanoes and mountain ranges alike.
It is just as if we were to refit the torn pieces of a newspaper by matching their edges and then check whether the lines of print run smoothly across. If they do, there is nothing left but to conclude that the pieces were in fact joined in this way.