The Idea Geologists Mocked for Fifty Years

Alfred Wegener was a meteorologist, not a geologist, which was held against him. In 1912 he published a paper arguing that the continents had once formed a single landmass — Pangaea — and had since drifted apart. He pointed at the obvious jigsaw fit between West Africa and eastern South America, the matching fossil beds of the small reptile Mesosaurus on both sides of the Atlantic, and rock formations that lined up across the join.

The geology establishment ridiculed him. Wegener could explain what but not how. He proposed that continents plowed through ocean crust, and the physics of that didn't work. The American geologist Rollin T. Chamberlin wrote in 1928 that if Wegener's theory were true, "we must forget everything which has been learned in the last 70 years and start all over again." Wegener died in Greenland on an expedition in 1930, his idea still dismissed.

The rescue came from the seafloor. After World War II, magnetic surveys of the mid-Atlantic ridge revealed long stripes of alternating magnetic polarity running parallel to the ridge, mirrored on either side. Drummond Matthews and Fred Vine in Cambridge worked out in 1963 what the stripes meant. New crust was being made at the ridge, recording the Earth's magnetic field as it cooled, then spreading sideways. By 1965 J. Tuzo Wilson had stitched the picture together: the surface of the planet is broken into rigid plates that are made at ridges, consumed at trenches, and slide past each other along faults.

Wegener had been right about the destination and wrong about the vehicle. The continents do move. They just ride on plates instead of plowing through the ocean.