John Tuzo Wilson's Theory of Plate Tectonics

On July 24, 1965 the British journal Nature published an article that revolutionized the way we all understand the Earth. The paper was written by the Canadian scientist John Tuzo Wilson, a man gifted with stunning vitality and extraordinary intuition. Scientific American called Wilson's explanation of the new theory of plate tectonics "one of the century's five major advances in science."

Wilson was born in Ottawa, the son of a Scottish engineer father and an adventurous, mountain-climbing mother. When in the mid-1920s he switched majors in university from physics to geology, his teachers were appalled. Physics was then in its Golden Age, uncovering the secrets of the universe. Geology was considered a field as intellectually respectable as collecting postage stamps.

Not least among geology's problems was the complete lack of understanding of the processes that create the Earth. How do continents form? What causes volcanoes or earthquakes? If the continents have always been where they are today, as everyone believed, why do distant parts of the world, especially South America and Africa, look like matching pieces in a jigsaw puzzle?

The idea that the continents actually move was first considered early in the 20th century. German meteorologist Alfred Wegener suggested that the continents "drifted," but no one took him seriously because he could not explain why. Opposition to the idea was universally vitriolic.

Geologists were never going to solve these mysteries, no matter how much time they spent with magnetometers, microscopes and hammers. They needed a new science and a theory that would explain the Earth. "It was the bluff, genial, approachable, and down-to-earth University of Toronto professor J. Tuzo Wilson who ... in essence created the new science," writes Simon Winchester in his book Krakatoa.

Wilson developed his theory of "plate tectonics" after several brilliant insights. First was the curious case of the Hawaiian Islands. Flying over the islands he saw something that the ancient Hawaiians had always suspected. While the big island of Hawaii itself was still a furnace of volcanic activity, the more distant island of Niihau was half dead, and clearly much older. Wilson deduced that there must be a stationary "hot spot" over which the islands moved. The mantle and crust along the chain of islands must be moving!

Wilson's second realization was a true Eureka! It came after he was experimenting with paper and a pair of scissors while on sabbatical in Cambridge. "I have discovered a new class of fault" he declared to his colleagues. "Rubbish" was the response. Wilson would just grin and show the skeptics a simple folded paper version of his new kind of fault by opening and closing his folded paper. "I was seeing something profoundly new and important," wrote John Dewey afterwards, "and that I was talking to a very clever and original man."

Wilson's new kind of fault explained why the great ridges down the centre of the Atlantic and Pacific oceans were incised by dozens of deep gashes. He gave the name "transform fault" to the new phenomenon. He made a paper and crayon diagram, cut it out and kept it in his wallet ready to show to anyone. Anyone who saw the impromptu demonstration knew that he was right.

"Many geologists have maintained that movements of the Earth's crust are concentrated in mobile belts, which may take the form of mountains, mid-ocean ridges or major faults," wrote Wilson, "this article suggests that these features are not isolated, that few came to dead ends, but that they are connected into a continuous network of mobile belts around the Earth which divide the surface into several large rigid plates."

This was Wilson's proof of the theory of plate tectonics. The day of believing that the continents had always been where they stand now was done. It was an incredibly exciting time for scientists. They could now see the Earth whole, with the oceans coming apart at the seams and the crust and upper mantle spreading across the ocean floors.

Wilson's distinguished career continued even after he quit university. As director of the Ontario Science Centre, he famously had "Please Touch" signs posted on the exhibits. He taught his new theory in more than 100 countries, taking time off to sail his Chinese junk in Georgian Bay and to climb the occasional mountain.