Alfred Wegener in 1929. Photo: Alfred Wegener Institute

“All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident.” This summary, usually attributed to German philosopher Arthur Schopenhauer, seem especially true of scientific knowledge. Take plate tectonics. The idea that surface of the earth is constantly changing as continents drift around on top of a layer of molten rock is so well established that it’s hard for most people to imagine otherwise. But exactly 100 years ago today, when a 31-year-old German meteorologist named Alfred Wegener presented this idea at a meeting of the Geological Association in Frankfurt, he was mocked. It would take decades and the work of many other scientists – including some prominent Canadians – to show that plate tectonics are as real as gravity and evolution.

Wegener didn’t pluck his idea out of thin air. Most people who look at a map of the world are struck by how neatly the ‘bulge’ of South America seems to fit into the ‘hollow’ of West Africa, but there’s more to it than that. In the fossil record, species found in places like Nova Scotia are often identical with those found in Europe, but radically different from those found just a few hundred kilometres further inland in North America. The idea that ancient creatures could get themselves from Lisbon to Lunenburg but then couldn’t find their way to Montreal required some explanation. Similar patterns are noted across India, South America, Africa, Australia and Antarctica, which were all once part of a supercontinent called Gondwana. “For this reason, Southern hemisphere geologists were convinced of continental drift long before anyone else,” says Andrew Miall, Professor of Geology at the University of Toronto.

One of the problems scientists had with Wegener was that no known natural process could provide the energy that would be required to move continents around. In a press release from the German research intitute that now bears Wegener’s name, science historian Reinhard Krause asserts that Wegener was entirely aware of this deficiency, yet he never doubted the fundamental correctness of his hypotheses. “He believed that the Newton of continental drift theory would come,” says Krause.

As it turned out, plate tectonics had many Newtons. One was the American geologist and naval captain Harry Hess. Using the newly-invented tool of sonar, Hess mapped many parts of the ocean floor and discovered that there is a contiguous chain of undersea ridges wrapping right around the planet, like the seams on an ancient baseball. He hypothesized that these were places where the seafloor was spreading apart, which would explain how related geological strata could be found on opposite sides of the ocean; the Atlantic wasn’t there when they were laid down. One of Hess’s graduate students was a Canadian, J. Tuzo Wilson. He wrote a series of influential papers in Nature between 1963 and 1968 which supported Hess’s theory of ‘seafloor spreading’. Among other things, he pointed to evidence showing that islands near the ridges were younger than those further away.

But the clincher was evidence from magnetic patterns trapped in undersea iron deposits on both sides of the Atlantic ridge. It turns out that the Earth’s magnetic poles reverse themselves from time to time, and that iron particles in the newly-forming crust along the Atlantic and Pacific ridges align themselves accordingly. By comparing the magnetic patterns trapped in crust from both sides of the ridges, it’s possible not only to show that they are indeed spreading apart, but to calculate the rate (it’s about the same speed as your fingernails grow). Another Canadian, Lawrence W. Morley, wrote a paper on this, but was rejected by both Nature and the Journal of Geophysical Research, only to see it published a few months later by a pair of British researchers, Vine and Matthews.

The skepticism which greeted the unfortunate Morley is characteristic of the attitude toward the new theory, and in some quarters it persisted well into the 1970s. “I was taught nothing at all about the topic in my undergraduate years at University of London, UK, in 1962-1965,” says Miall. “At the International Congress in 1984 in Moscow, it was interesting to note that Russians appeared to have accepted sea-floor spreading but not the drifting of continents . . . how they managed to do this I don’t know!”

Today, 100 years since Alfred Wegener first proposed it, plate tectonics is accepted as fact by pretty much everyone. Modern investigations continue to confirm the theory: a notable Canadian example is the Lithoprobe project, a long-term, multidisciplinary project involving over 900 scientists which produced a wealth of information about Canada’s unique geology. As for the other characters in the story, J. Tuzo Wilson became a well-known proponent of science communication, serving as Director General of the Ontario Science Centre from 1974-1985; to this day a geodetic monument dedicated to him stands outside the front doors. He even hosted his own television program called The Planet Of Man. Here’s a clip from another program in which Wilson comments on the reluctance of the scientific community to accept Wegener’s theory of plate tectonics.

Sadly, Wegener did not live to see his theories embraced. He died on an expedition to Greenland in 1930.

[Big props to mineguy101 who’s got a ton more clips from The Planet of Man on his YouTube site]

1 Comment

Add a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.