Mover and Shaker

In 1961, the geophysicist and geologist John Tuzo Wilson looked out over the world’s largest active volcano, Mauna Loa. He saw how, beyond its “smoking crater rim,” the Pacific islands of Maui, Moloka‘i, O‘ahu, and Kaua‘i trace a shallow curve and recede into the distance, “much like a convoy of ships some 600 km long.” Inspiration struck, and Wilson ripped a page from his notebook, flicked his cigarette lighter, and proceeded to move the page horizontally over the flame, “momentarily pausing to burn a hole before pulling the paper onwards, leaving a track of singed craters.” Hawai‘i’s volcanic archipelago, he realized, had been born on the ocean’s floor, originating from a fixed column of red-hot magma bubbling through the earth’s crust. Mountains had arisen from thea sea in succession over millions of years, each moving on to make way for the next. Wilson was witnessing the action of plate tectonics.

Nick Eyles, a professor of geology at the University of Toronto, opens his charming book Tuzo with this memorable anecdote. In doing so, he introduces readers to a man whose “profound insights on the workings of the planet” helped bring about one of the great paradigm shifts of the twentieth century. Today, the accepted theory of plate tectonics holds that the rigid outer layer of the earth — the lithosphere — is broken into pieces (or plates) that move independently over another layer of “hot weakened mantle rocks,” which Wilson called the asthenosphere. But in the early 1960s this concept was far from the consensus view. The dominant opinion, held by the permanentists, was that the position of continents and oceans was fixed. The mobilists challenged that view by claiming that the planetary surface was ever shifting.

After his epiphany, Wilson sided with the mobilists and argued that “the entirety of Earth’s crust was on the move.” He theorized that midocean ridges (“areas of active sea floor spreading”), transform faults (“where crust slides past other crust”), and subduction zones (“where oceanic crust is consumed”) were all connected. Building on and clarifying earlier models — like the theory of continental drift proposed in 1915 by Alfred Wegener — Wilson’s hypothesis imagined the continents as “passengers on a raft” embedded in the crustal plates that ebb and flow constantly. Sometimes plates smash into each other with gargantuan force, thrusting up mountains in a process known as orogeny. And sometimes they grind together, causing earthquakes and tsunamis.

Eyles goes to great lengths to explain the processes that shape the planet while he outlines the contours of Wilson’s career. The result is a memorable portrait of an “unlikely” hero from Ottawa whose “impact on the science of geology and well beyond, is akin to that of Charles Darwin on the biological sciences.” We learn, for instance, that as a teenager Wilson worked for mining companies and helped supervise drilling and blasting into the Canadian Shield. He then pursued degrees in geophysics and geology from the University of Toronto as well as Cambridge and Princeton. After his studies, he worked for the Geological Survey of Canada, mapping a “broad expanse of the Canadian Shield” in the Northwest Territories, on foot. When the Second World War broke out, he enlisted as a sapper with the Royal Canadian Engineers and put his expansive tool kit to use. In 1946, he was awarded the Order of the British Empire in recognition of his contributions to the war effort.

This “revolutionary of plate tectonics” was also a champion of education. He taught at the University of Toronto from 1964 to 1974 and lectured in seventy-three countries. He also served as the director of the Ontario Science Centre, in Toronto, from 1974 to 1985. Years later, that museum would honour his memory with a huge railroad spike driven into the earth. The sign in front of the sculpture asks viewers to imagine the structure penetrating right down through the North American plate, which shifts westward a few centimetres every year. Next to the iron shaft, a 2.3-metre section of pavement is torn up to symbolize how far the plate moved during Wilson’s lifetime.

Today the geologist’s legacy can be found across the globe. About 200 kilometres west of Vancouver Island, the Tuzo Wilson Seamounts — two active volcanoes likely created by the same hot spot phenomenon that triggered that eureka moment back in 1961 — sit 1,410 metres beneath the water’s surface. In Antarctica, a mountain group rising approximately 1,600 metres bears Wilson’s name. And the model that describes the “life history of individual ocean basins” and sea floor spreading is called, appropriately, the Wilson Cycle.

A “man of tremendous vitality and energy,” Wilson is now inextricably associated with the fundamental rhythm of the planet’s surface. So it is fitting that he spent his few spare moments happily sailing his Chinese junk around the Thirty Thousand Islands of Ontario. His beloved Georgian Bay is, after all, a land of living rock always in flux.