Wilson, John Tuzo
WILSON, JOHN TUZO
(b. Ottawa, Canada, 24 October 1908;
d. Toronto, Canada, 15 April 1993), geophysics, geology, plate tectonics, transform faults, hot spots.
Wilson’s most significant work involved finding support for continental drift and seafloor spreading, especially with the development of the transform fault concept. He also proposed that groups of linear volcanic islands were caused by mantle plumes, foreshadowing W. Jason Morgan’s idea of hotspots. Wilson led an enormously rich life, as a student traveler attempting to learn geophysics, as a member of the Geological Survey of Canada, as an active researcher at the University of Toronto, as the first principal of the Erindale College, and as director general of the Ontario Science Centre. To avoid confusion with another J. T. Wilson, he used his middle name, and became known professionally as J. Tuzo Wilson or simply Tuzo Wilson.
Education and Early Career. The eldest child of three children of John Armistead and Henrietta Wilson (née Tuzo), Wilson was born in 1908 in Ottawa, Canada. His Scottish father, just sixteen when his own father died, was forced to learn engineering as an apprentice. After contracting malaria in India, he sought a colder climate, settling in Alberta, Canada. Spending most of his professional career working for the Canadian government, he helped develop civil aviation in Canada. Thus, Wilson met many aviators while growing up; he later attributed his love of travel to their influence. Wilson’s mother was born in British Columbia, Canada. Her father, trained as a physician at McGill University in Montreal, joined the Hudson Bay Company in 1853 and traveled with fur traders by canoe to Manitoba, on horseback through the mountains of Alberta, and down the Columbia River by longboat to the Pacific. He died while Wilson’s mother was in medical school, and she had to leave before getting her degree to take care of her own mother. An avid mountain climber, she and her Swiss guide Christian Bohren were the first to climb “Peak Seven” in the Valley of the Ten Peaks, Alberta, Canada. In honor of the accomplishment, the mountain was named Mount Tuzo.
Although Tuzo’s family was not rich, they still traveled, and Tuzo obtained an excellent education. He and his siblings were expected to study, work in the garden, and walk four miles to and from school. Their weekends were filled with swimming, canoeing, and skiing, and, like his mother, he developed a love for the outdoors. He excelled academically at a private school in Ottawa. Often alone, he became accustomed to following his own path, and developed a distrust of orthodoxy. At seventeen, he became a field assistant for Noel Odell, the English geologist and mountaineer, who introduced him to geology.
Wilson majored in honors mathematics and physics his first year at the University of Toronto (1926). However, in part because of his encounter with Odell, he switched to geology, much to the dismay of his physics teachers. Even though he appreciated the elegance of physics, he preferred working in the field to the laboratory. His geology professor told him that he would have to repeat his first year because he needed introductory geology and biology courses. However, Professor Lachlan Gilchrist, a classical physicist who realized the promise of geophysics for prospecting, proposed a double major for Wilson in physics and geology. Wilson graduated in 1930 as the first Canadian to obtain a geophysics degree. Awarded a Massey Fellowship to study at Cambridge University, he decided to pursue a second BA degree in geophysics. Edward Bullard was to be his tutor, but was delayed in East Africa doing gravity work. Wilson took Harold Jeffreys’s course of lectures in geophysics but failed to understand them. Jeffreys told him not to worry. Tuzo spent much of his time learning how to fly, rowing, and traveling throughout Europe. Nonetheless, he was influenced by Jeffreys, and later adopted his contractionist account of mountain building.
Wilson returned to Canada with his BA from Cambridge, and spent a year working under William Henry Collins, director of the Geological Survey of Canada. Although Collins recognized the need for geologists to work with geophysicists, he was unable to secure Wilson a position, and suggested that he get a PhD in geology and return to Canada once the economy improved. Tuzo chose Princeton University over Harvard University and the Massachusetts Institute of Technology (MIT) because Princeton offered him more money, and Professor Richard M. Field told him that Princeton was going to begin teaching geophysics. Although Field failed to recruit a geophysicist to Princeton, he obtained funding from the U.S. Coast and Geodetic Survey to support Maurice Ewing’s seismic study of the New Jersey coastal plain, and Wilson occasionally worked with Ewing at nearby Lehigh University. Wilson also became friends with Harry Hess, who joined the Princeton faculty in 1934, a year after Wilson arrived. Wilson’s dissertation advisor was the structural geologist Professor Taylor Thom, an expert on the Beartooth Mountains of Montana. Thom gave Wilson $180, told him to buy a car for $50 and spend the summer mapping a section of the Beartooth Mountains. Wilson’s assigned area included the 3,749-meter (12,300-foot) Mount Hague, which he was the first to ascend.
Obtaining his PhD from Princeton in 1936, he spent three years at the Geological Survey of Canada before joining the Royal Canadian Engineers during World War II. In the field for most of his time with the survey, he worked in the Maritime Provinces, Quebec, and the Northwest Territories. Once short of food in the Northwest, Wilson found an ancient Indian birch-bark canoe, paddled up to a moose in a large lake, and killed it with a blow to the head with his ax. It was during this time with the survey, that he learned the value of surveying by air, and showed his skeptical colleagues in the survey that major trends could be spotted and mapped more successfully from the air than on foot. His appreciation of flight, learned from his father, proved professionally helpful. It also gave him a way to look at huge areas in ways accenting large structures, a theme that he would later exploit. Wilson married Isabel Dickson of Ottawa in 1938, a year before he joined the war effort. She accompanied him to England during the war.
In 1946, a year after his return to Canada, Wilson had three career choices: stay in the army, where he had reached the rank of colonel; return to the survey, where he was promised the directorship; or accept a position as professor of geophysics in the Department of Physics at the University of Toronto in 1946. He followed the advice of Chalmers Jack Mackenzie, then president of the National Research Council of Canada, who told him to return to university life and spend twenty years doing basic research. Indeed, he remained at the University of Toronto until 1967, becoming one of the most creative Earth scientists of his generation.
Research on Earth’s Crust. Wilson began making a name for himself as a researcher in 1949/1950 when several of his papers, one coauthored with the applied mathematician Adrian E. Scheidegger, appeared, defending and expanding Jeffreys’s contractionism to explain the origin of continents, their growth, and the origin of mountains and island arcs. Wilson proposed that Earth first solidified without a sialic (continental) outer crust; that its outer crust repeatedly fractured as Earth contracted by cooling; that uprising sial reached the surface through fractures and first formed volcanic islands; that eroded sediments from the islands combined with repeated rising sial through old and new fractures and formed mountain ranges surrounding the original volcanic islands; that these new structures combined to become continental shields; and that the repetition of such processes led to continental growth by addition of peripheral island arcs and mountain ranges. He paid particular attention to the geometry of groups of island arcs (1949a, 1950b); extending the British geologist Philip Lake’s (1931) suggestion that such groups typically form circular or spiral arcs, he proposed that similarly shaped fractures would occur in Earth’s outer layer as it contracted. Wilson argued that his updated contractionism was superior to mantle convection, which he considered to be the only alternative worth serious consideration. He discarded continental drift in a single paragraph arguing that there are no physical forces strong enough to break apart a supercontinent, that it could account only for formation of recent orogenic belts, and that there was no reason, as Alfred Wegener had proposed, that continental drift should have occurred only once and, in geological terms, so recently (1949b, p. 173).
Wilson espoused the same view throughout most, if not all, of the 1950s, as witnessed by the 1959 publication of his 1957–1958 Sigma Xi National lecture. He incorporated the new discovery by Bruce Heezen, Marie Tharp, and Ewing of the mid-ocean ridge system into his contractionist theory, claiming that it should be viewed as a gigantic fracture system rivaling the terrestrial one formed by mountain belts and island arcs, and arguing that it was caused by uprising basalt that reached the surface through a continuous fracture zone that formed early in Earth’s history (1959). He made no mention of developments in paleomagnetism that suggested continental drift and polar wandering, and again effortlessly dismissed continental drift: “Continental drift is without a cause or a physical theory. It has never been applied to any but the last part of geological time” (1959, p. 23)—Wilson, apparently, had never read Émile Argand, who spoke of a proto-Atlantic and formation of Wegener’s supercontinent, and he either thought little of Arthur Holmes’s mantle-convection mechanism of continental drift or did not know of it. Wilson did, however, acknowledge the possibility of polar wandering, and noted that it could be included within his contractionist theory.
Wilson had yet to waver from contraction theory. Within a few years, however, he became inclined toward continental drift. Wilson retrospectively claimed that he “was too stupid to accept, until I was fifty, the explanation which Frank Taylor and Alfred Wegener had advanced in the year I was born” (1982). The “too stupid” was likely said in good humor; he was wrong in claiming that Taylor and Wegener advanced their views in 1908; Wilson probably misremembered how old he was when he accepted continental drift. He favored Earth expansion in 1960 without drifting continents when he was already fifty-one, and did not “welcome” continental drift in print until October 1961, when approaching his fifty-third birthday. Regardless of his age, once Wilson let go of contractionism, he began to apply his fertile mind to the consequences of continental drift, and developed a series of interesting, often original, hypotheses.
Wilson entertained Earth expansion but explicitly rejected its use as an explanation for continental drift (1960). After noting Paul A. M. Dirac’s suggestion that the gravitational constant G may be decreasing over time and Heezen’s hypothesis that Earth expansion not only explains the formation of the system of mid-ocean ridges but causes the widening of ocean basins and drifting continents, Wilson argued that the rate of Earth expansion needed to cause continental drift was unreasonably high (1960). He suggested that a much slower and reasonable rate of expansion could explain formation of ridges, and, just as with Earth contraction, formation of arcuate fracture zones where island arcs and mountains form. He argued that his view, unlike mantle contraction, avoided the difficulty of continental flooding by ocean waters with the shrinking of ocean basins.
Wilson came out in favor of continental drift and seafloor spreading, approximately a year and a half after entertaining slow expansion (1961). He favorably reviewed both Hess’s and Robert Dietz’s versions of seafloor spreading. Instead of analyzing seafloor spreading per se, he acknowledged the paleomagnetic support of continental drift put forth by Kenneth Creer, Edward Irving, Keith Runcorn, Patrick Blackett, John A. Clegg, and Peter H. S. Stubbs. He also removed a difficulty facing seafloor spreading, and in so doing was the first to suggest that ridges themselves may migrate (1961, p. 126). Given that ridges entirely surround Antarctica, if new seafloor flows toward Antarctica from all directions, it seemed that Earth would have to expand because Antarctica lacks sinks where seafloor is destroyed. To avoid the difficulty, he proposed that the surrounding ridges themselves migrate northward.
Once committed to seafloor spreading and continental drift, Wilson applied them to a nest of problems. Turning his attention back to his homeland, he suggested that previous pre-Pangea breakups and collisions of drifting continents could explain ancient mountain systems and differently aged provinces of the Canadian Shield (1962a). He then argued that Cabot fault, which he claimed extends through New England and the Canadian Maritime Provinces, and the Great Glen fault in Scotland once formed a single fault before the continents separated (1962b, 1962c). Turning to the rest of the world, Wilson wondered about the origin of the Hawaiian Islands and other such parallel, linear chains of volcanic islands and seamounts found in the Pacific (1963). Most claimed that such island chains formed as lava reached the surface along large linear faults. Invoking seafloor spreading, he argued that the upwelling basalt comes from “a deep source” below the mass of moving sea floor and upper mantle (1963). As the spreading seafloor went over the plume, islands were created when the basalt reached the surface. He noted that this solution explained, unlike the received view, why the age of islands within such island chains increases the further the islands are from the East Pacific Rise (1963). His “deep source” was the precursor for W. Jason Morgan’s (1968) hotspots. Wilson first sent the paper to the Journal of Geophysical Research where it was rejected; he then sent it to the Canadian Journal of Physics.
Transform Faults. His next major contribution, and his most important, was his concept of transform faults. Wilson (1965) was impressed by the fact that movements of Earth’s crust appeared to be concentrated in three types of tectonic features, mid-ocean ridges, mountain ranges (including island arcs and trenches), and major faults with large horizontal displacements. These features seemed to end abruptly, and up to the middle 1960s were generally viewed as unconnected. He proposed that they were connected, not isolated features. Although the features end abruptly, he claimed that they actually are transformed into one of the other features. A ridge, for example, could be transformed into a horizontal fault, which could be transformed into a trench. Wilson named these horizontal faults transform faults. These horizontal faults had been viewed previously as transcurrent faults. Wilson further applied his transform fault concept to fracture zones that connect segments of oceanic ridges. Mid-ocean ridges are not continuous, but are made up of ridge segments that are offset from each other by fracture zones. He reasoned that if seafloor spreading occurs, the fracture zones connecting ridge segments should be transform not transcurrent faults. He further explained how seismological data could be used test his idea. If the fracture zones were transform faults, then movement along them should be in the opposite sense to that of transcurrent faults. He also noted that current seismicity should be confined to the segment of the fault between ridge segments, whereas it should extend along the whole of the fracture zone, if transcurrent faulting occurs. When Wilson proposed his idea the relevant seismological data were missing to determine if the faults between ridge segments were transform or transcurrent. Lynn Sykes (1967) presented the missing data, and confirmation of Wilson’s transform fault concept and the Fred J. Vine–Drummond H. Matthews hypothesis (1963) led to the acceptance of seafloor spreading and continental drift by many who had vehemently argued against them. Indeed, Vine and Wilson (1965) coauthored a paper that explained generation of seafloor from the Juan de Fuca and Gorda ridges south of Vancouver Island in terms of seafloor spreading, the Vine-Math-ews hypothesis, and transform faults. Wilson’s transform fault concept became a crucial element of plate tectonics. Morgan, coinventor of plate tectonics, went so far as to characterize plate tectonics as “an extension of the transform fault hypothesis [Wilson, 1965] to a spherical surface”(1968, p. 1959).
Later Career and Honors. Wilson recalled that by 1967 his “research had reached an impasse” and that he was unsure as to whether he had enough “will and strength” to continue (1990, p. 281). Moreover, he had spent about twenty years doing research, as his old mentor Mackenzie had advised. So, with strong encouragement by his wife, he accepted the offer to become the principal of Erindale College, a suburban campus of the University of Toronto. In just seven years, when he was forced to take mandatory retirement at age sixty-five, he turned 300 acres of land with just one building into a thriving campus.
With his impending retirement, Wilson was asked by the premier of Ontario to become director general of the Ontario Science Centre. With usual enthusiasm he directed the Science Centre from 1974 until 1985. During his directorship, the Science Centre expanded its “hands-on approach,” which allows visitors to “do experiments” and see science as a creative and fun activity. He also organized traveling exhibits to remote places in Ontario, and with his support, a northern extension of Science Centre, Science North, was built in Sudbury, Ontario.
Recognized as one of the most imaginative Earth scientists of his generation, and a leader among Canadian scientists, Wilson received many honors and awards. He was Officer, Order of the British Empire (1946); Order of Canada, Officer (1970); Order of Canada, Companion (1974). He was elected Fellow of the Royal Society of London (1968). His awards and medals include the R. M. Johnston Medal, Royal Society of Tasmania (1950); the Willet G. Miller Medal, Royal Society of Canada (1958); the S. G. Blaylock Medal, Canadian Institute of Mining and Metallurgy (1959); the Logan Medal, Geological Association of Canada (1968); the Bancroft Award, Royal Society of Canada (1968); the Bucher Medal, American Geophysical Union (1968); the Penrose Medal, Geological Society of America; the J. J. Carty Medal, U.S. National Academy of Sciences (1974); the Gold Medal, Royal Canadian Geographical Society (1978); the Wollaston Medal, Geological Society of London (1978); the Vetlesen Prize, Columbia University (1978); the J. Tuzo Wilson Medal, Canadian Geophysical Union (1978); the Ewing Medal, American Geophysical Union (1980); the M. Ewing Medal, Society of Exploration Geophysics (1980); the Albatross Award, American Miscellaneous Society (1980); the Huntsman Award, Bedford Institute of Oceanography (1981); the Alfred Wegener Medal, European Union of Geosciences (1989); and the Killam Award, Canada Council (1989). Wilson died on 15 April 1993. He was eighty-four and was survived by his wife, two daughters, and three grandchildren.
Tuzo Wilson was a remarkable scientist. An antidrifter until his fifties, he, unlike many of his peers, was able to change his mind relatively late in his career and embrace continental drift. He also was able to transcend the regionalism that he shared with most Earth scientists, and begin to take a more global approach. The permanence of the Canadian Shield spoke against continental drift. But once he began to appreciate continental drift’s paleomagnetic support, and realized the explanatory promise of seafloor spreading, he changed his mind, and then, through hard thinking and voracious reading of the literature relevant to a mobilistic Earth in fields beyond those in which he was trained, he drew out unsuspected consequences of continental drift and seafloor spreading, culminating in his transform fault concept.
WORKS BY WILSON
“An Extension of Lake’s Hypothesis concerning Mountain and Island Arcs.” Nature 164 (1949a): 147–148.
“The Origin of Continents and Precambrian History.” Transactions of the Royal Society of Canada 43 (1949b): 157–184.
With Adrian E. Scheidegger. “An Investigation into Possible Methods of Failure of the Earth.” Proceedings Geological Association of Canada 3 (1949c): 167–190.
“Recent Applications of Geophysical Methods to the Study of the Canadian Shield.” Transactions-American Geophysical Union 31 (1950a): 101–114.
“An Analysis of the Pattern and Possible Cause of Young Mountain Ranges and Island Arcs.” Proceedings Geological Association of Canada 3 (1950b): 141–166.
“Geophysics and Continental Growth.” American Scientist 47 (1959): 1–24.
“Some Consequences of Expansion of the Earth.” Nature 185 (1960): 880–882.
“Continental and Oceanic Differentiation.” Nature 192 (1961): 125–128.
“The Effect of New Orogenetic Theories upon Ideas of the Tectonics of the Canadian Shield.” In The Tectonics of the Canadian Shield, edited by John S. Stevenson, 174–180. Royal Society of Canada, Special Publications, no. 4. Toronto: University of Toronto Press, 1962a.
“Some Further Evidence in Support of the Cabot Fault, a Great Palaeozoic Transcurrent Fault Zone in the Atlantic Provinces and New England.” Transactions of the Royal Society of Canada 56 (1962b): 31–36.
“Cabot Fault, an Appalachian Equivalent of the San Andreas and Great Glen Faults and Some Implications for Continental Displacement.” Nature 195 (1962c): 135–138.
“A Possible Origin of the Hawaiian Islands.” Canadian Journal of Physics 41 (1963): 863–870.
“A New Class of Faults and Their Bearing on Continental Drift.” Nature 207 (1965): 343–347.
With Fred J. Vine. “Magnetic Anomalies over a Young Oceanic Ridge off Vancouver Island.” Science 150 (1965): 485–489.
“Early Days in University Geophysics.” Annual Review of Earth and Planetary Sciences 10 (1982): 1–14.
“J. Tuzo Wilson, Killam Laureate, 1989.” In In Celebration of Canadian Scientists: A Decade of Killam Laureates, edited by Geraldine A. Kenney Wallace, Mel G. MacLeod, and Ralph G. Stanton, 266–286. Winnipeg, Canada: Charles Babbage Research Centre, 1990.
Garland, George D. “John Tuzo Wilson.” Biographical Memoirs of Fellows of the Royal Society 41 (1995): 535–552.
Glen, William. The Road to Jaramillo: Critical Years of the Revolution in Earth Science. Stanford, CA: Stanford University Press, 1982.
Lake, Philip. “Island Arcs and Mountain Building.” Geographical Journal 78 (1931): 149–160.
Morgan, W. Jason. “Rises, Trenches, Great Faults, and Crustal Blocks.” Journal of Geophysical Research 73 (1968): 1959–1982.
Sykes, Lynn R. “Mechanism of Earthquakes and Nature of Faulting on the Mid-Oceanic Ridge.” Journal of Geophysical Research 72 (1967): 2131–2153.
Vine, Fred J., and Drummond H. Matthews. “Magnetic Anomalies over Ocean Ridges.” Nature 199 (1963): 947–949.
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Wilson, J. Tuzo (1908-1993)
Wilson, J. Tuzo (1908-1993)
An early proponent of the continental drift theory , J. Tuzo Wilson is chiefly remembered for his proposition that transform faults were present in the ocean floor, an idea that led to conclusive evidence that the sea floor and the earth's crust are constantly moving. Wilson later hypothesized that an ancestral Atlantic Ocean basin had opened and closed during the Paleozoic Era , in turn creating the huge land mass known as Pangaea. This theory helps account for the presence of the Appalachian mountains in eastern North America , the striking similarity of many rock features in Western Europe and North America, and parallel cyclical developments on the seven continents.
John Tuzo Wilson was born in Ottawa, Ontario, Canada. His father, John Armitstead Wilson, was an engineer who held a civil service position. His mother, Henrietta Tuzo, was an avid mountain climber who met her husband at the first gathering of Canada's Alpine Club. The Wilsons later shared their love of geology and the outdoors with their children, who were brought up to respect the pursuit of knowledge and were educated under the direction of an English governess.
In 1924, Wilson's father obtained a position for him at a forestry camp. Wilson grew so fond of outdoor work that he signed on as an assistant to the legendary mountaineer Noel Odel, who persuaded him to pursue a career in geology. Following his freshman year at the University of Toronto, Wilson switched majors from physics to geology. After earning a B.A. in 1930, Wilson received a scholarship to study at Cambridge University under Sir Harold Jeffreys. When Wilson returned to Canada in the early 1930s, he had difficulty finding work, so he continued his education, enrolling in Princeton University, where he earned a Ph.D. in 1936. He made the first recorded ascent of Mount Hague in Montana in 1935, and in 1938 married Isabel Jean Dickson, with whom he eventually had two children.
With the outbreak of World War II in 1939, Wilson joined the Canadian Army. During his seven-year stint, he authored more than 500 technical reports and later claimed that these military papers had helped him develop the lucid prose style that he utilized in a number of scientific studies. By 1946, he had reached the rank of colonel. That same year, after resigning from the army, he succeeded his professor at the University of Toronto. Geophysics had finally become a lucrative field of study in Canada, thanks in large part to the discovery of oil in Alberta, which increased demand for geophysical exploration and led to the development of more advanced instruments and measurement techniques. Wilson investigated a number of geological mysteries, including Canadian glaciers , mountain building, and mineral production. He conducted these investigations with a characteristic reverence toward nature: "Everywhere in science modern tools and ideas bring to light the elegant and orderly skeins by which nature builds the glory that we see about us, knit in regular patterns from simple stitches," he wrote in I.G.Y.: The Year of the New Moons (1961). "Indeed, we may think of all nature in terms of music, as infinitely ingenious and elaborate variations on a few simple themes."
From 1957 to 1960, Wilson served as president of the International Union of Geodesy and Geophysics. During his tenure he led a series of geologic expeditions to China and Mongolia, the details of which are recorded in his highly praised book, One Chinese Moon (1959). In the early 1960s, he became a key figure in what was then the most controversial issue in geology—the continental drift theory.
The origins of the continental drift theory date back hundreds of years. Since the time of the first global maps people have reasoned that at one time the continents might have been a single huge land mass. However, the first formal hypothesis of continental drift was made by German geophysicist Alfred Wegener in 1912. The idea was generally overlooked for decades but reemerged prominently in 1960, when geologist Harold Hess theorized that the ocean floors were being continuously created and changed. Hess attributed this activity to two physical structures: mid-ocean ridges , where the ocean floor is created, and ocean trenches , where the sea floor is destroyed.
Wilson was one of the first scientists to recognize the immense implications of this idea. For the next decade, he was at the very center of this theoretical debate. Using Hess's theory, Wilson postulated the existence of a third category of physical structure on the ocean floor which he called "transform faults," horizontal shears located between ridge sites and trenches. He suggested that transform faults could not exist unless the earth's crust was moving, and that the physical confirmation of these faults might prove the scientific validity of the continental drift theory. In 1967, seismologist Lynn Sykes partially tested Wilson's theory by studying seismic patterns and oceanic focal mechanisms. Wilson brought the idea to the attention of the general public by exhibiting a continental drift model at Montreal's Expo '67. By the late 1960s, the theory had gained wide acceptance and was eventually incorporated into the larger concept of plate tectonics , which maintains that the Earth's lithosphere is made up of a number of plates that move independently.
Wilson's hypothesis and the publicity it garnered earned him numerous honors, including a Fellowship in the Royal Society (1968), the Penrose Medal of the Geological Society of America (1968), the Walter H. Bucher Medal of the American Geophysical Union (1968), the John J. Carty Medal of the National Academy of Sciences (1975), the Vetlesen Prize of Columbia University (1978), and the Wollaston Medal of the Geological Society of London (1978).
Wilson retired from his professorship at the University of Toronto in 1974. He then assumed the directorship of the Ontario Science Centre and in that capacity helped transform the center from a traditional science museum into an interactive science lab for public use. Of the center's roughly 1,000 exhibits, 400 were designed to be handled by patrons, and during the late 1970s and 1980s, the exploratory museum attracted approximately 1.5 million visitors annually.
Throughout his life Wilson traveled extensively. He lectured at more than 200 colleges and universities. One of his passions was collecting books on the Arctic and Antarctic, both of which he had visited. A mountain range in Antarctica was named the Wilson range in his honor. He died in Toronto at the age of 84.
See also Convergent plate boundary; Divergent plate boundary; Sea-floor spreading
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