John Tuzo Wilson

Born 1908, Canada; Died 1993.

By

Alan Peterson, Christian Lollar

Title image (RUGU).


Background

John Tuzo Wilson was born on October 24th 1908 in Ottawa, Canada. John was the eldest child of John Armistead and Henrietta Wilson. His father was a skilled Scottish engineer, his career included sites in India and Canada. Hentrietta Wilson was a skilled mountain climber in the Canadian back country. Hentrietta was also heavily involved with the League of Nations, Red Cross, and the overall enrichment to Canada’s National Park system. John “Tuzo” Wilson was heavily influenced by geology at a young age. His first job was working in the summer in Canada for the Geologic Survey of Canada. This sparked an overall interest in the geologic field and he became one of the great geophysicists of the 20th century.

College Career

After his high school career he sought to further his knowledge in the geologic field at the University of Toronto. “There was no program for geophysics in 1926, and not even a way to study both geology and physics. However Wison was enrolled in the “Honours Programme” in Mathematics and Physics, but worked geological field parties in the summer (University). During his college years he was given the great opportunity to study and be guided by Professor Lachlan Gilchrist. This opportunity was financially and logistically supported by the Canadian Government. The purpose was to investigate mineral deposits via geophysical data. He was soon experienced in the use of several field tools including magnetometers and other types of electrical field instruments. Following his career at Toronto he enrolled at Cambridge University where he received a second bachelor’s degree. His classes consisted of well-known professors which included Sir Harold Jefferys, Sir Edward Bullard, as well as James Wordies. Shortly after his Cambridge career he returned to North America where he attended Princeton University where he would receive his Ph.D. Wison again was influenced by a great teacher named Professor Richard M. Field known to be “one of the outstanding American Earth Scientists of all time" (University).

Wison performed his thesis research in the Beartooth Mountains of Montana. He was given 200 dollars to purchase a second hand car, drive to Montana, and live on the remaining balance. He performed all of the field work on his own and felt that previous assumptions concerning this area needed to be revised and altered slightly (University).


Geological Survey of Canada

After Wison’s Ph.D. from Princeton he joined the Geological Survey of Canada in 1936 as a Geologist Assistant. During his time in this career he worked on map scaling and glacial features in Nova Scotia. This research was soon published by the Royal Society of Canada. Soon after Wison explored areas of the Northwest Territories where one other previous “non-native” had gone. Samuel Hearne had surveyed the area in 1771-72. A historical account submits that Wison’s survey party was running low on supplies weeks from civilization whereupon Wison acquired meat by paddling his canoe next to a swimming moose and dispatching it with an axe. He was, reputedly, somewhat of a physical specimen. Although his closely accounted for stories were similar to Hearne’s, Wison also made a name for himself by surveying the Canadian Shield via the newly developed method of interpreting aerial photography. He studied and pointed out geomorphic features visible in the photo (University).


Royal Canadian Engineers

Shortly after he was married to Isabel Dickson in 1938, he was summoned to the army in 1939. His new job in the army was being a part of the Royal Canadian Engineers. Wison watched over workers who labored on such projects as undersea tunneling. He would end his army career as a colonel of the Director of Army Optional Research (University).


University of Toronto

Following his army career, he returned to Toronto in 1946, where he accepted a job as a Geophysics professor. He quickly noticed that the department was not up to date and that the department's reputation was not what it used to be. Wison was determined to return the department back to its former standard of excellence. Wison’s focus on bringing the department back included dating distinct regions of the Canadian Shield using an old mass spectrometer. That research would broaden the department and also gain credit worldwide. His efforts of bringing the department back to its former glory first started with his research on the Canadian Shield upon which several papers were written. It was the beginning of scientific geochronology in Canada. The view that shields are formed through the process of accretion of smaller Archean cratons (in the case of the Canadian shield, the Superior and Slave provinces) was reinforced. The age zoning of continents could be extended into Phanerozoic time, and Wison wrote several papers on the growth of continents, still considered by him to be fixed on Earth. (University).

Figure 1. Wilson's work in the dating of distinct intercontinental geologic regions has been expanded to include the rest of North America. (Karlstrom)

After his research on the Canadian shield he turned to a grander project. His new project focused on a contracting Earth, a possible rising of continental crust due to the cooling and constriction of the Earth as a whole. This would not only cause mountain building but also a possible sea floor forming. Later, in 1959, after much research had taken place Wison finally accepted the idea of continental drift.


Wison’s Continental Drift

As early as the late 1600s Abraham Ortelius had noticed that the western coast of Africa and the eastern coast of South America fit together like puzzle pieces. The idea was proposed several times over the centuries until the early 20th century when Alfred Wegener more completely grasped the concept and driving forces required for the hypothesis to be true. By this time it was well established that the interior of the Earth was fluid. After Wegener’s death the theory of continental drift lost favor for a time and efforts were focused on a cooling and contracting-earth model. Military research during World War Two drove advances in SONAR. Following the war, SONAR was used to map the ocean floor. Linear mountain ranges in the oceanic basins called mid-ocean ridges were mapped, and further exploration at these ridges showed that the rocks along these ridges were much younger than the ocean floor closer to the continental margins. This meant that new crust was being formed at the mid-ocean ridge where it expanded away from the axis of the ridge and pushed the continents away from the ocean ridge.

Figure 2. Created by author using ArcMAP version 10.1.

When Wison finally accepted this theory he began to examine the implications of moving tectonic plates. He reexamined some of his earlier work in Nova Scotia and realized that physiographic features and stratigraphic formations found in North America can be extended into Europe. This means that at one time the two were connected. An animation of the modern interpretation of this process and the dates associated with relative positions of continents in the northern hemisphere centered in the Atlantic is below.

Animation 1. Copyright permission allowed for non-commercial teaching purposes (Scotese).

As the pieces were slowly put together the scientific community was able to extend the theory of continental drift to encompass more and more of the physical phenomena observed on planet Earth. Wison not only supported the idea that the Atlantic Ocean was once nonexistent and that the land masses had coalesced into once large landmass, but that the same process of continental collision and breakup was a repeating cycle. This was called the Supercontinent Cycle, or the Wilson Cycle. The principle is as follows: pieces of continental crust driven by expansion along a mid-ocean ridge over a hot mantle convection plume collide and suture themselves together. A large land mass is formed (A. Hallam).

The large land mass insulates against heat loss coming from the Earths' core providing an area or greater heat flow and convective currents under the large land mass. The landmass splits apart along these convection currents. A modern analog for this splitting of continental crust over an area of high heat flow would be the African Rift Valley.


Hot Spots

With Wisons’ acceptance of continental drift he began to study the effects and implications of the theory. One of Wison’s several studies on continental drift was the theory of subduction and the creation of volcanic mountains in the continental interior. He recognized that volcanic activity separated from the collision of tectonic plates required a new mechanism to describe the genesis of these features. This soon turned his curiosity to the processes involved in forming island chains. With relatively new knowledge of subduction and hot spots he soon theorized how island chains were formed. His idea was that island chains were formed by a stationary hot spot while oceanic crust moved over it. The theoretical conveyer belt of oceanic crust moved over a hot spot that periodically ruptured through the crust and deposited large extrusive volcanic flows. This would cause island chains such as those seen in the Hawaiian Islands and the Emperor Seamounts.

Figure 3. (Hawaii)

Figure 4. (Southeastern)


Later Life

In 1985 he grounded himself strictly to the University of Toronto and focused on global tectonics. “More than 20 years had passed since the early days of plate tectonics. Wison acknowledged the progress that had been made, but his writing from this period gives the impression that he felt that important aspects were being overlooked. He returned to the study of hot spots, which in the intervening time period had been actively pursued by others. Following Crough (1983), he accepted the view that rifts themselves may result from the coalescing of lithospheric fractures radiating from uplifts over hot spots and extended this to investigate the consequences of continents over-riding rifts" (University).

Wison following the logic he had proposed for the formation of island chains, he sought a similar pattern in continental plates. A major focus to him was on the North American Plate moving while the Yellowstone magma plume was anchored and stayed throughout the movement of the plate. He gave such examples of the large quantities of gold in Nevada being related to the Yellowstone magma plume.


Legacy

John Tuzo Wilson started and finished his career as a decorated geologist and geophysicist in Canada and had many friends. From his early years of being part of the Geologic Survey of Canada to completing the picture of continental drift he was always attracted to the Earth and its geologic processes. Wison lived a legendary life with a large outlook on life as well. Wison died April 15th 1993, he was 85 years old when he passed. Two seamounts 200 kilometers west of Vancouver Island are named the Tuzo Wilson Seamounts.

The J. Tuzo Wilson Medal, annually presented by the Canadian Geophysical Union in recognition of of scientists that have made a substantial contribution to geophysics in Canada. The medal is named after the first person to receive the medal.


References

A. Hallam. Alfred Wegener and the Hypothesis of Continental Drift. Scientific American vol (232/2), p. 88-97 (1975)

GGE News 1996. Vanícek 1996 Winner of J. Tuzo Wilson Medal. Geodesy and Geomatics Engineering. University of New Brunswick, Frederickton, NB, Canada. http://gge.unb.ca/News/1996/1996.html

Karlstrom, Karl E., Whitmeyer, Steven, J. Tectonic model for the Proterozoic growth of North America. http://geosphere.gsapubs.org/content/3/4/220.full

Hawaii hotspot.jpg. Wikimedia Commons. National Geophysical Data Center/USGS, 2006. https://commons.wikimedia.org/wiki/File:Hawaii_hotspot.jpg

RUGU The Most Comprehensive Blog. John Tuzo Wilson Photos. Page last modified February 13, 2013. http://www.rugusavay.com/john-tuzo-wilson-photos/

Scotese, C. R., 1997. Paleogeographic Atlas, PALEOMAP Progress Report 90-0497, Department of Geology, University of Texas at Arlington, Arlington, Texas, 37 pp. www.scotese.com

Southeastern Hawaiian islands, with bathymetry and lava flows - oblique view.jpg. Wikimedia Commons. Joel E. Robinson, USGS, 2006.

University of Toronto. “The Life of John Tuzo Wilson.” Physics Computing Services. n. d. Web. 25 Apr. 2013. http://www.physics.utoronto.ca/physics-at-uoft/history/the-life-of-john-tuzo-wilson