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John Dewey: Thoughts from one of the founding fathers of the theory of plate tectonics on geology, education and his own illustrious career

John Dewey. Illustration by John Maisano.

There are few living geologists who have shaped modern scientific thought as much as John Dewey.

Since his first field studies in Newfoundland in the 1960s, he has helped build the foundation of the theory of plate tectonics and continental drift, specifically laying out how tectonic movements explain the geology of mountain belts.

Dewey, now an emeritus professor of geology at Oxford, has lived and participated in a history that students, and many professors, can only read about. And with a personality and wit straight from central casting, the noted scholar is a master of bringing that history to life.

Over the past few years, select Jackson School students, faculty and even
alumni have experienced Dewey’s brilliance firsthand thanks to a longstanding friendship with Jackson School Dean Sharon Mosher that dates back to her days as a master’s student at Brown University. Dewey led field trips for the Jackson School as a visiting professor emeritus in the summers of 2014, 2015 and 2016.

In 2014 he led a group to Ireland and in 2016 to western Newfoundland
to visit the very locations where he first discovered a half century ago that the two regions on opposite sides of the Atlantic Ocean had nearly identical geology. Sandwiched in between, in 2015, he led a group to northern England and Scotland, to visit some of the most famous formations in the world in an area credited with being the birthplace of geology.

Dewey’s tenure as a Jackson School visiting professor is over, but he
happily shared his thoughts on the state and future of the science he loves and more.

Q: You’ve had an extremely long and prestigious career in geology. What are you doing these days?

A: I spend time at home in Oxford writing. I’m writing my memoirs at the moment, which is great fun. You remember things you think you’ve forgotten. Plus I do a lot of little bits of local geology around Scotland and England, France, Switzerland, within Europe. I’ve given up all the field work in South Africa and New Zealand and California.


Q: You’ve conducted research all over the world. Is there one spot you haven’t been that you would still like to visit?

A: Yes, Antarctica. That’s the only continent I have not been on. [Jackson School Professor] Ian Dalziel has been trying to get me there quite a lot, but something always transpires, and I can’t go. Trying to go down there is awkward in a way, because I did much of my work when I was gainfully employed during summer vacation. But of course in Antarctica, you’ve got to go in our winter.


Q: How did you come to be connected to the Jackson School?

A: When I retired I was in my 70s, and I thought, ‘Well do I want to keep on going until I’m old and decaying or do I want to sort of pull out now of a full-time university job and just do research at my own pace?’ If you’re teaching a course, you can’t just take off for field work in Australia or something like that. You’ve got students to look after. I thought perhaps the way to do it is to not go anywhere permanently, but simply attach myself for a few weeks or months every year. Go somewhere and talk to the students so I haven’t got a long-term commitment, and I haven’t got masses of teaching to do. So I wrote to [Jackson School Dean] Sharon Mosher and said, ‘Would you like some sort of short-term arrangement? I’ll run a field trip every year. I’ll come for a few weeks every year and you can give me a consulting fee to cover my costs.’ It has worked very well.

Q: What’s your impression of the students at the Jackson School?

A: Really top-class. Absolutely top-class. Both the undergraduate and the
graduate students are very, very good. The reason of course is they’re very fussy about who they take as graduate students here. I
guess undergraduates, too. It’s highly competitive, so they can afford to be picky and choosy about who they have.

Q: One of the Jackson School’s major focuses is to make sure that undergraduates have time in the field. Do you think that is an important part of an undergraduate geosciences education?

A: It is essential and has become a problem. Geological research, and obviously the people who do it, are becoming much more quantitative and machine driven. [There are] lots and lots of new techniques [to] measure the ages of rock. A lot of really fantastic new techniques, so people are really going straight into that more and more. They’re spending time doing that rather than spending time in the field looking at rocks and teaching students how to look at rocks.

I’m not saying it’s decaying, and [UT] Austin is much better than most
places in terms of going out into the field. [Jackson School Professor] Danny Stockli goes out in the field even though he’s a machine man. [Jackson School professors] Mark Cloos, Randy Marrett, Ian Dalziel are often out in the field. But in many places they’ve stopped teaching optical mineralogy, for example. What I would call basic core disciplines in geology have stopped being taught. But Austin is very unusual in the modern world in keeping core disciplines going. I think that’s very important.

Q: So you are seeing field work de-emphasized at some schools?

A: Yes. Training the students to look at rocks and how to analyze and understand them; some departments do it by remote sensing and virtual geology. That’s not the way to do it. You need to go in the field and look at rocks. Francis Pettijohn, the great sedimentologist, once said, ‘The truth resides in the rocks.’ You can model it all you want, but ultimately you’ve got to go look at the rocks and see what they say. And the students love it of course. They love being in the field. That’s why many kids go into geology. They want to go in the field and look at rocks and study the Earth that way. And many kids get upset at some universities when they find they’re spending all their time doing chemistry and physics and god knows what in the lab.

Q: What was your first teaching job?

A: I came through undergraduate and graduate school in ’55 through ’60 at Imperial College in London, and then I got my first teaching job. In those days you could get a teaching job in academia straight away if you were any good. Nowadays people have postdocs and fellowships. It’s now tough to get an academic position. Some people are 30 or 31 by that time. I was 23 when I got my first academic position as a lecturer in Manchester (the University of Manchester).

Q: You are credited with being one of the pioneers of plate tectonics. Can you discuss those early years of your career and how you became interested in plate tectonics?

A. I spent four years in Manchester. Then I got a job in Cambridge University from ’64 to ’70, and most of that time I was working away at structural geology. I was invited to Nova Scotia in 1964 to join an expedition looking at some Silurian and Ordovician rocks. I loved that. First of all it was great fun. It was the first time I’d been to the North American continent. I started mapping with a variety of people, and these rocks were fantastic over the whole area of Nova Scotia. And realized some of these rocks were quite like some of the rocks I’d looked at in Ireland. It’s not surprising because actually the Caledonian belt comes through Scandinavia, through Scotland, through Ireland, is chopped off by the Atlantic and reappears in Newfoundland and Nova Scotia.

It’s the same belt on both sides of the Atlantic. All that happened is that the Atlantic pulled it apart. They obviously do fit, you know, and that’s what I worked on a lot.

That, in 1964, opened my eyes to the Appalachians. And I got very interested because I’d been in the Caledonian belt until then looking at small-scale structures. And then I got the opportunity to spend a sabbatical leave in Columbia at Lamont-Doherty. I was getting interested then in the correlation across the Atlantic and how the Appalachian Caledonian chain worked, what it was made of. I thought the way I should find out is this: I’m going to make a map, an incredibly long detailed map from Newfoundland all the way through to Alabama. I went through all the state geological maps: Vermont, New Hampshire, Maine, right down through the Carolinas, right down to Alabama. I synthesized and generalized the geology, and I put it on this map. And gradually, it was amazing, there was a belt of Ordovician volcanics that runs right down through there. It runs right down through Vermont, down through New York. It goes down to Pennsylvania; what is it? And I started to see patterns of rock associations. And then I said, ‘What do they mean?’ They must mean something in terms of the modern world — this was in 1967. And it’s got to have something to do with this new emerging plate tectonics that was developing at the time with Tuzo Wilson and people like (Dan) McKenzie and (Walter) Pitman and god knows who. I was in Lamont at exactly the right time. Serendipity. I was just dead lucky

Q: What was your role in the emerging research?

A. I was doing this great map, which was emerging as a fossil example of things that are happening in the world today in plate tectonics. And I realized that this is a place where an arc has collided with a continental margin in mid-Ordovician times 470 million years ago. It’s the sort of thing that’s happening in northern Australia in present day. It was kind of exciting. Lamont was the hotbed of the development of plate tectonics. Princeton, Scripps in California and Lamont in New York and Cambridge, too. So I just got swept up in it completely. My role was taking old rocks, looking at the history of the world and saying, ‘Can we explain all this in terms of this new emerging science of plate tectonics?’ And I said, ‘Yes, you can do it, at least back for 600 million years.’ Before that, things are different, but for that Phanerozoic time, it clearly is the result of the evolution of plate motion going on, making arcs and splitting and pulling continents apart and colliding them again and making mountains and all that kind of stuff. So that’s how I got into it.

Q: Was the plate tectonics theory controversial at the time?

A: In the early days BPT —before plate tectonics — the world was divided into the bulk of the people who thought continental drift was rubbish, and a small group including me and Lester King in South Africa and probably 20 or 30 people in the science who thought it must have happened because if you compare West Africa and South America, A, they fit together perfectly and B, you find old mountain belts coming through and it continues where they fit.

It’s like a jigsaw, and jigsaws don’t lie. Obviously, there had been continental drift taking place by some mechanism. There was a man called Harold Jeffreys who was extremely anti-continental drift. He said, rightly in a sense, that the continents are made of weak rocks, rocks that deform and squash easily. Oceans are made of strong rocks. The continents are dominated by quartz, whereas the oceans are dominated by olivine, which is a very strong mineral. So if oceans are strong, how can you have continents plowing through hard stuff? But he thought of it wrongly. The continents don’t plow around. They split, and then you have seafloor spreading, which means the middle opens up. There is a gap, which keeps on filling up, and the continents are basically just passive passengers on the plates. They keep moving around where the plates move. They are not plowing through anything at all. Harold Jeffreys had a big influence on the world, particularly Britain. He was a professor at Cambridge, and what he was saying was rubbish because he hadn’t thought about it in quite the correct way. That happens in science a lot.

Nevertheless, in Britain there were a lot of geologists who thought continental drift must have happened. In North America, it was different. It was a very anticontinental- drift nation at the time. They said in the ’50s, if you espoused the idea of continental drift you would never get a job at a university in America. There was a change. It was progressive, and it was partly generational. The people who were proposing plate tectonics were mostly the younger generation, including me, Walter Pitman, Lynn Sykes. The only one who was older was Tuzo Wilson. If you asked who was the founder of plate tectonics, it was a number of people of course, but it was really Tuzo Wilson who had the idea in 1965. He wrote a really classic paper in ’65. He didn’t call it plate tectonics back then, but all the classic elements of plate tectonics were in it. And then, by 1968, the cat was out of the bag. 1965 to ’68 was the period where the idea was proposed and then it became generally accepted. But there was
still a rear-guard action by some of the older people who didn’t like it. But basically by ’68 the thing had taken off, and it was all over. It was taught in some university courses in ’68 to ’70.

And then in the ’70s and even today lots of ideas are developing on the theme and how it works. There’s a huge amount of work left to be done, but the basic theory is there. It looks pretty good. It may be all wrong, but I’d be amazed if it is wrong. I take Karl Popper’s view of science. You can never prove anything right. All you can do is prove things wrong.

Q: How has geology changed since you started?

A: Geology has changed a great deal. For the better and the worse. There have been some wonderful developments in geology, mostly new ways of
measuring things. The machines we have now were unthought-of even 20 years ago. Danny Stockli’s lab, for instance, is just state-ofthe- art. Right at the cutting edge of the science. You can actually measure the ages of the rock vastly more accurately right down to plus or minus a million years. It’s incredible. It’s unbelievable the things you can do. And you can do the chemistry of rocks very thoroughly and the physics of rocks. You can really pull rocks apart right down to the submicroscopic level.

There’s an amazing lady at the Bureau of Economic Geology, (Research Associate) Esti Ukar, the things she can do would make your mind boggle. For somebody in the last century, they would say it couldn’t be done. It’s just necromancy. They wouldn’t believe it. But on the other hand, we’re losing sight of some of the classic core of geology, which is very important. Not here. Not in Austin. I think it’s maintained very well. This is partly because at one time you went around a geology department 50 years ago and everyone had a degree in geology. Now you go around a geology department, and there are people with degrees in physics, materials science, engineering, biology. It’s good. It’s become multi-and interdisciplinary, and that is what you want in science. You want people coming at things from a range of angles, but that in itself has taken its toll on the science. It’s lessened the basic core of geology. I’m afraid it’s gone too far for the moment. It’ll come back. Things go in cycles. In another 10 years we may have the young people saying, ‘Oh, this crazy instrumentation period back then.’ Attitudes change always, and old people tend to complain about the young. It’s inevitable. It’s probably healthy. It keeps the young under control (laughs).

Q: What advice do you have for young geoscientists?
A: I think I would tell them, ‘Don’t do what old people tell you to do. Follow your own nose. If you have an idea, a series of ideas, just follow it.’ If old people say, ‘No you shouldn’t do that, do something else or come into my lab or work with me,’ ignore them. Forge your own career doing your own thing. Most of the great ideas in science come from relatively young people. So forge your own career, and don’t kneel or
bow before the old. I think that’s about it.


Dewey in Newfoundland in 1968. In 2016, he led a Jackson School field course on tectonics in the province.