Plate Tectonics: A Very Short Introduction

Very Short Introductions #425

by Péter Molnár

The 1960s revealed a new and revolutionary idea in geological that the continents drift with respect to one another. After having been dismissed for decades as absurd, the concept gradually became part of geology's basic principles. We now know that the Earth's crust and upper mantle consist of a small number of rigid plates that move, and there are significant boundaries between pairs of plates, usually known as earthquake belts.

Plate tectonics now explains much of the structure and phenomena we see how oceans form, widen, and disappear; why earthquakes and volcanoes are found in distinct zones which follow plate boundaries; how the great mountain ranges of the world were built. The impact of plate tectonics is studied closely as these processes the Himalaya continues to grow, the Atlantic is widening, and new oceans are forming. In this Very Short Introduction Peter Molnar provides a succinct and authoritative account of the nature and mechanisms of plate tectonics and its impact on our understanding of Earth.

ABOUT THE
The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable.

Genres: Science, Nonfiction, Geology, Geography

160 pages, Paperback

First published February 7, 2015

Reviews

[Sahel Tamjeed · Rating 5 out of 5]

Fantastic insight into tectonic plates, and how the different theories of plate movement has evolved.

[Daniel · Rating 4 out of 5]

Plate Tectonics: A Very Short Introduction (2015) by
Péter Molnár

As the title suggests, Péter Molnár introduces plate tectonics. In so doing, Molnár presents an illustrative episode in the history of science, which transformed geology from a mere jumble of field observations (analogous to butterfly collecting) into a quantitative framework for making sense of the observations. While reading Molnár, I thought of the quote from Francis Crick:

“The hallmark of a successful theory is that it predicts correctly facts that were not known when the theory was presented, or, better still, which were then known incorrectly. A good theory should have at least two characteristics: it should be in sharp contrast to at least one alternative idea and it should make predictions which are testable.”

Molnár makes much the same point:

“[...] A new idea becomes believable when it predicts something that has not yet been measured or explained, especially when the idea is really trying to explain other facts.”

The book elaborates on how this triumph of an idea played out. Anyone who had previously looked at a globe for example could see the correspondence in shape between the eastern coast of South America and the western coast of Africa, as if the two continents had once fit together like puzzle pieces. Alfred Wegener was among the first to seriously suggest that this was not mere coincidence, but that the continents had in fact fit together in the past and then drifted apart. Few geologists took the idea seriously before around the year 1958, however, because nobody knew of a mechanism that could push continents across the surface of the Earth. Molnár explains how geologists collected more data after World War II, much of it from under the oceans where tectonic processes such as seafloor spreading and subduction occur. As scientists gained additional power to "see" under the ocean (both instrumentally, and in some cases directly), they found unmistakeable indicators of tectonics. Perhaps the figurative cherry on top came from the introduction of the Global Positioning System (GPS), which for the first time allowed scientists to measure the speeds and directions of land movements directly. The first prototype spacecraft for the GPS project was launched in 1978 and the full constellation of 24 satellites became operational in 1993.

Thus plate tectonics found its place among the archetypal paradigms of science, similar to Darwin's theory of evolution by mutation and natural selection. These are powerful central ideas which allow millions of seemingly disparate facts and observations to be organized and explained. The biologist Theodosius Dobzhansky once famously proclaimed that Nothing in Biology Makes Sense Except in the Light of Evolution, and something similar could almost be said about geology and plate tectonics now. Molnár does, however, explain how the clean predictive power of plate tectonics tends to break down in the geological chaos of some continental interiors, where continental collisions have jumbled together rocks that originated in multiple different locations far away and long ago.

While the book is not long, it is technically dense. If you're looking for a light read, keep looking. Most people with no prior knowledge of geology may struggle on the first read. For example, if you've never heard of words such as olivine or peridotite, breezing through the book may be difficult. You'll need time to absorb the new terms, concepts, and personalities, perhaps by a second (or third!) reading of the book, taking notes, looking up articles on Wikipedia, and/or reading additional books about geology. However, the book fits well with other VSIs on related topics, such as Rocks: A Very Short Introduction (2016) by Jan Zalasiewicz. And you'll see the topic of plate tectonics coming up in discussions of the possibility of life on other planets, such as in Planetary Systems: A Very Short Introduction (2022) by Raymond T. Pierrehumbert, and Astrobiology: A Very Short Introduction (2014) David C. Catling.

Molnár focuses on the book's topic (understandably), and almost fails to mention the impact that human activities are having on the planet. That would almost be excusable since humans had nothing to do with causing plate tectonics (duh), but he lets slip that geologists are interested in resource extraction:

Geology’s greatest impact on society surely derives from resources that the Earth provides, such as oil and gas or iron, aluminum, and copper, as well as rarer metals used in sundry ways. We might ask: Has plate tectonics facilitated the discovery and acquisition of such resources?

If he's going to mention geology's impact on society, it boggles the mind that he stays mum on geology's biggest impact of all: enabling humans to destroy Earth's habitable climate, and thereby themselves along with a million other species, largely by burning fossil fuels and dumping the combustion products straight into the atmosphere. At the barest minimum, Molnár ought to mention this problem that geologists facilitated and might help to remedy. He could explain how Nature recycles carbon dioxide back into rocks, and how geologists might find ways to accelerate the process. Natural rock weathering processes might eventually reverse the human-enhanced greenhouse effect (barring a runaway greenhouse effect that transforms Earth into a second scorching Venus and thus literally baking carbon dioxide out of carbonate rocks), but far too slowly to save our current civilization. The fate of humankind might depend on geologists, among many other people, stepping up to the plate. It's a shame that Molnár doesn't acknowledge that, as loudly and insistently as the scale of the impending crisis demands. We're far past the stage where responsible people can pretend climate change is a problem they can safely ignore.

[Gin · Rating 4 out of 5]

A good introduction to plate tectonics. It can get quite technical at times, and having some basic understanding of the subject (e.g. O Level geography) will help.

[Pablo Magaña Fernández · Rating 4 out of 5]

My background in plate tectonics boils down to John McPhee’s excellent Annals of the Former World and the few ideas I’ve been able to retain from high school. So, not much of a background at all. Still, I managed to understand most of this (rather dense but clear and accessible) book - happily, really "very short" and really an "introduction."

[earthshattering · Rating 3 out of 5]

Well, it is what it is. It’s a book on plate tectonics. If you aren’t interested in plate tectonics, you probably don’t want to read it. I personally wasn’t that interested. I did like the last part, which includes causes behind ore deposits in volcanic arcs. It’s not bad.

[Tim · Rating 4 out of 5]

Knew next to nothing about Plate Tectonics before reading. Very nice introduction and will give me interesting talking points at the pub with the lads.