(2007) Ted Nield, Granta, £18.99, hrdbk, 288pp, ISBN 978-1-862-0-79434
Supercontinent is a fascinating exploration of the longest planetary cycle, how it was elucidated and the people involved. In essence it is the story of the dance of continents across time. Anyone visiting Earth 250 millions of years ago would not see the outline of the continents as they are today but, aside from a few islands, one large supercontinent called Pangaea. 250 million years before that, continents were again fragmented across the planet. And so there is a cycle of supercontinent and fragmented continents driven by plate tectonic motion that lasts 500 million years (half a billion in new money). Indeed 250 million years hence the continents will once again be assembled into a new supercontinent. Given we know current tectonic movements and can guess likely future ones, it is possible to use a computer to model what this new supercontinent will look like. Though this last involves some guesswork, the idea is real and this supercontinent to come even has a name, 'novopangaea'. It is because this book looks forward as well as back in time that gives it the 10 billion years in its subtitle.
Ted Neild's Supercontinent also describes what Pangaea was like and how we know this. But it is the back story with which current knowledge is interweaved, of how our thinking about this area of science has evolved, that provides a valuable additional dimension. I never knew that Abraham Ortelius speculated that the shape of the west African coast and east South American coast had a causal similarity as far back as 1596. (Something I did at school and was roundly told off by my teacher for asking stupid questions.) Ortelius' musings were then filed in a library not to be rediscovered until 1994. (I wish my geography teacher had been lost filed in a library.)
Naturally, as a biologist who is into biosphere science I have a particular interest in this subject of the way the Earth works, though I must stress that this book is written in a very accessible and easy-to-digest style as those who regularly read Geoscientist magazine that Ted edits know. Ted has also has a couple of pieces elsewhere on this site (see science article index) so you can check this out for yourself. The subject of supercontinents and the continental cycle will not just interest general enjoyers of popular science but also those interested in alien worlds, hence some of you who regularly visit this site: the Earth scores of millions of years ago was quite alien in many respects to today's planet and also how can you begin to contemplate alien worlds if you do not even understand the basics of how our own one works. Supercontinent is a good quick guide to how geology has underpinned the evolution of our biosphere.
Before this turns into a gush fest -- by now you may be beginning to think that I rate this as a marvellous and scholarly work of science communication (I do) -- I should say that Ted, bless him, is coming at the subject from a geologist's perspective and this is probably because Ted is indeed a geologist. Conversely I come to geology through biosphere science and biology and so have a slightly different take on one aspect of this book. It does (correctly) note that there were key events resulting in a snowball world. It does speculate that these events may have spurred evolution. My personal take is that actually evolution (such as the evolution of eukaryotes 2.2 billion years ago or the rise 600 million years ago of metazoans (multicelled animals)) actually contributed to the onset of these events. Even the evolution of vascular land plants that helped cause the late Devonian glaciation and pave the way for the Carboniferous atmospheric hiatus affected the global climate. This last was in part explored in 1997 Royal Society discussion meeting (Phil Trans (B) v353, p1-171). Now my personal take does not detract from Ted's: we are talking about thinking at the cutting edge of research geology and palaeobiosphere science and there is room for a number of informed hypotheses. My personal difference does though illustrate that Ted is making, not just the history of geological science and thinking but, the latest thought accessible to a broad audience.
It is surely the common duty of every sentient being across the Galaxy to know how their planet works. For if not, how else are they going to look after it? Supercontinent: Ten Billion Years in the Life of our Planet provides the geological perspective.
Jonathan Cowie
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