Volcanoes are some of the most awe-inspiring natural spectacles on our planet. There is much more to them, though, than the stereotypical image of a conical fire-spitting mountain, and I have been keen to learn more. As I searched for serious introductory books on volcanology, this was one title that kept coming up. But wait, why is a biologist reviewing geology textbooks?
Volcanoes, written by the late Peter Francis and Clive Oppenheimer, published by Oxford University Press in December 2003 (paperback, 521 pages)
A short preamble seems in place. My choice to study biology went at the expense of geology, although the latter topic continued to fascinate me. Two decades later, my job exposes me to many fascinating-sounding but advanced-level earth science books. I have since started to make inroads into this field for the sheer joy of expanding my knowledge. And thus I found myself eyeing up the new book Volcanotectonics. Yet, as I recently rediscovered, there is still a gap between having covered the essentials of geology and diving headlong into an advanced topic. Hoping to bridge that gap, I turned to Francis & Oppenheimer’s Volcanoes.
The first edition of this book was published in 1993 and authored by volcanology professor Peter Francis. When he passed away in 1999, his former PhD student Clive Oppenheimer, now a professor of volcanology in his own right, took it upon him to revise the text and bring it up to date for this second edition, published in 2003. Francis’s desire was to write a book to be read rather than consulted. Volcanoes is thus less of a textbook than you might think: there are no chapter summaries or student exercises. What you will find is a logical flow of chapters detailing the inner workings of volcanoes, glued together by the fascinating stories of past eruptions and, occasionally, Francis’s trademark humour, lampooning the field of volcanology.
“Volcanoes is […] less of a textbook than you might think: there are no chapter summaries or student exercises. What you will find is a logical flow of chapters detailing the inner workings of volcanoes, glued together by the fascinating stories of past eruptions […]”
Volcanoes starts with very primordial questions. Where do the heat and the rocks that drive volcanism come from? This introduces you to planetary formation and the radioactive decay of isotopes. In case you were expecting to start with plate tectonics, that is the next subject to be tackled. This explains the difference between volcanoes at plate margins where the oceanic crust is either formed or destroyed, and the minority occurring far from margins, such as the volcanic islands of Hawai’i.
Chapters four to twelve form, to my mind, the nuts-and-bolts section of this book, going into all the glorious and gory details of an eruption from beginning to end. This covers everything from formation and movement of magma; different eruption styles; types of lava; eruption columns and the deposits of ash and pyroclastic rocks they leave behind; pyroclastic density currents, debris avalanches, and mudflows or lahars—and their deposits; the different landscape forms left after eruptions, including types of volcanoes and how they erode, and the landscape depressions known as calderas; super-eruptions; and, finally, the common but hard-to-observe phenomenon of underwater volcanism.
The last four chapters cover closely allied topics: volcanoes in the solar system; the effects of recent eruptions on climate and the palaeoclimatological evidence of older ones; and, new to this edition, two chapters on monitoring of volcanoes, and assessing and managing the risks they pose.
“I was fascinated by some of the technicalities. For example by […] the physics behind eruption columns and the interplay with the wind, and how to deduce eruption intensity from them […]”
Two aspects, I thought, make this book very enjoyable to read. First, it broaches subjects without overwhelming you. When it talks of magma, it mentions the physics of gas bubble formation and growth (vesiculation), and the flow of liquid rock (rheology) without smothering you in detail. It will list different eruption styles (Hawaiian, Strombolian, Vulcanian, Plinian, etc.) and lavas (andesitic, dacitic, rhyolitic, etc.) while highlighting the arbitrary nature of such classifications, as these things exist on a continuum. And where formulas are given, for instance in the chapter on eruption columns, it is to demonstrate principles rather than go deep into the mathematics. If you are so inclined, each chapter comes with recommended sources and literature references for further research.
The authors explain terminology as they go, supported by many photos and diagrams. I would have liked a glossary—lacking that, I occasionally had to grab my dictionary to jog my mind. Even so, I was fascinated by some of the technicalities. For example by the distinction between central vent and large-scale fissure eruptions. By the underground movement of magma and intrusion of dikes. By the physics behind eruption columns and the interplay with the wind, and how to deduce eruption intensity from them. By the detective work that uses palaeoenvironmental records such as tree rings, and the extent and thickness of deposits to reconstruct eruptions for which there is no eyewitness testimony. Or by what makes pyroclastic density currents so terrifyingly destructive.
The second aspect that makes Volcanoes very readable is that this is not a theoretical treatise with hypothetical scenarios. Explanations are given by means of real-world examples of past eruptions. Four classic ones are introduced early on (Vesuvius, Krakatau, Mount Pelée, and Mount St. Helens), but plenty of others are recounted throughout. This includes those familiar from popular accounts (e.g. Tambora, Laki, and Toba), technical books (e.g. Pinatubo and the Soufrière Hills volcano), and those only known to volcanologists and victims (e.g. El Chichón and Nevado del Ruiz). You will learn as much about these eruptions as about what we learned from them.
“Having read the book cover to cover, there remains one important question that is difficult for me to answer. Given its publication date, how up to date is it? And is it time for a new edition?”
Having read the book cover to cover, there remains one important question that is difficult for me to answer. Given its publication date, how up to date is it? And is it time for a new edition? Technological advances and new space missions have revealed much more about extraterrestrial volcanoes—this book was published before the Opportunity and Curiosity rovers started trundling over the surface of Mars, for example. But what about volcanism here on earth? Recent eruptions have probably taught us new lessons (2010 tongue-twister Eyjafjallajökull no doubt revealing more about ash clouds), but not being a student of earth sciences, this is a hard question for me to answer. The only other more recent book I could think of was The Encyclopedia of Volcanoes, published in a second edition in 2015. But at over 1400 pages this can hardly be called an introductory textbook.
I decided to contact Clive Oppenheimer who kindly replied that there have not been any paradigmatic shifts in volcanology since then, but he did mention, in addition, the 2010 Merapi eruption, and highlighted new technology such as synchrotron radiation sources for fine-scale chemical analysis of volcanic rocks. Additionally, he pointed out Volcanoes: Global Perspectives (2022) as a recent textbook. And a third edition? It is not yet in the making, though he hopes to get around to it when time allows.
So, in sum, if you are looking for a good introductory volcanology textbook, I found this one both enjoyable and accessible. I came away feeling I understood much more about volcanoes. Bring on Volcanotectonics.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
Other recommended books mentioned in this review:
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“The Dinosaurs Rediscovered: How a Scientific Revolution is Rewriting History”, written by Michael J. Benton, published by Thames & Hudson in April 2019 (hardback, 320 pages)
If this sounds familiar, indeed, when I reviewed Steve Brusatte’s book The Rise and Fall of the Dinosaurs: The Untold Story of a Lost World, I praised the enviable ease with which he explained modern methodologies. Now, with all due respect to Brusatte (and I really, really enjoyed his book), Benton has almost 30 years on him. Next to having authored standard textbooks such as Vertebrate Palaeontology (currently in its fourth edition) and co-authored Introduction to Paleobiology and the Fossil Record (currently in its second edition), he is also the series editor for Wiley-Blackwell’s textbook series Topics in Paleobiology, and he has previously authored When Life Nearly Died: The Greatest Mass Extinction of All Time with Thames & Hudson, dealing with the end-Permian mass extinction. With a career spanning some four decades, if anyone can comment first-hand on the evolution of the field, it is Benton.
After a brief introduction on how scientific discoveries are made, and a short foray into the philosophy of science, the bulk of the book consists of nine chapters documenting areas where palaeontology has been revolutionised. Partially by new fossil finds, but, much more importantly, by new tools, new technologies, more powerful computers, lateral thinking, and interdisciplinary approaches.
Benton’s opening of the book is perhaps slightly risky, as he has put the most technical chapters first. There is the question of when the dinosaurs first evolved. After the giants of the Paleozoic went extinct (see my last review of Carboniferous Giants and Mass Extinction: The Late Paleozoic Ice Age World), did the dinosaurs opportunistically explode onto the scene, or did other reptile groups slowly fade with dinosaurs taking over the proverbial relay race? New computational tools have pushed the origin story further back in time, but have also shown that both explanations have something going for it.
“Ancient DNA may have revolutionised archaeology […], but Benton explains why we shouldn’t expect Jurassic Park to become reality anytime soon.”
Similarly, the picture of the dinosaur family tree benefited first from the cladistic revolution, which saw a different way of thinking about classifying species, collecting and analysing as many informative characters as possible to determine relationships. Then, with access to supercomputers, Benton and his team have been involved in producing an all-encompassing family tree, a so-called supertree (which you can explore in all its glory here), revealing how the dinosaur lineage diversified rapidly early on, but the rate of speciation slowed down after that. That things never stay still was shown only recently with Baron et al.‘s 2017 Nature paper that proposed some radical changes to the family tree (for an accessible take on it, see Darren Naish’s blog post at Scientific American).
If this is all a bit technical, despair not, the remainder of the book deals with more “mundane” questions your typical six-year-old might ask. Excavation techniques might have changed little since the dawn of the discipline, but imaging tools such as photogrammetry have revolutionised what palaeontologists can document at a dig site, while CT scanning offers a non-destructive technique afterwards to image what you have dug up. And new microscopy techniques, together with some fantastically preserved fossils, have revealed much about the colour of dinosaurs (and hey, feathers!).
“What really helps this book shine are the illustrations. Thames & Hudson […] has redrawn many of them specifically for this book.”
Ancient DNA may have revolutionised archaeology (see my review of Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past), but Benton explains why we shouldn’t expect Jurassic Park to become reality anytime soon. Nevertheless, even without dinosaurs stomping around here and now, we have learned so much about how they lived. Bone histology and X-ray imaging have revealed growth rates, while finite element analysis (a method borrowed from structural engineers who use it to stress-test designs of bridges and buildings on computers) has allowed calculations of bite forces and how dinosaurs ate, while analyses of microwear on tooth surfaces (see my reviews of The Tales Teeth Tell: Development, Evolution, Behavior and Evolution’s Bite: A Story of Teeth, Diet, and Human Origins) has shed light on their diet. Biomechanical computations and careful analyses of trackways tell us more about their posture, how they moved, whether they could run, and what the deal is with them flying, or at least flapping about.
And there is, of course, the always fascinating topic of their extinction. Benton has first-hand seen the rise and rise of the Alvarez asteroid impact hypothesis (see T. rex and the Crater of Doom and my review of The Ends of the World: Volcanic Apocalypses, Lethal Oceans and Our Quest to Understand Earth’s Past Mass Extinctions), despite the initial pushback from the uniformitarian crowd (see my review of Cataclysms: A New Geology for the Twenty-First Century), and he provides a great overview of why this idea has become so widely accepted. Even here, facts move quicker than book publishing can keep up, and the reveal (not two weeks ago!) of a site potentially recording the direct aftermath of the impact has raised eyebrows around the world (see DePalma et al.‘s PNAS paper and the accompanying article in The New Yorker). And it probably has more than one palaeontologist fervently hoping this is not an elaborate hoax. I am cautiously optimistic so far – this could be mindblowing, but let’s see more hard proof first.
“[Benton] convinces that now is a very exciting time, indeed, to be a palaeontologist. I can’t wait to see what surprises lie in store in the near future.”
In addition to Benton’s accessible writing, what helps this book shine are the illustrations. I regularly bemoan how few publishers get this right; complex figures are reproduced directly from their source in greyscale so you can’t tell apart the different lines and symbols in graphs, they are often too small, or the source material is so poor that resolution suffers or compression artefacts are visible. Not this book. Thames & Hudson is obviously known for their illustrated books, and checking the illustration credits suggests that their in-house art studio (?) has redrawn many of them specifically for this book. This in addition to two colour plate sections and some really nice species profiles. A job well done, and I wish more publishers went to this effort.
The Dinosaurs Rediscovered is easy to recommend. Benton’s enthusiasm is infectious, and his skill at packing so many exciting developments in this book speaks of his deep involvement in this field. He provides a fantastic overview of the revolutions in palaeontology over the last few decades and convinces that now is a very exciting time, indeed, to be a palaeontologist. I can’t wait to see what surprises lie in store in the near future.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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“Carboniferous Giants and Mass Extinction: The Late Paleozoic Ice Age World“, written by George R McGhee, Jr., published by Columbia University Press in September 2018 (paperback, 368 pages)
McGhee has devoted some 40 years to studying the late Paleozoic* extinctions. He has previously authored The Late Devonian Mass Extinctions: The Frasnian/Famennian Crisis (1996) and When the Invasion of Land Failed: The Legacy of the Devonian Extinctions (2013), both published by Columbia University Press, and seeing how frequently he references the latter, the book under review and the 2013 title deserve close reading together.
McGhee first sets the stage, primarily focusing on (from older to younger) the Devonian, Carboniferous, and Permian Periods. This was a time of repeated planetary ice ages lasting millions to tens of millions of years. What characterises this section, and the book as a whole, is that it goes beyond a popular science account of the consensus view. The resolution of the information conveyed, if you will, is higher and McGhee goes into the nitty-gritty: the different explanations, competing models, and different datasets obtained by different scholars working on this. This is science in all its messy, real-world, complicated glory.
After outlining the different ideas of how these long ice ages came about 
(the position of the continents being one important factor, see my review of Earth History and Palaeogeography), the book takes a roughly chronological approach, dropping down to the resolution of geologic Ages. McGhee has included reference tables throughout the book, but if, like me, stratigraphy is not part of your background, names such as the Famennian, Visean, or Serpukhovian will be new. If you don’t want to constantly be flipping back and forth between pages, you might want to have a print-out of the latest chronostratigraphic chart or a reference work such as the latest version of the Geologic Time Scale at hand. This is obviously not a complaint, but it will give you an indication of the level this book is pitched at.
“McGhee goes into the nitty-gritty […] this is science in all its messy, real-world, complicated glory.”
The world McGhee reveals here is strange indeed. With flowering and woody plants yet to evolve, the land was dominated by rainforests of giant lycophytes, horsetails, ferns, and other trees. Some of their descendants are still with us (lycophytes as the diminutive club mosses, for example), others have gone extinct. But not only were the species different, they grew differently too. As McGhee describes vividly, rather than dense canopies of leaves, Carboniferous rainforests looked more like fields of giant green stalks without branches, topped by spore-bearing organs. As opposed to modern long-lived trees, Carboniferous trees grew trunks once, dispersed their spores, and then died.
Important, too, was the rise in atmospheric oxygen levels (hyperoxia). Water locked in ice sheets led to a drop in sea levels that are thought to have exposed vast areas of land that were prime territory for these new rainforests. The onset of photosynthesis on a massive scale pumped oxygen into the atmosphere (see also Oxygen: The Molecule that Made the World or Oxygen: A Four Billion Year History). One intriguing line of evidence McGhee mentions are huge charcoal deposits that indicate that Earth, for the first time in its history, started experiencing wildfires (I wrote more about this in my review of Andrew Scott’s Burning Planet: The Story of Fire Through Time, he is an authority on this topic). At atmospheric oxygen levels of 30% (vs. our current 21%) fires burn much hotter, even consuming wet plant material. This and other factors here discussed resulted in some 90% of the world’s coal reserves being deposited during this period (hence the name Carboniferous).
Hyperoxia has also been proposed to have driven the observed animal gigantism. McGhee enthusiastically introduces the many super-sized versions of insects, scorpions, and millipedes; vertebrates that were distant ancestors of today’s amphibians, reptiles, and mammals; and giant marine invertebrates. The illustrations reveal these animals to often be five, ten, or more times bigger than their modern counterparts. Here, too, some authors have argued for the importance of other factors, though hyperoxia seems the best explanation.
“Carboniferous rainforests looked like fields of giant green stalks without branches, topped by spore-bearing organs.”
And then the party ended. A first crisis at the end of the Capitanian Age some 265 million years ago removed not so much a large number of species, but it did remove important players in the ecosystems. This has led McGhee and others to argue it was the fifth-most-severe extinction event ecologically, even though it doesn’t normally feature in the list of the classic five mass extinctions as defined by the work of palaeontologists Sepkoski & Raup and others, which is based on the number of families disappearing.
The Capitanian crisis was just a prelude to the mother-of-all-extinction events at the end of the Permian. This has been written about by noted scientists such as Douglas Erwin (Extinction: How Life on Earth Nearly Ended 250 Million Years Ago) and Michael Benton (When Life Nearly Died: The Greatest Mass Extinction of All Time), and I have touched on it when I reviewed The Ends of the World: Volcanic Apocalypses, Lethal Oceans and Our Quest to Understand Earth’s Past Mass Extinctions. But the science is regularly updated and McGhee provides a detailed overview of the latest findings, revealing just how apocalyptic this event was.
Not only did it involve the largest-ever instance of continental flood basalt volcanism, forming the Siberian traps (see Large Igneous Provinces for more), but the rising plume of magma responsible for it erupted in a place where earth’s crust contained thick deposits rich in sulfur, bromide, and chloride-containing compounds, making the area, in McGhee’s words, a giant petrochemical bomb. The volumes of carbon dioxide and other gases emitted are given in the tens to hundreds of trillions of tonnes, resulting in a rapid temperature increase of an estimated 16°C**. The proposed kill mechanisms for the extinction encompass everything from heat death and suffocation to acid, carbon dioxide, and radiation poisoning. A hugely impoverished world resulted, but life squeezed through, just, and the world entered the Triassic Period and the age of the dinosaurs.
“The end-Permian mass extinction involved the largest-ever instance of continental flood basalt volcanism in an area that was, in McGhee’s words, a giant petrochemical bomb”
In his final chapter, McGhee explores the relevance of the late Paleozoic world to us now, little known as it is outside of academia. It is safe to say that the huge coal deposits from this time enabled both the Industrial Revolution and subsequent anthropogenic climate change. But it also saw major innovations in the history of life: the invasion of land by animals (see Gaining Ground: The Origin and Evolution of Tetrapods), largely driven by the evolution of the amniote egg that eliminated water loss; while the end-Permian extinction and the subsequent drop in oxygen levels may, some argue, have driven the evolution of four-chambered hearts and even warm-bloodedness (see my review of Fires of Life: Endothermy in Birds and Mammals). McGhee engages in an interesting bit of speculative alternative history, asking how life would have been different if the late Paleozoic ice age had not happened or if the end-Permian mass extinction had panned out differently.
Carboniferous Giants and Mass Extinction is a fascinating and well written scholarly overview of this exceptional period in deep history. The subject matter is technical, and readers will certainly benefit from having some background in palaeontology. But McGhee’s entertaining and captivating writing prevents this book from being a hardcore geology snooze-fest. If you want to know more about what came before the dinosaurs, this, and his other books, come highly recommended as overviews of the academic debates and developments.
*For the uninitiated like myself: geologists employ a hierarchical naming system for time periods: Eons, Eras, Periods, Epochs, Ages. The Paleozoic Era contains the Carboniferous and five other geologic Periods. The Carboniferous, in turn, is divided into two epochs, each containing a number of ages. Epochs usually have two to three ages in them, each typically lasting some 3 to 10 million years.
**To put this into perspective, humanity has emitted roughly 350 billion tonnes of carbon dioxide since about 1750, and annual emissions in 2014 were about 10 billion tonnes.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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“Essentials of Geology“, written by Frederick K. Lutgens and Edward J. Tarbuck, published by Pearson in January 2017 (paperback, 608 pages)
The task of picking a textbook sounds simpler than it is. Many major academic publishers publish their own undergraduate earth science textbooks. So do you pick Oxford’s Physical Geology Today, Wiley’s Physical Geology: The Science of Earth, or rather Norton’s Essentials of Geology? As I have only read this textbook, this review will unfortunately not help you decide. So, why did I choose Pearson’s Essentials of Geology?
Frederick K. Lutgens and Edward J. Tarbuck are both emeritus professors, so should know the field well, and with the book now in its 13th edition, I figured there has been plenty of opportunity to revise the book in response to feedback from instructors and students. Other reasons were more prosaic: the title sounded just what a geology-newbie like myself would need, and it seemed the book was available in hardback (alas, that was not the case, some databases and retailers are not displaying the right information). Comparing with other textbooks though, it seems that the core material being taught is very similar across these books. If, like me, you are not assigned a textbook by a course instructor, one could legitimately ask whether it even matters which book you pick.
Starting with plate tectonics, which has become the basis on which geology rests nowadays (see also my review of The Tectonic Plates are Moving!), Essentials of Geology takes you through all the important topics and gives you the basics on minerals, the different types of rock, the dynamics of Earth (volcanoes, earthquakes, mountain building, and ocean crust formation), as well as weathering of rocks, desert formation, and landslides (pardon me, mass movement). The hydro- and cryosphere also get attention in a series of chapters dealing with running water, groundwater, glaciers, and shorelines. Finally, there are chapters dealing with geologic time and earth’s evolution, and, required nowadays, global climate change.
“videos accessible via QR codes […] seem like a gimmick, but really are not”
This book is very accessibly written and has all the trappings you have come to expect of an undergraduate textbook: chapters opening with a list of learning goals, questions at the end of each section, and, at chapter’s end, a point-wise summary and a list of assignments. To make sure students remain engaged there are “Did you Know?” sections sprinkled throughout the text, and a huge number of full-colour illustrations and photos. Especially the artwork of Dennis Tasa deserves mention.
Like many modern textbooks, Pearson has an online platform called MasteringGeology that I have not explored yet. It is supposed to give instructors the option to assign interactive media and reading before a class, allow the use of laptops or tablets during classes to assign questions, and hand out assignments after the class. There are also outlines of PowerPoint lectures, test banks, and other teaching resources.
One feature that not all above-mentioned textbooks have is videos accessible via QR codes. If you are a techno-Luddite like myself without a smartphone to scan these, not to worry, each figure also has a shortened URL to access these. This may seem like a gimmick, but having watched them, they really are not. The majority are so-called SmartFigures where contributor Callan Bentley talks you through some of the book’s drawings while annotating them (an example here – don’t you just love how publishers use random capitalisation to spice things up?) His voice is pleasant enough but I felt that these did not always add that much. If you want information explained to you in a different way they will be helpful. Far more impressive and really adding something are the Mobile Field Trips, where contributor Michael Collier takes you into the field in his Cessna aeroplane (an example here), and the use of drones to show you field footage of geological formations (an example here). There are also some proper animations, as well as videos provided by NASA. I admit that I found these clips and animations surprisingly useful.
“[…] despite being a core text, the authors do not present the field as a dogmatic monolith of knowledge”
Something to keep in mind is that the book is quite US-centric, using many examples of geological structures and landscapes found in the USA. Mercifully, the book uses metric units, mentioning imperial units in brackets, though it is not 100% consistent throughout, mentioning imperial units only in “Did you Know?” sidebars and some questions. My biggest gripe, something true of most textbooks, is the floppy paperback format and thin paper used. This book will not stand up on a shelf on its own and is very prone to dog ears and creased pages. I understand that publishers are trying to save weight while producing a book that lies open flat during lectures, but it is hard not to feel they have built in obsolescence by producing books that will last just a semester before being tossed out for the next obligatory edition.
Having worked my way through the book I feel I learned a lot. There were some nice a-ha moments (such as the insight that sedimentary, metamorphic, and igneous rocks are on a continuum determined by temperature and pressure) and it clarified the jargon for me. I also appreciated that, despite being a core text, the authors do not present the field as a dogmatic monolith of knowledge. Where scientists disagree and multiple explanations have their own adherents, this is mentioned (examples include the debate over mantle plumes, see Plates vs Plumes: A Geological Controversy, or the different models to explain the formation of desert pavement). Similarly, the book feels up-to-date by acknowledging how many scientists think that the extinction of the dinosaurs was a one-two knockout of Deccan volcanism and a meteorite impact (see my review of The Ends of the World: Volcanic Apocalypses, Lethal Oceans and Our Quest to Understand Earth’s Past Mass Extinctions), or that ancient DNA is showing we interbred with Neanderthals.
Essentials of Geology does what it says on the tin and does so very well. I feel far more confident now to tackle more advanced textbooks (see my review of CUP’s Structural Geology, but I am also salivating over Large Igneous Provinces, Mid-Ocean Ridges, and Orogenesis: The Making Of Mountains). Though I can not say how it holds up in comparison to other textbooks, I can at least say that if you want to get started learning more about geology this is a very good starting point that offers a lot of bonus material other than the book.
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“The Tectonic Plates are Moving!“, written by Roy Livermore, published by Oxford University Press in April 2018 (hardback, 482 pages)
Livermore has divided this book into two parts, beginning with the first generation of scientists exposed to plate tectonics. I was surprised he didn’t start with Alfred Wegener, whose 1912 theory of continental drift is the intellectual progenitor of today’s plate tectonics (recognition for it evaded him during his lifetime, see the splendid biography Alfred Wegener: Science, Exploration, and the Theory of Continental Drift). Instead, Livermore starts in the 1960s with the discovery of the zebra-skin-like pattern of past magnetic polarity stored in spreading seabed (see my review of The Spinning Magnet: The Force That Created the Modern World – and Could Destroy It). The chain of events that led scientists to link this observation to others and suggest that the earth’s plates were moving, and the stubborn resistance by especially the US geological to this idea has been told elsewhere in brief (see Four Revolutions in the Earth Sciences: From Heresy to Truth) and at gruelling length (Frankel’s four-volume opus The Continental Drift Controversy), but Livermore here provides an excellent 180-page executive summary.
The real value of this book, however, lies in the second half, which takes the reader through all the subsequent developments in the 1980s and onwards. This part gives a wonderfully balanced overview of all sorts of controversies and new insights that complicated the picture developed so far. Plate tectonics turned out to not only destroy and create oceanic plates – continental crust could also be subducted and returned to the planet’s surface. Then there is continued disagreement over whether the supercontinent Pangaea that existed between approximately 320-175 million years ago was simply the latest iteration in a very long-term cycle of supercontinent formation and breakup. Nield popularised this idea in Supercontinent: 10 Billion Years in the Life of Our Planet, but it is not accepted by all geologists.
The US military makes repeated appearances in Livermore’s story, and geologists have often benefited from technologies developed during the Cold War when the military was trying to spot Russian submarines or listen out for tremors of nuclear explosions. Development of satellite technologies assisted in mapping the seabed, revealing the wonderfully complicated world of underwater subduction zones and mid-ocean ridges (see Searle’s Mid-Ocean Ridges for a technical lowdown).
“To paraphrase evolutionary biologist Theodosius Dobzhansky: nothing in geology makes sense except in the light of plate tectonics.”
Then there is the influence of plate tectonics on global climate through the long-term geochemical cycles described in The Oceans: A Deep History. Carbon dioxide is added to the atmosphere via volcanic eruptions and at spreading mid-ocean ridges (both obviously require plate tectonics). Removal of carbon dioxide happens when rocks erode over time. The chemical reactions involved turn carbon dioxide into various other compounds that are washed into seas by rivers. These compounds are used by marine organisms large and small to make their shells, which then end up buried in seafloor sediments when they die, and ultimately get recycled into the Earth’s interior when oceanic crust is subducted. How is that for a neat little long-term thermostat? Additionally, the continents waltzing around and the formation of land bridges (see my recent review of Land Bridges: Ancient Environments, Plant Migrations, and New World Connections) influence oceanic and atmospheric circulation, and thus climate, directly.
Finally, the current frontier of knowledge where all the action is: geophysics. What happens to the pieces of crust once they are subducted into the Earth’s interior? Do they descent all the way to the core to form evocatively called “slab graveyards”, from whence they rise up in the form of plumes as in a giant lava lamp? Or do they hover close under the planet’s surface in a separated convection layer? (A fiercely contested subject, see Plates vs Plumes: A Geological Controversy – Livermore sides with the idea of plumes). What of these mysterious entities at the boundary between the Earth’s core and the mantle called Tuzo and Jason? Torsvik & Cock described them in Earth History and Palaeogeography as plume generating zones responsible for the majority of the large volcanic eruptions linked to previous mass extinctions (see Brannen’s The Ends of the World: Volcanic Apocalypses, Lethal Oceans and Our Quest to Understand Earth’s Past Mass Extinctions, and see Ernst’s Large Igneous Provinces for the technical lowdown). Have they been fixed in place over deep time? Are there really only two of them? And what of interactions and heat exchange between the Earth’s molten core and the mantle? What does this mean for the Earth’s magnetic field? When did plate tectonics start? Has it gone through different phases?
Since we can drill and dig just a few kilometres into the Earth’s crust, the answers to all these questions are far out of our reach. It has only been in recent decades with the refinement of visualisation techniques such as seismic tomography and the development of complex computer models that we have been able to gather data and theorise on what happens in the Earth’s interior. I came away from this last section with a renewed respect for, and interest in, geophysics.
“What of these mysterious entities at the boundary between the Earth’s core and the mantle called Tuzo and Jason?”
So, what has plate tectonics ever done for us? From providing water to fill our oceans, hydrothermal vents where life probably first evolved, a carbon cycle to control long-term climate, to a geodynamo generating a magnetic field that prevents our protective atmosphere from being obliterated by the charged particles the sun hurls our way… plate tectonics has provided us with a planet that has been relatively stable for billions of years, providing just the right conditions for the evolution of complex life (see also The Goldilocks Planet: The Four Billion Year Story of Earth’s Climate). Having surveyed neighbouring planets, astrobiologists (they who study the possibility of life on other planets) have realised that plate tectonics will be a prerequisite for a habitable planet (for readable introductions, see How to Build a Habitable Planet: The Story of Earth from the Big Bang to Humankind and Lucky Planet: Why Earth is Exceptional – and What that Means for Life in the Universe).
The Tectonic Plates are Moving! is a rock-solid read (here, Livermore, have one of my puns): the pacing of the book is great, the irreverent jokes and anecdotes genuinely amusing, the overview of different schools of thought balanced, and the explanations lucid. Most of the jargon used is introduced and clarified, though I struggled a bit with all the names for rock and mineral types (there is no glossary included). I hope to remedy that with a basic geology textbook I have finally bought. There is a good number of helpful illustrations included, some of which would have been better had they been reproduced in a colour plate section.
Neither a dull textbook nor an overly technical read, Livermore strikes just the right balance and manages to deliver a compelling book on the importance of plate tectonics and the many exciting developments in past and current research.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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“Earth History and Palaeogeography“, written by Trond H. Torsvik and L. Robin M. Cocks published by Cambridge University Press in December 2016 (hardback, 317 pages)
Trond H. Torsvik and L. Robin M. Cocks, both established geologists, draw on a huge body of interdisciplinary knowledge for this book. This includes, amongst others, palaeomagnetism and polar reversals (see my recent review of The Spinning Magnet: The Force That Created the Modern World – and Could Destroy It for an introduction), past volcanic eruptions, geophysics and tomography (a technique to visualise the inside of the planet), the rock record, and fossil distribution. Putting this all together allows them to reconstruct the face of the Earth over the last 540 million years. We know that plate tectonics was happening earlier in time as well, the geological story at the heart of the lyrical A Wilder Time: Notes from a Geologist at the Edge of the Greenland Ice was that we have evidence for plate tectonics as far back as approximately 2 billion years, and this book even mentions 3 billion years. But details just become too sketchy to make reliable planetary-scale reconstructions. So, as the authors make clear, this is by no means the definitive story but a work in progress. This book shows the current state of our knowledge, which will no doubt be further refined in the future.
After outlining their methodology and introducing, with maps, all 268 tectonic units that they have recognised as currently making up the surface of our planet (that’s a lot more you typically see on schematic maps) we get to the bulk of the book. This consists of eleven chapters that cover each geological period from the Cambrian (541-487 million years ago) to the Neogene and Quaternary (23 million years ago to today). Each chapter starts with several overview maps of the whole planet at various stages of each geological period which are already worth their weight in gold if this floats your boat. But that’s just the beginning.
“[these] overview maps […] are already worth their weight in gold if this floats your boat.”
A large number of maps and diagrams show different projections and perspectives, systematically going through each of the major continents as they existed back then. These maps show current continent outlines and estimated coastlines and deep and shallow seas back then, but also divisions between plates where the seabed was spreading apart or where plates were being subducted or colliding to form mountains chains. Symbols indicate approximate locations of major reefs, ice caps, lakes, areas of volcanic activity including large igneous provinces (the massive volcanic eruptions implicated in mass extinctions that we met in The Ends of the World: Volcanic Apocalypses, Lethal Oceans and Our Quest to Understand Earth’s Past Mass Extinctions
), areas where coal was deposited, areas that dried up and left evaporites, faunal provinces that show the distribution of important fossil groups, as well as side-bars with approximate sea-level and climate conditions compared to today, and many other details. In the later chapters on geologically younger periods, when more details can be reliably reconstructed, many other diagrams and maps are shown, detailing the formation of mountain ranges such as the Himalayas, the appearance and disappearance of oceans, movements of the oceanic plates, etc. etc. The amount of information that is packed into these figures is breathtaking.
The text, meanwhile, links together the different events depicted and provides further context and details. Some things cannot be shown on the maps, such as the location of certain minor plates. We know they were somewhere, but we often lack enough information to place them on a map in any meaningful way. The text not only covers the geological details but also contains a section describing the dominant flora and fauna and important developments in the evolution of life during the period in question.
The book is not what you would call bedtime reading (though that did not stop me from doing so anyway) and is suffused with jargon. This comes from three sources. All geological periods are divided into shorter stages that have their own names, as shown on the official International Chronostratigraphic Chart that is printed on both endpapers. All 268 tectonic units have their own names that are introduced in detail in chapter 3. But on top of that is the terminology for geological processes and rock types. This is where my decision to study biology rather than geology comes back to bite me (I am looking at investing in some undergraduate geology textbooks because the subject continues to interest me). So if, like me, you can’t tell your ignimbrite from your gneiss, or don’t know the difference between volcanoclastic intercalations and diachronous migration, you might struggle with the text. Now, to fault the book for this would be completely missing the point. This is an advanced-level reference work, squarely aimed at an audience of geologists and palaeontologists with the relevant background knowledge – but it is good to know going in. Even so, with my limited knowledge of geological processes mostly gleaned from popular academic books, I was able to follow the grand narrative just fine. And what a fantastic story it tells!
“This […] advanced-level reference work [is] squarely aimed at an audience of geologists and palaeontologists with the relevant background knowledge”
I cannot think of another book that takes such a clear, graphic approach as Earth History and Palaeogeography does. Not being familiar with the field, I am hesitant to claim this is a first, but it is obviously a very valuable compilation of the current state of our knowledge. For geologists and palaeontologists this is a mandatory reference work, but academically-minded book readers might also find this very interesting. I expect I will regularly be pulling it off the shelf to consult it while reading other books on palaeontology or geology.
For those interested, there are supplementary online resources, including several programmes that allow you to make your own reconstructions, including graphics and maps like the ones shown in the book. I have not played around with this, but it is fantastic to see the authors willing to keep this project alive post-publication.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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“The Rise and Fall of the Dinosaurs: The Untold Story of a Lost World”, written by Steve Brusatte, published in Europe by Macmillan in April 2018 (hardback, 404 pages)
Brusatte has previously authored the textbook Dinosaur Paleobiology. The current book, however, is a pop-science account of these fascinating reptiles. Ordered roughly chronologically, it starts off with the Permian mass extinction some 252 million years ago. Brannen’s recent book The Ends of the World did a marvellous job introducing the five major mass extinctions, but Brusatte can be equally evocative in his descriptions. As in Martin’s The Evolution Underground, Brusatte advances the idea that underground burrows were crucial to survival.
Brusatte introduces the dinosauromorphs, the close evolutionary forebears of the dinosaurs. He talks us through the Triassic, when all the world was united in the supercontinent Pangaea, small dinosaurs competed with early mammal relatives, and the world was ruled by a reptilian sister group that would leave us the crocodiles. After the end-Triassic mass extinction, the dinosaurs were left standing and rose to dominance during the Jurassic and Cretaceous. We meet the sauropods, gigantic long-necked herbivores, and the various theropod carnivores that terrorised them. Two chapters introduce the tyrannosaurs and its most famous representative: Tyrannosaurus rex, which Hone details further in The Tyrannosaur Chronicles: The Biology of the Tyrant Dinosaurs.
And then there is the evolution of flight and the fantastic fossil discoveries of feathered dinosaurs in recent decades (some good entry-level books are Feathered Dinosaurs: The Origin of Birds or Flying Dinosaurs: How Fearsome Reptiles Became Birds). Brusatte ends with the Cretaceous mass extinction, Alvarez’s impact hypothesis, detailed in T. rex and the Crater of Doom, and the various lines of evidence leading up to it. The reign of the dinosaurs may be over, but Brusatte reminds us that some dinosaurs survived and are still with us today as birds, on which much more in The Ascent of Birds: How Modern Science is Revealing their Story.
“[…] Brusatte excels at making current scientific methods that have been crucial in the study of dinosaurs understandable”
Brusatte livens up the science with enthusiastic stories of discoveries in the field and the many talented palaeontologists he has worked with. Never too chatty of forcedly funny, these anecdotes are woven in skillfully and are relevant to the story at hand. Similarly, he introduces important historical figures such as, of course, Marsh and Cope, whose infamous rivalry known as the Bone Wars has been detailed in books such as The Bonehunters’ Revenge: Dinosaurs, Greed, and the Greatest Scientific Feud of the Gilded Age or The Gilded Dinosaur: The Fossil War Between ED Cope and OC Marsh and the Rise of American Science. But also Barnum Brown (the title of his biography, Barnum Brown: The Man Who Discovered Tyrannosaurus rex, explains his fame), or the eccentric Transylvanian Baron Franz Nopcsa von Felsö-Szilvás who offered a credible explanation for why Transylvanian dinosaurs were so small (see more about this phenomenon of dwarfism in Transylvanian Dinosaurs). Brusatte successfully brings these figures to life, shining a light on what palaeontology involved in decades gone by.
The thing that really makes this book stand out for me, though, is that Brusatte excels at making understandable current scientific methods that have been crucial in the study of dinosaurs. Whether it is radiometric dating, morphological disparity analysis, photogrammetry or finite element analysis, Brusatte casually but skillfully explains these methods with an ease that is enviable. So much so that he doesn’t even need to use illustrations to make himself clear. Instead, the book is illustrated with both period and contemporary black-and-white photos of fossils and the scientists who discovered them.
As befits a book of this scope, the production is rather lavish. The American version, published by William Morrow, has a really nice cover illustration by Todd Marshall. I was initially a bit disappointed by the more abstract illustration of Macmillan’s UK version, but the embossing of the drawing and the title gives it class. And Marshall’s drawings are still present opening each chapter.
The Rise and Fall of the Dinosaurs has received rave reviews, and it is easy to see why. The enthusiasm Brusatte has for his profession virtually drips off every page. I used this phrase before when reviewing Squid Empire, and it applies here: this book is fiendishly readable – I tore through it in just two evenings. Brusatte is a masterful storyteller who knows how to keep your attention, and the book is both wonderfully written and admirably accessible. Be warned though, you might just want to become a palaeontologist after reading it.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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“Squid Empire: The Rise and Fall of the Cephalopods”, written by Danna Staaf, published by ForeEdge, a University Press of New England imprint, in December 2017 (hardback, 237 pages)
Cephalopods have a long and illustrious evolutionary history, stretching back some 500 million years. The fact that they are still here means they have lived through their fair share of mass extinctions. After some basic morphology, Staaf quickly introduces us to the three groups on the family tree, as these are the main protagonists whose fate we will follow here.
A large chunk of the book deals with the now-extinct group of Ammonoids whose familiar whorled fossil remains are so numerous that they can be used to date rock strata. Although many species went extinct at the end of the Devonian, Permian and Triassic, some members of the lineage managed to survive, allowing the group to thrive, again and again, all the way until the end-Cretaceous. With Brannen’s recent The Ends of the World still fresh on my mind I was quite familiar with the details, but if you’re not, Staaf does an excellent job in giving a balanced picture of the various mass extinctions. She is equally capable of giving a short history of the Alvarez impact hypothesis, as she is able to explain anoxic events or large igneous provinces and flood basalts.
The second group are the slow-and-steady (evolutionarily speaking) Nautiloids who seem never to have diversified terribly much, but have kept on keeping on to this day. And, finally, there are the Coleoids who radiated to become today’s cuttlefish, squid and octopuses.
“[…] ongoing academic discussions are combined with Staaf’s narrative which is fiendishly readable”
And yes, I said octopuses rather than octopi. Staaf provides the best overview I have read so far of the whimsical discussion around how to pluralise this word. But far from mere whimsy, this book provides page upon page of fascinating insights. Whether it’s the intricacies of evolving buoyancy mechanisms allowing cephalopods to float, the way Coleoids internalised and in some groups virtually eliminated their shell, the continued confusion around the lower jaw or aptychus of the Ammonoids, or the arms race between cephalopods and their predators (first fish, then whales)… who knew there was so much fascinating research buried in the scientific literature?
Being a marine biologist herself, she is well-situated in these academic circles and has interviewed many scientists including Christian Klug, Dieter Korn, Kenneth de Baets, and Isabelle Kruta, all of whom are editors on the 2nd edition of the Ammonoid bible Ammonoid Paleobiology. Interesting findings and insider insights into ongoing academic discussions are combined with Staaf’s narrative which is fiendishly readable. In my opinion, her writing style strikes just the right balance between informative and understatedly entertaining (I sniggered throughout the book), without feeling forcedly funny. Admittedly, I have a soft spot for these squishy invertebrates, but I tore through this book in the space of a single seven-hour sitting! Squid Empire is a shining example of good use of illustrations supporting the text, especially the cephalopod family tree on page 46 is something you’ll be referring to time and again and has some clever details. Next to that, the book is also beautifully designed with stylised chapter headings and a beautiful Haeckel lithograph gracing the cover.
Dinosaurs may have time and again stolen the limelight, but Staaf shows an accessible book on the evolutionary history of cephalopods has been long overdue. With Squid Empire – which, can you believe it, is only her first book – she has established herself as cephalopod-champion par excellence. I know that 2018 has only just started, but already this book will be a strong contender as my book-of-the-year. This, ladies and gentlemen, is how you write a good popular academic book.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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“Cataclysms: A New Geology for the Twenty-First Century”, written by Michael R. Rampino, published in by Columbia University Press in September 2017 (hardback, 211 pages)
So, bit of a history lesson first. The British geologist Charles Lyell (1797-1875) published the textbook Principles of Geology that went through 12 editions between 1830 to 1875 and influenced generations of geologists. Three of his ideas became axioms in geology:
1. Geological change is slow and gradual and the result of processes we can see in operation today (to evolutionary biologists like myself this axiom sounds familiar, as Charles Darwin has written the same about evolution. Not strange when you consider Lyell was Darwin’s contemporary and mentor, and heavily influenced his thinking).
2. No need to invoke astronomical influences, geologic forces are intrinsic to the planet.
3. The geologic record does not contain regular patterns influenced by astronomical cycles.
This idea of slow and gradual change is known as uniformitarianism: “the present is the key to the past”. Lyell was firmly opposed to the idea of past catastrophes having influenced the planet, which at the time often took the form of attempts to shoehorn the Biblical flood into the picture (with the exception of Cuvier and some others, who favoured natural explanations). Mind you, Lyell’s ideas are not free from theological underpinnings either. As Rampino shows, close reading of his work clearly shows that a slow unfolding of geological history was God’s plan to shape a world perfectly suited for humans to live in.
Lyell’s views won the day. Discontinuities in the fossil record were explained away with the argument that the geological and fossil record are highly incomplete and fragmentary, like a book from which many pages are missing. So, what seems like species suddenly disappearing is just an illusion, perhaps the result of missing fossils, or of periods of geological strata not being deposited. If the record were complete, it would reveal gradual extinction. There. Done and dusted.
These views continued to dominate geology well into the 20th century, and with that in mind, you can understand how the Alvarez paper, which proposed the dinosaurs were killed by an asteroid impact, caused such a splash. Rampino spends several chapters describing their work, and the subsequent work to gather more supporting evidence. You see, impacts leave tell-tale signs in the geological record due to the extreme forces and temperatures generated upon impact, and Rampino describes these in much more technical detail than The Ends of the World that I read just before this book. Good job that the book is accessibly written, as I was able to follow along just fine during these chapters. Plenty of these signs have been found at the Cretaceous/Paleogene boundary, 65 million years ago, and by now this impact is a widely accepted fact. But was this a one-off? Rampino argues it was not. He describes work by geoscientists who have found signs of impacts at other times in deep history and tries to link these to other (sometimes minor) mass extinctions. For a while I felt a bit sceptical: was he another person who suddenly saw asteroids everywhere? But Rampino is clear-headed enough to admit that not all mass extinctions are impact-related, and highlights the important role of flood basalt eruptions. These episodes of massive catastrophic volcanism were responsible, amongst others, for the end-Permian mass extinction, which wiped out some 95% of species 252 million years ago.
“It’s an interesting idea, and certainly one step up from the Nemesis hypothesis […]”
Even so, it is clear Rampino favours the impact explanation. He points out the incomplete sampling of the geologic record to detect traces of impact, and the difficulties in finding these. Not every asteroid will be a dino-killer. Size, composition, and location of impact will all influence what traces past impacts have left. Add to that that some impact craters, especially older ones, may never be found if they occurred in regions that have since disappeared down the planet’s gullet in subduction zones and have been erased. Clearly, there is a lot more work to be done before we can pin other extinctions on impacts as clearly as has been done for the end-Cretaceous mass extinction. But he thinks that if we look harder, we’ll find more evidence of this.
Rampino goes a step further though – this is where the book gets more controversial – and suggests these impacts occur at roughly 30-million year intervals. These ideas have met with opposition, as many scientists have hypothesised periodic cycles before that have not stood up to scrutiny.
Rampino and co-workers are convinced they are onto something though. They even have a mechanism in mind that, by their own admission, is rather speculative. As our solar system goes around our galaxy (which, as you might know, we have good reason to believe is a disk-shaped spiral galaxy) it oscillates up and down, passing through this disk at intervals of about 30 million years. This would disturb the Oort cloud, a hypothetical band of icy bodies circling the Sun at a great distance, well beyond Pluto Neptune in interstellar space, sending comets our way. It’s an interesting idea, and certainly one step up from the Nemesis hypothesis, which invoked an as-of-yet undiscovered distant planet as the source of these comets (see The Nemesis Affair: A Story of the Death of Dinosaurs and the Ways of Science for the controversies around that idea).
The really speculative part, which was also recently put forward by Lisa Randall in the book Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe, is the role given to dark matter. Supposedly, above-mentioned disk also houses dark matter, which would add further gravitational pull disturbing the Oort cloud. But wait, there’s more. Some astrophysicists think that dark matter particles could be captured by earth and, once sufficient densities have been reached, could undergo a process of mutual annihilation, producing enormous amounts of heat in the planet’s interior, which would trigger rising plumes of hot material that cause flood basalt eruptions.
“[…] we are at the cusp of a revolution in geological thinking, one that gives more credence to catastrophist explanations, from above and below”
Obviously, these ideas have met with plenty of opposition. Rampino argues that many geologists are still stuck with the heritage of Lyell’s ghost, unwilling to accept any astronomical explanation for geological processes. He thinks we are at the cusp of a revolution in geological thinking, one that gives more credence to catastrophist explanations, from above and below.
I am totally on board with Rampino’s call to abandon Lyell’s uniformitarianism, but almost 40 years after Alvarez’s paper, that’s hardly a revolution anymore, is it? I thought the scientific community is already well on its way to accepting catastrophist explanations. Rampino furthermore outlines some interesting ideas in this book, but until we have gathered more data to support or reject them, they are just that. Speculative ideas. If scientific consensus rolled over at every left-field idea that is presented as the next revolution, we’d be nowhere. So I think the criticism and scepticism levelled at these particular ideas is both necessary and deserved. Luckily, Rampino is enough of a scientist to recognize this himself, which certainly helps his credibility. And Cataclysms is sufficiently well written that I’ll say: “Sure, I’ll entertain your ideas. Let’s see what future research brings.”
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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“The Ends of the World: Volcanic Apocalypses, Lethal Oceans and Our Quest to Understand Earth’s Past Mass Extinctions”, written by Peter Brannen, published in Europe by Oneworld Publications in September 2017 (hardback, 330 pages)
Extinction and speciation happen, geologically speaking, continuously. You may have come across the term “background extinction rates”. But the geological record reveals there are episodes when species diversity, again geologically speaking, suddenly plunges, and a significant proportion of life forms disappear around the globe. If the concept of extinction didn’t really exist until Cuvier put it forward in 1796, the idea of sudden mass extinctions didn’t really catch on until Walter Alvarez and his team published their idea of death by comet in 1980 (Elizabeth Kolbert gives an excellent overview of the intellectual history in The Sixth Extinction).
The Ends of the World is science journalist Peter Brannen’s first foray into book writing. He has set himself the ambitious target to give an overview of what we currently know of the Big Five mass extinctions (end-Ordovician, Devonian, Permian, Triassic, and Cretaceous respectively) by interviewing scores of scientists.
In nimble prose that is readable and amusing (I found myself sniggering throughout the book) he walks us through them chronologically, starting off with the oldest. Without repeating the many fascinating details and ideas covered, the consensus is that if there is one thing that all these events have in common, it is that there never is just a single cause. All of these events are characterised by an extraordinary set of circumstances coming together to create some truly challenging conditions for life on earth. And, despite the popular notion of asteroid impacts, most often the threat has come from within. Twice in the form of ice and anoxic (i.e. oxygen-starved) seas at the ends of the understudied Ordovician (445 million years ago, or mya for short) and Devonian (two extinction pulses at 374 and 359 mya), together with a raft of other circumstances. Twice in the form of volcanism-induced global warming with accompanying misery at the end of the Permian (252 mya) and Triassic (201 mya). And then, of course, the asteroid impact at the end of the Cretaceous (65 mya).
Brannen does an excellent job giving airtime to different viewpoints and theories, because the above summary is very brief, and the science isn’t all settled on this. Even the by now widely accepted asteroid impact hypothesis is more complicated than that. When Walter Alvarez and his team put their theory forward in their 1980 Science paper, it was initially met with disbelief and scepticism. And healthy scientific scepticism is good. It has forced the scientific community to gather more data to see if this idea could be supported. By now enough supporting evidence is available and, after being known to the wrong people for over a decade (geophysicists working for an oil company), we have located the site of impact around the Mexican peninsula of Yucatán (this story is also chronicled in Alvarez’s book T. rex and the Crater of Doom). But other, similarly massive impacts have not caused any mass die-offs, giving more credence to the ideas of a few vocal critics who think earthquakes in the impact’s wake ramped up episodes of ongoing volcanism.
“[…] to be a geologist means changing your perception of time.”
If there is anything that ought to be highlighted in Brannen’s writing, it is how he manages to convey the absolute vastness of the time scales we are dealing with. Consider that all of recorded human history, all the thousands of years, have taken place in the most recent interglacial period, which is only one of twenty such balmy 10,000-year intervals in the earth’s most recent 2.6 million year ice age, and you will come to understand that to be a geologist means changing your perception of time.
The other thing Brannen does exceedingly well is to evoke the sheer scale of the destruction that has been wrought in the distant past. If you thought the 2013 Chelyabinsk meteorite was frightening, buckle up for the end-Cretaceous impactor. Similarly, the volcanism that wiped out some 95% of all life-forms at the end-Permian, making it the single most destructive event in the history of life, is hard to fathom. Forget the picturesque volcanoes that you know: continental flood basalts are literally the earth puking out its guts and covering whole continents with lava that gets stacked up miles high. As we have never witnessed these rare events, they defy comprehension.
Having discussed the Big Five, Brannen is not quite done yet. This book would not be complete if he not also touched upon the current ongoing loss of biodiversity. There is an eerie correlation between our ancestors arriving in new regions and megafauna disappearing. The overkill hypothesis, put forward by Paul S. Martin (also see his book Twilight of the Mammoths), has not been well received by politically correct anthropologists and social scientists, but I see no problem with it. Brannen speaks to British geologist Hallam who thinks it’s high time we get rid of this romanticized notion of the wild savage living in harmony with nature. I couldn’t agree more. [Edit: having now reviewed End of the Megafauna: The Fate of the World’s Hugest, Fiercest, and Strangest Animals, I have changed my mind on this somewhat.]
“The tempo with which we are burning fossil fuels like there is no tomorrow […] is comparable to the episodes of large-scale volcanism of the past. Deep history teaches us how the planet’s climate will react.”
Even so, it’s interesting to read that many of the palaeontologists in this book don’t consider this the sixth extinction. Yet. They all agree that we are inflicting tremendous damage to our environment and have caused the extinction of many species. And the fact that we are exerting multiple pressures (climate change AND overhunting/fishing AND habitat fragmentation etc.) means we could pass a tipping point somewhere along the line. But the current losses pale in comparison with the truly staggering losses incurred during previous mass extinctions. Many palaeontologists think it’s way too early, and overly dramatic, to already talk about a sixth mass extinction, as much as it makes for juicy headlines. In the long run, this may make for no more than a blip in the geological record.
Throughout the book, Brannen skilfully highlights the relevance of studying Earth’s deep history to the here and now. The tempo with which we are burning fossil fuels like there is no tomorrow, and releasing greenhouse gases into the atmosphere is comparable to the episodes of large-scale volcanism of the past. Deep history teaches us how the planet’s climate will react. The geochemistry is simple and uncontested, and our planet has been here many times before. Natural geochemical cycles can mop up this excess, but these cycles play out on time scales of hundreds of thousands of years. As some scientists point out here, it is far more likely that our civilization will buckle under the strain of overpopulation, failing agricultural systems and climate refugees well before we can release comparable amounts of greenhouse gases, as even a few degrees of warming will drastically change the world in which we live.
What could have been a book of doom and gloom has become a phenomenally good read in the hands of Brannen. His writing is witty and irreverent in places and had me both amused and intrigued throughout. His balanced coverage of this massive topic is excellent, giving voice to the many opinions and ideas currently circulating. If you want an up-to-date picture of what we know, this is the best place to start in my opinion.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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