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journey-to-the-centre-of-the-earth-by-david-whitehouseJourney to the Centre of the Earth: A Scientific Exploration into the Heart of Our Planet, David Whitehouse (Weidenfeld & Nicolson 2015)

Can you touch anywhere on your body with your right hand? Replying quickly, you might say you can. But what about your right elbow? You can’t touch that with your right hand. Science is like that, because distant things are often easier to study and understand than close things. We have a good understanding of how stars work, for example, but not of how the earth’s magnetic field is generated.

And while we’ve been able to predict solar eclipses for millennia, we still can’t predict earthquakes or volcanic eruptions. Understanding the deep earth is difficult, so there are a lot of mysteries and conjectures in this well-written and compelling book about the interior of our home planet. Scientists have landed probes on Mars, millions of kilometres away, but the “deepest hole ever drilled on earth – the Kola Superdeep borehole in northern Russia” reached only 12,262 metres. That’s a mere pinprick by comparison with the radius of the earth. To get beyond that, scientists have had to study the shockwaves generated by earthquakes. The medium is the message: as the waves pass through or hit different regions and materials, they behave in different ways.

For example, when the Croatian scientist Andrija Mohorovičić (1857-1936) “studied the records from several seismometers” after an earthquake near Zagreb, “he realised that some of the shockwaves […] were being reflected back to the surface from a boundary region between the crust and mantle.” (pg. 82 of the 2016 paperback) The region is now called the Mohorovičić discontinuity. But that discovery was made before the First World War and deep geology hasn’t advanced very much in the intervening century. This book borrows the title of a Jules Verne novel published in 1864. If Verne came back to life, he would be pleased to see that his work is still popular, but he would be disappointed to see that the human race was no nearer reaching the centre of the earth.

Or would he? The American geologist Don Anderson says: “Almost everything known or inferred about the inner core from seismology or indirect inference is controversial.” (pg. 211) Deep geology is a difficult science, but that’s part of what makes it so interesting. Something else that makes it interesting is that the inner earth can visit catastrophes on the outer earth and the film of the life that clings there:

The big question is: can we see mass extinction events on the way up? Some scientists believe that we can by looking for the plumes [i.e., giant plumes of rising magma]. Such a thing is seen in the south-west Pacific near the Fiji Tonga subduction zone. It’s 700 km deep, has a structure consistent with a massive temperature anomaly and may be rising. It could render the earth uninhabitable for humans and it will reach the surface in an estimated 200 million years. (ch. 17, “Plumes”, pg. 146)

Asteroid impact and gamma-ray bursts are not the only catastrophes that threaten the continued existence of the human race. They may not even be the most likely. The film of life on the surface of the earth is fragile and one day it won’t be there any more.

But there’s also life deep inside the earth, living in conditions of extreme pressure, heat and darkness. We still know little about this “deep biosphere” and it may hold some big surprises. The rest of the deep earth almost certainly does. And the deep earth is just the beginning: as Whitehouse describes in chapter 26, there are “Other Worlds, Other Journeys” to come, including the even more extreme conditions at the heart of Jupiter, where the temperature is a “staggering 37,000 degrees C” and the pressure is “over ten times that found at the centre of the Earth.” (pg. 239)

Or so scientists estimate. Will scanners be invented to prove their theories? Will probes ever get there and find out for real? We can hope so. In the meantime, this book is an excellent introduction to the ideas, the pioneers and the modern researchers into mysteries that are right beneath our doorsteps. Whether it’s discussing diamonds, demons or “Double-D-Prime”, Journey to the Centre of the Earth is popular science that’s interesting, entertaining and informative all at once.

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Volcano Discoveries by Tom Pfeiffer and Ingrid SmetVolcano Discoveries: A Photographic Journey around the World, Tom Pfeiffer and Ingrid Smet (New Holland 2015)

Volcano Discoveries is a dull title for a dazzling book. I would have called it Gods of Fire instead. Mountains are naturally awe-inspiring, but ordinary ones are like slumbering or watchful gods. Volcanoes are mountain-gods that come to life, spewing fire, breathing smoke, devastating the landscape and sometimes wiping out cities. And volcanoes have been worshipped, as this book describes:

For the Mayans, in an interesting parallel to the ancient Egyptians, the pyramid was a very special shape and a holy place that connected the world with the gods. In the mountainous regions of western Guatemala, the Mayans interpreted volcanoes as natural pyramids and, unless in eruption, climbing to their summits was their way to worship them. (“Guatemala: Volcanoes of the Mayans”, pg. 153)

In Italy, the fire-god Vulcanus gave his name first to one fire-mountain, in the Aeloian archipelago, then to all of them (“Vulcano”, pg. 50). In Hawaii, Pele is the volcano-goddess, appearing either as “a tall beautiful young girl or a bent, ugly old woman” (“Hawaii”, pg. 122). Gods, goddesses and demons are everywhere in the stories told about volcanoes. That’s why Gods of Fire would have been a much better title.

But the German volcanologist Tom Pfeiffer is presumably plugging his company VolcanoDiscovery. He supplies the photographs; the Belgian geologist Ingrid Smet supplies the text. His images and her words work well together, but there’s a collaboration in the images too, like the two aspects of Pele. Some of the images are fiery and full of action, as blazing lava fountains against starry skies or pours in blood-red rivers down a slope. Others are bleak: lifeless cones, grey ash-fields, black pavements of cooled lava.

The two kinds of image contrast very effectively, as the book tours every volcanic region of the world from Iceland to Indonesia. And while some images are spectacular, some are small. The huge snow-covered cone of Shishaldin, “in the Aleutian chain”, is spectacular (pg. 141), like the vast plume of smoke belching from Fuego de Colima in Mexico (pg. 149) and the churning lava lake of Marum in the Pacific (pg. 175). Small images include ferns growing in cooled lava (pg. 139); yellow crystals of sulphur around the mouth of a “fumarolic vent” (pg. 74); and a close-up of “Pele’s hair”, or “elongated lava strings that quickly cooled down and became glass” (pg. 126).

So there’s every scale, every stage of volcanic activity, and every kind of slope, steam-plume and smoke-cloud, plus lots of facts, figures and interesting asides in the texts. If you’re interested in volcanoes, the gods of fire are waiting here. If you can raise a glass of tequila to them, even better: “whereas volcanic soils are being used throughout the world to grow grapes for wine production, in Mexico they are used for cultivation of the blue agave – the plant from which tequila is distilled” (“Mexico”, pg. 143).

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The Million Death Quake by Roger MussonThe Million Death Quake: The Science of Predicting Earth’s Deadliest Natural Disaster, Roger Musson (Palgrave Macmillan 2012)

“As solid as the earth,” we say. That’s why even mild earthquakes are often frightening and always memorable. Suddenly you can’t rely on the earth any more: it’s not rock-steady, it’s dancing. And it might be about to dance you to death.

But Robert Musson, author of this excellent guide to the history and future of seismology, points out that even in a big earthquake you’ll usually be safe in the open away from buildings. The problem is that few people spend much time like that. Cities are getting bigger and more crowded, which is why he suggests that one day an earthquake could kill a million people or more. Tehran is one candidate. So is this:

The case of Istanbul is unnerving for another reason. The North Anatolian Fault, the great strike-slip fault that starts in eastern Turkey and dies out in the middle of the Aegean, has an interesting property. Earthquakes along it tend to occur in sequences, starting in the east and moving progressively west. Each quake, as it occurs, throws more stress on the next section of fault to the west, which then fails a few years to a decade or so later. it’s like a series of dominoes toppling. […] The current sequence began with a 7.8 magnitude event near Erzincan, at the eastern end of the fault line, in 1939. This was followed by quakes progressively further west in 1942, 1943, 1944, 1957 and 1967. Then, after a lull, the next most westerly stretch of fault broke in 1999 with the Izmit earthquake. The next stretch of fault to the west goes straight through the Sea of Marmara, just south of Istanbul. This is the next domino to fall, and it could happen at any time. (ch. 12, “Stay Safe”, pp. 233-4)

Or there could be another lull. That is one of the interesting things about earthquakes: their unpredictability. The subtitle of this book is misleading, because there is no reliable science of prediction for earthquakes. Seismologists can say in great detail why and how they occur, but they can’t say where or when or what size. We are far better at predicting the behaviour of the sky above our heads than we are at predicting the behaviour of the earth beneath our feet. Meteorologists are refining and extending their forecasts further all the time. Astronomers have been accurately predicting eclipses and planetary orbits for thousands of years.

Seismologists would like to make their discipline predictive rather than reactive, but it’s proving very difficult. Masson discusses one team of Greek seismologists who claimed to be able to predict quakes using “seismic electrical signals, or SES for short” released by “rocks once they are stressed beyond a certain degree” (ch. 8, “Next Year’s Earthquakes”, pg. 172). But the team, led by Professor Panayotis Varotsos, made their predictions by sending telegrams to each other rather than informing an official body. When the earthquake occurred, they would produce the telegram and its date-stamp: “The question that was whispered in the corridors at conference sessions was this: How many telegrams were quietly burned when the prediction failed?”

Then a “moderate earthquake” hit Athens in 1999 and although the team claimed to have predicted it, they hadn’t said so in public. Apparently stung by the criticism that followed, Professor Varotsos issued a public prediction of a larger earthquake on its way in central Greece. But it never happened and the team were no longer taken seriously.

It’s not difficult to understand why earthquake prediction is so difficult: rocks aren’t transparent and gathering data from the depths of the earth is much harder than gathering data from the sky. Seismologists would be delighted if they could realize the suggestion made by Arthur C. Clarke in his short story “The Fires Within” (1949):

Sonar, as you will know, is the acoustic equivalent of radar, and although less familiar is older by some millions of years, since bats use it very effectively to detect insects and obstacles at night. Professor Hancock intended to send high-powered supersonic pulses into the ground and to build up from the returning echoes an image of what lay beneath. The picture would be displayed on a cathode ray tube and the whole system would be exactly analogous to the type of radar used in aircraft to show the ground through cloud.

Nearly seventy years on, we’re still waiting for a geoscope like that. Seismology is still a hobbled science and earthquakes are still mysterious and frightening things. As Sherlock Holmes says in “The Adventure of the Copper Beeches” (1892): “Data! data! Data! … I can’t make bricks without clay.” But seismologists have done a lot with the limited data they’ve got, as you’ll learn here. Writing clearly and colloquially, Masson traces the history of mankind’s attempts to understand earthquakes, describes their effects on history, discusses related phenomena like volcanoes and tsunamis, and explains why seismologists don’t use the “Richter scale”. The Million Death Quake has a hyperbolic title and a misleading subtitle, but it’s one of the best popular science books I’ve come across.

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Volcanoes A Beginners Guide by Rosaly LopesVolcanoes: A Beginner’s Guide, Rosaly Lopes (Oneworld 2010)

My first introduction to volcanoes was fictional: Willard Price’s Volcano Adventure (1956), which stands out in his Adventure series because it centres on something inanimate, not on animals like lions or gorillas or elephants. This book by the NASA scientist Rosaly Lopes is factual but equally enjoyable. And some of it would fit well into Volcano Adventure anyway:

[V]olcanoes come with different sizes, shapes and temperaments. It is fascinating to study what causes these differences and understand that, while generalizations are possible, each volcano has its distinct quirks, just like people. We could also compare volcanoes to cats: with few exceptions, they spend most of their lives asleep. (ch. 1, “What are volcanoes?”, pg. 1)

When a volcano wakes, look out. They’ve slain cities, devastated eco-systems and shaped landscapes. They’re also shaped cultures. Like a thunderstorm or earthquake, an erupting volcano raises a big question in the minds of human observers: What caused something so powerful and impressive? Our explanations began with myth and moved to science. And they moved a long time ago: the ancient philosopher Anaxagoras “proposed that volcanic eruptions were caused by great winds within the Earth, blowing through narrow passages” (pg. 5) and becoming hot by friction. Two-and-a-half millennia later, scientists are plotting “silica (SiO2) content” against “alkali content” as they classify “different volcanic rocks” (ch. 2, “How volcanoes erupt”, pg. 15).

But Anaxogaras’ principles are still at work: seek the explanation in mindless mechanism, not in supernatural mind. Classification is another essential part of science. In vulcanology, the scientific study of volcanoes, magmas are classified and so are eruptions, from subdued to spectacular: Icelandic and Hawaiian are on the subdued side, Peléean, Plinian and Ultraplinian on the spectacular, with Strombolian and Vulcanian in between. Some eruptions are easy to understand and investigate. Some are difficult. Volcanoes can be as simple or complicated as their names. Compare Laki, on Iceland, with Eyjafjallajökull, also on Iceland.

Laki is an example of an eco-slayer:

Although the eruption did not kill anyone directly, its consequences were disastrous for farmland, animals and humans alike: clouds of hydrofluoric acid and sulphur dioxide compounds caused the deaths of over half of Iceland’s livestock and, ultimately, the deaths – mostly from starvation – of about 9,000 people, a third of the population. The climatic effects of the eruption were felt elsewhere in Europe; the winter of 1783-4 as noted as being particularly cold. (ch. 3, “Hawaiian and Icelandic eruptions: fire fountains and lava lakes”, pg. 31)

Lopes goes on to look at city-slayers like Mount Pelée and Vesuvius, but they can be less harmful to the environment. A spectacular eruption can be over quickly and release relatively little gas and ash into the atmosphere. And death-dealing is only half the story: volcanoes also give life, because they enrich the soil. They enrich experience too, not just with eruptions but with other phenomena associated with vulcanism: geysers, thermal springs, mudpools and so on.

And that’s just the planet Earth. Lopes also discusses the rest of the solar system, from Mercury, Venus and Mars to the moons of gas giants like Jupiter and Saturn. The rocky planets have volcanoes more or less like those on earth, but the moons of the gas giants offer an apparent paradox: cryovolcanoes, or “cold volcanoes”, which erupt ice and water, not superheated lava. On Neptune’s moon Triton, whose surface is an “extremely cold” -235ºC, cryovulcanism may even involve frozen nitrogen. The hypothesis is that under certain conditions, it’s heated by sunlight, turns into a gas and “explodes” in the “near-vacuum of Triton’s environment” (ch. 11, “The exotic volcanoes of the outer solar system”, pg. 138).

Hot or cold, big or small, on the earth or off it, volcanoes are fascinating things and this is an excellent introduction to what they do and why they do it.

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Front cover of Granite and Grit by Ronald TurnbullGranite and Grit: A Walker’s Guide to the Geology of British Mountains, Ronald Turnbull (Francis Lincoln 2011)

For a small country, Britain has had a big influence on the world. Like a lot of other things, modern geology started here. There are several reasons for that and one is very simple: pioneering geologists had mountains of material to work with. According to the author, “Britain has the most varied geology of any country in the world.” This is an excellent introduction to the rocks of the realm, from gneiss in the Outer Hebrides to granite on Dartmoor. I like the way Turnbull discusses not only how rocks affect your eyes – their colour, texture and contours – but also how they affect your boots. He’s a hillwalker, not a professional geologist, so he conveys a strong sense of place and of how Britain’s landscape varies. But there’s more than geological variation here: Britain isn’t just rich in rocks and its landscape is shaped by more than physics and chemistry. This is the caption to one spectacular photo of a misty mountain:

Bwlch y Saethau, where according to legend King Arthur battled his nephew Mordred; behind, Y Lliwedd stands at the centre of a far greater act of violence, the Lower Rhyolite Tuff event. (ch. 10, “Redhot Flying Avalanches: Ignimbrites in Snowdonia”, pg. 98)

Britain’s varied mountains are named in Britain’s varied languages: Welsh, English and Gaelic give different flavours to the landscapes they describe, from Carnedd Dafydd to Eskdale, from Ingleborough to Stuc a’ Chroin, from Ardnamurchan to Mynydd Mawr. But English names split into Norse and Anglo-Saxon, which have different flavours too. Underlying all these languages is a common ancestor, just as some very different rocks have common ancestors too. Heat, compression and erosion change rocks; time, separation and mutation change languages. So Turnbull is writing about two kinds of history as he discusses different parts of Britain: geological history and linguistic history.

Linguistics dwarfs geology in complexity, but geology dwarfs linguistics in time. To understand why Britain looks the way it does, you have to go back billions of years and trace its movement over many thousands of kilometres. You also have to study seemingly exotic things like volcanoes, glaciers and tropical botany, all of which are central parts of Britain’s geology. Turnbull is a relaxed but knowledgeable guide to some big events and some big transformations and because he isn’t a professional he knows how to write for a general reader. He doesn’t just inform, he re-orientates: you won’t look at Britain in the same way:

Black pointy islands of volcanic ash rise above the sea, the water around them a froth of falling ash. The shores of the new islands get washed away by tsunamis as chunks of other islands fall into the sea. Lava slides down and then runs level, to form black land made of glass. The glassy ground crackles as it cools, and then quickly weathers to orange shards and gravel. Showers of sharp-edged volcanic rubble fall into the sea, forming seabed layers 300m deep which will eventually be the summit of Snowdon itself. (ch. 10, pp. 103-4)

Geology is like cuisine in reverse: from the cooked dish you have to work out the recipe. Landscapes that seem inert can have cataclysmic pasts, full of fire and thunder or flood and frost. There are centuries of ingenious deduction and painstaking observation behind the chatty text and attractive photos in this book, but there are still mysteries to solve. More maths will be needed, because matter obeys mathematical rules in all its transformations, whether geological or culinary. And those material transformations have immaterial parallels in linguistics and sociology, where maths is the key to understanding too. And science itself has metamorphosed and mutated. Geology is an important subject not just for its contemporary research but also for its influence on other fields. It made scientists realize the vast age of the earth. Charles Darwin used that idea to transform biology. Like the pioneering geologists, he was British. That isn’t a coincidence and it’s something else that increases the power of this book. The planet starts here. So does the universe.

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