Footprints

Some geologists think that this staggering rate of change justifies the naming of a new phase in planetary history. For more than one hundred years the International Chronostratigraphic Chart, which lays down the sequence of geologic time, has culminated with the Holocene, the period of benign climate that began around 11,700 years ago with the end of the last ice age and coincided with the development of human society. But in 2009, the International Commission on Stratigraphy (ICS) charged a group of geologists, biologists, atmospheric chemists, polar and marine scientists, archaeologists and Earth scientists with establishing whether or not the chart should be updated to reflect the onset of a new unit of geological time: the Anthropocene, or the time of the human. The Anthropocene Working Group has focused its efforts on a search for evidence of wholesale change in the way the earth works as a system of interdependent geochemical, sedimentary and biological processes. For the evidence to be compelling, they determined, it must produce new and distinct layers in the stratigraphic record. The group explored human-mediated acceleration in the rates of erosion and sedimentation, disturbances to the major chemical cycles (carbon, nitrogen, and phosphorus), the likelihood of significant changes in sea level, and the effect of human activity on the diversity and distribution of species across the globe. They examined the potential for synthetic materials, from artificial radionuclides produced by nuclear testing to plastic waste, to leave an identifiable signal in the strata. Many of these changes and signals, they concluded, are not only present and observable now but also effectively a permanent part of the archaeological and stratigraphic record.

When determining the boundaries of geologic time, stratigraphers search for sites where evidence of the shift from one geological age to another glitters in the dark of deep time. Such boundary sites are sometimes referred to as ‘golden spikes’, and marked by a bronze plaque hammered into the rock. But what the Anthropocene Working Group sought was the flash of enargeia: not the residues of worlds past, but the difficult brightness of a new world arriving. Geology is a cautious discipline: many who practise it feel that the process for introducing a new entry in the International Chronostratigraphic Chart ought to be as patient as forming a novel layer in the strata. But in 2016, at the International Geological Congress in Cape Town, the members of the ICS voted nearly unanimously that the Anthropocene was a stratigraphic reality and that it coincided with the eruption of technological innovation and material consumption in the middle of the twentieth century. The AWG is currently working on a proposal to formalize the Anthropocene as a new unit in geologic time.

Hutton learned to read the deep past in the rocks he saw every day, and according to the Anthropocene Working Group we can now read something of the deep future in even the most ordinary artefacts. The evidence of the Anthropocene is all around us, inextricably woven into the way we live our lives. But to see it, we need to face the ‘bright unbearable reality’ of the world we have made.

IN MY CLASS, as the crags loom darkly outside our window, we busy ourselves with words on the page. For ten weeks, my students and I share ideas about what others have said about the natural world. We tour vicariously through Scottish moors and English woods, following in the footsteps, if only figuratively, of writers who have traced a river from source to sea or pursued a bird of prey across winter fields. Field trips aren’t usually undertaken by literature students, but as if to acknowledge that ours is only a second-hand study of nature, at the end of the course we finally step outside the classroom. One Saturday morning in March we board a train to Dunbar, fifty kilometres east of Edinburgh, on the Lothian coast.

Our route from the train station to Barns Ness Lighthouse is only around twelve kilometres there and back, along a low, rocky shore. The walk begins by skirting the edge of the well-disciplined greens of the town golf course, following a thin ribbon of turf marked out for the benefit of walkers. The manicured lawns contrast strikingly with the disorderly flotsam piled up where the green gives way abruptly to pebbled beach. But as the last hole tapers away in a tangle of unruly grass, a much more complex scene starts to take shape.

It is, in truth, a rather functional landscape, pinned to a narrow strip of coastline by the grey barrier of the A1, the faint susurrus of distant traffic mingling with the sighing waves. At the far end of the beach that curls away from the golf course, a modern cement works, fed by a huge open-cut pit, overlooks a clutch of derelict nineteenth-century kilns, relics of the time when layers of coal and limestone were stripped and burned to provide quicklime for local farmers. The kilns, too dangerous to enter, are encircled by a chain-link fence and wreathed with warning signs. The whole scene sits on top of a limestone pavement, source of the materials cooked up in the kilns 150 years ago. Most of the fossils here are, like the Happisburgh footprints, trace fossils. Thousands of curved tubes, the tiny marks of long-extinct animals burrowing for shelter or food, are strewn across the pavement like pieces of macaroni. A large area is pockmarked with dozens of shallow basins, thought to mark the sites of individual trees that grew in a tropical Carboniferous forest when Scotland lay nearly at the equator. Some basins are filled with seatearth, a fossilized wetland soil in which you can still see the fine tracery of ancient roots.

As the naturalist Adam Nicolson has said, in geological terms northern Europe is a landscape in recovery, still reeling from the immense trauma of glaciation. Since the ice sheets melted away, the British Isles have been rising slowly through a process called isostatic uplift – rebounding into shape like a pillow relieved of the weight of a sleeper’s head. Just as the mountains in the Highlands of Scotland, which once rose higher than the Himalayas, have been ground down to nubs, the town, the motorway, the lime kilns, and the cement works will weather away over time until virtually no trace remains. But before that erasure they will have marked the earth indelibly. The cement works are a reminder of the truly sublime quantities of concrete that we have produced, and the processes involved. Humans have been earth movers for thousands of years. It’s thought that if all the evidence of human geomorphology to date were heaped together, the spoil would form a mountain range four thousand metres high, forty kilometres wide, and one hundred kilometres long. But by the end of the twenty-first century we will have shifted as much stone and sediment in 150 years, through mining, construction, and road building, as humans moved in the preceding five millennia. Every year we move around eighteen thousand times more rock than the Krakatoa eruption in 1883. Around half a trillion metric tonnes of concrete have so far been cast for human use, enough to spread a kilogram layer across every square metre of the earth’s surface, half of it produced in the last twenty years.

A few miles to the south of the limestone pavement lies Torness Nuclear Power Station. In time to come, there will be nothing left of the installation itself except perhaps an irradiated patch of ground. But the waste it has produced, even in the thirty or so years since it opened, will leave a trail across the globe. Much of the uranium processed at Torness comes from Australia, from underground mines like Olympic Dam in South Australia or open-cast mines like Ranger in the Northern Territory – a vast crater, stepped like an Incan city, which has displaced tens of millions of tonnes of rock. At present, spent fuel from Torness is delivered to Sellafield in Cumbria, the largest nuclear facility in the UK, along with 80 per cent of all the country’s high-level waste. Thousands of cubic metres of waste, accumulated in the first four decades since the plant opened in the 1950s, are still stored in huge open-air concrete storage ponds. Photographs leaked to the press in 2014 showed seagulls bathing in the water. In some of the oldest laboratories, now decommissioned, it is unclear exactly how much or what kind of deadly material they contain. Most of the waste received at Sellafield today is reprocessed, but a stubborn remainder of around 3 per cent is left over. In lieu of a more permanent solution, this is mixed with liquid glass at 1,200 degrees Celsius. When it cools, the mixture vitrifies, forming solid blocks of irradiated glass. Sellafield houses six thousand steel containers of vitrified waste like huge toxic sugar cubes. The bitter material within will be lethal for thousands of years – still harmful to people for whom we will be little more than a rumour.

Other, more banal materials on this shore possess the same astonishing reach through time. We all carry packed lunches with us on our trip, which include a lot of foil- or plastic-wrapped sandwiches. We diligently take all our rubbish away with us, until we can deposit it in the nearest bin. The majority of Edinburgh’s household waste in fact ends up not far from this beach, in a landfill site lined with clay and plastic. Most modern landfills are constructed this way, creating an airtight and watertight seal to prevent toxic materials from leaching into the groundwater, effectively mummifying their contents. In the 1970s, an archaeologist called William Rathke became interested in what happens inside landfills. For the next twenty years he excavated sites around Tucson, Arizona, and reported finding forty-year-old hot dogs, twenty-five-year-old lettuce still in storefront condition, and – in the mid-1980s – an order of guacamole that looked ready to eat despite having been buried alongside a newspaper from 1967. If food can last for decades in mid-twentieth-century landfills, more durable materials like plastic and aluminum buried in modern landfill conditions will certainly retain recognizable forms for far longer.

Since the middle of the twentieth century we have produced enough aluminium, around five hundred million metric tonnes, to cover the whole of the United States in kitchen foil. The majority of the millions of tonnes of plastic that enter the ocean each year falls to the ocean floor, where it will be folded into the sediment as a layer in the geological strata, effectively a permanent addition – at least until the heat and pressure turn it back into oil or the section of seafloor is raised up and eroded, processes that will be measured in tens of millions of years. Even the contents of our sandwiches can tell a story. Sixty billion chickens are killed for human consumption each year; in the future, fossilized chicken bones will be present on every continent as a testimony to the intrusion of human appetites in the geological record. These most ordinary and familiar things, each with the potential to become a new fossil, bring the intimacies of the Anthropocene up close.

As we leave for our train back to Edinburgh, we turn away from this beach, but it will remember us.

FOOTPRINTS IS MY ATTEMPT to discover how we will be remembered by the very deep future. People have been modifying the land and changing ecosystems for thousands of years, but the alterations to the planet and the ever-more-durable materials we (mostly in the global North) have made since the industrial revolution have come with unprecedented speed and invention, and will leave long-lasting marks, beyond anything humans have produced before. In my search for future fossils, I look to the air, the oceans, and the rock, from a bubble of ice drawn from the heart of Antarctica to a tomb for radioactive waste deep beneath the Finnish bedrock. I examine the landscapes and objects that will endure the longest and the changes they will undergo: the processes that will transform a megacity into a thin layer of concrete, steel and glass in the strata; the future of the fifty million kilometres of roads that circle the planet and supply our cities with materials moved over vast distances; and the stories of those materials themselves, like the five trillion pieces of plastic waste already circulating in the world’s oceans.

But it is also a search for what will be lost. As biodiversity declines, silence will itself be a signal, absence another kind of trace. Bleached coral reefs, like the one I saw in Australia, will be monuments to this loss, but so will marine dead zones such as the huge area of anoxic water I visited in the Baltic Sea. Ice cores represent an astonishing archive of past climates, including the changes introduced by human activity, but as the ice melts, part of this record will go with it, while the loss of ice will write a new story in the planetary archive. There are also dangerous and highly durable substances like nuclear waste that we hope will remain hidden and forgotten altogether. And for all the many marks we will leave that cannot be mistaken – the deep pits we gouged in the earth and the rich pockets of landfill that hoard our waste – we will also leave our impression on worlds we can’t see. Microbial life is responsible for engineering virtually every key life process and chemical cycle, flooding the atmosphere with life-giving oxygen, but its role has been usurped. At the end of my journey I examine how our prints will linger in the cells of some of the smallest life-forms on earth.

To perceive future fossils means to see what the Anthropocene’s bright unbearable reality reveals; to look at a city as a geologist might, and to approach the problem of making nuclear waste safe from the perspective of an engineer; to understand the chemical stories in a piece of plastic waste, and to listen to the silences that echo in collapsed ecosystems. But it has also sent me back, again and again, to the essential elements of what I talk about with my students: to narrative, myth, image, and metaphor. I want to discover the world we will leave behind, but also how we will appear to the people who may live in that world. It’s an account of what will survive of us, and for that we need poets as much as we need palaeontologists. With stories we can see the world as it is and as it might be; art can help us imagine how close we are to the extraordinarily distant future.

We already know that the Anthropocene is a global story, but we don’t need to go far to find evidence of it. Future fossils are all around us, in our homes, in our workplaces, and even in our bodies. So my journey began in Edinburgh, and while it also led me to some very faraway places, it returned periodically to the North Sea world in which I feel at home. Much of my search also took place while I held a visiting fellowship at a university in Sydney, about as far from Scotland as it is possible to go, and a sweltering contrast with the northern climes I am accustomed to. At times, I found I had to seek out particular places to better understand their role in shaping our future traces: to learn about how cities might become fossils, I visited Shanghai, a city of twenty-four million people that has sunk under its own massive weight by over two metres in less than a hundred years. But what struck me most forcefully was how ubiquitous future fossils are. Our present is saturated with things that will endure into the deep future. As you read this, you will also, in all likelihood, be surrounded by objects and materials that could contribute to making a trace fossil. Before you begin to take this journey with me, look up from the page and imagine how the things around you – the plastic casing of your laptop and its titanium innards or the coffee cup standing beside it – might remain, even just as an impression in stone, millions of years from now.

Future fossils are not just a distant prospect to be left to the patient care of geological processes or the curiosity of generations yet to be born. They touch our lives hundreds of times every day, and we can see in them, if we choose, not only who we are but also who we could be. We have already fundamentally altered the systems that support life on the planet, in ways that are deeply sobering. The most vulnerable will be the worst affected, and the full costs to future generations have yet to be calculated. Our future fossils are our legacy and therefore our opportunity to choose how we will be remembered. They will record whether we carried on heedlessly despite the dangers we knew to lie ahead, or whether we cared enough to change our course. Our footprints will reveal how we lived to anyone still around to discover them, hinting at the things we cherished or neglected, the journeys we made and the direction we chose to take.

ONE

THE INSATIABLE ROAD

It was billed as a once-in-a-lifetime opportunity: the chance to walk Scotland’s newest stretch of road, spanning the banks of the Firth of Forth.

Since 1964, all road traffic across the estuary had been borne by the Forth Road Bridge, a burden comprising hundreds of millions of journeys north and south. The old bridge had begun to show the strain, though, and so a new one was commissioned. It took six years to complete. My family had followed its unhurried construction as the deck inched over the water and the web of cables slowly knitted together. From the beach near our house we could see the rising towers nudge above the hill between Edinburgh and South Queensferry, where the bridge was being built. Whenever we drove west from the city, my children would point out changes in its shape and size. Now it was finally ready to open, and to celebrate, a ballot had selected fifty thousand people to walk its 2.7-kilometre span across the estuary. We were lucky enough to be among them, and so on a golden Saturday in September, we set off to make on foot a journey that would thereafter be possible only at fifty miles per hour.

We met the bus that would take us the eight kilometres or so to South Queensferry in an industrial park on the outskirts of Edinburgh, and the new bridge rose into view as we travelled west along the estuary. At a distance, the Queensferry Crossing is a miracle of light and air, held in place by gleaming white threads strung from three spindle-like towers. The cables that lace it together resemble strings on the soundboards of a series of upended pianos, and the deck rises and dips like the harmonic curve in the neck of a harp. ‘How could mere toil align thy choiring strings!’ wrote Hart Crane of Brooklyn’s famous bridge. I wondered what enchanted music a strong North Sea wind might make as it barrelled down the estuary.

Our bus pulled into the empty multi-lane motorway just before the bridge’s southern rampart rose over the water, and we joined the crowds strolling north towards Fife. As the asphalt crunched under my feet, the airy impression I’d had from a distance resolved into something much weightier. The white cables, which had looked so slender, were thicker than my body. Viewed obliquely, they seemed to bond into a single white wall. The road surface was hard and unyielding, and fist-like rivets bulged from every knuckled stanchion and guardrail. The lightness, rather, was in me. I felt giddy walking on a surface never intended for foot traffic; it was as if in stepping out over the water we had also stepped into a wholly different relationship with the space around us. Uniquely, the bridge’s textures were there to be sampled: the cables’ bone-white smoothness, the glaucous sheen on the barriers between the carriageways, the road’s coarse grain. There was a thrill in the air, a mood of trespass. In reality, the event was subject to airport-levels of organization and stricture; bag-searched and photo-ID’d before we arrived at the bridge, we had firm instructions not to take longer than an hour or we would risk missing our return bus. But for a brief, beguiling moment, it felt like we were reclaiming the road.

Really, we have conceded so much. Most of us live and wander only where road networks permit us to, creeping along their edges and lulled into deafness by their constant roar. Man ‘sets his house upon the road’, lamented Ralph Waldo Emerson in 1849, and every day the human race goes forth and cuts a path for him to follow. But on this journey we could roam where we pleased, no longer confined to the curb; rather than the growl and whine of engines, the sounds were light and textured, of voices, laughter and the soft crump of hundreds of footsteps. This new road, built to withstand more than twenty million motorized journeys every year, seemed more like a road out of the pre-industrial past, a pilgrim route made by tramping feet. Or perhaps a vision of roads to come, when the oil is gone and the engines are silent.

At the base of each tower, a large sign listed the facts and figures of its construction. The bridge, which at a distance seemed to float above the water, was bound to the earth by superlatives. One hundred and fifty thousand tonnes of concrete and thirty-five thousand tonnes of Chinese steel, shipped to Rosyth from Shanghai shipyards, went into its construction, and thirty-seven thousand kilometres of cables, only just short of enough to circle the Earth at the equator. Laying the foundations for the south tower involved the longest ever continuous underwater pour of concrete: nearly seventeen thousand cubic metres, tipped night and day for fifteen days into the rock beneath the river. Excavating the site for the new network of roads that would connect to the bridge had revealed the remains of a Mesolithic sunken-floored house, the oldest dwelling ever discovered in Scotland. The remains of a clutch of post holes, now just shadows in the earth, along with charred hazelnut shells and fragments of burnt bone had survived in the mud for perhaps as long as eleven thousand years. But the aggregate seam of concrete pressed into the bedrock beneath the south tower, crushed Scottish granite or English limestone mixed with sand from India or China, will have a far more long-lasting presence, posing a riddle for future geologists to puzzle over.

A rude honking from the river barged through the chatter of voices as a container ship passed beneath us, sounding its horn in acknowledgment as it followed its own watery road.

At the bridge’s northern end, a small crowd had gathered around a knot of photographers. Scotland’s first minister was giving an interview, and we hovered for a chance to take our children’s picture with her. As they grinned for the camera, I looked to where the road flowed north through a coil of raised carriageways and sunken slip roads. Maybe a hundred metres away, a huge dolerite cliff loomed along the road’s eastern side. Engineers who built the first rail crossing over the estuary in the 1880s had punched their way through the gently rolling landscape, exposing to the air stone that had not felt wind or rain for millennia. They had cleaved their way through this mound of rock as if they were splitting a skull. If I had been passing over the bridge by car, I would have had barely seconds to notice it, lulled by the blur of asphalt slipping like grey silk under the car’s nose, perhaps registering the weight of rock as no more than a shadow in my peripheral vision. But free as I was to stand and stare, the exposed stone seemed to catch me up out of the present and draw me in, and through, and down into the memory of a younger earth.

At my back, that huge bolus of concrete slumbered beneath the river, curled around the base of the south tower like a dragon around a hoard of gold. As I gazed at the cutting, the bridge ceased to be a connection between the opposite banks of the river; it was, for an instant, poised between moments in time that flew beyond my imagination.

One million years from now, the bridge’s thin towers, its choir of shining cables and elegantly curving deck, will be long gone. The surface of the road will be washed away. But even as the eroding forces of weather and time take their toll, grinding down the cliff and filling the engineers’ clefts with sediment, the concrete foundation and the rock cutting will still be legible, written into the earth like speech marks around a lost quotation, bearing witness that here, once upon a time, a road crossed a river that will itself long since have vanished.