To explore the messy future that modern industrial society is making for itself, it’s necessary now and again to stray into some of the odd corners of human thought. Over the decade and a bit that this blog has been engaged in that exploration, accordingly, my readers and I have gone roaming through quite an assortment of topics—politics, religion, magic, many different areas of history, at least as many sciences, and the list goes on. This week, it’s time to ramble through geology, for reasons that go back to some of the basic presuppositions of our culture, and reach forward from there to the far future.
Over the last few years, a certain number of scientists, climate activists, and talking heads in the media have been claiming that the Earth has passed out of its previous geological epoch, the Holocene, into a new epoch, the Anthropocene. Their argument is straightforward: human beings have become a major force shaping geology, and that unprecedented reality requires a new moniker. Last I heard, the scholarly body that authorizes formal changes to that end of scientific terminology hasn’t yet approved the new term for official use, but it’s seeing increasing use in less formal settings.
I’d like to suggest that the proposed change is a mistake, and that the label “Anthropocene” should go into whatever circular file holds phlogiston, the luminiferous ether, and other scientific terms that didn’t turn out to represent realities. That’s not because I doubt that human beings are having a major impact on geology just now, far from it. My reasons are somewhat complex, and will require a glance back over part of the history of geology—specifically, the evolution of the labels we use to talk about portions of the past. It’s going to be a bit of a long journey, but bear with me; it matters.
Back in the seventeenth century, when the modern study of geology first got under way, the Book of Genesis was considered to be an accurate account of the Earth’s early history, and so geologists looked for evidence of the flood that plopped Noah’s ark on Mount Ararat. They found it, too, or that’s what people believed at the time. By and large, anywhere you go in western Europe, you’ll be standing on one of three things; the first is rock, the second is an assortment of gravels and compact tills, and the third is soil. With vanishingly few exceptions, where they overlap, the rock is on the bottom, the gravels and tills are in the middle, and the soil is on top. Noting that some of the gravels and tills look like huge versions of the sandbars and other features shaped by moving water, the early geologists decided the middle layer had been left by the Flood—that’s diluvium in Latin—and so the three layers were named Antediluvian (“before the flood”), Diluvian, and Postdiluvian (“after the flood”).
So far, so good—except then they started looking at the Antediluvian layer, and found an assortment of evidence that seemed to imply that really vast amounts of time had passed between different layers of rock. During the early eighteenth century, as this sank in, the Book of Genesis lost its status as a geology textbook, and geologists came up with a new set of four labels: Primary, Secondary, Tertiary, and Quaternary. (These are fancy ways of saying “First, Second, Third, and Fourth,” in case you were wondering.) The Quaternary layer consisted of the former Diluvian and Postdiluvian gravels, tills, and soil; the Tertiary consisted of rocks and fossils that were found under those; the Secondary was the rocks and fossils below that, and the Primary was at the bottom.
It was a good scheme for the time; on the surface of the Earth, if you happen to live in western Europe and walk around a lot, you’ll see very roughly equal amounts of all four layers. What’s more, they always occur in the order just given. Where they overlap, the Primary is always under the Secondary, and so on; you never find Secondary rocks under Primary ones, except when the rock layers have obviously been folded by later geological forces. So geologists assigned them to four different periods of time, named after the layers—the Primary Era, the Secondary Era, and so on.
It took quite a bit of further work for geologists to get a handle on how much time was involved in each of these eras, and as the results of that line of research started to become clear, there was a collective gulp loud enough to echo off the Moon. Outside of India and a few Native American civilizations, nobody anywhere had imagined that the history of the Earth might involve not thousands of years, but billions of them. As this sank in, the geologists also realized that their four eras were of absurdly different lengths. The Quaternary was only two million years long; the Tertiary, around sixty-three million years; the Secondary, around one hundred eighty-six million years; and the Primary, from there back to the Earth’s origin, or better than four billion years.
So a new scheme was worked out. The Quaternary era became the Quaternary period, and it’s still the Quaternary today, even though it’s not the fourth of anything any more. The Tertiary also became a period—it later got broken up into the Paleogene and Neogene periods—and the Tertiary (or Paleogene and Neogene) and Quaternary between them made up the Cenozoic (Greek for “recent life”) era. The former Secondary era became the Mesozoic (“middle life”) era, and was divided into three periods; starting with the most recent, these are the Cretaceous, Jurassic, and Triassic. The former Primary era became the Paleozoic (“old life”) era, and was divided into six periods; again, starting with the most recent, these were are the Permian, Carboniferous, Devonian, Silurian, Ordovician, and Cambrian. The Cambrian started around 542 million years ago, and everything before then—all three billion years and change—was tossed into the vast dark basement of the Precambrian.
It was a pretty good system, and one of the things that was pretty good about it is that the periods were of very roughly equal length. Thus the Paleozoic had twice as many periods as the Mesozoic, and it lasted around twice as long. The Mesozoic, in turn, had three times as many complete periods as the Cenozoic did (in pre-Paleogene and Neogene days)—the Quaternary has just gotten started, remember—and it’s around three times as long. I don’t know how many of my readers, as children, delighted in the fact that the whole Cenozoic era—the Age of Mammals, as it was often called—could be dropped into the Cretaceous period with room to spare on either end, but I did. I decorated one of my school notebooks with a crisp little drawing of a scoreboard that read DINOSAURS 3, MAMMALS 1. No, nobody else got the joke.
In recent decades, things have been reshuffled a bit more. The Precambrian basement has been explored in quite some detail, and what used to be deliciously named the Cryptozoic eon has now sadly been broken up into Proterozoic and Archean eons, and divided into periods to boot. We can let that pass, though, because it’s the other end of the time scale that concerns us. Since Cenozoic rock makes up so much of the surface—being the most recently laid down, after all—geologists soon broke up the Tertiary and Quaternary periods into six shorter units, called epochs: from first to last, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene. (These are Greek again, and mean “dawn recent, few recent, some recent, many recent, most recent,” and “entirely recent”—the reference is to how many living things in each epoch look like the ones running around today.) Later, the Eocene got chopped in two to yield the Paleocene (“old recent”) and Eocene. Yes, that “-cene” ending—also the first syllable in Cenozoic—is the second half of the label “Anthropocene,” the human-recent.
The thing to keep in mind is that an epoch is a big chunk of time. The six of them that are definitely over with at this point lasted an average of almost eleven million years a piece. (For purposes of comparison, eleven million years is around 2200 times the length of all recorded human history.) The exception is the Holocene, which is only 11,700 years old at present, or only about 0.001% of the average length of an epoch. It makes sense to call the Holocene an epoch, in other words, if it’s just beginning and still has millions of years to run.
If in fact the Holocene is over and the Anthropocene is under way, though, the Holocene isn’t an epoch at all in any meaningful sense. It’s the tag-end of the Pleistocene, or a transition between the Pleistocene and whichever epoch comes next, whether that be labeled Anthropocene or something else. You can find such transitions between every epoch and the next, every period and the next, and every era and the next. They’re usually quite distinctive, because these different geological divisions aren’t mere abstractions; the change from one to another is right there in the rock strata, usually well marked by sharp changes in a range of markers, including fossils. Some long-vanished species trickle out in the middle of an epoch, to be sure, but one of the things that often marks the end of an epoch, a period, or an era is that a whole mess of extinctions all happen in the transition from one unit of time to the next.
Let’s look at a few examples to sharpen that last point. The Pleistocene epoch was short as epochs go, only a little more than two and a half million years; it was a period of severe global cooling, which is why it’s better known as the ice age; and a number of its typical animals—mammoths, sabertooth tigers, and woolly rhinoceri in North America, giant ground sloths and glyptodons in South America, cave bears and mastodons in Europe, and so on—went extinct all at once during the short transition period at its end, when the climate warmed abruptly and a wave of invasive generalist predators (i.e., your ancestors and mine) spread through ecosystems that were already in extreme turmoil. That’s a typical end-of-epoch mess.
Periods are bigger than epochs, and the end of a period is accordingly a bigger deal. Let’s take the end of the Triassic as a good example. Back in the day, the whole Mesozoic era routinely got called “the Age of Reptiles,” but until the Triassic ended it was anybody’s guess whether the dinosaurs or the therapsid almost-mammals would end up at the top of the ecological heap. The end-Triassic extinction crisis put an end to the struggle by putting an end to most of the therapsids, along with a lot of other living things. The biggest of the early dinosaurs died off as well, but the smaller ones thrived, and their descendants went on to become the huge and remarkably successful critters of the Jurassic and Cretaceous. That’s a typical end-of-period mess.
Eras are bigger than periods, and they always end with whopping crises. The most recent example, of course, is the end of the Mesozoic era 65 million years ago. Forty per cent of the animal families on the planet, including species that had been around for hundreds of millions of years, died pretty much all at once. (The current theory, well backed up by the data, is that a good-sized comet slammed into what’s now the Yucatan peninsula, and the bulk of the dieoff was over in just a few years.) Was that the worst extinction crisis ever? Not a chance; the end of the Paleozoic 251 million years ago was slower but far more ghastly, with around ninety-five per cent of all species on the casualty list. Some paleontologists, without undue exaggeration, describe the end-Paleozoic crisis as the time Earth nearly died.
So the landscape of time revealed to us by geology shows intervals of relative stability—epochs, periods, and eras—broken up by short transition periods. If you go for a walk in country where the rock formations have been exposed, you can literally see the divisions in front of you: here’s a layer of one kind of rock a foot or two thick, laid down as sediment over millions of years and then compressed into stone over millions more; here’s a thin boundary layer, or simply an abrupt line of change, and above it there’s a different kind of rock, consisting of sediment laid down under different climatic and environmental conditions.
If you’ve got a decent geological laboratory handy and apply the usual tests to a couple of rock samples, one from the middle of an epoch and the other from a boundary layer, the differences are hard to miss. The boundary layer made when the Mesozoic ended and the Cenozoic began is a good example. The Cretaceous-Paleogene boundary layer is spiked with iridium, from space dust brought to earth by the comet; it’s full of carbon from fires that were kindled by the impact over many millions of square miles; and the one trace of life you’ll find is a great many fungal spores—dust blown into the upper atmosphere choked out the sun and left most plants on Earth dead and rotting, with results that rolled right up the food chain to the tyrannosaurs and their kin. You won’t find such anomalies clustering in the rock sample from the middle of the epoch; what you’ll find in nearly every case is evidence of gradual change and ordinary geological processes at work.
Now ask yourself this, dear reader: which of these most resembles the trace that human industrial civilization is in the process of leaving for the rock formations of the far future?
It’s crucial to remember that the drastic geological impacts that have inspired some scientists to make use of the term “Anthropocene” are self-terminating in at least two senses. On the one hand, those impacts are possible because, and only because, our species is busily burning through stores of fossil carbon that took half a billion years for natural processes to stash in the rocks, and ripping through equally finite stores of other nonrenewable resources, some of which took even longer to find their way into the deposits we mine so greedily. On the other hand, by destabilizing the climate and sending cascading disturbances in motion through a good-sized collection of other natural cycles, those impacts are in the process of wrecking the infrastructure that industrial society needs to go its merry way.
Confronted with the tightening vise between accelerating resource depletion and accelerating biosphere disruption, the vast majority of people in the industrial world seem content to insist that they can have their planet and eat it too. The conventional wisdom holds that someone, somewhere, will think of something that will allow us to replace Earth’s rapidly emptying fuel tanks and resource stocks, on the one hand, and stabilize its increasingly violent climatic and ecological cycles, on the other. That blind faith remains welded in place even as decade after decade slips past, one supposed solution after another fails, and the stark warnings of forty years ago have become the front page news stories of today. Nothing is changing, except that the news just keeps getting worse.
That’s the simple reality of the predicament in which we find ourselves today. Our way of life, here in the world’s industrial nations, guarantees that in the fairly near future, no one anywhere on the planet will be able to live the way we do. As resources run out, alternatives fail, and the destructive impacts of climate change pile up, our ability to influence geological processes will go away, and leave us once more on the receiving end of natural cycles we can do little to change.
A hundred million years from now, as a result, if another intelligent species happens to be around on Earth at that time and takes an interest in geology, its members won’t find a nice thick stratum of rock marked with the signs of human activity, corresponding to an Anthropocene epoch. They’ll find a thin boundary layer, laid down over a few hundred years, and laced with exotic markers: decay products of radioactive isotopes splashed into the atmosphere by twentieth-century nuclear bomb testing and nuclear reactor meltdowns; chemical markers showing a steep upward jolt in atmospheric carbon dioxide; and scattered freely through the layer, micron-thick streaks of odd carbon compounds that are all that’s left of our vast production of plastic trash. That’s our geological legacy: a slightly odd transition layer a quarter of an inch thick, with the usual discontinuity between the species in the rock just below, many of whom vanish at the transition, and the species in the rock just above, who proliferate into empty ecological niches and evolve into new forms.
In place of the misleading label “Anthropocene,” then, I’d like to propose that we call the geological interval we’re now in the Pleistocene-Neocene transition. Neocene? That’s Greek for “new recent,” representing the “new normal” that will emerge when our idiotic maltreatment of the planet that keeps us all alive brings the “old normal” crashing down around our ears. We don’t call the first epoch after the comet impact 65 million years ago the “Cometocene,” so there’s no valid reason to use a label like “Anthropocene” for the epoch that will dawn when the current transition winds down. Industrial civilization’s giddy rise and impending fall are the trigger for the transition, and nothing more; the shape of the Neocene epoch will be determined not by us, but by the ordinary processes of planetary change and evolution.
Those processes have been responding to the end of the so-called Holocene—let’s rename it the Late Pleistocene, given how extremely short it turned out to be—in the usual manner. Around the world, ice caps are melting, climate belts are shifting, acid-intolerant species in the ocean are being replaced by acid-tolerant ones, and generalist species of animals such as cats, coyotes, and feral pigs are spreading rapidly through increasingly chaotic ecosystems, occupying vacant ecological niches or elbowing less flexible competitors out of the way. By the time the transition winds down a few centuries from now, the species that have been able to adapt to new conditions and spread into new environments will be ready for evolutionary radiation; another half a million years or so, and the Neocene will be stocked with the first preliminary draft of its typical flora and fauna.
It’s entertaining, at least to me, to speculate about what critters will roam the desert sands of Kansas and Nebraska or stalk its prey in the forests of postglacial Greenland. To many of my readers, though, I suspect a more pressing question is whether a certain primate called Homo sapiens will be among the common fauna of the Neocene. I suspect so, though of course none of us can be sure—but giving up on the fantasy that’s embodied in the label “Anthropocene,” the delusion that what our civilization is doing just now is going to keep on long enough to fill a geological epoch, is a good step in the direction of our survival.
Photo credit: CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=605720
