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 layed 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.
