Wrinkled Time

Anyone born on Earth knows that our home is remarkable. If you were prompted to think about what makes this planet so special, you might mention the vast oceans and abundant oxygen, perhaps the protective magnetic field. But an equally exceptional yet less obvious attribute is the way that Earth preserves accessible records of countless earlier versions of itself, condensing events of billions of years into the volume of the present-day continents. In achieving this feat of compression, Earth effectively wrinkles time—accordioning eons and juxtaposing moments in its long history—through the medium of rocks.

In Earth’s crust, past worlds coexist with the present in the form of rocks from all chapters in the planet’s biography, but few of us give much thought to this extraordinary archive. If we would remember that we are first and foremost Earthlings, a term describing our shared heritage that should never have been ceded to science fiction, we might start paying more attention to what the planet itself has to say. We don’t realize how unusual it is to have easy access to nearly the entire history of our planet. None of our neighbors in space have maintained such a long and continuous rock record.

To grasp the peculiarity of Earth’s crustal archives requires an appreciation for the semiotics of rocks. First, rocks are best understood not as nouns but verbs, signifying events and processes. If nothing is happening on a planet, there will be no new rocks. Thinking of rocks as verbs is like seeing a painting not merely as an object that is, but as the manifestation of the motions that led to its creation. Like artists who paint only in oils, some planets work only in one medium: magma is the most common. Mercury, Venus, and the Moon fall into this igneous-only group. But generating magma requires a continuing heat source, and if a body cools too much, its output will end. This has been the fate of Mercury and the Moon, which are now silent museum worlds whose rocks are monuments to a dimly remembered volcanic past, vandalized by eons of meteorite impacts.

A wider range of creative possibilities is available to planets with liquid water, because erosion, sedimentation, dissolution, and reprecipitation make it possible to create new rocks by reconstituting existing ones. Among the inner planets, Mars and Earth have both practiced the watery art of sedimentation, but Mars lost its atmosphere early on and stopped recording its experiences while still in its childhood. Earth, in contrast, has continued to experiment with sedimentary techniques and has invented countless new ways to lay down rock, many done in collaboration with life-forms such as algae and coral.

So the first criterion for a long-duration planetary record is that rocks must be continuously generated over time—i.e., a planet must be active and dynamic, always creating new rock through one or more processes. But this creates a paradox, because on such a planet, the same processes that generate new rocks—magmatism, tectonics, sedimentation, erosion—are also likely to melt, alter, bury, and destroy older ones. One can easily imagine a world on which tectonic or hydrologic processes are so vigorous—like a dissatisfied artist who obsessively repaints the same canvas or destroys works as soon as they are finished—that no rocks of one period survive into the next.

Our sister planet Venus seems to behave in this impulsive way, at least episodically. Based on the relatively small number of craters on its surface, it appears to have had a global volcanic paroxysm that lacquered the entire planet in lavas a few hundred million years ago,¹ making any earlier records of its history permanently inaccessible. Given Venus’ subdued topography and lack of erosive processes, any older rocks that may survive beneath its surface cannot be “read”—here, the past is static and sequestered beyond our knowing.

And now we begin to see why Earth’s long rock record is exceptional. Even though Earth is exuberantly active, with countless parts in constant motion, from a churning mantle and shifting plates, to roaring rivers and crashing surf, this planet has consistently managed to set aside some of its rocky work over the past four billion years—and make those archives open to those of us who live on the surface. This is strange and remarkable.

How can a planet crenulate so much time into the finite dimensions of its outer crust? Two requirements need to be met. First, rates of rock formation must, on average, outpace rates of destruction, and second, the surviving rocks must be continuously reconfigured for access from the surface. Earth has rather elaborate mechanisms for accomplishing both.

The first requirement is in fact not true for rocks of the deep-sea floor. The oceanic crust, which covers more than two-thirds of Earth’s solid surface, lives fast and dies young. Made of the volcanic rock called basalt, the ocean floor is recycled at the rate it’s created, with no net accumulation. Each year, about 20 km³ (4.8 mi³) of new ocean crust is extruded as lava from the mid-ocean ridges²—but an equal amount is consumed by subduction. If we had to rely on ocean crust to tell the Earth’s story, the narrative would take us back only to Jurassic time—just the last three percent of the planet’s history. (Also, it would not have much to say about what was happening on land during that time, like the rise and fall of certain terrible lizards and the subsequent proliferation of mammals.)

Fortunately, from an archival standpoint, Earth’s continents are underlain by a second, distinct type of crust with a much longer life expectancy. The heterogeneous but broadly granitic continental crust has too low a density to be taken back into the mantle by subduction, giving it the potential to survive billions of years. In fact, much of the extant continental crust formed prior to about three billion years ago. Continental crust is vulnerable to erosion—from which the ocean crust is exempt—but erosion is slow relative to the total volume of the continents, so even its incessant gnawing does not consume them entirely. And counterintuitively, erosion is actually essential to creating Earth’s archives—as well as making them accessible to land-based readers. Herein lies Earth’s secret to wrinkling time.

Most sediment that is eroded from the continents does not reach the deep ocean floor but instead gets deposited by rivers, which lose their steam when they reach the sea, in the shallow offshore regions called the continental shelves. The shelves are a liminal zone, untouched by the forces that destroy fully continental or fully oceanic crust. They are continental in the sense of being granitic, and therefore non-subductable, but marine in that they lie below sea level and are thus non-erodable. At the same time, they are sensitive to events on both land and sea, receiving detritus from continents while in communication with the global ocean. As a consequence, the continental shelves are the ideal site for long-term planetary recordkeeping.

Continental shelf sediments are the primary source for almost everything we know about the atmosphere, hydrosphere, and biosphere in the geological past; they provide eyewitness accounts of evolutionary innovations, tectonic upheavals, climate oscillations, and mass extinctions. These sprawling chronicles—the many-volume memoirs of the Earth—are sometimes boring, often humbling, and occasionally terrifying.

But we humans would never have an opportunity to read these sedimentary tomes if Earth didn’t have ways of making them available to land dwellers. Its most direct method is simply to let sea level fall, leaving erstwhile expanses of submarine shelf high and dry. We humans, creatures of the Ice Age, happen to live in a time of relatively low sea level, with easy access to records of the greenhouse world that came before. A second, more dramatic, mechanism for lifting continental shelf sediments into the open air involves tectonics. When subduction has consumed an entire ocean basin, causing continents to collide, their flanking shelves are the first points of contact. As the slow-motion crash continues, the accumulated records of a hundred million years are crumpled and buckled, raised into great mountain belts. Erosion by rivers and glaciers then make inroads into these reshelved documents by carving valleys and canyons through them, making it possible for creatures at the surface to study the ancient texts.

By this Rube Goldbergian concatenation of processes, Earth has squeezed four billion years of its biography into just one-third of its surface area. It’s almost as if the planet wants its biography to be read. We live in a vast, labyrinthine library of time.

Yet most of us Anthropocene Earthlings are barely aware of the rich legacy of natural history that envelopes us. We are like squatters living amid the remains of earlier empires, worlds defined by different geographies, governed by alternate rules, inhabited by other residents. Consider the variety of ancient realms represented by a few North American cities: Milwaukee lies on a teeming coral reef; Minneapolis is perched on the edge of a vast volcanic rift; Montreal and New York City rise from the roots of great mountain belts; San Francisco sits, unsteadily, on rocks churned in an ancient subduction zone; Mexico City, also precarious, on the bed of a vanished lake. All vividly remember other versions of Earth.

We self-absorbed humans, meanwhile, mostly ignore the stories that lie just beneath our feet, believing them to be irrelevant, subordinate to our own reality, reducible to the convenient cubbyhole of “prehistory.” If we bothered to notice it, Earth’s crinkled crust would reveal how the past not only persists but in fact shapes the present. The rock record would show us that earlier iterations of the world are no less real for having occurred before we happened onto the scene. Rocks would remind us that we too live in geologic time, that our own moment will one day be long ago.

When we do pay attention to rocks, it is usually because of their utility, not their long memory. Although we humans like to think that we are in charge of our own destiny, the technological ages of humankind—Stone, Bronze, Iron, Fossil Fuel, Nuclear, and yes, even Digital—have always been dictated by rocks, and our own short-lived empires have risen and fallen in the pursuit of their riches. The science of geology has of course been entangled with all of this looting, but along the way, as geologists hammered at rocks, they began to understand that each gold vein and coal seam was part of a grand illuminated manuscript recording the history of the world. In an ironic twist, geology’s richest discovery is arguably an intellectual and philosophical one—an understanding of Deep Time.

Like all creatures on Earth, we need to use the planetary materials at hand to make a living, and our species has been exceptionally clever at appropriating those materials for our own purposes. As our technological prowess has grown, however, our respect for these works of time has declined. We rarely pause to consider that rocks and minerals have their own life stories—that they are emissaries bearing messages from across eons.

Our cavalier attitude toward geological antiquities reminds me of an unplanned stop—and a bit of time travel—on a field trip I took with students in southern Croatia. We were in the tiny town of Vid, in the fertile fruit-growing region along the Neretva River. Vid was once the Roman city of Narona, an important trading post in the province of Dalmatia. A great Roman temple with statues of emperors Augustus, Claudius, and Vespasian was built there in the first century CE, but by the early Dark Ages it had fallen into ruin.

As we climbed the steep slope above the town on our way to look at some rocks, we passed a crude stone house dating to the seventeenth or eighteenth century. Most of the rocks in its walls were rough-hewn limestone, no doubt locally quarried, but even from a distance we had noticed that about a third of them, incorporated randomly into the structure, were made of something different. As we drew closer, we saw that these were sculpted chunks of milky marble—part of an elbow, a sandaled foot, a toga-draped shoulder, even a head with a broken nose. We laughed—partly at the comic ignominy of the anatomical parts, but also at the audacity of the builder, the sheer indifference to history demonstrated by the haphazard way Roman statuary had been pragmatically repurposed.

It occurred to me later that that house on a Croatian hillside embodies the way we in the modern world thoughtlessly scavenge the monuments of the geologic past. Our cities are just scaled-up versions. Every asphalt roadway and concrete structure contains fragments, often still readable, from the chronicles of prior geologic regimes, irreverently blended and reconstituted. The metals in our cars, phones, and computers, having been separated from their source rocks, are more akin to individual letters in a shredded manuscript, but still whisper of their deep geologic origins. All the coal, oil, and natural gas we’ve burned—the photosynthetic memories of earlier ecosystems—hovers now in the air, the ghosts of combustion that haunt us in the Anthropocene.

Does it matter whether or not we acknowledge the histories of nonliving components of nature? Not every rock in Earth’s time-wrinkled crust can be treated as a precious artefact, and we Earthlings have no option other than to use what the planet provides. But simply developing an awareness of the deep history that enfolds us—and the immense amount of time embodied in the planet’s generous gifts—can foster a perceptual shift with radical psychological and practical implications.

At some point in the last few hundred years, Western culture ceased to find, in Shakespeare’s words, “books in the running brooks, sermons in stone,” and instead began to view rocks, soils, and, by extension, the planet itself as dumb matter. Purging nature of agency helped prepare the way for the Scientific Revolution, when Newtonian physics began to claim intellectual dominion over matter. From that point on, the mechanistic logic of physics—paired dangerously with the insatiable appetite of capitalism—defined Western attitudes toward the natural world. Nature is now the passive backdrop to “real” world politics and economics. It seems that stones have long since gone mute, no longer in the habit of delivering sermons. Or perhaps amid the din of modernity, our incessant narcissistic clatter, we just can’t hear them. If we did stop to listen again, what would we learn?

First, among the involuted volumes of the Earth library, we would discover genre-defying stories so numerous, varied, hair-raising, and awe-inspiring that all of human literature would seem flat and predictable in comparison. We would find that this planet was not necessarily predestined to become the blue-green world we know. Earth began with the same raw materials as Venus, Mercury, and Mars but adopted certain habits—tectonic, hydrologic, and biological—early on that have enabled it to continuously reinvent and renew itself. Its rock record is the exhilarating biography of an endlessly creative, resilient, experienced planet.

Scanning the text, we would discover that in the main, times of prosperity have prevailed throughout Earth’s history, with biogeochemical systems settling into nice repetitive grooves as seas languorously rose and fell, life-forms diversified, and plates drifted. Reading further, however, we would also encounter horrific accounts of cataclysm and collapse, some sudden, others in agonizing slo-mo. The well-known deus-ex-machina story of the dinosaurs’ death by asteroid is in some ways less terrifying than the more protracted and ultimately more devastating mass extinctions triggered by internal failures in Earth’s capacity for self-regulation. Most nightmarish of all is the end-Permian extinction, set in motion by rogue carbon dioxide–spewing volcanoes and then amplified through knock-on effects in the atmosphere and hydrosphere, including ozone depletion and ocean acidification and anoxia. Ecosystems that ruled the world for hundreds of millions of years were brought down in tens of thousands of years, leaving denuded continents and empty seas. The biosphere eventually righted and reinvented itself—but it took ten million years. Anthropocene readers may wish to devote particular attention to this chapter.

Becoming familiar with Earth’s monumental autobiography, and getting to know the characters and plots that fill the vast expanses of geologic time, forces one to abandon the notion that the only stories that matter are those with human protagonists. Once free from that deep-seated prejudice, one begins to see even the nonliving components of the Earth, including rocks and rivers, atmosphere and ocean, not as dumb matter but rather as part of a dynamic, animate, evolving—and self-documenting—collective.

Although there is a tendency to think of biological evolution as a steady march of progress, with primitive organisms being systematically replaced by more sophisticated ones, the fact is that when new lineages of organisms have emerged, they have simply joined the other branches on the Tree of Life. Bacteria and archaea, the progenitors of all subsequent life-forms, are still very much with us, as are myriad other microorganisms and invertebrates, as well as fish, amphibians, and reptiles, all living together in the wide crown of the tree with Johnny-come-lately species like us.

Similarly, old rocks are not merely relics of the distant past but active participants in current events and ecosystems, thanks to the way that Earth has crumpled rocks of all ages into the crust. Rocks young and old take part with equal vigor in present-day earthquakes. Strata that formed as desert dunes a hundred million years ago lap up today’s rain, having found new careers in middle age as aquifers. Schists that remember the dawn of Life carry on intimate discourse with modern microbes and root systems, on their way to becoming soils of the future. Basalts that were erupted as lavas eons before Homo sapiens appeared now attempt valiantly to absorb our carbon emissions.³ In other words, even the oldest rocks are responsive to new conditions, taking note of changes in the air, interacting in real time with the present.

This view of Earth’s rocky crust as dynamic and reactive—an ancient archive with comments to make about the current state of the world—suggests that we need a radical reappraisal of the way we live, farm, and build infrastructure on it. Even over human timescales, rocks and landscapes are not static but instead inherently mutable, and their capacity for shape-shifting will only increase in the face of anthropogenic changes in the surface environment. Yet most training for designers and engineers is still predicated on the view of rocky matter as timeless and inert. This reflects certain aesthetic preferences that were adopted early on in the history of Western science.

Berkeley ecologist John Harte has articulated a useful distinction between two philosophies that reflect prevailing scientific attitudes toward the natural world: what he calls the “Newtonian” and “Darwinian” worldviews.⁴ The Newtonian view is of course the approach of physics. Harte acknowledges that modern physics has moved beyond Newton’s classical mechanics, but he uses “Newtonian” as a shorthand for an approach that values reductionism, or dismantling complex entities to simpler components; idealization, the stripping away of “noisy” detail to allow precise mathematical description; and universality—prioritizing phenomena that are outside or exempt from time. Over the past few centuries, the Newtonian approach has become the definition of science in the mind of the public.

The Newtonian view is clearly a powerful approach that has facilitated great technological advances and fostered understanding of certain aspects of matter and the cosmos, but it can often lead to hubris, tempting us to think that having discovered the laws of nature we are therefore in control of nature. In the first two-thirds of the twentieth century, with the rise of automobiles, the frenzy of the space race, and the promise of “better living through chemistry,” it seemed possible that perhaps we were in control. But then the seemingly docile natural world began to resist our intellectual preference for reductionism, idealization, and timelessness. In the tidy realm of the laboratory, no one imagined that the internal combustion engine would one day destabilize global climate or that technological marvels like plastics, pesticides, refrigerants, and antibiotics would begin to behave in menacing ways in the real world.

Studying nature’s more unruly tendencies requires an alternative set of scientific values: what Harte calls the “Darwinian” worldview. Harte uses the term not to connote a natural world that is “red in tooth and claw” but to stand for a perspective that recognizes the central role of time in the ceaseless branching of evolution—the power of time to generate marvelous diversity, in Darwin’s own words, “endless forms most beautiful.” The Darwinian view prioritizes systems thinking, or the idea that components of a complex whole cannot be understood in isolation. And it honors the idiosyncrasies of entities like particular species, ecosystems, or mountain belts as worthy of study, embracing nature’s exuberant tendency for creating variety rather than stripping natural phenomena down to oversimplified idealizations and “first principles.”

The Darwinian view, which recognizes the capacity of time to create unexpected outcomes, tends to lead to humility. Statistics is the mathematics appropriate to characterizing a natural world that never will reach an idealized equilibrium state and for which there are rarely precise solutions, only probabilities. But because the public has been inculcated with the idea that “real science” produces precise answers, probabilistic scenarios about things like climate change are dismissed as unscientific.

Neither the Newtonian nor Darwinian approach is intrinsically better; they are complementary, if limited, lenses for understanding the nature of nature. Still, it could be argued that our most intractable environmental problems can be attributed to applying a Newtonian, time-exempt mindset to Darwin’s world of time-saturated entities like aquifers, lakes, rivers, soil, the atmosphere, or the planet as a whole.

Despite these sobering lessons, the Newtonian attitude and its disdain for time still reign unchallenged in the world of technology. There is a new and powerful generation of engineers and entrepreneurs who believe that humans can simply opt out of time—not appreciating the irony that their worldview is in fact an antiquated misconception from a bygone era. These are the moguls who think that “colonizing” Mars is not only possible but in fact right and inevitable, who advocate for stratospheric sulfate injection as an instant solution to the long-brewing climate crisis, and who actually seem convinced that they personally will be exempted from dying.⁵ At the same time, in another irony, obsolescence is a constant threat in their world, where someone who has been in the business for two decades is regarded as an ancient sage.⁶ All of these delusions are symptoms of temporal dysmorphia, or more bluntly, time illiteracy.

This condition is harmful to any human but particularly pathological when it afflicts the rich and influential. Spewing sulfate into the upper atmosphere to correct for a century’s worth of fossil fuel burning is considered by geoscientists to be madness, sure to have a torrent of unintended consequences not only for global weather patterns but also geopolitical stability.⁷ Time illiteracy seduces otherwise intelligent people into believing a planet with no soil, oceans, or active tectonics could become an Earthlike Eden in a matter of decades—somehow overlooking the fact that even if we could homestead on a new planet, we would still be us: the same flawed creatures expelled from the first Eden.

Schemes like climate engineering or terraforming Mars sound easy if you are completely ignorant of the intrinsic timescales of geological and biological phenomena, the deep evolutionary pathways that gave rise to the world we live in, the intricate, behind-the-scenes biogeochemical logistics—the teeming, tireless, housekeeping crew—that have made Earth such a hospitable place for billions of years.

The idea of terraforming Mars—an enticing mashup of myths ranging from the book of Genesis to the American frontier and Star Trek—is appealing because we so desperately want to be able to start over, wipe the slate clean, break free from the past. The wish is understandable; the world is such a mess. Striving to escape history, however, is not only futile but also self-destructive—an unhealthy denial of our own inherently timeful nature. Rather than fleeing from our Earthly roots, we need now more than ever to reconnect with our evolutionary origins as we face an uncertain geologic future.

ONE REASON the current moment feels so perilous is that we are hurtling forward with no shared vision—no common text or set of principles to consult for guidance. We humans have always craved a sense that we are part of something larger than ourselves, that our quotidian lives play out against the backdrop of some greater, grander presence. Traditionally, religions have met this yearning. But these days existential meaning is often sought in ways that, perversely, act to isolate us further: conspicuous consumption, political tribalism, conspiracy mongering, addictions of various sorts.

The spiritual solace we crave may lie in the records of deep time that are our common heritage as Earthlings. The rocky archives have been patiently awaiting our notice. In them, we may find reassurance in the persistence of earlier worlds all around us; a sense of wonder at how extraordinary their preservation is; gratitude for the way they permeate the present with mystery, gravitas, and the promise of continuity. A spirit of evolutionary camaraderie may come from the knowledge that we have shared the arduous journey to the present with so many other long-lived lineages and have kin everywhere in nature. Accepting that we too live in geologic time can free us from narcissism. Letting go of the illusion that only the present is real, allowing the undulations of time to wash over us, may carry us with less fear into the future.

We might begin to notice that in contrast to our technologies, which become outmoded in a matter of years, billion-year-old rocks still function perfectly well. We may then realize that the text of the Earth itself is full of guidance on durable design and start laying the groundwork for a post-Anthropocene world in which our species will have learned at last to be law-abiding Earth citizens. But this new relationship with time will require social change, which takes … time.

Still, we can make a start. We can write songs of gratitude for the biogeochemical cycles that keep the planet on an even keel. We can celebrate ecosystems—peat bogs and cloud forests, savannas, and kelp groves—and all their timeful idiosyncrasies. We can develop new geocentric curricula that teach children from an early age about how their magnificent planet works, from its mid-ocean ridges to subduction zones, continental shelves to crumpled mountain belts. And we can all strive to become more time-literate Earthlings, at peace with our temporal, and temporary, nature. Then we may learn to savor our moment on this wrinkled old planet, enfolded cozily within the creases of deep time.