I’m wearing a fossil trilobite pendant around my neck right now. Black with prominent ribs in a silver bevel, it resembles a wood louse, and I wonder if it could rolypoly itself and somersault as wood lice do. Mostly, I wonder what its compound eyes saw so long ago. My trilobite is only an inch long, but I’ve held one nearly two feet wide in a neighbor’s private collection, its ribs a xylophone impressive enough to play a tune upon. Trilobites are uncanny instruments of life.
Millennia before the Pliocene’s celebration of the spine, when grazing quadrupeds roamed, silver birch leaves flickered like tiny salmon, and grebes first hinted at lunacy, trillions of trilobites prowled the ocean floors and paddled mud banks ajell with bacterial slime. In the evolutionary arms race, they grew armor plates, jointed legs, tough, chitinous jaws—anything to beat extinction’s warrant. When they died, they bedded the muzzy swamplands. Today human bone-tumblers ogle their chalky remains, their exquisite herringbone shells. Trying to understand their habits, we sometimes allude to their cousins, the crab, spider, and millipede, and say “adaptive radiation about a common theme.” As if that explained the papery organs within, or all the crises that fed their opportunity.
The most successful water animal ever embalmed as fossil, trilobites kept refining and upgrading themselves, over three hundred million years, until around twenty thousand different species freewheeled through deep and shallow seas on what must have seemed a trilobite-smitten planet. Some worked as stealthy ocean predators and scavengers, others as mild-mannered plankton-grazers, and still others fell into cahoots with sulfur-eating bacteria. Some developed protruding antlers and crackerjack spines. They scanned their realm with some of the oldest eyes on record, bug-eyed peepers with many lenses that weren’t organic but mineral, made of six-sided crystal calcium prisms. These radically different eyes didn’t provide crisp images but did offer a very wide field of view and motion. When a mass extinction wiped out trilobites 260 million years ago, their ancient lineage yielded to our world of insects with multifaceted eyes. But in their heyday, trilobites trolled the water world, and when they died their calcium carcasses fell to the bottom, crystal eyes and all, where layer upon layer of sediment enshrined them, gluing and compacting their bones with bits of coral and other calcium-cored creatures. Then time stacked its heavy volumes upon them, squeezing out the excess water and leaving behind limestone laced with skeletal remains. Today we use raw limestone in our roads, and grind it for paints and toothpastes—which means we use ancient trilobites, coral, and other fossils to help scrub our mouths.
That’s also what it would take to fossilize humans—not as populous as trilobites but the most successful land animal ever. Just as well. I don’t know how I’d feel brushing my teeth with the remains of ancient in-laws, or outlaws.
DRIVING DOWN THE highway that skirts Lake Cayuga, between glacial chunks of rock, I pass the uncanny work of erosion, a great sculptor of landscapes. Geologic eras are piled one on top of the other like Berber rugs, trilobites and other fossils bear witness to the evolution of life, and a host of creeks and waterfalls fume into the deep, gray-blue lake a thousand feet below. The wide ribbons of gunmetal gray and black shale I pass came from low-oxygen mud. Once this region was a shallow tropical sea that, as it evaporated, left not only mud full of marine-life skeletons that hardened into limestone but salt deposits, some of the deepest in the world. Colliding continents, 250 million years ago, stressed some of the rocks until fractures formed, land lifted, sea levels rose and fell. It’s easy to forget, when you look out over the rolling hills, that you’re seeing what once was the bottom of a sea, not the top of a mountain.
By the time dinosaurs appeared, 240 million years ago, the seas had retreated, leaving dry land, where dinosaurs stomped their footprints. When the ice age arrived, only 2 million years ago, it spread vast sheets of ice that repeatedly charged forward and dragged back, in the process gouging the deep Finger Lakes while streams cut the gorges of upstate New York. Sometimes large fossils appear from that era, like the mastodon (a hulking relative of the elephant with exceptionally long tusks) that a bemused local farmer found in his field several years ago.
Most of the life forms that once inhabited the planet have vanished, leaving no trace behind. Their remains have been polished down by the elements and bulldozed by the slow-motion avalanche of the glaciers. But geologists like Cornell University’s Terry Jordan can read a tale in the rock strata, the Earth’s dialect of stone, including the chevrons that tell of some sea-tossing event, maybe a hurricane like Sandy or Haiyan.
I like Terry Jordan from the first moment we meet in her office beside one of the sinuous plummeting gorges that are a hallmark of this lake district, a place for the geologically curious, loaded with fossils. It’s her blue argyle socks—the crisscrossing design echoes the angles one sometimes sees in rock creased by spells of turmoil, the shadow of a buckling or churning calamity so long ago that we can only date it to within tens of thousands of years.
Specializing in sediment, the earth scruff that remains long enough to petrify into pinnacles and mutate into mesas, she’s taught geology for much of a human lifetime. That seems long to me, but in her view of the past it’s only a speck.
“Does it ever feel strange thinking in such long, slow units of time, when today’s world is all about speed?” I ask.
Shaking her head with a laugh, she says, “No, I’m amazed by people who don’t think this way. How can they not see it?”
The “it” is our place in the rocky bones of history. Admiring a chunk of rock on a table by Terry Jordan’s window, I lift it in my hands and peer at the embossed fossils on its surface, where ram’s-horn-shaped ammonites look like they’re butting their way out.
“This is a wonderful place for fossils,” I say. “Do you think our bones will show in the fossil record in this way, oh, say, ten million years from now?”
“Only if we’re trapped in sediment!” she says, with a slightly impish smile. Then, seriously: “Maybe people living in coastal areas like New Orleans, Tokyo, or the Netherlands, or island nations—areas that will sink and disappear in mud when the sea level rises.”
When we talk about the Age of the Dinosaur or the Age of the Trilobite, we expect to find fossils. But that’s not true in the Age of Humans. It’s not necessarily our bones that future geologists will ponder, but an altogether different kind of evidence. Not our bones but our residue will signal the beginning of the Anthropocene, a point delineated by a “golden spike”—a marker scientists pound into the rock strata to denote an internationally agreed-upon start of a geological time period. Most spikes are in Europe’s heavily studied ribbons of exposed rock, with seven golden spikes in the United States, and dozens more throughout the world.
Let’s suppose once more that we are astronauts, this time visiting Earth millions of years after humans have left to pioneer other worlds, allowing Earth to lie fallow for a spell and restore its bounty. Few signs of us remain—on the lush, overgrown surface, that is. Exposed rock and ice cores outline our story, and a future geologist—we’ll call her Olivine—is looking for “time-rock,” layers that show magnetic, chemical, climatic, or paleontological signs of the new age that we created.
From the warmth of her sky-tent tethered above what once was Patagonia, she travels the world and digs, measures, and tests, unearthing clues like shards of pottery. In sedimentary rock near the coasts, she pores over the fossil remains of cities: low-lying mazes once called Miami or Calcutta. She detects radioactive pulses from nuclear waste dumps. She finds a layer of woodland pollen suddenly replaced by agricultural pollen, and another ribbon where agriculture gave way to cities. Seams of concrete and metal abound. Scouting the oceans, she detects how, in our age, we plowed up the seabeds by bottom-trawling with large heavy nets dragged across the ocean floor, scooping up any marine life in their paths. Olivine is briefly envious. They were the first generation of humans, she thinks, with the instruments and satellites to be able to measure how geology was changing during their own lifetime. What an exciting era that must have been.
Everywhere she travels, she stumbles upon a mass of fossils of species far from their native habitats, and clumped together, on a scale unique in all of Earth’s geological history. Long before we began shuffling life forms, species invaded new lands when continents collided in slow motion. But during our geologic moment, we’ve rushed the process, and quickly surpassed plate tectonics as a rearranger of species.
Olivine smiles as she identifies rose and Scotch broom pollen in a rock sample not far from her tent, in Patagonia, once a wild and windswept frontier where armadillos roamed and the beach pebbles were jasper. Roses in Patagonia, she thinks. Those old Anthrops were rose addicts. And Scotch broom—didn’t they realize it would spread for miles? Probably transplanted by settlers. She knows the Scotch broom flailed long pokers of yellow flowers and, with weedlike momentum, colonized hundreds of acres and retuned the chemistry of the soil.
Special prizes are bits of human bones, whose DNA shows how our species began continent-jumping like hopping spiders, with some lineages predominating but most mixing, homogenizing, traveling far from their native shores, in a worldwide flux binding us all together.
She and her colleagues have argued some about the exact start of the Anthropocene—Agriculture? Industry? Nuclear bombs?—but they all agree that our world dramatically changed around the year 1800. That’s when the Industrial Revolution, powered by a massive use of fossil fuels, led to rising carbon dioxide levels. We tend to forget that the steam engine was first invented to pump water out of coal mines, and only later adapted to move boats, cars, and trains. It’s also when land clearing speeded up, and ecosystems were converted from mostly wild to mostly human-centered. Agriculture and mining became mechanized giants, spilling more fertilizer into the rivers and oceans, and more pollution into the air. The new textile mills and factory system drew laborers from the country into rapidly booming modern cities. That’s when we first began adapting the planet to us on a large scale—changing the climate, changing the oceans, changing the evolution of plants and animals.
In the process, we’ve left our signature everywhere. Our impact is already measurable in the geologic record. The rocks hum with radioactive elements from atom bomb tests of the 1960s. The fossil pollen Olivine studies in the strata will reflect how, during our epoch, the wild brew of species that once thrived for centuries on the prairies and in the forests suddenly gave way to unbroken fields of single crops—corn, wheat, soy—and vast clans of cows, pigs, and chickens.
Because plastics take so long to degrade, they, too, will show up in the fossil record. Not as flattened lawn chairs and PVC pipes, but as veins of tiny plastic tears, which is as far as plastic denatures. Quasi-crystals (crystals with orderly but nonrepeating patterns), transparent aluminum, and other newly invented forms of matter will appear in the matrix as well.
That alone is astonishing. We’re adding new elements to the sum of creation. The wide world of nature, with all its chemicals and potions, plants and animals, rocks, crystals, and metals, is not enough for us.
We’re also minting brand-new states of matter, metals no earthly eyes have ever seen—photonic clusters that can slice like light sabers, ultracold quantum gas known as polar molecules, fleecy electric, synthetic radioactive elements from einsteinium through copernicium to ununoctium, among many other artificial sprinklings. Monuments needn’t be large, or even visible to the naked eye, to declare our godlike powers. It’s one thing to rearrange bits and bobs of nature to create, say, an antibiotic or an atom bomb. But it’s quite another to cook up exotic blazons of matter, adding them like new spices to the cosmic stew. I’m amused to think of a future geologist like Olivine puzzling over weird taffylike wads, trying to figure out what chem lab sport might have spawned them.
All of these elements will ultimately show up as indisputable signs of our presence. We’re leaving tracks in the strata never seen before in Earth’s five billion years. What did you add to the fossil record today? The plastic from a six-pack or a water bottle? A midden of candy wrappers, plastic bags, and orange juice cans? Did you drive your car? If so, you’ve changed the weather by a whisker, and that, too, will ultimately add to the patterns in the rock, a legacy of our meddling from deep sea to outer space.