It is the dawn of a new geological age. A teeming swarm of Homo sapiens gathers on the banks of an estuary at the edge of the North American continent. The glaciers have retreated; the seas have risen more than 400 feet since the last ice age; and the gleaming new steel-and-glass hives of Manhattan rise up from the marshes. Looming over the confident city, just across the Hudson River, is the sheer cliff face of the Palisades. The gigantic columns of basalt sit in unimpressed, stony silence, as they have for 200 million years. These cliffs, covered in highway weeds and graffiti, are monuments to an ancient apocalypse. They’re made of magma that once fed burbling fountains of lava at the surface—lava that once smothered the planet from Nova Scotia to Brazil. The eruptions flooded the atmosphere with carbon dioxide at the end of the Triassic period, roasting the planet and acidifying the oceans for thousands of years. Brief blasts of volcanic smog punctuated this super-greenhouse with cold. The runaway volcanism covered more than 4 million square miles of the planet and killed off more than three-quarters of animal life on earth in a geological instant.
I struggled to keep up with Columbia University paleontologist Paul Olsen as he bounded up the scraggly path leading from the banks of the Hudson to the base of the Palisades. In front of us, smothered under this enormous wall of now-solid magma, were the remains of a quarter-billion-year-old lake bottom, complete with exquisitely preserved fish and reptile fossils. Behind us, faintly droning, was the skyline of New York City.
I asked Olsen whether the city across the river would be preserved for future geologists to discover, like this peaceful Triassic diorama at the bottom of the rocks. He turned to consider the scenery.
“You might have a layer of stuff,” he said dismissively, “but it’s not a sedimentary basin, so eventually it would erode away to nothing. You’d have bits that would make it out into the ocean and would be buried and might show up—some bottle caps, maybe. There would be some pretty heavy-duty isotopic signals. But the subway system wouldn’t fossilize or anything. It all would erode away fairly quickly.”
It is from this disorienting perspective that geologists operate: to them, millions of years run together, seas divide continents, then drain away, and great mountain ranges erode to sand in moments. It’s an outlook that’s necessary to cultivate if one wants to get a handle on the staggering depths of geological time, which recedes behind us hundreds of millions of years and stretches out before us to infinity. If Olsen’s attitude seems dispassionate in the extreme, it’s a symptom of a lifetime’s immersion in Earth’s history, which is both vast beyond comprehension and, in some exceedingly rare moments, tragic beyond words.