The Great Dying

 The White Rim

To set a camera here, in the Island in the Sky district of Canyonlands, is to frame a question of geology. The landscape demands it. A prominent bench of stone, a stark and brilliant white, circles the canyons below the rim, providing the route for a hundred-mile track known as the White Rim Trail. This rock is more than a foundation for a road; it is a line drawn in the strata, a division between two worlds. The White Rim Sandstone marks the boundary between the Permian Period and the Triassic—the end of the Paleozoic Era. It is the geologic chapter break for the most profound biological crisis in the planet’s history. The story told at the contact between this white stone and the red rock laid down above it is one of a planet’s climate pushed past a threshold by carbon dioxide, of oceans turned hostile, of a biological reset. The mechanisms of that ancient catastrophe, written here in stone, carry a certain resonance now.

The world of the Late Permian was a system under immense and protracted stress.For tens of millions of years, the planet had been tectonically reconfiguring itself into the supercontinent Pangaea, a process that created extreme climates and, more critically, began to dismantle the planet’s primary climate-regulating mechanism. In the preceding Carboniferous Period, the mountain-building collisions that formed Pangaea had exposed vast quantities of silicate rock. For millions of years, the chemical weathering of these mountains drew enormous amounts of CO₂ from the atmosphere, acting as a planetary thermostat. But by the Late Permian, those mountains had largely eroded. The tectonic activity had waned. The Earth had lost its most effective tool for sequestering carbon, leaving the climate exquisitely vulnerable.

The consequences are recorded in the chemistry of the seas. With the thermostat broken, atmospheric CO₂ began a slow, inexorable rise. The oceans absorbed it, and their pH began to fall. In the Early Permian, shallow seas were dominated by prolific “carbonate factories”—reefs and shelled organisms. By the Late Permian, these were gone, replaced by a “silica factory” of chert, composed almost entirely of the glassy spicules of sponges. The calcite compensation depth—the water depth at which seawater becomes corrosive to shells—had shoaled dramatically, making it biochemically impossible for most calcifying life to survive even near the surface. Simultaneously, the deep oceans were becoming progressively anoxic, starved of oxygen. The biosphere was being driven toward a precipice.

The final push came from deep within the crust. Two hundred and fifty-two million years ago, in a region now known as the Siberian Traps, fissures opened and began to spew immense volumes of basaltic lava.This was not a volcano but a large igneous province, an event that bled magma for perhaps a million years, ultimately covering an area the size of western Europe. Critically, this magma did not just flow over the surface; it intruded into and ignited the vast, carbon-rich coal basins of Permian Siberia.It set a continent-sized fossil fuel reserve on fire.

The geochemical fingerprints of this event are undeniable. In marine sediments from Arctic Canada, precisely at the extinction horizon, researchers have found microscopic particles of fly ash, morphologically identical to the waste from a modern coal-burning power plant. In the very same layers, there is a sharp and dramatic spike in mercury concentrations. This evidence forms an indelible link: the Siberian Traps, amplified by continental-scale coal combustion, had triggered a runaway thermal event.

The result was a cascade of interconnected kill mechanisms that affected every part of the Earth system. Atmospheric CO₂ may have risen to thirty times modern values, pushing the global average temperature to exceed forty degrees Celsius. Halogens released from the eruptions ripped apart the stratospheric ozone layer, leading to lethal spikes in ultraviolet radiation—an increase of five thousand percent at the poles. The oceans absorbed the CO₂, leading to extreme hypercapnia and acidification. Warmed to the temperature of a hot tub, the equatorial seas became lethal to plankton, collapsing the entire marine food web from its base.

In these suffocating, anoxic waters, certain anaerobic microbes could now thrive. Green and purple sulfur bacteria, which produce hydrogen sulfide (H₂S) as waste, bloomed in unparalleled numbers, turning the seas a lurid, alien purple. A chemical fingerprint of these organisms, a biomarker called isorenieratene, confirms their presence. Eventually, the toxic gas would have exsolved from the water, poisoning the terrestrial realm. As the paleontologist Peter Ward has said, "The microbes are still out there… they really want their world back and they’ve tried over and over and over again."

The biological toll was staggering. In the seas, ninety-six percent of all species vanished. The trilobites, after a run of two hundred and seventy million years, were gone. On land, seventy percent of vertebrate species perished. In the face of this near-total annihilation, the synapsid Lystrosaurus, a pig-sized herbivore, emerged as a key survivor.Its compact body was well-suited for a burrowing lifestyle, which would have offered protection from the heat and radiation. It was one of the few winners of the apocalypse.

For the next five million years, the world was an ecologically monotonous landscape. These “disaster faunas” were overwhelmingly dominated by a single genus; in some places, Lystrosaurus accounted for ninety-five percent of all terrestrial vertebrates. The recovery was uniquely prolonged because the Siberian Traps did not fall silent. For millions of years, the volcanic system remained active, delivering renewed pulses of CO₂ and mercury, each pulse acting as a hammer blow, knocking back any attempt by life to rediversify.

A Modern Resonance

The agent of the Great Dying was carbon, liberated from the lithosphere and injected into the atmosphere on a geologic timescale. The Siberian Traps, by igniting Permian coal, tapped into a vast fossil fuel reserve. We are now, through industrial means, engaged in a similar enterprise. The critical difference, and the one that is a matter of sobering concern to paleoclimatologists, is one of tempo. The rate at which humanity is releasing carbon into the atmosphere is, by most estimates, at least an order of magnitude faster than the rate of release that triggered the End-Permian extinction. In the rock record, our current emissions spike will look nearly instantaneous.

The symptoms of this rapid injection show a disquieting family resemblance to the Permian crisis. As atmospheric CO₂ rises, the oceans are once again absorbing it, leading to a measurable drop in pH.6 The collapse of the Permian "carbonate factories" finds a modern echo in the global bleaching of coral reefs and the struggles of shell-building plankton. The warming of the seas is likewise causing the expansion of oxygen minimum zones—"dead zones"—a modern prelude to the widespread anoxia that characterized the Permian seas. The Great Dying serves as a planetary-scale case study in how interconnected systems respond to a massive carbon pulse. It demonstrates that the consequences are not linear but can cascade, triggering feedback loops that push the entire biosphere past a threshold from which recovery is a matter of millions of years.

An Evolutionary Echo

There is a final, startling postscript to this story of ancient poison. The researcher Mark Roth, exploring ways to preserve wounded soldiers, discovered that exposing a mammal to a low concentration of hydrogen sulfide can induce a state of reversible hibernation. The gas appears to trigger a metabolic shutdown, an evolutionary echo from a time when our distant ancestors endured these sulfidic events by waiting them out. An ancient planetary kill switch, repurposed as a life-preserver.

Driving the White Rim today, you travel on the tranquil, sun-baked surface of that final Permian desert. Below you are the rock layers holding the complex Paleozoic world. Above you, in the red cliffs of the Moenkopi, is the evidence of the empty world that followed. The profound silence of the Triassic is palpable in the stone. There are few fossils. It is the physical record of the long, slow dawn that followed The Great Dying, a world reset by its own internal machinery.

Thanks for stopping by and having a read.

All images posted on the buzzshawphoto.blogspot.com 2025 are copyrighted. All rights reserved

There and back again

 I started out at 4:40, at the Canyonlands Identity Sign at 6:40, I drove straight in to the Green River Overlook. The gods were angry at dusk. Snapped away as a storm moved in. Home by before 11. Here are a couple from the cell phone. I'll unload the camera later today.