The Morrison Formation

 

The Morrison Formation

To see it is to be centered in a section of time. The road cuts through the high desert of the Colorado Plateau, a landscape of heroic scale and subtle color, and there it is: a particular set of bands, a sequence of muted purples and battleship greys, decorating the hills. It’s a marker bed. Geologists know it as the Brushy Basin Member, the most widespread and recognizable face of the Morrison Formation. But for anyone with a passing interest in the deep past, it is something more. It is a signal, a signpost in stone. When you see it, you know, with a certainty that resonates deeper than academic knowledge: here were dinosaurs.

Rabbit Valley, Colorado  Red, Purple, Gray Mudstones and Bentonite Paleosols (ancient soils) of the Brushy Basin Member of the Morrison Formation

The story of the Morrison is written in mud, but it begins with fire. Picture the world 150 million years ago, in the waning days of the Jurassic Period. The map of North America is a half-formed thought. The Atlantic is a nascent rift, widening slowly, pushing the continent westward. From the north, a shallow, speculative finger of the ocean, the Sundance Sea, probes down into what will one day be Wyoming and the Dakotas. And to the west, along the continental edge, a chain of volcanoes, immense and active, stands as the consequence of a tectonic collision, a subduction zone where one plate dives beneath another. These volcanoes are the engines of the Morrison.

For millions of years, they pump ash into the sky—a fine, glassy dust that drifts eastward on the prevailing winds and settles like a blanket over a vast, low-lying basin. This basin is not a desert but a sprawling alluvial plain, a depositional apron sloping gently toward the distant Sundance Sea. It is a landscape defined by water. Great river systems, ancestors to none we would recognize, meander across the plain, carrying sediment from highlands that are now long gone. They are the circulatory system of this world, and their primary cargo is that volcanic ash.

The ash itself is geologically unstable, a temporary substance. Over the immense span of time, as it is buried, soaked, and compressed, its glassy silica structure breaks down. It alters. It devises a new identity, transforming into a peculiar type of clay mineral called bentonite. This is the material that forms the "candy-striped hills" near Hanksville, Utah, the pastel badlands that look so much like a "Mars almost like landscape." Bentonite clay has a singular, dramatic property: it shrinks and swells with phenomenal force. When wet, it becomes a slick, impassable gumbo; when dry, it cracks into a popcorn-textured crust. This constant turmoil in the soil makes it profoundly difficult for plants to gain a foothold, which is why, to this day, the exposures of the Brushy Basin can be so "completely devoid of vegetation." The chemistry of a long-extinct volcano dictates the botany of the present.

The rivers, though, were not merely passive conduits for ash. They were dynamic, energetic systems, and they left their own signatures in the rock. A river is a sorting machine. In its main channel, where the current is strongest, it moves sand and gravel. During flood stages—"higher pulses of energy," as a geologist might say—it can roll pebbles the size of a fist. In calmer times, it lays down fine sand. As the river snakes across its floodplain, it abandons old channels and carves new ones, leaving behind lenses of sandstone and conglomerate embedded within the finer muds of the floodplain.

Morrison Formation, Rabbit Valley  Remnant River Channel Sands of the Saltwash Member

These sandstone bodies are the architectural bones of the Morrison today. Being harder and more resistant to erosion than the surrounding bentonitic clays, they form cliffs, ledges, and caprocks. You see a feature that locals call a "toadstool," a whimsical balanced rock, and you are looking at a cross-section of an ancient river. A durable cap of sandstone, the fossilized riverbed, protects the soft pedestal of clay beneath it from being washed away. Look closely at the side of that sandstone. You might see fine, angled lines cutting across the main horizontal layers. This is cross-bedding, the preserved structure of ripples and sandbars that migrated along the river bottom 150 million years ago. The rock remembers the direction of the current.

It is within these river channel deposits—the sandstones and conglomerates—that the Morrison yields its most famous cargo. The formation is, by a wide margin, "the most fertile source of dinosaur fossils anywhere in North America." The bones are not found in the altered volcanic ash of the floodplains. An animal that died on the plain would have its bones scattered, weathered, and ultimately dissolved. But an animal that died in or near a river channel stood a chance of being quickly buried by sediment, its bones protected from the elements, beginning the long process of fossilization. A river in the Jurassic was both a giver of life and a potential tomb.

And what a life it was. The roster of the Morrison fauna is a litany of superlatives. This was a world of giants, an ecosystem seemingly designed to test the limits of what vertebrate life could achieve. The dominant herbivores were the sauropods, the long-necked titans that have defined dinosaurs in the popular imagination. There was Camarasaurus, the most common of them, a 75-foot-long, 50-ton behemoth built like a fortress. There was Diplodocus, whippet-thin by comparison, stretching nearly 80 feet but weighing a mere 15 tons, much of its length taken up by an incredible whip-like tail. And then there was Brachiosaurus, the giraffe of the Jurassic, its front legs longer than its back, holding its head high above the floodplain, standing nearly 70 feet tall and weighing upwards of 64 tons. These creatures, all of them, would go extinct at the end of the Jurassic, a "total wipe out" that cleared the stage for new forms to evolve.

Preying on them, or perhaps just scavenging their immense carcasses, were the large theropods. The king was Allosaurus, the most abundant large predator in the ecosystem, a 39-foot-long carnivore with a massive skull and serrated, blade-like teeth. It was the apex predator, the top of the food chain. But it had competition. There was Ceratosaurus, a medium-sized predator with a distinctive horn on its snout, and the truly formidable Torvosaurus, a massive, 33-foot theropod that may have specialized in hunting near waterways. Alongside the giants lived a menagerie of other creatures. Armored dinosaurs like Stegosaurus and the early ankylosaur Mymoorapelta browsed on lower vegetation. Bipedal plant-eaters like Camptosaurus and the small, nimble Dryosaurus filled out the middle tier of the herbivore community.

For a long time, the life of these animals was understood only through their skeletons. But in recent decades, paleontologists have begun to decipher the more subtle traces they left behind, reading the finer print in the Morrison’s pages. The story of dinosaur eggs is a case in point. For years, the utter lack of sauropod eggs from the Jurassic led to wild speculation. Perhaps, some suggested, these animals were viviparous, giving live birth to their enormous young. The discovery of soccer-ball-sized titanosaur eggs in Cretaceous rocks proved that at least some later sauropods laid eggs, but the Jurassic mystery remained. The working hypothesis now is that shelled eggs evolved independently in different dinosaur lineages, and that perhaps the Morrison sauropods laid soft-shelled eggs that were far less likely to fossilize.

Another view from the Rabbit Valley. It may not look too appealing, but here there be dinosaurs and other treasures.

The Morrison has, however, given up the oldest known dinosaur eggshell in North America. It is not from a sauropod, but from an ornithopod, likely belonging to the family of Dryosaurus. At sites like the Young Egg Site in the Salt Wash Member and the Sheets Nesting Site, discovered by a 12-year-old boy, paleontologists have found troves of eggshell fragments and the bones of baby dinosaurs. The evidence from these nests paints an intimate picture of dinosaur family life. Unlike the colonial nesting grounds of later hadrosaurs, these Jurassic dinosaurs appear to have been "solitary nesters," returning to the same favored locations year after year.

More intriguing still, the nests contain bones from two distinct size classes: tiny hatchlings and much larger "yearlings." This suggests the young were precocial—able to walk and follow the adults almost immediately after hatching, like ducklings. The theory is that the hatchlings would mimic the adults to learn what to eat, rather than being fed in the nest. The yearlings found dead at the site may have been the ones who failed to follow, waiting in vain to be led to food. The nests also contain the remains of another creature: a small terrestrial crocodile, nicknamed the "bunny croc," perhaps a nest thief, adding a layer of ecological drama to the scene.

Reading these stories requires an understanding of the grammar of the rock itself. At a certain level in the Brushy Basin Member, there is a "dramatic change." Below this line, the clays are of one type; above it, they are the puffy, swelling bentonites derived directly from volcanic ash. Geologists call this line the J-7 Unconformity. An unconformity is a break in the record, a missing piece of time. This particular line represents a major shift in the volcanic activity that defined the region, a moment when the character of the ashfall changed fundamentally. The book of the Morrison has missing pages, moments of the story that were never written down or were erased before they could be preserved.

For a visitor today, driving north of Highway 24 near Hanksville, with the solemn peaks of the Henry Mountains in the distance, this deep history is written across the land. The "candy-striped hills" are the legacy of ancient volcanoes. The "toadstool" hoodoos are the ghosts of ancient rivers. The dark patina on a rock, a desert varnish that a geologist might chip away to see the stone’s true color, is a thin veneer of the present drawn over an immense past. To stand in this landscape, to see the purplish band of the Brushy Basin, is to feel the presence of that past. It is to understand that the ground beneath your feet is not merely ground, but the compressed and altered remnant of a world stranger than any you could imagine, a world of giants that walked here when the rock was just mud.

In a future post, I'll provide a walkabout of the Colorado Walk Through Time in Rabbit Valley. There is a trail through the Morrison Fm. where you can see dinosaur bones in situ. It's a great walk to get a good feel for what is around you in dinosaur country.

Thanks for stopping by and having a read.

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

 To call oneself a GeoPhotographer is to coin a term, but it feels apt. Before any field trip, my preparation involves not just maps and lenses, but a review of geologic columns and descriptions of the paleoenvironments I will be traveling through. Living in the arid American West makes this a uniquely visceral experience. Here, the geology is not hidden beneath a blanket of soil and green; it is right in front of you, a brazen, sun-bleached pronouncement. You don’t have to dig for the story; you simply travel through it. You read the rock like the book of time.

With a little knowledge, you can become a deep-time traveler. The greatest events in Earth's history are written here, and none are more dramatic than the mass extinctions. We are still learning about the whys and wherefores, the full causality of these global catastrophes, but the evidence of how they happened is clear, etched into the canyon walls and badlands. The story of how the Earth recovers, and the changes in life that follow, is an incredible one that remains unknown to too many. I have summarized these events for my own reference. I have taken some of the information I keep in notebooks and have attempted to make it readable and offer it to you. I hope it enlightens and informs. Please take this as a jumping-off point to explore further. It is a profound story, and it is the story of us and all the creatures we share our world with.

Mass Extinctions

Of all the books in the world, the thickest and most violent is the one whose pages are made of rock. To read it is to walk through the canyons and badlands of the American West. The cover, so to speak, is the soil under your boots, the present day. But as you descend, as you drop through the strata, you are turning back the pages into a time so deep it defies human comprehension. Each layer of sandstone, shale, or limestone is a chapter, telling of ancient seas, sprawling forests, and bygone creatures. But sometimes, between two thick chapters, you find a single, thin, almost imperceptible line. This is not a pause in the narrative. It is a tombstone. It is the epilogue for a world that was, a world that ended so abruptly the planet scarcely had time to record its passing. These are the scars of mass extinctions, and the American West is a library of them.

The First Poison: A World Rusted Shut

Before the dinosaurs, before the fish, before even the first wriggling trilobite, life had a catastrophic falling out with itself. It was an act of planetary self-poisoning, and its evidence is written in stone across the continent. Two and a half billion years ago, Earth was a "Pale Orange Dot," a world swaddled in a methane haze, its oceans a murky green with dissolved iron. In these shallow seas, a revolutionary microbe, cyanobacteria, began to harness the sun. Its great innovation was oxygenic photosynthesis, a brilliant new way to make a living. Its great flaw was the waste product: oxygen, a gas so corrosive it was toxic to nearly every other living thing on the planet.

For millions of years, the planet's chemistry buffered the assault. The oceans, rich in dissolved iron hydroxide, effectively rusted. As the cyanobacteria pumped out oxygen, it bonded with the iron, which then precipitated out and settled on the seafloor in crimson layers. This rhythmic cycle—oxygen buildup, iron precipitation, microbial die-off, recovery—created one of the planet’s most striking geological features: banded iron formations. A 19th-century surveyor named William Burt, working in Michigan, first noticed his compass needle going haywire, leading him to these immense deposits of iron ore, the very signature of this ancient atmospheric revolution. You can find their equivalents in the ancient rocks of Wyoming, remnants of a time when the world’s oceans were bleeding rust.

Around 2.4 billion years ago, the oceans simply ran out of iron to absorb the poison. The oxygen flooded the seas and, for the first time, the atmosphere. It reacted with the potent greenhouse gas methane, stripping the sky of its warming blanket. The planet, having rusted, now froze. The Huronian Glaciation was an ice age of unimaginable scope, a "Snowball Earth" that lasted 300 million years. The chemical revolution and the climate crisis it triggered caused the Great Oxygen Extinction, the single largest disappearance of life in Earth’s history. An estimated 99% of all species, overwhelmingly microbial, were wiped out by the very air they breathed. Life survived, huddled in oxygen-poor refuges or by evolving a tolerance for this new, volatile world. But the planet was forever changed, its atmosphere now charged with the gas that would, paradoxically, fuel the rise of all complex life to come.

The Paleozoic Culls: When Plants and Pangaea Wreaked Havoc

The next few chapters of Earth’s stone-bound book tell of a flourishing. The oceans teemed with life—trilobites, sea scorpions, and strange, armored fish. Then, around 445 million years ago, another thin line appears in the rock. This was the Late Ordovician mass extinction, and once again, a biological innovation was the culprit.

The first tiny, moss-like plants had begun to colonize the barren, rocky continents. Clinging to the rock, they accelerated the process of weathering, breaking down minerals and releasing them into the rivers and seas. A key nutrient, phosphorus, poured into the oceans, triggering colossal algal blooms. When these blooms died and sank, their decomposition sucked the oxygen from the water, creating vast dead zones. The supercontinent Gondwana drifting over the South Pole didn't help, triggering a massive glaciation and a sharp drop in sea level. The one-two punch of glaciation and anoxia was devastating. In two distinct pulses, up to 85% of marine species vanished. In the exposed Ordovician limestones of Nevada and California’s Death Valley National Park, you can stand on the seafloor of this ancient world and touch the graves of countless trilobites, victims of life's first tentative steps onto land.

The planet recovered, and life grew even more ambitious. The Devonian period saw dense forests of primitive vascular plants spread across the land, populated by giant tree-like fungi called Prototaxites and early four-legged vertebrates like Ichthyostega. The oceans were ruled by monsters like the 10-meter-long armored fish, Dunkleosteus. But this greening of the planet had consequences. The explosion of plant life drew down enormous amounts of carbon dioxide from the atmosphere, causing global temperatures to plummet once more. This, combined with more ocean anoxia—perhaps from the same nutrient run-off problem as before—triggered the Late Devonian mass extinction around 375 million years ago. It was a prolonged agony, a series of extinction pulses spanning millions of years that ultimately wiped out 75% of all species. The great coral reefs were massacred, taking 100 million years to recover. The mighty Dunkleosteus was gone forever. Land life was largely spared, but the oceans were once again a graveyard.

The final act of the Paleozoic Era was the assembly of the supercontinent Pangaea. This colossal landmass, stretching from pole to pole, brought with it the most severe extinction event the world has ever known. The Permian-Triassic extinction, or "The Great Dying," was an apocalypse. The prime suspect is the Siberian Traps, a volcanic event that beggars belief. For roughly a million years, fissures in modern-day Siberia bled lava, covering an area larger than Western Europe and releasing staggering quantities of carbon dioxide and other toxic gases.

The world cooked. Oceans acidified. Methane, a greenhouse gas far more potent than CO2, may have belched from the warming seafloor, pushing the climate past a point of no return. Around 252 million years ago, the curtain fell. In what may have been as little as 50,000 years, an estimated 96% of marine species and 70% of terrestrial vertebrates vanished. The trilobites, survivors of two previous mass extinctions, were finally erased after a 270-million-year run. The sail-backed Dimetrodon and the giant dragonflies were gone. It is the only time in history that insects have suffered a mass extinction.

To witness this boundary, one can travel to the Grand Canyon. The Permian Kaibab Limestone, teeming with the fossils of marine invertebrates, forms the canyon’s rim. Below it lie older layers, but above it, after a gap in time, lie the red Triassic rocks of a new, emptier world. That boundary represents the greatest reset button in the history of complex life. In the silence that followed, a few hardy survivors, the archosaurs, began to radiate, setting the stage for the next great dynasty.

The Dinosaur Disruption: Rain, Rupture, and Reign

The world the dinosaurs inherited was a strange one. For those who visit Petrified Forest National Park in Arizona, you are walking through the Late Triassic, a world defined by a bizarre and transformative extinction event: the Carnian Pluvial Episode (CPE). Around 230 million years ago, massive volcanic eruptions from the Rangelia province—a slab of crust that now makes up parts of Alaska and Canada—pumped the atmosphere full of CO2.

The result was a supercharged water cycle that triggered a rain that lasted for over one million years. This "Million-Year Rain" transformed the arid interior of Pangaea. While it was an extinction event for many species stressed by the acid rain and acidified oceans, it was a "reinvention period" for others. It wiped out many of the archosaurs' competitors, and in the new, wetter world, the dinosaurs thrived. In the park’s Chinle Formation, the fossil record shows this takeover in stark relief. Dinosaur footprints, once non-existent, suddenly account for over 90% of all fossilized imprints. The CPE cleared the stage, and dinosaurs like Herrerasaurus took the lead.

But one final hurdle remained. At the Triassic-Jurassic boundary, 201 million years ago, another wave of volcanism tore the world apart. As Pangaea began to split, the Central Atlantic Magmatic Province (CAMP) erupted, an event even larger than the Siberian Traps. More CO2, more ocean acidification, more death. The Triassic-Jurassic extinction wiped out 75% of species, including the last of the giant amphibians and the remaining reptilian rivals to the dinosaurs.

Now, the world truly belonged to them. Visiting Dinosaur National Monument on the Utah-Colorado border is like stepping into their kingdom. Here, the Morrison Formation preserves a world from 150 million years ago. This was the Jurassic at its peak: a hot, high-CO2 world where towering sauropods like Supersaurus grazed on ferns and conifers, stalked by the formidable carnivore Allosaurus. In the skies, pterosaurs soared, and in the undergrowth, small, furry mammals like the multituberculate Tabis scurried, their time yet to come. The dinosaurs had passed through the crucible of two extinctions and emerged as the undisputed rulers of the planet. Their reign seemed eternal.

The Day the Sky Fell

The end, when it came, was not a slow burn from within, but a sudden, violent blow from the heavens. Sixty-six million years ago, a 10-kilometer-wide asteroid struck the Yucatán Peninsula with the force of billions of nuclear weapons. This was the Cretaceous-Paleogene (K-Pg) extinction.

The story of its discovery is centered on a thin layer of clay. In the 1980s, the father-son team of Luis and Walter Alvarez were studying rock layers in Italy when they found a strange anomaly at the boundary between the Cretaceous and the subsequent Paleogene period: a concentration of the element iridium hundreds of times higher than normal. Iridium is rare on Earth's surface but common in asteroids. They had found the murder weapon.

That same iridium-rich layer can be found all over the world, a geological breadcrumb trail leading back to the Chicxulub Crater. In the American West, it is starkly visible in the Hell Creek Formation of Montana and the Dakotas. Below the line, the rock is filled with the fossils of the last great dinosaurs. Above the line, they are simply gone.

The immediate effects of the impact were apocalyptic. A blast of thermal radiation incinerated everything for a thousand kilometers. A fire rain of superheated debris burned 70% of the world’s forests. For at least 15 years, a thick shroud of dust and soot blocked the sun, creating an "impact winter" that collapsed food chains. Sulfuric acid rained from the sky, acidifying the oceans. The ongoing eruptions of the Deccan Traps in India may have already been stressing global ecosystems, and the impact pushed them over the edge.

Seventy-five percent of all species were annihilated. All dinosaurs, save for their avian descendants (the birds), were gone. Being large was a death sentence. The survivors were the small, the adaptable, and the lucky. Mammals, no bigger than rats, survived in burrows. Crocodiles and turtles survived due to their versatile diets and slow metabolisms.

In the eerie quiet of the Paleocene epoch, the mammals emerged. In a world with few predators, they exploded in size, their bodies growing much faster than their brains. Thinking, it seemed, was "overrated" in a post-apocalyptic world. But as ecosystems recovered and competition returned, intelligence again became an advantage. Brains grew, diversified, and set the stage for the Cenozoic Era—the Age of Mammals.

The Sixth Act

To walk the canyons of the West is to be humbled by the sheer scale of geologic time and the brutal fragility of life. From the rusted rocks of Wyoming to the dinosaur boneyards of Utah and the iridium scar in Montana, the land tells a story of five great interruptions in the history of life. Each time, the world was irrevocably changed.

Today, scientists warn that we are living through the Sixth Mass Extinction. This time, the agent of change is not a volcano or an asteroid, but a single species. Extinction rates are a thousand times higher than the background average, driven by deforestation, climate change, and pollution. We are the first species to knowingly preside over a mass extinction. The stone pages of the future are being written now. The question that hangs in the quiet air of the badlands is what story they will tell. Will it be another thin, dark line in the rock, or will it be the chapter where the one species aware of the pattern chose to write a different ending?

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

Resources One

 A journey into photography often begins with a simple, mechanical act. For me, it was the click of a shutter on a camera loaded with Plus-X Pan, a film as common and unassuming as the drugstore where I bought it. In those early days, the darkroom was a distant dream, a place of arcane chemistry and specialized equipment that my teenage budget couldn't fathom. So I learned by reading, by studying the work of others, and by the slow, iterative process of comparing my own prints to the masters I found in library books.

My own personal shortcut, my "Hudson River School," came into focus during a high school era trip to the National Gallery of Art. There, in the grand landscapes of painters like Albert Bierstadt, I found a language of light and composition that spoke to me more directly than any textbook. They were painters, yes, but they were also masters of capturing a sense of place, of time, of the almost spiritual quality of light on the land. I never learned to paint, but in their work, I found a way to see. To this day, before I go on a shoot, I spend time with Bierstadt's canvases, not just for inspiration, but to embed his vision of light into my own mind's eye. It is, as it has always been, all about the light.

Title: Western Landscape Painted by: Albert Bierstadt

The modern age, of course, has its own set of shortcuts, its own digital libraries and virtual galleries. For the aspiring photographer, YouTube has become a landscape in itself, a place of endless exploration and tutelage. I am still a student, and these are some of my teachers:

• Gavin Hardcastle () is a photographer who seems to thrive on the atmospheric and the unpredictable. In one video, he takes us on a journey to the Isle of Skye, a place of moody light and dramatic scenery. He shows us the ruins of a 15th-century castle and then, with a modern flourish, sends a drone soaring for an aerial panorama. But the digital age has its own perils, and in a moment of technological tragedy, the drone, with all its footage, is lost to the sea. It’s a lesson in both the potential and the fragility of modern photography, but Hardcastle, undeterred, continues his quest for the perfect shot, a testament to the perseverance that the craft demands.

• Simon d’Entremont is a technician of the modern age, a photographer who shows us how to bend the digital medium to our will. In his video on “frame grabbing,” he demystifies the process of pulling still images from video footage. He explains the technical nuances of resolution and shutter speed, comparing the results from a simple screenshot to the more sophisticated output of professional editing software. It’s a deep dive into the pixels and the process, a look under the hood of the digital image that would have been unimaginable to the photographers of the film era.

• Henry Turner takes us to the coast, to a place where the light and the tides are in a constant state of flux. He is a photographer who understands the importance of adaptability, of being willing to abandon a preconceived plan when the elements present a different opportunity. He shows us how to use a circular polarizer to cut through the reflections on the water, how to balance the exposure in a wide-angle shot, and how to find a compelling composition in a landscape that is constantly changing. His video is a reminder that photography is not just about capturing a scene, but about responding to it.

• Thomas Heaton is a photographer who finds beauty in the storm. He takes us to a remote English beach in the wake of a tempest, a place of dramatic skies and ethereal light. He embraces the rain and the wind, using the challenging weather to create images that are both powerful and serene. In his video, he demonstrates the art of finding composition in the vast emptiness of a windswept beach, and then, as if on cue, a glorious sunset rainbow appears, a reward for his patience and his willingness to endure the elements.

So have a look. The tools have changed, from darkrooms to desktops, from film to files, but the essence of the craft remains the same. It is not about the equipment; a cell phone is an excellent starting place. It is about the light, the composition, and the eye of the photographer.

Thanks for stopping by and having a read.

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

From the Bluff

 McInnis Off the Bluff

From the overlook on Bluff, the problem presents itself. Down below, McInnis Canyons opens up, a landscape written in a language of rock, and the dominant sentence is spelled W-i-n-g-a-t-e. I’ve been making studies from here, editing the test panoramas, trying to get a feel for the story I want to tell. The rock, of course, is patient. The photographer is less so.

The composition is beginning to resolve in my mind. The main piece must be an expansive, almost impossibly wide panorama, an attempt to translate the sheer horizontal scale of the Wingate Sandstone into a single frame. This is the establishing shot, the piece that says, This is the world we are in, a world of Triassic desert sands turned to stone.

But the grand statement is made of smaller clauses. To complement the wide view, I’ll need a series of tighter shots, vignettes that draw the eye to the specific features that give the canyon its character: a sheer pour-off stained black with desert varnish, the architecture of a particular side canyon, the way the late sun catches an arête.

For now, though, the project is on pause. The air is thick with heat, and the afternoons have been building into the sort of strong, violent thunderstorms that rearrange the landscape in a hurry. A cool front is supposedly on its way, due in a couple of days. If it comes, and if the trail has had a chance to dry out, I’ll make another attempt. The Wingate has waited two hundred million years; I suppose I can wait another forty-eight hours.

Running back to the hard road, escaping from the storm.

Thanks for stopping by and having a read.

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

On the Mesa

the Why of it

To travel west from the Rockies is to watch the landscape stand up and announce its history. The story is not written in words but in stone, in the abrupt rise of a plateau or the stubborn line of a cliff face. Out here, you learn to read the land, or you find someone who can read it for you. These posts are my attempt to do that do that reading.

To the Grand Mesa

From the valley floor, the Grand Mesa is a constant presence, a great wall defining the eastern edge of the world. For weeks, it has sat there in the uniform dark green of late summer. But the angle of the light has changed, and the nights have grown teeth. The question of the aspens arises, as it does every year. So we went up to see.

The Forest Service Visitors Center, Grand Mesa National Forest one section of
Grand Mesa, Uncompahgre and Gunnison (GMUG) National Forests in western Colorado.

The drive itself is a journey through the geologic column, a climb from the baked Mancos Shale of the lowlands, past the cliff-forming Mesaverde sandstones, and onto the flat, dark basalt cap that gives the mesa its form. You leave one world and arrive in another. Up here, ten thousand feet above the sea, the air carries a different message.

We found the answer not in a shout but in a whisper. The change has just begun. It is not yet the unambiguous, incandescent gold of calendars and postcards, but something more subtle—the first hint of a chemical decision. On the edges of the great meadows, entire groves—clonal colonies that are, in essence, a single organism spread over acres—were showing a faint, uniform blush of pale yellow. The chlorophyll is in retreat, unmasking the carotenoids that were there all along. It is the color of transition, a slow-motion fire just now finding its fuel.

Against this incipient blaze, the white trunks of the Populus tremuloides stand out, a forest of chalky skeletons waiting for winter. They are the promise written into the landscape—the stark, beautiful structure that will endure the coming snows and guarantee the return of all this fleeting, spectacular color. We had caught the very beginning of the annual display, the first communiqué from a season preparing to let go. The fire had been lit yesterday.

Regarding the Grand Mesa

You see it from the floor of the Grand Valley, a presence on the horizon east of Grand Junction. It doesn’t aspire to a peak, doesn’t tear at the sky with jagged spires. Instead, it rises some six thousand feet to an impossible flatness, a tableland vast enough to have its own weather, its own ecosystem, its own ZIP code. This is the Grand Mesa, a five-hundred-square-mile anomaly that is, by sheer acreage, the largest flat-topped mountain in the world. It looks like a piece of the Great Plains that a god picked up and set on a pedestal.

The question it asks is one of inversion. How does a tabletop get to be ten thousand feet in the air? The answer lies in its hat. Ten million years ago, this was not a mountain but a valley, a drainage for an ancient river system. Then, from fissures near a place we now call Crag Crest, the earth bled. Lava, dark and fluid, ran down the valley, filling it, paving it with what would become a hard, dense, three-hundred-foot-thick layer of basalt. The lava cooled, and the land fell quiet.

For the next ten million years, the agents of erosion—water, wind, and ice—went to work. The rivers that flanked the basalt-filled valley, the ancestral Colorado and Gunnison, began to chew through the surrounding country. They were relentless, carving into the soft Cretaceous Mancos Shale, a rock so friable you can practically break it apart in your hands. The shale melted away, the cliffs of the Mesaverde Group retreated, but the basalt cap, the lava-forged shield, held its ground. The land that was once lowest, the valley floor, refused to yield. Everything around it did. The rivers, in their steady work of taking the land down, had inadvertently created a mountain. Geologists have a name for this trick of topography: topographic inversion. The valley became the peak.

Today, that ancient valley floor is a subalpine world afloat in the sky. Its basalt bowl holds the meltwater of heavy winter snows, creating a lacework of more than three hundred lakes. It is an island of cool, damp air and spruce-fir forest looking down on the arid sagebrush plains, a world made, unmade, and remade by fire and water.

Thanks for stopping by and having a read,

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