After A Cliff Collapsed In The Grand Canyon, Experts Made A Startling Discovery In The Rock

As Allan looked at the boulder, the geologist began to suspect that he had stumbled onto a remarkable find. He was right, too. Etched onto the stone was something amazing: a relic from before the dinosaurs walked the Earth. For someone in Krill’s line of work, he had hit the jackpot.

Now, Krill’s discovery has been acknowledged as a one-of-a-kind ancient specimen. Even better, it shines a light on the distant past. But had the rocks surrounding the Bright Angel Trail not crumbled – and had a geologist not just happened to have been walking by – this secret may well have remained hidden for generations to come.

Mind you, the Grand Canyon has been telling stories long before Krill was even born. Its history dates back nearly two billion years to a time when the world looked very different from how it does today. Slowly, though, the supercontinents shifted, and the landscape of what is now Arizona began to emerge. Krill’s special boulder may have appeared at that time, too.

In the region that would become the Grand Canyon, compressive forces and soaring temperatures caused metamorphic and igneous rocks to form. Later, sedimentary layers were laid down – each capturing a moment in the region’s history that can still be read by modern geologists. It wasn’t until towards the end of the Cretaceous Period that the ravine really began to take shape, however.

From roughly 70 million years ago, the activity of tectonic plates beneath the region caused the Colorado Plateau to form. This high, flat area would ultimately cover some 130,000 square miles. And today, this huge expanse stretches across the borders of Arizona, Colorado, Utah and New Mexico. You may even have walked across the great plain yourself. But as the Colorado Plateau rose, drainage in the region changed drastically.

Melting ice and rainwater trapped in parts of the Rocky Mountains began to leach predominantly westwards. And, over time, the increased volumes of liquid turned the waterway we know today as the Colorado River into a destructive and powerful force.

Then, over the course of millions of years, the Colorado River raged across the plateau, carrying debris that wore away the rock below. It also gradually began to carve a downwards path through the sedimentary, metamorphic and igneous layers. And when the exposed banks eroded, there was a canyon with a fast-flowing current at its base.

As time passed, the mighty Colorado River continued to slice its way through the plateau. Then, from about two million years ago, a series of ice ages occurred. And as the climate became wetter, the river’s current grew even stronger, enabling it to cut a deep groove in the ancient rock. And this groove ultimately became – you guessed it – the Grand Canyon.

Today, the Grand Canyon is considered one of the Seven Natural Wonders of the World. According to geologists, it reached something close to its current depth roughly 1.2 million years ago, when the floods and spring melts of the last ice age finally eased. And, much more recently, the canyon would be the place where Krill made his remarkable find.

But the Grand Canyon is far from a complete phenomenon. You see, the Colorado River continues to erode the plateau even today, gradually wearing away layer after layer of rock. And in the future, this means the natural wonder may be even deeper and wider than it is now – although nobody can say exactly how much it could change.

Given the geological activity in the area, though, it may surprise you to hear that people have long had a presence here. At about the same time that the Colorado River carved the deepest parts of the ravine, humans first arrived in this part of Arizona. Then, more than a million years later, the first Europeans peered over the lip into the crevice below.

Eventually, President Benjamin Harrison designated the canyon a forest reserve – the first step taken towards preserving this unique landmark. In 1919 it was also named an official National Park. Fast-forward to the present day, and the ravine now annually welcomes some six million people – all drawn by the location’s dramatic beauty, jaw-dropping landscapes and challenging hiking trails.

But tourists aren’t the only ones who flock to Arizona to see the Grand Canyon for themselves. Since 1858 the region has been visited on many occasions by scientists keen to observe the fascinating geology of the ravine – with Krill among them. And thanks to these experts, we know a great deal about the canyon. For example, it’s been said that its walls contain no fewer than 13 different types of rock.

Today, some of these rocks form the most famous parts of the Grand Canyon, taking center stage in countless tourist snapshots throughout the year. Along the northern rim, for example, the outcrop known as Isis Temple towers some 7,000 feet above sea level. Then there’s a stretch known as the Granite Gorge, which cradles the Colorado River as it flows through the crevasse.

Despite the almost constant flow of visitors, though, the Grand Canyon still holds plenty of secrets. For instance, in 2014 geologists from the University of New Mexico published a paper that challenged long-held beliefs about the formation of the ravine. And according to the study, one widely accepted theory may have been wrong all along.

In the journal Nature Geoscience, geologist Karl Karlstrom argued that the famous landmark was actually far younger than 70 million years old. “Different segments of the canyon have different histories and different ages,” he wrote, “but they didn’t get linked together to form the Grand Canyon with the Colorado River running through it until five to six million years ago.”

Karlstrom’s findings have proved controversial, and not everyone agrees with this new assessment of the Grand Canyon. But, worryingly, time to get to the bottom of things may be running out. In a 2019 interview with Boston radio station WBUR, geologist Wayne Ranney explained, “The Colorado River is constantly tearing away at the walls of the canyon and removing the evidence of its earliest history.”

Thankfully, it’s not all bad news. As the rocks of the Grand Canyon continue to erode, other secrets are being revealed for the first time in millions of years – secrets like the one that Krill managed to unearth. And among these finds are ancient fossils – relics of the primitive creatures that walked this landscape in the distant past.

Back in May 2019, for example, the National Park Service, or NPS, announced that a set of fossilized footprints had been discovered in a far-flung part of the canyon. Apparently, these had once belonged to a type of tetrapod, or four-footed creature, that lived in the region some 280 million years ago. These beasts were so ancient, too, that they had actually existed before the dinosaurs.

Then, after studying the tracks, paleontologists realized that they were a type of marking known as an Ichniotherium. Typically attributed to a clade of tetrapods dubbed diadectomorphs, they had never been spotted in a desert environment before. And as a consequence, this discovery shed exciting new light on the creatures that once roamed the Grand Canyon.

“These new fossil tracks discovered in Grand Canyon National Park provide important information about the paleobiology of the diadectomorphs,” Dr. Heitor Francischini, a Brazilian paleontologist, explained in a 2019 press release from the NPS. “The diadectomorphs were not expected to live in an arid desert environment because they supposedly did not have the classic adaptations for being completely independent of water.”

That same year, the NPS also announced that it would be compiling its largest database of paleontological data ever. A comprehensive catalog of the fossil history of the Grand Canyon, the resource is intended to help both experts and members of the public develop a better understanding of the region.

But even though academics and amateurs have spent decades combing the Grand Canyon for fossils, there are still some surprises to be had there. And that takes us back to Krill. In 2016 the Norwegian geologist took a group of students hiking along the Bright Angel Trail. When he set off, though, he probably didn’t expect to play a part in changing what we know about prehistoric life in the region.

Bright Angel Trail is pretty impressive by itself, too. Beginning on the ravine’s southern rim at Grand Canyon Village, the path runs for roughly eight miles, dropping over 4,000 feet to the Colorado River. Along the way, the trail also passes several well-known rock formations, such as Brahma Temple and the Cheops Pyramid. It was something far less showy, however, that ultimately captured Krill’s attention.

As he was hiking, Krill spotted a boulder resting alongside the trail. Then, when he took a closer look at the rock, he realized that its surface was marked by a series of strange patterns. And the source of the boulder was evident. Clearly, it had come from an exposed section of cliff known as the Manakacha Formation.

Part of the layer of rock known as the Supai Group, the Manakacha Formation is a mudstone and limestone cliff that runs through the Grand Canyon. And for millions of years, it has formed part of the complex geological cocktail that makes up the Colorado Plateau. Eventually, though, a portion of the Manakacha Formation had crumbled, sending the boulder in question into Krill’s path.

Intrigued by the marking that he had spotted, Krill then snapped a photograph and sent it to Rowland, a University of Nevada paleontologist. Looking at the image, the American researcher subsequently confirmed what his colleague had suspected: the patterns were fossilized footprints from long ago. And two years later, the awe-inspiring find was announced at the annual meeting of the Society of Vertebrate Paleontology.

However, it would take another couple of years before the true details of Krill’s ground-breaking discovery were revealed. On August 19, 2020, Rowland and his colleagues Zachary Jensen and Mario Caputo published a paper in the scientific journal PLOS ONE. And in the work, the trio discussed fossilized trackways from the Grand Canyon – including the Bright Angel Trail find.

By looking at previous studies of the Manakacha Formation as well as geological maps of the region, the researchers had been able to pinpoint the age of the tracks with surprising precision. And as it turned out, Krill had been right to stop and take a closer look at the innocuous boulder that he had found at the side of the trail.

You see, after studying the footprints, Rowland had concluded that they were roughly 313 million years old, dating back to the Carboniferous Period. And this made them record-breakers. Apparently, they’re believed to be the oldest fossilized vertebrate footprints ever found in the Grand Canyon.

Amazingly, though, that’s not all. Although experts are unsure exactly what type of organism made the footprints, they are confident that it was some kind of reptile. And as Rowland explained in an August 2020 statement from the NPS, this makes them really special. “They are among the oldest tracks on Earth of shelled-egg-laying animals and the earliest evidence of vertebrate animals walking in sand dunes,” he said.

According to reports, the tracks were formed back when the land we today know as Arizona was a plain located close to the Equator. Then at some point, Rowland believes, two prehistoric creatures walked diagonally across the ground that would go on to become part of the Manakacha Formation, leaving their footprints behind.

Not everyone assumes that two separate creatures were responsible for leaving the historic tracks behind. There’s been speculation, for instance, that they could have been created by the same vertebrate crossing the area at different times. But whatever the truth, it is clear that the two sets of prints reflect journeys conducted at varying speeds.

It also appears that at least one of the creatures moved using what is known as a lateral-sequence walk. In an August 2020 interview with The Arizona Republic, Rowland described this gait as being “where the left rear foot moves and then the left front, and then the right rear and the right front and so on.”

“Living species of tetrapods – dogs and cats, for example – routinely use a lateral-sequence gait when they walk slowly,” Rowland explained in the statement. “The Bright Angel Trail tracks document the use of this gait very early in the history of vertebrate animals. We previously had no information about that.”

But just how had the footprints managed to stay in such incredible condition for so long? Well, they were most likely preserved by being covered with water and sand. Then, as time passed, the impression remained in the rock. And for millions of years, this remarkable treasure lay hidden within the Manakacha Formation, waiting to reveal its secrets to the world.

That all said, it seems as though Rowland’s findings are far from conclusive. And they may yet stir up controversy within the paleontological world. Speaking to the Associated Press in August 2020, the Grand Canyon’s Mark Nebel explained, “There’s a lot of disagreement in the scientific community about interpreting tracks [and] interpreting the age of rocks – especially interpreting what kind of animal made these tracks.”

But for now at least, the Bright Angel Trail boulder remains an object of fascination for paleontologists and geologists visiting the Grand Canyon. “A lot of people walk by and never see it,” Nebel continued. “Scientists, we have trained eyes. Now that they know something’s there, it will draw more interest.” And Krill’s monumental discovery will likely become yet another draw to one of America’s most celebrated attractions.