The Grand Canyon is a deep and gorgeous canyon in Arizona that has been carved by the Colorado River for millions of years, and it's still full of secrets waiting to be revealed. On a trail that winds its way through the red cliffs, a geologist discovered a boulder that had fallen from an ancient rock formation. Upon closer examination, the geologist noticed something surprising. What he found changed what we know about prehistoric life in Arizona.
It All Started At Bright Angel Trail
This whole incredible story begins after a cliff face alongside Bright Angel Trail collapsed. This launched a boulder onto the path below, and although the rock was hiding a remarkable piece of history, it was frequently stepped over by both tourists and hikers that didn't think anything of it.
It was overlooked for so many years, but eventually, someone with the right knowledge finally came upon it and understood its importance.
The Man Behind The Discovery
The man who finally noticed the importance of rocks that collapsed was a biologist named Allan Krill. As he observed the boulder, he realized that there was something exceptional about it. In the stone, Krill found something that pre-dates the dinosaurs.
Just four years later, one of Krill's friends went on to publish a paper that explained what made this piece of rock so extraordinary in the vast span of Grand Canyon history.
A Breakthrough Discovery
Today, Krill's discovery is considered to be one-of-a-kind, and his finding is something that we can learn about our world far before humans ever walked it.
If the rocks hadn't fallen on the Bright Angel Trail, and Krill had never seen it, it's likely that the secret within the stone would have never been discovered. This is especially incredible since the Grand Canyon dates back more than two billion years.
Creation Of The Grand Canyon
In the area that would become the Grand Canyon, compressive forces and increasing temperatures caused metamorphic and igneous rocks to form together. Then, sedimentary layers began to pile up, with each layer leaving behind pieces of the region's history that modern geologists use to track the history of the canyon's creation.
However, it wasn't until the end of the Crustaceous period, around 145 million to 65 million years ago, that the actual ravine began taking shape.
Millions Of Years In The Making
Around 70 million years ago and over the course of the next 40 million years, the activity of the tectonic plates beneath the area around Arizona caused the Colorado Plateau to form. This plateau is elevated 10,000 feet above sea level and incredibly covers more than 130,000 square miles.
This region stretches across the modern-day borders of Arizona, Colorado, Utah, and New Mexico. It's a place deep with a history that has taken millions of years to develop.
A Lack Of Drainage Forged The Canyon
During the time when the Colorado Plateau began to form, the drainage system in the area began to undergo a drastic shift. Melting ice and rainwater became trapped in parts of the Rocky Mountains, which began to seep westwards.
As time went by, this water began to develop into what we know as the Colorado River, one of the most powerful and destructive rivers in the entire world. Only such an immense force could carve the Grand Canyon.
A River At The Bottom Of The Canyon
For the following millions of years, the Colorado River blasted through the plateau, breaking away parts of the canyon and wearing down the rocks. It also began carving a path through the sedimentary, metamorphic, and igneous layers of rock.
The exposed banks then began to suffer from erosion too, creating a canyon that the water would flow through at the bottom of the canyon. Now, there's a river at the base of the canyon.
The River Was Affected By Ice Ages
As time passed, the river continued to cut deep into the rock, causing the canyon to grow even wider. Then, around two million years ago, a series of ice ages occurred, which resulted in the climate becoming wetter, making the river's current stronger, allowing it to cut even deeper into the rock.
So, as the ice ages came and went, it drastically affected the size of the canyon and transformed it into what we know it as today.
The Canyon Grew Over Time
Carved out by the waters of the Colorado River, today, the Grand Canyon is considered to be one of the Seven Natural Wonders of the World.
According to geologists, the canyon reached its current depth around 1.2 million years ago, right around when the floods and spring melts of the last ice age finally ended. The canyon would also be the place where Allan Krill would make his incredible discovery.
People Have Lived In The Area For A Long Time
By looking at the geological evidence in the area, it may be surprising to learn that people have had a presence in the area for a very long time.
Around the same time that the last ice age helped shape the Colorado River into the canyon, humans first began arriving in this region of Arizona. Then, in the mid-16th century, the first Europeans stumbled across this incredible piece of nature.
It's Not Only Tourists Who Visit
Although tourists make up the majority of the park's visitors, they aren't the only people that make the journey to Arizona to see the Grand Canyon. Since 1858, the region has become an extremely popular area for scientists like Allan Krill who are fascinated with the geology of the canyon.
Thanks to these scientists, we have a better understanding of the past, present, and future of the canyon. One such discovery is that the walls contain no fewer than 13 different types of rock.
Famous Rocks
Today, some of these rocks form the most famous areas of the canyon and are the center of many famous locations and the pictures taken throughout the year.
For example, along the northern rim, there is an outcrop known as Isis Temple towers are around 7,000 feet above sea level. Also, there's a part of the canyon known as Granite Gorge, which holds the Colorado River as it flows and cuts its way through the canyon.
Secrets Of The Canyon
Although tourists and scientists have been flooding the canyon for years, the Grand Canyon still holds plenty of secrets.
For example, back in 2014, geologists from the University of New Mexico published a paper that went against the long-held beliefs about the creation of the canyon. According to the study, one theory that was widely believed for a long time actually turned out to be wrong.
The Canyon May Actually Be Younger Than Thought
In the academic journal Nature Geoscience, geologist Karl Karlstrom argued that the canyon known worldwide is far younger than 70 million years old, which is the age most people believe it to be.
Karlstrom wrote, "Different segments of the canyon have different histories and different ages [...], 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." So, it may actually be far younger than originally thought.
His Claim Was Controversial
Karlstrom's findings have been considered controversial by many, with numerous other scientists disagreeing with Karlstrom's beliefs about the age of the canyon. However, evidence for Karlstrom's claim is constantly disappearing.
In an interview with Boston radio station WBUR in 2019, geologist Wane Ranney states, "The Colorado River is constantly tearing away at the walls of the canyon and removing the evidence of its earliest history." So, it's important that they perform their research sooner rather than later.
The Erosion Is Not All Bad
However, this doesn't mean that we're going to be losing important areas of the Grand Canyon anytime soon. It's even a kind of blessing.
As the rocks in the canyon continue to erode, other secrets are being exposed for the first time in millions of years. One of these secrets is what Krill managed to discover. Among these ancient secrets are fossils of very old animals that used to call the Grand Canyon home all those years ago.
Fossilized Footprints
Allan Krill found animal footprints in the rock! In May 2019, the National Park Service announced that a set of fossilized footprints had been discovered in a distant part of the canyon. Supposedly, these prints once belonged to a tetrapod, which was four-footed creatures that lived in the area around 280 million years ago.
In fact, these animals were so ancient that they walked the Earth during a time even before the dinosaurs! So, it was incredible when geologists were able to identify these ancient footprints, thanks to Krill's keen eye for rocks.
Discovering The Creature
After some analysis, it was discovered by paleontologists that the marking was the work of a creature known as an Ichniotherium.
This is a group of tetrapods known as diadectomorphs that had never been seen in a desert environment before. This is what made the discovery so incredible because it shed light on the types of animals that once lived in the area, although they are all gone today.
New Information
In 2019, Dr. Heitor Francischini, a Brazilian paleontologist, explained in a press release that "These new fossil tracks discovered in Grand Canyon National Park provide important information about the paleobiology of the diadectomorphs."
He continued, "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."
Compiling A Database
In 2019, the National Parks Service announced that it would be putting together its largest-ever database of paleontological data ever.
This includes a comprehensive catalog of the fossil history of the Grand Canyon, which will greatly aid in helping both experts and everyday tourists gain a better understanding of the region and the animals that both used to live there and currently do now. This way it's likely there could be more surprise fossil finds in the area.
The Surprises Didn't Stop
Even though experts and amateurs alike have spent the past decades searching the Grand Canyon for fossils, there are still some surprises that are yet to be found, which brings us back to Krill.
In 2016, the Norwegian geologist was taking a group of students along the Bright Angel Trail. Krill assumed that it was going to be another typical hike like he had done before, yet little did he know he would become involved in the prehistoric life in the area.
A Secret In The Rocks
Bright Angel Trail is renown for its beauty, and begins on the ravine's southern rim at the Grand Canyon and has a path that runs for eight miles, which simultaneously drops 4,000 feet to the Colorado River.
While on the trail, hikers pass several well-known rock formations, including Brahma Temple, and Cheops Pyramid. However, it wasn't the magnificent rock formations that caught Krill's attention, but something much smaller and almost unnoticeable inside the wall of rocks.
A Unique Boulder
As he was hiking with his students, Krill spotted a boulder resting on the side of the trail. Yet, this wasn't any typical boulder, as Krill noticed that strange markings were covering it.
Also, Krill was able to deduce where the boulder had come from. It was clear that it had come from an exposed section of the cliff known as the Manakacha Formation. It had obviously fallen to the ground.
A Specific Type Of Rock
The boulder came from a part of a rock layer known as the Supai Group, with the Manakacha Formation being a mudstone and limestone cliff that runs throughout the Grand Canyon.
For millions of years, it has formed the geological mixture that makes up the incredible Colorado Plateau. However, eventually, a portion of the Manakacha Formation has collapsed, resulting in the boulder being on the trail.
Sending Photos To Experts
Interested in the markings that he had found on the boulder, Krill decided to take a few photos and sent them to Rowland, a University of Nevada paleontologist. Just by looking at the image, the American researcher then confirmed what his colleague had suspected.
The patterns were fossilized footprints from millions of years ago. Then, just two years later, Krill's surprise discovery was finally announced at the annual meeting of the Society of Vertebrate Paleontology.
A Lot Happened In The Following Years
It would still be another few years before the truth behind Krill's discovery was finally revealed. On August 19, 2020, Rowland and his fellow colleagues, Mario Caputo and Zachary Jenson went on to publish a paper in the scientific journal PLOS ONE.
In their writing, the three experts discussed the fossilized tracks around the Grand Canyon, including what Krill discovered when hiking on the Bright Angel Trail with his students.
They Could Tell The Age Of The Prints
Incredibly, just by looking at previous studies done on the Manakacha Formation as well as geological maps of the area, the researchers were able to figure out the age of the tracks with astonishing precision.
As it turns out, Krill had made the right decision to stop and take a closer look at the boulder on the side of the trail. His small decision to do this resulted in one of the most notable recent discoveries at the canyon.
They Were Millions Of Years Old
After studying the footprints, Rowland had come to the conclusion that incredibly, there were around 313 million years old! This means that they originated from the Carboniferous Period.
The prints also broke records and are believed to be the oldest fossilized vertebrate footprints ever discovered at the Grand Canyon. So, not only was Krill lucky to find these prints by chance on a rock, but they also turned out to be quite the groundbreaking discovery.
There Were Still Questions
Although the researchers were able to determine approximately how old the footprints were, they weren't positive exactly what kind of animal made them. However, what they were sure of was that they were from a reptile.
In August 2020, Rowland explained in a statement from the National Parks Service that "They are among the oldest tracks on Earth of shelled-egg-laying animals and the earliest evidence of vertebrate animals walking in sand dunes."
Arizona Looked Much Different Back Then
According to the experts' reports, the tracks were formed back when Arizona was nothing more than a plain that was located close to the Equator during a time when the terrain was much different.
Rowan claims that at some point, all those millions of years ago, two prehistoric creatures walked diagonally across the ground, which would eventually become a part of the Manakacha Formation, and leaving their footprints behind, only to be discovered by Krill so many years later.
Some Have Their Doubts
Although some of the experts were convinced, not everyone is sure that two separate creatures were responsible for leaving these ancient tracks behind.
For instance, some argue that the tracks could have been created by the same vertebrate that was crossing the area on two separate occasions. Yet, no matter the case, it's clear that there are two different sets of prints that were made with varying speeds.
A Strange Walking Pattern
Although it's clear that there are two sets of tracks either made by two animals or the same one on different occasions, it also seems that at least one of the creatures moved using what's called a later-sequence walk.
In a 2020 interview with The Arizona Republic, Rowland described the movement of the creature 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."
Many Animals Today Walk In A Lateral Sequence
In his statement, Rowland continued to explain that "Living species of tetrapods - dog and cats, for example - routinely use a lateral-sequence gait when they walk slowly." So, by no means is this style of movement considered to be particularly rare in the animal kingdom, no matter how old the creatures might have been.
Rowland went on, "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."
How The Prints Were Preserved
A question remained: how did the prints manage to last in the rock for all those millions of years and stay in such good condition? The experts assumed this is possible after the track was covered with sand and water.
Then, as the years passed, the impression remained and became part of the rock. For millions of years, these ancient prints remained hidden in the Manakacha Formation until they were discovered and shown to the world.
Nothing Is Certain
Although the experts seem to know as much as they can about the fossilized print, Rowland understands that his findings are far from conclusive. This could lead to some further controversies in the paleontological world.
When speaking to the Associated Press in August 2020, Mark Nebel of the Grand Canyon commented, "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."
The Boulder Is Now A Tourist Attraction
Although several questions remain about the prints, the Bright Angel Trail boulder remains where Krill first discovered it. Now, it's a tourist attraction that regular hikers visit, as well as paleontologists and geologists that travel to see it.
Nebel explained, "A lot of people walk by and never see it [...] Scientists, we have trained eyes. Now that they know somethding's there, it will draw more interest." Today, discussion of the boulder has spread, and it has become a popular attraction at the canyon. Would you go visit?
