The Grand Canyon is a fantastic attraction with so much beauty to see! In this deep canyon, you wouldn’t think that a boulder would be one of the most fascinating discoveries to explore. But one geologist found an incredible discovery in this seemingly common rock.

This story begins at Bright Angel Trail, the primary tourist starting point for exploring the Grand Canyon. This popular trail moves into the Canyon itself, while running parallel to the edge, lowering in elevation some 4,000 feet for eight miles.

The boulder itself was no recent creation. The massive, compacted rock was easily dated by millions of years, well before the Grand Canyon ever reached the depths of its meandering caverns today.

Allan Krill had been a trained geologist for years, studying the intricacies of rocks, soil, water, and the rest of the earth’s formations. However, he couldn’t have guessed that his vacation would lead to an amazing geological discovery.

In the geology world, it’s hard to be the discoverer of something new, much less novel. So much of geology has been documented, surveyed, tracked, studied, and photographed that anything someone thinks they “found” turns out to be already thoroughly examined in one research paper or another.

The boulder itself was not the prize. Instead, what was preserved in the stone of the boulder was amazing and worth the world’s attention. Krill now just had to get others to confirm his suspicion was correct. If he was right, the find easily dated back deep into the era of the dinosaurs at least.

As so often happens, it took a number of coincidences and special circumstances for Krill’s discovery to even be visible by the geologist. The sequence of crumbling, cracking, gravity and falling in just the right exposed way made the difference in making the boulder’s secret see the light of day for Krill to “discover” it.

The above said, the Grand Canyon has long been a repository of secrets. Inaccessible caves can be seen but not explored. Yet, as erosion cuts through the layers like a hot knife through cheese, the natural wonder is stuffed with geological finds.

Back then, the world was amazingly different. Even the continents themselves were in different positions globally. What used to be clearly lush, heavy vegetation-covered land disappeared over time. The Arizona desert and arid conditions replaced the climate in the region to what we know today.

As every sedimentary layer was applied with time, it also became what geologists study intently as their version of history books. Not only the type of minerals and what was buried in them tell stories, but how the sedimentary layer was created and deposited makes a huge difference as well.

Long after all this activity came the Cretaceous Period. It was about this time that many experts agree the Grand Canyon likely started being formed, at least in terms of something becoming the gap in the Earth we know today. At that time it didn’t cover the 130,000 square miles the Canyon encompasses today.

Water came in the form of rainwater and ice that froze during cold periods. The Rocky Mountains became the watershed, generating much of the moisture and its build up. At first, the condensation factors had very little effect. However, with millennia to work with, water and time can do amazing things.

Erosion also has an abrasive effect. As water tears apart rock, it breaks it down, turning rock into boulders and boulders into stones and pebbles, all of which bang against the remaining rock and create multiple points of impact, some with significant force. Damage cascades into more damage and that in turn creates more erosion.

In modern times, the Grand Canyon enjoys National Park and Monument protection. Internationally, it is easily within the Seven Natural Wonders of the World. Even more interesting, the Canyon is not staying the same. While its current form was realized about 1.2 million years in the past, minuscule changes continue to occur that add up over time.

Interestingly, humans and the Canyon have a long history as well. Ancient peoples frequented the Canyon on a regular basis, easily noting its significance in the landscape by then, even though humanity was still a blip in the geological history range.

The Grand Canyon region was first designated a forest reserve in 1919, an early federal government predecessor to what would later become a National Park designation.

Tourists aren’t the only ones visiting though; researchers spend an extensive amount of time in the Canyon on a regular basis. Studies and research have been on a steady diet in the area since before its designation, dating back to 1858.

The Grand Canyon easily gains recognition in photographs and films for some of its more famous locations. Created by an assortment of water movements, wind, arid conditions, and erosion, a number of locations within the National Park have become go-to spots for tourists from around the world.

In 2014, researchers pushed out an academic paper which said that the majority view of how the Colorado River formed the Canyon seemed to be incorrect. Instead, the River’s behavior had moved in a very different way.

Fossils are mineral leftovers from organic life. They can be created either by animals or plants. Under the right circumstances, the organic material gets preserved and replaced by minerals.

That was the case with a 2019 Grand Canyon discovery announced by the National Park Service involving the footprints of a tetrapod, a four-legged creature older than ordinary dinosaurs.

Krill’s discovery proved that no amount of research can compare to time spent out in the field and walking the ground still tends to be the best way to understand the geology of the Grand Canyon. Despite how much research has already been collected, discoveries still pop up.

The out of place boulder was easy enough to spot, making it a natural attractant to an observer on the trail. However, for Krill, there was a lot more going on, and he wanted a closer look at the boulder’s story. His eye caught an aberration in the stone’s surface that didn’t look right and definitely didn’t look geological.

For geologists, the Manakacha Formation is a geology playground. Originally mud and soft Earth in its original form millions of years ago, the mudstone and limestone now tends to be a treasure trove of fossils and captured material preserved in the ancient mud.

What caught Krill’s eye on the boulder’s surface was a marking that looked like a footprint. And, there was more than one. In fact, he discovered a pattern of footprints fossilized in the boulder. Krill took a number of photographs and then sent one of them to a paleontologist for confirmation.

While Krill’s eye had made the original discovery, the depth of the finding took another year or two to be fully understood. Paleontologists who studied the boulder and formation intently detailed their findings in the fall of 2020, again crediting Krill with a major find. As it turned out, the footprints involved were far older than previous conclusions.

Scientists concluded that, while they couldn’t identify the creature, it was definitely reptilian and living in an arid location.

For today’s reader, it’s a bit hard to understand how dinosaurs long depicted being in jungles ended up in the desert arid regions of Arizona. Part of the perspective problem comes from the fact that today we think of the world as it is, not as it was.

It’s likely that instead of eroding flat, the tracks were subsequently covered up by water and more mud, which caked and preserved their form.

A lot of the academic debate continues to rage back and forth whether the reptiles tracked through the area are the same time or were separate tracks. Were there two separate reptiles or only one?

However, all accounts do agree that there are two distinct sets of footprint tracks preserved in the boulder. And the mechanics of the walk pressure, impression, gait, and depth of the print say a lot about the type of creature that caused it.

Yet, despite all the academic research published since Krill’s discovery, the boulder and its secret are still being hotly debated. Much of the disagreement centers around exactly what kind of reptile made the tracks, how they were made, and what one should infer from their shape and presence.

As for the rest of the world, those hiking down the Bright Angel Trail just see a big boulder that stands out as a visible shop to stop and catch one’s breath.

However, for the scientists, the prints might as well have a blazing neon sign posted over them, enticing all to come visit and check it out. The boulder is truly that exciting of a find and geologists love to visit with its history.

It’s incredible that discoveries like this from millions of years ago can still be made today. We’re fortunate that geologists with keen eyes, like Krill spend the time studying to be able to identify these discoveries which help inform us of life before we roamed the earth.