Canyon Ministries

The Great Unconformity in the Grand Canyon

The Great Unconformity, then, becomes a powerful visual representation of the type of geological event one would expect to see if there had been a worldwide flood as described in the Bible.

One of the places we often explore on our Grand Canyon river trips is a fascinating little side canyon found at river mile 120 called Blacktail Canyon. Blacktail is a very narrow slot canyon, carved predominantly into the golden-brown latticed ledges of the Tapeats Sandstone, a formation known for its striking visual characteristics and its importance in the geological history of the Grand Canyon.

For many of our guests, the time spent in Blacktail Canyon is the highlight of their Grand Canyon river trip experience. The location is a perfect setting for learning about both the natural beauty of the Grand Canyon and its biblical significance. Blacktail holds special importance not just for its stunning geological features, but for its role in Flood geology—an area of interest that holds great meaning for those of us who view the world through a biblical lens.

In Blacktail Canyon, we have the privilege of seeing, touching, and learning about one of the most significant geological features in the Grand Canyon—the Great Unconformity. The Great Unconformity is a major geological feature that is of great interest to those who study the canyon, yet its significance is often interpreted in radically different ways, depending on one’s worldview.

From a conventional geological perspective, the Great Unconformity presents a major mystery. Geologists often see it as a massive gap in the earth’s geological record, an interval of time during which layers of rock were either never deposited or have been lost due to erosion. In Blacktail Canyon, mainstream geologists would say that the Great Unconformity represents approximately 1.2 billion years of earth’s history for which there is no record. This period of time is often viewed as an enigma, a puzzle in the earth’s timeline with no clear explanation.

What makes the Great Unconformity so remarkable is the vast gap in rock layers it represents. In Blacktail Canyon, you can observe a massive erosional plane, a large section of the earth’s crust that has been sheared off. Sitting directly above this plane is the Tapeats Sandstone, the first sedimentary rock layer visible in the Grand Canyon. The Tapeats rests directly on top of the crystalline basement rock below, which forms the foundation of the canyon’s geological structure. The presence of this large erosional gap between these two rock layers has led geologists to question what happened during the supposed missing period of time.

However, when we examine the Great Unconformity from a biblical perspective, we interpret the same geological features, but with a different understanding. Instead of seeing the gap as evidence of slow and gradual processes spanning millions or even billions of years, we believe that the Great Unconformity reflects the massive erosion that would have occurred during the global Flood described in Genesis. This catastrophic event, according to our biblical interpretation, would have caused widespread geological upheaval, leading to rapid erosion and the deposition of massive amounts of sediment in a short amount of time.

The Great Unconformity, then, becomes a powerful visual representation of the type of geological event one would expect to see if there had been a worldwide Flood as described in the Bible. From this perspective, the layers we see in the Grand Canyon—including the Tapeats Sandstone and the rock layers above it—are not the result of millions of years of gradual erosion and deposition, but rather the aftermath of a global catastrophe. What we believe we are seeing in Blacktail Canyon is not the result of slow, uniform geological processes, but the outcome of a massive, worldwide Flood that dramatically reshaped the earth’s surface in a relatively short period of time.

Blacktail Canyon is a deeply significant place for us as believers in God’s Word. The rocks we see here serve as a tangible connection to the Bible’s account of Creation and the Flood. Properly understood, the foundation rock beneath the Great Unconformity boundary line was created by our Creator on Day 3 of Creation Week. Above it, the first layers of sedimentary rock, like the Tapeats Sandstone, were deposited during Noah’s Flood, a time when the earth was reshaped in ways that are still visible today. In Blacktail Canyon, we see creation and destruction side by side.

For many of our guests on the river trips, visiting Blacktail Canyon and witnessing the Great Unconformity firsthand is a powerful experience. As we stand there, placing our hands on the rocks that tell the story of the earth’s history, it’s hard for anyone to keep a dry eye. The connection between the physical evidence in the rocks and the biblical narrative becomes so clear, and the realization that God’s creation and His judgment are intricately intertwined is deeply moving.

As Job said, “Speak to the earth, and let it teach you” (Job 12:8), the earth itself speaks to us, teaching us about the works of the Lord. The rocks of the Grand Canyon cry out, telling the story of the earth’s past. Perhaps no location in the canyon makes this message so loud and clear as deep in Blacktail Canyon. Here, we not only see the evidence of God’s creative power, but we also see a profound testimony to His judgment and His mercy. The Great Unconformity stands as a reminder that the world was once judged by a great flood, but that judgment also made way for new beginnings.

For those who take the time to listen, the rocks in Blacktail Canyon have a story to tell—a story of creation, destruction, and redemption. This is the message that we carry with us as we share the Grand Canyon experience with others. The canyon, with all of its beauty and its mysteries, is not just a natural wonder; it is a testimony to the Creator, whose work is still visible to all who are willing to see.