When visiting natural wonders such as the Grand Canyon, the beauty is so great that it is impossible not to be amazed. In short, to enjoy the deep gorge of Arizona you don’t need to be a geologist or someone fascinated by the formation of the Earth, just open your eyes!
However, it is also true that having some information on the process of formation of this immense natural abyss (and perhaps knowing how to recognize some characteristics) can further enrich the visit, allowing you to understand more deeply what you are observing.
For this reason, I have gathered here some information about the origins and history of the Grand Canyon, which I think will be useful not only for those who are about to visit it but also for those who are simply curious. So, how Grand Canyon was formed?
What formed the Grand Canyon?
The history of how the Grand Canyon was formed is as fascinating as it is mysterious, so much so that scholars have not yet agreed on many aspects, especially the depth and width of the gorge, which remain real mysteries and people have tried to explain in many ways.
For this article, I’ve been using one of the most recent and accredited theories, but if you’re looking for an exhaustive overview, take a look here. For the sake of convenience, I have divided the story into two parts.
Step 1: Emergence from the Sea, from Mountains to a Plateau
Originally, where the desert area of Arizona now lies, there were mountains 31,500 ft high, forming a mountain range comparable to today’s Himalayas. Over the next 500 million years, glaciations and thaws formed rifts on the mountainsides and floods (at least 8) covered the entire area several times.
When visiting the Grand Canyon, one of the characteristics that most easily comes to mind is the rock layers of the rock faces, each one distinguished by a different shade of color.
Each layer corresponds to a different flood, which deposited certain types of rock in different periods. On site you will easily notice at least 3 layers: one of sandstone, one of dark schist and another of light limestone, which correspond respectively to previous deposits of sand, mud and calcified remains of marine organisms. The dominant color is red, which derives from the oxidized iron present in all the rocks.
On the rocks, there are also signs of strong volcanic activity, which has contributed significantly to the formation of the canyon. Throughout the Grand Canyon there are about one hundred conical mountains on which you can easily find calcified dark rock flows descending from the sides. These phenomena are about 725,000 years old and can be easily observed from Toroweap Point, for example. The last eruption that caused lava to flow to the bottom of the canyon dates back 100,000 years ago and some geologists believe that there are still active volcanoes that are potentially dangerous.
When the water finally receded from the area, an immense and vast plain was revealed that, due to the collisions of the plates, rose up to become a plateau. At this point, the area was completely exposed, but there was still no trace of the Grand Canyon.
Step 2: Formation and Mysteries of the Canyon
While the beginning of the whole process sinks into a remote past, it seems that the origins of the Grand Canyon are relatively more recent. The famous Arizona deep canyon was born “only” 5.5 million years ago, carved by the Colorado River which, carrying rocks and debris, has deeply affected and modified the formation of the plateau.
This data was deduced by dating some debris from the area with sophisticated instruments and it would imply that the canyon was dug at a rate of 200 meters every million years (3 centimeters every century!). Does it look like it took that long? Actually, for geological standards, it’s a remarkable speed!
That’s when a series of questions were asked that scholars have struggled with:
- How could the Colorado River dig the canyon so fast?
- How can the canyon be so deep and long?
- Why does the Colorado River take this route? And how did you dig it?
Obviously, there are multiple theories, including that of the Spill-Over Theory, developed in 2000 by geologist John Douglass.
According to the scholar, the Colorado River, continuing its course from the Rocky Mountains, had filled a basin known as Bidahoci Lake, transforming it into an immense lake (now drained) from which the river overflowed until it dug into the rock the first crack of what would become the Grand Canyon.
The speed of excavation and the depth of the gorge would be due to the slope of the river bed, witnessed by the numerous rapids, while the width of the gap is due to the numerous landslides caused by the weakening of the less resistant rock layers (shale) in contact with natural elements (once weakened the rocks give way to the force of gravity and landslide).
The most fascinating aspect is that the story is not yet over. The Grand Canyon is in constant transformation. This wonder of nature is able to reveal 2 billion years of the earth’s geological history to all curious visitors.ù
Grand Canyon 4k Video