While driving for a field trip in geology, my college professor once told the class that the most common cause of death for geologists is a car accident. Surely that was a made-up statistic, but he gave the logical reasoning that while driving, geologists always look out the windows and wonder, “What is this ?!”
In just one drive along Interstate 70, locals, visitors and geologists can peek out the window and observe the curious geology of all the mysterious rocks, peaks and canyons that make up the Colorado landscape. . How did the dynamic processes of uplift, faulting and erosion create such different and unique landscapes? In much simpler terms: what is this and how did it form?
Exploring the beautiful mountains behind my own wheel brought me to fully understand my teacher’s claim. Many readers have dreamed of the shotgun seat and drop down convertible to fully enjoy the surroundings, especially the geology.
Between Vail and Frisco, dividing the Gore Range from the Tenmile Range, is the Tenmile Canyon. Due to unique geological processes, the stretch of I-70 through Tenmile Canyon presents a peculiar, yet breathtaking, landscape that is quite unique.
The initial uplift of the Rocky Mountains during the Laramide Orogeny created the base of the Colorado Mountains. From this mountain building event, the Gore and Tenmile formed a continuous chain. Since then, the chains have been broken by faults to form a canyon exposing the core of these mountains and the metamorphosed rock.
A fault is a break between two blocks of earth or rock that can move up, down, or sideways. Evidence of this type of action at Tenmile Canyon is not just in the offset of the canyon, but in the polished and coated rocks called slickensides. Visible along the eastern wall of the canyon, this feature was formed as a result of the rock sliding against the rock. Some scientists believe the canyon fault may be an extension of the mosquito fault, but little geological evidence makes such conclusions difficult.
Through your car window, or sitting by the water’s edge at Officer’s Gulch, looking at the canyon walls, you can see metamorphosed (metasedimentary) and metamorphosed igneous (metaigne) sedimentary rocks, appearing in tight layers or in smaller, packaged grains. These rocks are evidence of layers of sediment and volcanic flows passed through the area that have been subjected to pressure and heat to create the transformed rock in the canyon. Lighter colored pegmatite veins run through parts of the canyon walls, where fractures allowed the rock to flow and solidify.
More recently, in geological terms, Tenmile Canyon has been shaped by glaciers, snow and water. Moraines, the accumulation of rocks due to the movement of glaciers, bear witness to the flow of glaciers in the Tenmile region. According to local geologist Randall Streufert, the eastern end of the Tenmile Glacier is established by the terminal moraine of the north-south ridge of the Frisco Peninsula.
From the great events that shape the landscape to specific features like Tenmile Canyon, to the geological processes that shaped the landscape, even the best of scientists may never know the whole story. That’s not to say that there isn’t much to learn from the breathtaking geology that surrounds it. Hopefully the next time you drive, or better yet, drive as a passenger, you take a closer look at the rocks around you and come a little closer to the answer, “What the hell is that?” is that! “
Carly Innis, a naturalist at the Walking Mountains Science Center, is intrigued by the processes of the earth and how everything, including geology, is interconnected.