Under the Rockpile: A deeper look at the Colorado Rockies (column)
June 6, 2016
Editor's note: This is the first in a series of columns on the unique geology of Colorado.
The moment I first saw the Rocky Mountains of Colorado as a freshman at the University of Colorado, I was hooked. Not only had the allure of skiing and hiking had its effect, but I was truly fascinated by the mountains. I suppose it was the combination of outdoor activities and my early interest in rocks that led me to eventually become a geologist.
I remember my father taking me to Cranbrook Museum in Michigan when I was about 5 years old. There, at the entrance to the museum, was a giant quartz crystal that was larger than myself … I was in awe! How could this exist? I then asked my father if this was man-made or natural. His answer awakened my curiosity.
In college, I soon found myself immersed in the fields of mineralogy, volcanology and mineral exploration. Field trips to the San Juan Mountains, Aspen and Crested Butte enhanced my appreciation for the beauty of the Colorado Rockies. My spare time was taken up with trips to Mount Antero to collect aquamarine, to Del Norte in search of geodes and to various mineral localities in search for galena, pyrite, rhodochrosite and other minerals and fossils that Colorado is known for. In the process of searching for these "hidden treasures," it wasn't long before I focused on the origin of minerals and the geologic history of our Colorado Rockies.
Now, when I look at our mountains, I see the rocks as silent sentinels of time; and, when I hike along the trails, I not only walk through space, I imagine myself walking through time..
Over the next several months, I will be presenting a series of articles that offer a glimpse of the minerals and the geology in this region of the Colorado Rockies.
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But first, a word about time.
For most of us, geologic time is very difficult to grasp. The sheer magnitude of geologic time, often referred to as deep time, is a challenge to anyone's imagination. Just consider the following information: The age of the universe is thought to be about 13.8 billion (BY) years old, but the age of Earth is only about one third of that, at about 4.5 BY, the oldest rocks in Summit County are about 1.8 BY and the age of the present day Colorado Rockies are less than 80 million years (MY). So the Rockies are significantly younger than the oldest rocks in Summit County.
80 MY falls within the Cretaceous Period, which is about when dinosaurs were last roaming the Colorado landscape, and this coincides with the time that the Colorado Rockies began to emerge from the Cretaceous Seaway. Note that the first use of tools by homo sapiens would take us back only 2-3 million years (the Pliocene), and the arrival of man in North America would only be about 13,000-20,000 years ago.
Although the time scale gives us some feel for the relative ages of events, it is difficult to conceptualize the actual passage of time on a deep time scale. To help with this concept, let's take a video approach:
Keep in mind that most movie films and videos are shown at a standard rate of about 24 frames/second. Imagine you had a time machine, so that you could go back in time and take one picture from one of the mountain peaks here in Summit or Eagle counties, and that you returned every 1,000 years to take one additional picture for each visit until you reached to the present. If you now played back these pictures at the standard video rate, you would film about 1 second of footage for every 24,000 yrs. Given this rate, a film showing just the last 80 million years to the present, would give us almost one hour of footage (56 minutes). The rise of the Colorado Rockies from the Cretaceous seafloor would occur after watching the video for about 7 minutes, and the extinction of the dinosaurs would occur about 11 minutes into the film. The advent of human's first use of tools would only be in the last few minutes of this film; and the arrival of human's in North America is subliminal, occurring within the last second of the video.
However, if we wanted to film the entire 4.5 BY of Earth's geologic history, we would require an episode of about 53 hours, and the whole undertaking would require about 4,500,000 pictures!
Alexander (Sandy) Gunow received his doctorate in geology from the University of Colorado. Following an undergraduate degree, also at C.U., he worked as a miner at the Henderson Mine and eventually worked as an exploration geologist for the Climax Molybdenum Company and subsequently worked as a geologist for the State of Georgia. He is currently enjoying his retirement in the mountains near Silverthorne.