Letter to the editor: The geologic history of Summit County is mind-boggling | SummitDaily.com

Letter to the editor: The geologic history of Summit County is mind-boggling

John O’Brien

Thanks to Antonio Olivero for his excellent description of the Buffalo Mountain hike, one of the iconic Summit County adventures. However, his description of the view of the mountain as a “volcano-like caldera” doesn’t do justice to the mountain’s actual geologic history which, in fact, is truly amazing.

The Gore Range’s rugged appearance, with its high elevation above the valley, sharp peaks, knife-edge ridges and sheer cliff faces is an amazing example of Alpine scenery. However, the mountain core isn’t the result of volcanism but of up-thrusting of deeply buried older rocks.

Glaciation has been a major factor in shaping these mountains as we see them today. In fact, the Gore Range is considered to be one of the best examples of glaciation in Colorado! The lower portion of the valley between Buffalo and Red Mountain, as seen from the Ptarmigan Trail, is an outstanding example of a U-shaped glacial valley.

As the climate warmed up, glaciers didn’t reach as far down into the valleys. Instead they were restricted to the upper slopes where they carved out gentle bowls, called cirques. These are the features which gave us the ski bowls on our ski slopes! Thank you, glaciation, on behalf of our ski bums.

As you view Buffalo Mountain from Interstate 70 traveling west, or from Keystone or Dillion Reservoir, what do you see? Not the results of a volcano but several glacial cirques stacked one above the other. Take a close look and see how many you can identify. We have many examples of cirques in Summit County, but the vertically stacked cirques of Buffalo Mountain are unique.

The geologic history of Summit County is mind-boggling; understanding it gives us an even deeper appreciation of the environment in which we live.

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