The mountains around Summit sure are pretty. But if you take a closer look, they tell you a lot more about Summit County history than most books can. Summit and the mountains that surround it were formed over hundreds of millions of years of geological turmoil. That geological history, presented by local geologist Joe Newhart, was the main event at this past week’s Forest Health Task Force meeting.
Summit County’s geological history extends as far back as 1.8 billion years. The amount of change that’s happened to the area is hard to summarize; suffice to say that Summit is the product of an unfathomable amount of earthly turmoil. The signs of those changes can be seen in layers of rock on cliffsides all around us.
The geological upheaval that is most visible — and important — to Summit County began comparatively recently in terms of the history of the planet.
About 66 to 45 million years ago, at the end of the Cretaceous period through the Paleocene period, a mountain-building episode called the “Laramide Orogeny” formed the main features that make up the Rocky Mountains we see today. The Laramide Orogeny was caused by millions of years of upheaval underground.
Two tectonic plates far off the west coast of what was then North America — the Kula and Farallon plates — mashed into and then under the North American plate over millions of years. A “shallow subduction” occurred which buried the edge of the Kula and Farallon plates under the North American plate, lifting a large part of the latter plate to higher elevations. This particular event is a big reason why Colorado is so high above sea level.
The friction of the plate subduction kept pushing inward, and crumpled the crust at the top of the North American plate, much like the hood of a car would look after a head-on wreck. That crumpling was “thick-skinned” in that it involved upheaval of a thick part of the upper crust, pushing ancient rock through the surface, enough so that rocks and geology from nearly 2 billion years ago can be seen in cliffsides and mountain faces.
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At one point, the High Country was part of a vast, high, dry plateau. The peaks and valleys we see now were formed through millions of years of erosion, as well as two sustained ice ages that froze the world and created giant glaciers that slide through the plateau, shaving off rock and laying sediment down as it went. The top of the Ten Mile Range, at the western end of Frisco Main Street that runs between Mount Royal and Mount Victoria, was carved out by one of those giant glaciers.
As with many things rock-related, seeing is much more descriptive than reading, and eons of geological history needs more than a few inches of newsprint to describe. Newhart, in association with the Friends of the Dillon Ranger District, will be conducting geology tours of Summit over the summer, pointing out areas of interest where ancient geology can be seen first-hand. Visit FDRD.org in the coming months for details of Newhart’s tours, as well as other events and volunteer opportunities.
Aside from the geology talk, Summit County community development director Jim Curnutte also spoke on the county’s preparations for the upcoming wildfire season. The county’s chipping program will be taking place again, but with more concentrated planning and tweaks to ensure that last year’s delays and backlogs are less of a problem.
The county will also look to once again bring a seasonal forest patrol back for dispersed recreation duties, with hope that the partial federal government shutdown will end and allow collaboration with the U.S. Forest Service with the patrol and other wildfire preparedness projects.
Curnutte also said the county is looking to updating its building codes this year, incorporating aspects of a uniform Wildland-Urban Interface code adopted by other counties and municipalities. He also mentioned that funding secured through a rcent ballot initiative will be put to use soon, paying for projects and improvements such as cistern building for developments without a central water system.