The location of this Earthcache can be reached via the Mount Evans Scenic Byway. This is the highest paved road in North America and is usually open between Memorial Day and Labor Day, but please check the availability on the USDA Forest Service website. The road climbs several thousand feet through five different climate zones. If you are petrified by switchbacks on a road with few guardrails, this is not the drive for you. I suggest having someone else put a blindfold on you and drive you to the top.
But that's not all! There are several other hazards: cold weather, dehydration, intense UV Ray exposure, oxygen deprivation, thunderstorms and.... cosmic rays?! Bring layered clothing, drink lots of water (not carbonated), wear sunscreen and sunglasses, bring oxygen (as needed and, yes, you can buy canned oxygen), check the weather before you go, and take it easy on your body. No idea what to do about those cosmic rays, though.
Standing on this rim, you can see the Chicago Lakes to your north and Summit Lake to your southwest. Close your eyes and imagine yourself between 170 and 120 thousand years ago or a scant 30 and 12 thousand years ago. Glaciers are carving this landscape. They're massive! They are made of packed snow and ice 800 to 1,00 feet high. As they move, they pick up boulders and carry them along, using them like a conveyor belt to grind the terrain in a wide and deep path. The glaciers gouge huge u-shaped ampitheaters called circques and bedrock basins that become lakes called tarns. They deposit a mass of rocks and sediment ranging in size from powdery silt to boulders called a moraines, which usually have a ridge or ridge-like appearance.
Face the Chicago Lakes and look to your left. The Black Wall is part of the Mount Evans batholith. It's about 1,442 million (around 1.4 billion) years old from the middle of the Protozeroic Eon (late Precambrian). You can think of it as pre-dinosaur or the single-celled organism time. The Wall is composed of granodiorite which is similar to a granite, but some of its feldspar content is akin to that found in diorites, so it's mineralogically partway between the two rock types. This is the type of rock that the glaciers carved, which created the area you are now occupying.
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To earn credit for this EarthCache, please email or message me your answers to the following questions. Please include your geocaching name and any others that were in your party. Please do not include answers in your log. You will have one week from your "Found It" log to submit your answers. No answers, no smiley. Thanks!
Questions
Think about the land around you and exactly where you are standing.
Do you suppose this is a:
- moraine (material like silt and boulders left behind by a glacier as it moves)?
- part of a circque (an ampitheatre-like valley formed by glacial erosion)?
- part of a tarn (a mountain lake, pond, or pool formed in a circque)?
What visual evidence have you noted to support your conclusion?
(Optional) Post a photo of yourself on your mountain adventure!
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Sources
Day Trips Around Colorado https://www.denver.org/things-to-do/day-trips-around-colorado/mount-evans/
"Hiking Colorado's Geology" by Ralph Lee Hopkins and Lindy Birkel Hopkins
Mr. Clay Martin from the U.S. Geological Survey Library - Denver
Mt. Evans brochure handed out by Park Rangers
National Park Service: Glaciers and Glacial Landforms https://www.nps.gov/subjects/geology/glacial-landforms.htm
National Snow and Ice Center Data: Glacial Landforms https://nsidc.org/cryosphere/glaciers/gallery/moraines.html
New Scientist. "Timeline: The evolution of life" https://www.newscientist.com/article/dn17453-timeline-the-evolution-of-life/
"Roadside Geology of Colorado" by Halka Chronic
"Rocks Above the Clouds: A Hiker's and Climber's Guide to Colorado Mountain Geology" by Jack Reed and Gene Ellis