Overview

Topic: The Geology of Evergreen: The First 100 Million Years
Speakers: Lisa and Thom Fisher
Date and Time: Thursday, May 4th at 7 pm (doors open at 6:30 pm for socializing)
Location–Hybrid: In person at Evergreen Christian Church & virtual attendance via Zoom

Presentation Details

Have you ever wondered about the rocks in your yard, looked at the rocks as you hike, or maybe tripped over more than a few while birding?  Have you ever wondered how all those rocks got here and where they came from? Would you be surprised to know that the rocks in the Evergreen area are key to understanding how Colorado became part of the North American continent?

The next Evergreen Audubon Chapter Meeting on Thursday, May 4, 2023, will be your chance to get answers to these questions and more: Thom and Lisa Fisher, Evergreen Audubon members and the driving research forces behind Escalante Resources Group, will present “The Geology of Evergreen: The First 100 Million Years.”

Evergreen sits in the midst of the 1780-1740 Million Year Old Idaho Springs Arc, a critical component of the multi-arc system that formed Colorado through plate tectonic forces over a period of perhaps 100 to 150 million years. While nearly two billion years have passed since this part of Colorado was formed, most of the geologic record has been lost to uplift and considerable erosion. Mountains have risen and eroded away, replaced by the present day Front Range. Rocks once deposited near or below sea level now sit high in the Rockies. Not only that, the area that is now Colorado has traveled from far south of the Earth’s equator to its present day position of about 39 degrees North Latitude. You might be surprised to know that Colorado is still rising and still moving north!

In the Evergreen area, we see all of the original components (now seen as their metamorphic equivalents) of that early Idaho Springs Arc:

• the basalts and rhyodacite volcanic rocks of the initial volcanic arc, apparent for example in Mt. Vernon, Beaver Brook, and Golden Gate Canyons;
• the basalts, limestones, shales, and sandstones of the backar

  

  c basin, found throughout the central Front Range

• the exhalative iron, copper, lead, and zinc deposits related to the hot waters circulating in the backarc basin, seen in several places including Bergen Park, Genesee, and Ralston Canyon.

The intrusive granitic bodies and pegmatites that occur throughout the area, forming many of the knobs and mountains such as those on Double Header, Three Sisters, Elephant Butte, Mt. Evans, and others tell their own part of the story.

This is your chance to learn about where our beautiful Evergreen area is going, literally, and to contemplate the seemingly ancient rock formations we see every day in all their dynamic context.

About the Speakers

Lisa Fisher first moved to Evergreen in 1982 and has lived on Bear Creek and Squaw and Bear Mountains. Her M.S. and Ph.D. research focused on metamorphic and igneous petrology, mineralogy, geochemistry, and Precambrian geology. Her research, through Colorado School of Mines, focused on the Evergreen and White Ranch Park areas.

Thom Fisher has lived and worked in Colorado on and off since 1970. His specialties are sedimentology and stratigraphy. His Ph.D. research, also through Colorado School of Mines, focused on Precambrian metamorphosed sediments of Africa. He is currently studying the Idaho Springs Arc, Coal Creek Quartzite, and the complex metasedimentary sequences along Snyder Gulch and Hwy 103.

Lisa and Thom combine their specialties in a continuing cross-disciplinary study of the Idaho Springs Arc. They own and operate Energy and Mineral companies under Escalante Resources Group, Denver.

Meeting Logistics

Be sure to arrive when doors open at 6:30 pm so you can grab a good seat (virtual or actual) and visit with your Evergreen Audubon friends & neighbors. If attending virtually, consult the Zoom Meeting Details below. The meeting proper begins at 7 pm with brief announcements to catch you up on Evergreen Audubon’s jam-packed calendar of events and outings, immediately followed by the evening’s program.

Zoom Meeting Details

https://us06web.zoom.us/j/83158390470?pwd=YnczUHJ4WExONTU4RWNDQXZDQzhLQT09

Meeting ID: 831 5839 0470
Passcode: 030633

Dial-in according to your phone’s area code.  If you are dialing in from a Colorado phone, the number is:
+1 720 707 2699 US (Denver)
Meeting ID: 831 5839 0470
Passcode: 030633

Or find the appropriate number for your area code visit the Zoom website https://us06web.zoom.us/u/kzc31iRPZ