Last week, ten students, two instructors, and a dozen natural resource professionals wove together the story of Wisconsin’s natural history. The students all finished the course as certified “Wisconsin Master Naturalist Volunteers.” This new program is based on a successful Minnesota Master Naturalist program and is similar to the Master Gardener program. It provides 40 hours of coursework in natural history, interpretation, and conservation stewardship, and then requires 40 hours of volunteer service per year.
The students learned that the basic plot of our Wisconsin story is universal: the landscape we see today is a result of geologic history, current climate, and recent disturbance. Endless variety in these three criteria results in the existence of every ecosystem from rainforests to deserts, and everything in between.
Our Northern Wisconsin story began 3 billion years ago, at an outcrop of very old rock near the town of Mellen. Professor Tom Fitz of Northland College guided the new geologists in making observations. Bands of different colors and crystal sizes gave the rock a striking striped appearance. “This is a very pleasant rock,” Tom chuckled at his own joke, “and geologists call it gneiss.”
Then Tom delved into interpretation--using information about the rock to imagine a sequence of events that could have created it. By looking at the minerals contained within the light and dark color bands, scientists can tell that this rock started out as many layers of different types of volcanic rocks. Those layers were buried deep within the earth, smashed and metamorphosed under heat and pressure, and then revealed at the surface by ages of erosion. Veins that cut across this gneiss have been dated to 2.7 billion years ago, so we know that this gneiss is even older. These rocks form the heart of the continent.
Racing forward in time--but traveling just a few miles down the road--we came to a mass of rock formed 1.1 billion years ago while the continent was trying to split itself apart along a fault that bisects Lake Superior. As the continent spread, the crust thinned, and magma welled up in huge shield volcanoes. During one such explosion, hot granitic magma rushed up from below, splintering chunks of black rock out of the volcano’s walls. Those chunks fell back into the pale magma, and it cooled underground into a formation that looks like chocolate chip cookie dough. Once again, erosion revealed it to us.
Luckily, the rift stopped spreading, and the North American continent didn’t rip apart. Millions of years passed while rocks formed and eroded. Glaciers came and went, eroding and depositing a mish-mash of sediments. When the ice melted most recently (about 10,000 years ago) it left behind the landscape much as we see it today. The ski trails around Cable, the huge pile of gravel known as Mount Telemark, the clay plain near Ashland, even the swath of sandy soil that extends southwest from the Bayfield Peninsula, are all the legacy of the glaciers.
And that legacy matters. Any ecosystem is composed of both biotic (living) and abiotic (non-living) components. The geology, plus our current climate (with plenty of moisture and seasonal temperature variation) provides the substrate for our local communities (both natural and human) to grow.
As the week flew by, we packed our days full of conversations with natural resource professionals. All of those scientists added events, plot twists, relationships, and layers of complexity to our Wisconsin story.
Up on the Moquah Barrens north of Ino, WI, we stood on hundreds of feet of sand washed out of the glaciers by rivers of melt. The dry soils, and the history of fire, logging, farming, and management, all resulted in a patchwork of oak scrub and pine savannah. Those habitats, in turn, attract certain birds. As the mid-morning sun burned the mosquitoes away, we extracted a clay-colored sparrow, Eastern towhee, and brown thrasher out of the mist net. While retired biologist Jim Bryce banded the birds, he commented on their close relationship to this dry, brushy habitat.
After Jim taught us the proper way to handle the tiny songbirds, we took turns holding and releasing the day’s catch.
Later, Matt Bushman, a botanist for the USFS, gave us a botanical tour of burned areas within the barrens. As we walked from thick brush to more open grassland, the effects of fire, selective logging, and targeted brushing drove home the importance of recent disturbance in shaping a landscape.
Finally, Tom Doolittle, wildlife biologist on the Chequamegon-Nicolet National Forest, integrated wildlife management into our story. The geology of the sand plain and the plant communities it supported had once attracted great flocks of dancing sharp-tailed grouse each spring. Now humans are trying to mimic historic disturbance patterns to help the dwindling population of sharp-tails recover.
We ended the week exhausted, but with a good understanding of how the landscape we see today is a result of geologic history, current climate, and recent disturbance.
Although the newly certified Master Naturalist Volunteers have a solid base of knowledge, they will be adding details and depth to this story of Wisconsin’s natural history for many years to come. Find out more about this program at wimasternaturalist.org.
For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! The current exhibit, “Nature’s Superheroes—Adventures with Adaptations,” opens in May 2014 and will remain open until March 2015.
Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com.