Wisconsin Volcanoes – Rib Mountain State Park, June 2018

view from tower
View from the observation tower at Rib Mountain State Park. Notice the hill off in the distance. More about that below.

It has always seemed like exaggerating to call anything in Wisconsin a mountain. We do have some nice hills and a lot of beautiful places. Rib Mountain? Probably not.

The name of the state park in Wausau just didn’t seem right. Of course, I had no knowledge or appreciation of the geology of the area.  But, that was before I got a copy of Wisconsin State Parks: Extraordinary Stories of Geology and Natural History by Scott Spoolman. I was heading north and would pass by Rib Mountain State Park. So, I read the book’s description of the park before I left home.

trail and rocks
Lots of rocks along the Red Trail at Rib Mountain State Park

About a billion and a half years ago, there were four volcanoes in what we now call Wausau. The forces below the volcanoes pushed up a mass of quartzite formed from 1.7-billion-year-old sandstone. Turns out, that is some extremely hard rock.

The volcano peaks eventually were eroded away. They shrunk from thousands of feet high — mountain heights — until they disappeared. Left inside the footprint of the volcanoes were hills made of the quartzite. Rib Mountain is one of those hills. Two other hills are visible from Rib Mountain. The photo at the top, taken from the observation tower at Rib Mountain, shows another of the remaining hills.

These hills had been submerged below shallow seas several times, according to Spoolman. They survived that. And, they survived being buried under layers of sedimentary rock that eventually eroded away due to the same forces of nature that had worn down the volcano peaks. The quartzite hills were so hard that they did not succumb to the erosive forces. They also survived the glaciers. (According to Spoolman, the last glacier didn’t reach the quartzite hills but stopped a few miles away.)

The ancient rock is exposed at Rib Mountain State Park. I hiked the Red Trail and had lots of opportunities to appreciate the rocks. The northern part of the trail is a northern mixed forest, and the south has birch and maple stands. It would be a nice trail, even without the 1.7-billion-year-old quartzite. Knowing the geologic history of what is now Wausau and the state park really added to the experience. I was hiking on a hill of super old and super hard quartzite, in the footprint of four volcanoes.

I might still quibble over calling Rib Mountain a mountain. But, it is more dramatic than calling it Rib Hill. For an area of volcanoes and ancient rocks, some drama does seem appropriate.

ancient rocks
Red Trail, Rib Mountain State Park


2 thoughts on “Wisconsin Volcanoes – Rib Mountain State Park, June 2018”

  1. This is fascinating. I had just read about volcanic rock in Wisconsin. It was a revelation to me.

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