Rochester, Minnesota — The middle of the summer is not the best time to do fieldwork in southern Minnesota. The thick and diverse plants make each journey to an abandoned quarry wall or roadcut a jungly adventure. It doesn’t help that some plants, like poison ivy and the abundant wild parsnip, are, shall we say, unfriendly. Ticks, so far, have been uncommon. I nevertheless go to sleep wondering if there is a tick somewhere I haven’t found, and whether that itchy spot means anything …
Today was our last day with our expert guide from the Minnesota Geological Survey (and Wooster Geology alumnus) Andrew Retzler. We visited three locations where the Decorah Formation is exposed. The top image is us on an abandoned slope of a quarry near Rochester.
Andrew is enjoying the many fossils in the Decorah at this site. Note the thin carbonate slabs that weather out of the shale.
Turkey Run was our second site of the day. The Decorah and lower part of the Cummingsville Formation are exposed here. We needed a machete!
The students are examining the Decorah shales on the left. Andrew is on the right with his hand on the base of the Cummingsville Formation.
Wang’s Corner was our third and last stop of the day. This exposure of the Decorah was right on the side of the road, making it the easiest outcrop yet. While we worked, Nick Wiesenberg on the left made us delicious salmon and cheese cracker snacks. That was a new field trip experience for me: fine dining while collecting!
Here we are in Hernke’s Rock Quarry with the Shakopee Formation, part of the Prairie du Chien Group (Early Ordovician).
All is thus well with Team Minnesota as Andrew Retzler leaves us and we’re on our own. We have four student projects we’ll outline here over the next few days. The temperatures dropped as a front moved through, so we had a cool, drizzly day. Tomorrow we return to Iowa.
