This full color book is the ninth in the "Roadside Geology of the Midwest" Series. This short geologic guidebook takes you through the Paleoproterozoic (Precambrian) sedimentary and igneous deposits of the Huronian Supergroup. The Huronian is a package of rocks that represents a passive margin sequence in deep time. Similar to modern continental margins like the American Gulf of Mexico coast. It just formed over 2.4 billion years earlier. You might be like, “But that’s the middle of the continent”. Yes, it is. But 2.5 billion years ago, it was the site of a rift that formed something similar to the Atlantic Ocean. Then over the next couple of billion years, other continental fragments and island arcs would accrete to North America until it grew to its present size. In the Espanola area we have a relatively complete exposure of the Huronian from the north where the oldest rocks are, to the south where the youngest ones are. The rocks also record the arrival of free oxygen in the atmosphere and the oldest glacial deposits.