Surrounded by prairie, farms, and wetlands, a modest ridge of woodland in southeastern Wisconsin might not seem noteworthy, but its story goes back about 430 million years and stretches across North America’s heart. To reach Brady’s Rocks, take a short spur off the 1,200-mile-long Ice Age National Scenic Trail, which leads up the ridge to a jumble of small cliffs, none much taller than the average hiker. Briefly quarried by an Irish immigrant named Michael Brady in the mid-19th century, these rock formations represent the southernmost surface exposure of a…
