 The Galena-Platteville Aquifer's spring water in the area travels south from Platteville and Glenwood, Wisconsin through layers of rocks into northern Illinois.Native Americans inhabited the region prior to European settlement and they kept the trees burnt off the stone bluffs to keep their roots from splitting the rock.When the earliest European settlers arrived they found groves of trees in the hollows, ravines, and lowlands near the river, which was where they built their first homes.