Chart showing the layers of rock (stratigraphy) present in Wisconsin, their geologic ages, and the associated rock units. The page-size version explains how to read and interpret this complex diagram. (The stratigraphic column is also available as a poster, see WOFR2006-06.)
Large downloads come in ZIP archives. You will need an application capable of unpacking ZIP archives, such as WinZIP, WinRAR, or 7-zip.