Sandstone with some dolomite and shale, undivided; includes Trempealeau, Tunnel City, and Elk Mound Formations
Dolomite with some sandstone and shale; includes Shakopee and Oneota Formations
Orthoquartzitic sandstone with minor limestone, shale and conglomerate; includes Glenwood and St. Peter Formations
Pink to maroon to light-gray, medium-grained, moderately sorted quartzite. Red argillite (pipestone) interbedded locally. At least 213 m thick
Dolomite with some limestone and shale; includes Galena, Decorah, and Platteville Formations
Ash-flow tuffs and interbedded volcaniclastic sedimentary rocks and cogenetic granite (unit Xga) exposed as inliers in southern Wisconsin. In central Wisconsin pink, flow-banded rhyolite and chert-cemented breccia inferred to be 1760 Ma.