Geologic units in Vernon county, Wisconsin

Prairie du Chien Group (Ordovician) at surface, covers 47 % of this area

Dolomite with some sandstone and shale; includes Shakopee and Oneota Formations

Cambrian, undivided (Cambrian) at surface, covers 41 % of this area

Sandstone with some dolomite and shale, undivided; includes Trempealeau, Tunnel City, and Elk Mound Formations

Ancell Group (Ordovician) at surface, covers 12 % of this area

Orthoquartzitic sandstone with minor limestone, shale and conglomerate; includes Glenwood and St. Peter Formations

Sinnipee Group (Ordovician) at surface, covers 0.2 % of this area

Dolomite with some limestone and shale; includes Galena, Decorah, and Platteville Formations

Middle and Upper Cambrian (Middle and Upper Cambrian) at surface, covers < 0.1 % of this area

Sandstone, siltstone, and shale; includes the Wonewoc Sandstone, Eau Claire Formation, and Mt. Simon Sandstone.

Wonewoc Formation (Middle-Upper Cambrian, upper Marjuman-Steptoean (formerly upper Dresbachian-lower Franconian)) at surface, covers < 0.1 % of this area

Surface exposures limited to northeastern Allamakee County; subcrops beneath Mississippi River alluvium in Allamakee County. Includes Ironton and Galesville members. Primary lithology: sandstone, fine to coarse grained, upper part fossiliferous (Ironton). Thicknesses: 125-155 ft (38-47 m).

Eau Claire Formation (Middle Cambrian, upper Marjuman (formerly Dresbachian)) at surface, covers < 0.1 % of this area

Subcrops beneath Mississippi River alluvium in Allamakee County; surface exposures absent. Primary lithologies: sandstone, very fine to fine grained, part argillaceous; shale, silty, gray to green-gray, part glauconitic. Secondary lithology: siltstone, part argillaceous, part dolomitic. Minor: dolomite. Thicknesses: 120-145 ft (37-44 m).