Sandstone, siltstone, and local conglomerate. Includes the Hinckley Sandstone and Fond du Lac (youngest detrital zircons ~1,000 Ma) and Solar Church Formations; deposition in eolian, fluvial, and lacustrine environments.
Primarily mafic flows.
Minong volcanic sequence (~1,095 Ma).
Sandstone, siltstone, and shale; includes the Wonewoc Sandstone, Eau Claire Formation, and Mt. Simon Sandstone.
Schist and slate of graywacke-mudstone protolith.
Granitic to granodioritic orthogneiss. Includes the McGrath Gneiss (~2,752 ± 15, 2,557 Ma) and unnamed units.
Gray basalt flows, interflow breccia, tuff, and minor sedimentary rocks
Lithic sandstone (reworked saprolite), marble, and mica schist (youngest detrital zircons greater than 2,000 Ma).
Red lithic conglomerate and sandstone; mafic to felsic volcanic flows similar to those of the unnamed formation (unit Yu) are interlayered with the sedimentary rocks.
Sandstone with some dolomite and shale, undivided; includes Trempealeau, Tunnel City, and Elk Mound Formations
Mafic intrusions including pyroxenite, peridotite, gabbro, and lamprophyre. Defined largely by magnetic signature. One intrusion in Morrison County is ~1,791 Ma, and lithologically similar intrusions cut the Foley Granite (~1,774 Ma).