Geologic units in Pine county, Minnesota

Sandstone, siltstone, and local conglomerate (Mesoproterozoic) at surface, covers 48 % of this area

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.

Chengwatana volcanic rocks (Mesoproterozoic) at surface, covers 34 % of this area

Primarily mafic flows.

Minong volcanic sequence (Mesoproterozoic) at surface, covers 9 % of this area

Minong volcanic sequence (~1,095 Ma).

Middle and Upper Cambrian (Middle and Upper Cambrian) at surface, covers 4 % of this area

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

Little Falls Formation (Paleoproterozoic) at surface, covers 3 % of this area

Schist and slate of graywacke-mudstone protolith.

Granitic to granodioritic orthogneiss (Neoarchean) at surface, covers 2 % of this area

Granitic to granodioritic orthogneiss. Includes the McGrath Gneiss (~2,752 ± 15, 2,557 Ma) and unnamed units.

Chengwatana Volcanic Group (Middle Proterozoic) at surface, covers 0.5 % of this area

Gray basalt flows, interflow breccia, tuff, and minor sedimentary rocks

Denham Formation (Paleoproterozoic) at surface, covers 0.4 % of this area

Lithic sandstone (reworked saprolite), marble, and mica schist (youngest detrital zircons greater than 2,000 Ma).

Copper Harbor Conglomerate (Middle Proterozoic) at surface, covers 0.1 % of this area

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.

Cambrian, undivided (Cambrian) at surface, covers < 0.1 % of this area

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

Mafic intrusions including pyroxenite, peridotite, gabbro, and lamprophyre (Paleoproterozoic) at surface, covers < 0.1 % of this area

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).