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Mineral Resources > Online Spatial Data > Geology > by state > Illinois Geology

Geologic units in Iroquois county, Illinois

Silurian (Silurian) at surface, covers 34 % of this area

Silurian

Lithology: dolostone (dolomite); limestone; coral

Kinderhookian Series (Mississippian) at surface, covers 3 % of this area

Kinderhookian Series

Lithology: limestone; shale; siltstone

Carbondale Formation (Pennsylvanian) at surface, covers 3 % of this area

Carbondale Formation

Lithology: shale; limestone; clay or mud; sandstone; coal; black shale

Borden Group (Mississippian) at surface, covers < 0.1 % of this area

Borden Group - Mostly siltstone; lenses of crinodial limestone in upper part. Much cherty and silty limestone and dolomite in northwest. NP, top of New Providence Shale

Lithology: siltstone; limestone; dolostone (dolomite); chert

Upper Devonian (Devonian) at surface, covers 13 % of this area

Upper Devonian

Lithology: shale; black shale; limestone; sandstone

Spoon Formation (Pennsylvanian) at surface, covers 20 % of this area

Spoon (includes Pa in northeast)

Lithology: shale; sandstone; clay or mud; limestone; coal; black shale

Lower Valmeyeran (Keokuk-Sedalia) Series (Mississippian) at surface, covers 2 % of this area

Lower Valmeyeran (Keokuk-Sedalia) Series

Lithology: limestone; shale

Middle Devonian (Devonian) at surface, covers 15 % of this area

Middle Devonian

Lithology: limestone; shale; dolostone (dolomite); sandstone; evaporite; sedimentary breccia;

Maquoketa Group (Ordovician) at surface, covers < 0.1 % of this area

Maquoketa Group

Lithology: shale; limestone; siltstone

Middle Valmeyeran (Salem, Warsaw, Borden, Springville; includes thin Mvl and Mk in south and east) Series (Mississippian) at surface, covers 9 % of this area

Middle Valmeyeran (Salem, Warsaw, Borden, Springville; includes thin Mvl and Mk in south and east) Series

Lithology: limestone; siltstone; shale