Prairie du Chien Group (ILOp;0)

State	Illinois
Name	Prairie du Chien Group
Geologic age	Ordovician
Original map label	8420
Comments	The Prairie du Chien group includes the following formations: Shakopee Dolomite, New Richmond Sandstone, Oneota Dolomite, and Gunter Sandstone. Based on the stratigraphic column on the 1967 paper map, this group consists of about 80% dolomite (some cherty), and 20% sandstone.
Primary rock type	dolostone (dolomite)
Secondary rock type	sandstone
Other rock types
Lithologic constituents	Major Sedimentary > Carbonate > DolostoneThe Prairie du Chien group includes the following formations: Shakopee Dolomite, New Richmond Sandstone, Oneota Dolomite, and Gunter Sandstone. Based on the stratigraphic column on the 1967 paper map, this group consists of about 80% dolomite (some cherty), and 20% sandstone. Minor Sedimentary > Clastic > SandstoneThe Prairie du Chien group includes the following formations: Shakopee Dolomite, New Richmond Sandstone, Oneota Dolomite, and Gunter Sandstone. Based on the stratigraphic column on the 1967 paper map, this group consists of about 80% dolomite (some cherty), and 20% sandstone.
Map references	Willman, H.B., and others, (compilers), 1967, Geologic Map of Illinois: Illinois State Geological Survey, scale= 1:500,000, paper.
Unit references	Willman, H.B., and others, (compilers), 1967, Geologic Map of Illinois: Illinois State Geological Survey, scale= 1:500,000, paper.
Geographic coverage	DeKalb - Kendall - La Salle - Lee - Ogle