Ancell Group (ILOa;0)

State	Illinois
Name	Ancell Group
Geologic age	Ordovician
Original map label	8160
Comments	The formations in the Ancell group include: Joachim Dolomite, Dutchtown Limestone, St. Peter Sandstone, Glenwood Formation. Based on the stratigraphic column on the 1967 paper map, collectively this group is about 60% sandstone, 30% dolomite, and 10% limestone, and incidental anhydrite.
Primary rock type	sandstone
Secondary rock type	dolostone (dolomite)
Other rock types	limestone; evaporite
Lithologic constituents	Major Sedimentary > Clastic > SandstoneThe formations in the Ancell group include: Joachim Dolomite, Dutchtown Limestone, St. Peter Sandstone, Glenwood Formation. Based on the stratigraphic column on the 1967 paper map, collectively this group is about 60% sandstone, 30% dolomite, and 10% limestone, and incidental anhydrite. Minor Sedimentary > Carbonate > DolostoneThe formations in the Ancell group include: Joachim Dolomite, Dutchtown Limestone, St. Peter Sandstone, Glenwood Formation. Based on the stratigraphic column on the 1967 paper map, collectively this group is about 60% sandstone, 30% dolomite, and 10% limestone, and incidental anhydrite. Sedimentary > Carbonate > LimestoneThe formations in the Ancell group include: Joachim Dolomite, Dutchtown Limestone, St. Peter Sandstone, Glenwood Formation. Based on the stratigraphic column on the 1967 paper map, collectively this group is about 60% sandstone, 30% dolomite, and 10% limestone, and incidental anhydrite. Incidental Sedimentary > Chemical > Evaporite > AnhydriteThe formations in the Ancell group include: Joachim Dolomite, Dutchtown Limestone, St. Peter Sandstone, Glenwood Formation. Based on the stratigraphic column on the 1967 paper map, collectively this group is about 60% sandstone, 30% dolomite, and 10% limestone, and incidental anhydrite.
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	Boone - Calhoun - Carroll - Cook - DeKalb - Grundy - Kendall - La Salle - Lee - Monroe - Ogle - Stephenson - Winnebago