The Harrodsburg Limestone is a geologic formation, a member of the Sanders Group of Indiana Limestone, of Mississippian age. It was named for Harrodsburg in southern Monroe County, Indiana by T. C. Hopkins and C. E. Siebenthal. It is made up primarily of calcarenite and calcirudite. It also may include some beds of dolomite and shale.
The Salem Formation is a geologic formation in Illinois, Indiana, Kentucky, and Missouri. It preserves fossils dating back to the Mississippian subperiod. This formation is quarried and used as a building material, known as "Indiana limestone", also called Bedford limestone.
The Fraileys Formation or Fraileys Shale is a geologic formation in Illinois. It preserves fossils dating back to the Carboniferous period.
The Keokuk Limestone is a geologic formation in Illinois, Iowa and Missouri. It preserves fossils dating back to the Mississippian sub-period.
The Bond Formation is a geologic formation in Illinois, Kentucky and Indiana. It preserves fossils dating back to the Carboniferous period.
The Patoka Formation is a geologic formation in Illinois. It preserves fossils dating back to the Carboniferous period.
The Warsaw Formation is a geologic formation in Illinois, Iowa and Missouri. It preserves fossils dating back to the Mississippian subperiod.
The St. Laurent Formation is a geologic formation in Illinois. It preserves fossils dating back to the Devonian period.
The Dunleith Formation is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.
The Wise Lake Formation is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.
The Glenwood Formation is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.
The Brainard Shale is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.
The Neda Formation is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.
The Scales Shale is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.
The Pecatonica Formation is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.
The Quimbys Mill Formation is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.
The Clayton Formation is a geologic formation in Illinois. It preserves fossils dating back to the Paleogene period.
The Franconia Formation is a geologic formation in the upper mid-western United States, with outcroppings found in Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, and Wisconsin. It preserves fossils dating back to the Cambrian period. It was named the Franconia Formation due to the first published documentation of exposures in vicinity of Franconia, Minnesota in the 1897 Ph.D. dissertation by Charles P. Berkley at the University of Minnesota titled Geology of the St. Croix Dalles. The Franconian stratigraphic stage was named after this formation.
Minnesota 
Illinois 
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Wisconsin 
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