Birkmose Member (MO), Davis Member (IL), Derby-Doe Run Member (IL), Ironton Member (IL, WI, MI), Mazomanie Member (WI), Reno Member (MO, MN, WI), Tomah Member (MO)
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.[1] It preserves fossils dating back to the Cambrianperiod. It was named the Franconia Formation due to the first published documentation of exposures in vicinity of Franconia, Minnesota[1] in the 1897 Ph.D. dissertation by Charles P. Berkley at the University of Minnesota titled Geology of the St. Croix Dalles.[2] The Franconianstratigraphic stage was named after this formation.
The formation consists of fine-grained dolomitic sandstone with interbedded shaly zones, becoming more dolomitic towards the east and south of its extent.[3]
