Franconia Formation

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 Cambrian period. 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 Franconian stratigraphic stage was named after this formation.

Franconia Formation
Stratigraphic range: Cambrian
Type	Formation
Unit of	Munising Group (IN,MI, WI), Knox Group (IL), Tunnel City Group (IA,MN,WI)
Sub-units	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)
Underlies	Potosi Dolomite and St. Lawrence Formation
Overlies	Ironton Sandstone
Location
Region	Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, and Wisconsin
Country	United States

The formation consists of fine-grained dolomitic sandstone with interbedded shaly zones, becoming more dolomitic towards the east and south of its extent.^[3]

See also

• Paleontology portal

• List of fossiliferous stratigraphic units in Wisconsin
• Paleontology in Wisconsin