| 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 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, Minnesota1 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.
The formation consists of fine-grained dolomitic sandstone with interbedded shaly zones, becoming more dolomitic towards the east and south of its extent.3
References
References
- "Geolex — Franconia". ngmdb.usgs.gov. Retrieved 2021-08-13.
- Berkey, Charles P. (1897). "Geology of the St. Croix Dalles". hdl:11299/177986.
{{cite journal}}: Cite journal requires|journal=(help) - "Franconia Formation". igws.indiana.edu. Retrieved 2021-08-13.
External links
External links
- Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 25 March 2022. Retrieved 17 December 2021.
- USGS National Geologic Map Database Unit Summary for "Franconia"
- Indiana Geological and Water Survey: Franconia Information at the University of Indiana