Galena Group
Galena Group | |
---|---|
Stratigraphic range: Ordovician | |
Type | Group |
Underlies | Dubuque Formation |
Overlies | Decorah Shale |
Location | |
Country | United States |
Extent | Minnesota |
Paleozoic Stratigraphy of the Upper Midwest, USA |
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Dates approximate |
Maquoketa Group (446–440 Ma) |
Galena Group (454–446 Ma) |
|
Platteville Limestone (455–454 Ma) |
Glenwood Shale (~455 Ma) |
St. Peter Sandstone (~459–~455 Ma) |
Knox Unconformity (~470-~459 Ma) |
Knox Supergroup (~497-~470 Ma) |
The Galena Group or Galena Limestone refers to a sedimentary sequence of Ordovician limestone that was deposited atop the Decorah Shale. It is part of the Ordovician stratigraphy of the Upper Midwestern United States. It was deposited in a calm marine environment, and is fossiliferous.[1]
References
- ^ Mossler, J. and Benson, S., 1995, 1999, 2006, Fossil Collecting in the Twin Cities Area. Minnesota at a Glance: Minnesota Geological Survey: University of Minnesota.