- Usage in publication:
-
- Sweeney Formation
- Modifications:
-
- Named
- Dominant lithology:
-
- Dolomite
- Clay
- AAPG geologic province:
-
- Wisconsin arch
Summary:
Name Sweeney Formation proposed for unit overlying Blanding Formation in Mississippi Palisades State Park, Carroll Co., northwestern IL. Consists of 17 m of pinkish-gray dolomite in thin wavy beds with clay partings. Conformably overlies Blanding and conformably underlies Marcus Formation (new name). Age is Early Silurian (Alexandrian).
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Sweeney Member
- Modifications:
-
- Revised
- Overview
- AAPG geologic province:
-
- Wisconsin arch
- Iowa shelf
Summary:
According to author, one of his primary aims in this report is to strongly encourage adoption of IA nomenclature in adjacent IL. The only major change is the incorporation of the Sweeney and Marcus as members within the Hopkinton and replacement of the Racine with upper members of the Hopkinton, the Scotch Grove Formation, and the Gower Formation. The Hopkinton in the Quad Cities area of IA and IL is divided into (ascending) Sweeney, Marcus, Farmers Creek, and Picture Rock Members. The Sweeney resembles the underlying Blanding Formation, but it is generally less cherty and more fossiliferous, commonly containing tabulate corals, laminar stromatoporoids, and stricklandid brachiopods. Age is Llandoverian.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).