|Geologic age||Late Devonian|
Sedimentary > Clastic > Mudstone > Shale (Bed)
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Sandstone (Bed)
|Comments||Secondary unit description from USGS Geologic Names lexicon (ref. MI016): Ellsworth Shale, exposed only in Antrim and Charlevoix Cos, is restricted to the western part of the Michigan basin where it replaces Antrim and Sunbury Shales. Averages about 152 m thick in the westernmost parts of the basin, but elsewhere it is typically 91 to 152 m thick. On the basis of conodonts, lithology, and stratigraphic position, the Ellsworth, Antrim, and Sunbury Shales of MI are considered equivalent in age to the New Albany of IN, IL, and KY. The Ellsworth is predominantly a silty shale of gray, greenish gray or more commonly green color. Siltstone and sandstone are minor components and are most abundant in the westernmost and southwestern parts of the basin.|
Milstein, Randall L. (compiler), 1987, Bedrock geology of southern Michigan: Geological Survey Division, Michigan Dept. of Natural Resources, scale 1:500,000.
USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/
|Counties||Antrim - Benzie - Berrien - Cass - Charlevoix - Grand Traverse - Huron - Kalkaska - Leelanau - Manistee - Mason - Otsego - Saint Joseph - Van Buren - Wexford|