Antrim Shale (MIDa;0)

State	Michigan
Name	Antrim Shale
Geologic age	Late Devonian
Original map label	Da
Comments	Secondary unit description from USGS Geologic Names lexicon (ref. MI016): The Antrim is dark gray or brown to largely black, highly carbonaceous, thinly laminated shale with meager fossil content except for profuse algal spores. Large dark brown, bituminous and pyritic limestone concretions occur in the lower Antrim and are typically from 9.6 to 1.5 m in diameter.
Primary rock type	black shale
Secondary rock type	limestone
Other rock types
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed) Incidental Sedimentary > Carbonate > Limestone (Bed)
Map references	Milstein, Randall L. (compiler), 1987, Bedrock geology of southern Michigan: Geological Survey Division, Michigan Dept. of Natural Resources, scale= 1:500,000
Unit references	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 (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Alcona - Alpena - Antrim - Benzie - Berrien - Charlevoix - Cheboygan - Emmet - Grand Traverse - Kalkaska - Leelanau - Lenawee - Macomb - Manistee - Monroe - Montmorency - Oakland - Oscoda - Otsego - Presque Isle - Saint Clair - Sanilac - Washtenaw - Wayne