|Name||Detroit River Group|
|Geologic age||Middle Devonian|
Sedimentary > Carbonate > Dolostone (Bed)
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Clastic > Sandstone (Bed)Revised the Detroit River to the Detroit River group. Includes the Sylvania sandstone at base.
|Comments||Secondary unit description from USGS Geologic Names lexicon (ref. MI016): Named the Detroit River dolomite in southeastern MI, western Ontario, CAN, and northern OH for the Detroit River. Includes (ascending) Flat Rock dolomite (40 to 150 feet thick), Anderdon limestone (40 to 50 feet thick), Amherstburg dolomite (20 feet thick), and Lucas dolomite (200 feet thick) members. Disconformably overlies Sylvania sandstone. The Detroit River is of Devonian age. Revised the Detroit River to the Detroit River group. Includes the Sylvania sandstone at base. Maximum thickness is 1,000 feet in wells in central part of Southern Peninsula of MI; outcrop thickness commonly less than 200 feet.|
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||Charlevoix - Cheboygan - Emmet - Leelanau - Lenawee - Monroe - Presque Isle - Washtenaw - Wayne|