Bayport Limestone (MIMb;0)

State	Michigan
Name	Bayport Limestone
Geologic age	Mississippian
Original map label	Mb
Comments	Secondary unit description from USGS Geologic Names lexicon (ref. MI016): The Bayport limestone consists of sandy yellow limestones, cross-bedded white sandstone, and a little dolomite. Unit is 20 to 50+ feet thick. The Bayport is the top unit in the Grand Rapids group or series. Maximum thickness of the Bayport is about 37 m but in most places is 15 to 30 m thick. Unit is lithologically variable, but is predominantly carbonate. It also contains significant amounts of sandstone and minor quantities of shale, bedded chert, and evaporites.
Primary rock type	limestone
Secondary rock type	dolostone (dolomite)
Other rock types	sandstone; shale; chert; evaporite
Lithologic constituents	Major Sedimentary > Carbonate > Limestone (Bed) Minor Sedimentary > Clastic > Sandstone (Bed) Sedimentary > Carbonate > Dolostone (Bed) Incidental Sedimentary > Chemical > Chert (Bed)banded chert Sedimentary > Chemical > Evaporite (Bed) Sedimentary > Clastic > Mudstone > Shale (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	Barry - Calhoun - Eaton - Genesee - Huron - Ingham - Ionia - Jackson - Kent - Lake - Livingston - Missaukee - Muskegon - Newaygo - Ogemaw - Ottawa - Roscommon - Shiawassee - Tuscola - Wexford