Saginaw Formation

Saginaw Formation
State Michigan
Name Saginaw Formation
Geologic age Pennsylvanian
Comments Secondary unit description from USGS Geologic Names lexicon (ref. MI016): Revised the Saginaw to the Saginaw group. Unit is composed of material of fresh water, brackish water, and marine origin, and consists of sandstone, shale, coal, and limestone. Comprises many cyclical formations, one which (Verne formation) contains a persistent shaly marine limestone member that makes it convenient to divide the group into pre- and post-Verne cyclical formations. Thickness of group is 400 feet. Overlies the Parma sandstone wherever that formation is present; in some areas, directly overlies the Bayport formation, as in area immediately north of Jackson; in several localities, may rest directly on Napoleon sandstone. Underlies Grand River group. The Saginaw is of Pennsylvanian age.
Primary rock type sandstone
Secondary rock type shale
Other rock types coal; limestone
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Mudstone > Shale (Bed)
Minor
Sedimentary > Coal (Bed)
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
Counties Arenac - Barry - Calhoun - Clare - Clinton - Eaton - Gladwin - Gratiot - Huron - Ingham - Ionia - Isabella - Kent - Lake - Livingston - Mecosta - Midland - Missaukee - Montcalm - Newaygo - Ogemaw - Osceola - Roscommon - Saginaw - Shiawassee - Wexford