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Garden Island Formation

Garden Island Formation
State Michigan
Name Garden Island Formation
Geologic age Early Devonian
Comments Secondary unit description from USGS Geologic Names lexicon (ref. MI016): Named the Garden Island formation for Garden Island, northeastern MI. Consists of dolomite and dolomitic limestone which occupies a position between Silurian St. Ignace formation and Middle Devonian Bois Blanc formation. Thickness at type locality is 3 feet; maximum thickness probably not more than 25 feet, and average thickness not more than 15 feet. The Garden Island is of Early Devonian age.
Primary rock type dolostone (dolomite)
Secondary rock type limestone
Other rock types
Lithologic constituents
Major
Sedimentary > Carbonate > Dolostone (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
USGS Geologic Names Lexicon (GEOLEX)
Counties Monroe