|Name||Garden Island Formation|
|Geologic age||Early Devonian|
Sedimentary > Carbonate > Dolostone (Bed)
Sedimentary > Carbonate > Limestone (Bed)
|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.|
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/