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Geologic formation in Michigan
The Bois Blanc Formation is a geologic formation in Michigan . It preserves fossils dating back to the Devonian period .
[better source needed
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Pz
P
C
D
Upper
Famennian
Venango Group Gantz, Hundred-foot sand, Fifty-foot sand, Thirty-foot sand, Nineveh-Snee, Gordon Stray, Fourth Sand, Fifth Sand, Bayard Sand, Elizabeth Sand, Sweet Richard,
Chadakoin Formation , First WarrenBradford Group Upper Warren, Lower Warren, Speechely Stray, Speechely, Balltown A, Balltown B, Balltown C, Sheffield, First Bradford, Second Bradford, Third Bradford, Kane Elk Group 1st Elk Sand, 2nd Elk Sand, 3rd Elk Sand, 4th Elk Sand, 5th Elk Sand Ohio Shale Catskill Group Frasnian
Middle
Lower
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