Stonington Formation

{{Short description|Geologic formation in Michigan}}

{{Infobox rockunit

| name = Stonington Formation

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| type = Formation

| age = Late Ordovician

| period = Late Ordovician

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| region = Michigan

| country = United States

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| unitof = Richmond Group (geology)

| subunits = Ogontz Member and Bay de Noc Member

| underlies = Big Hill Formation

| overlies = Bill's Creek Shale

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The Stonington Formation is a geologic formation in Michigan. It preserves fossils dating back to the Ordovician period.