Sentinel Butte Formation

{{Short description|Geological formation in North Dakota, USA}}

{{Infobox rockunit

| name = Sentinel Butte Formation

| image = Big Blue Bentonite (Sentinel Butte Formation, Upper Paleocene; Coal Vein Trail, Roosevelt National Park, Little Missouri Badlands, North Dakota, USA) 5.jpg

| caption = Bentonite (Big Blue Bentonite) in the Sentinel Butte Formation (North Dakota)

| type = Formation

| age = Thanetian
~{{fossil range|58|55}}

| period = Thanetian

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| region = North Dakota

| country = United States

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| unitof = Fort Union Formation

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| underlies = Golden Valley Formation

| overlies = Bullion Creek Formation

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The Sentinel Butte Formation is a geologic formation of Paleocene age in the Williston Basin of western North Dakota.{{cite web|last1=Bluemle|first1=John P. 1988|title=Generalized Bedrock Geological Map of North Dakota|url=https://www.dmr.nd.gov/ndgs/documents/Publication_List/pdf/MisMaps/MM-28.pdf|publisher=North Dakota Geological Survey, Miscellaneous Map 28|access-date=2017-02-03}} It preserves significant assemblages of non-marine plant and animal fossils.