Nacatoch Formation

{{Short description|Geological formation in Arkansas}}

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| name = Nacatoch Formation

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| type = Formation

| age = Late Cretaceous

| period = Upper Cretaceous

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| namedfor = Nacatoch Bluff on the Little Missouri River, Clark County, Arkansas

| namedby = Albert Homer Purdue{{cite journal|last1=Veatch|first1=A.C.|title=Underground waters of eastern United States|journal=U.S. Geological Survey Water-Supply Paper|date=1905|volume=114|page=183}}

| region = Arkansas

| country = United States

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| underlies = Arkadelphia Marl

| overlies = Saratoga Formation

| thickness = 150 to 400 feet{{cite journal|last1=McFarland|first1=John David|title=Stratigraphic summary of Arkansas|journal=Arkansas Geological Commission Information Circular|date=2004|orig-year=1998|volume=36|pages=30–31|url=http://geology.ar.gov/pdf/IC-36_v.pdf|access-date=2018-01-12|archive-url=https://web.archive.org/web/20161221195953/http://www.geology.ar.gov/pdf/IC-36_v.pdf|archive-date=2016-12-21|url-status=dead}}

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The Nacatoch Formation is a geologic formation in Arkansas, USA. It preserves fossils dating back to the Cretaceous period.