Cotter Formation

{{Short description|Geologic formation in the United States}}

{{Infobox rockunit

| name = Cotter Formation

| image =

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| type = Formation

| age = Ordovician

| period = Ordovician

| prilithology = Dolomite

| otherlithology = Chert, sandstone, shale

| namedfor = Cotter, Baxter County, Arkansas

| namedby = Edward Oscar Ulrich{{cite journal|last1=Purdue|first1=A.H.|last2=Miser|first2=Hugh D.|title=Description of the Eureka Springs and Harrison quadrangles|journal=U.S. Geological Survey Geologic Atlas of the United States|date=1916|volume=202|page=4|url=https://pubs.usgs.gov/gf/202/text.pdf}}

| region = Arkansas, Missouri, Oklahoma,

Virginia

| country = United States

| coordinates =

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| underlies = Powell Formation

| overlies = Jefferson City Formation

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The Cotter Formation is a geologic formation in Arkansas,{{Cite web |url=http://www.geology.ar.gov/geology/ozark_ordovician.htm |title=Cotter Dolomite |access-date=2014-07-11 |archive-url=https://web.archive.org/web/20140714131645/http://www.geology.ar.gov/geology/ozark_ordovician.htm |archive-date=2014-07-14 |url-status=dead }} Missouri,[http://www.dnr.mo.gov/geology/geosrv/ogc/docs/RI-073.pdf Thompson, Thomas L., 2001, Lexicon of Stratigraphic Nomenclature in Missouri, Missouri Department of Natural Resources, Division of Geology and Land Survey, Report of Investigation Number 73, p 72-3] Oklahoma{{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=3–4|url=http://geology.ar.gov/pdf/IC-36_v.pdf|access-date=2018-01-10|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}} and in Virginia. It preserves fossils dating back to the Ordovician period.