The Polk Creek Shale is a Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned Polk Creek in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated.
Paleofauna Graptolites
Amplexograptus Climacograptus C. mississippiensis C. putillus C. tridentatus var. maximus C. ulrichi Dicellograptus D. anceps D. complanatus D. elegans D. forehammeri flexuosus Diplograptus D. calcaratus D. calcaratus var. trifidus D. crassitestus Glossograptus G. quadrimucronatus G. quadrimucronatus var. paucithecatus Lasiograptus Mesograptus Nymphograptus N. velatus Orthograptus O. quadrimucronatus O. spinigerus
See also
List of fossiliferous stratigraphic units in Arkansas Paleontology in Arkansas
References