The Polk Creek Shale is a Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892,[3] this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas.[2] 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.

Polk Creek Shale
Stratigraphic range: Ordovician
TypeFormation
Unit ofnone
Sub-unitsnone
UnderliesBlaylock Sandstone
OverliesBigfork Chert
Thickness50 to 225 feet[1]
Lithology
PrimaryShale
Location
RegionArkansas, Oklahoma
CountryUnited States
Type section
Named forPolk Creek, Montgomery County, Arkansas
Named byAlbert Homer Purdue[2]

Paleofauna

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C. mississippiensis[5][6]
C. putillus[5][6]
C. tridentatus var. maximus[6]
C. ulrichi[5][6]
D. anceps[6]
D. complanatus[4][5][6]
D. elegans[4]
D. forehammeri flexuosus[4]
D. calcaratus[5]
D. calcaratus var. trifidus[6]
D. crassitestus[5][6]
G. quadrimucronatus[5]
G. quadrimucronatus var. paucithecatus[6]
N. velatus[4]
O. quadrimucronatus[4]
O. spinigerus[4]

See also

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References

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  1. ^ McFarland, John David (2004) [1998]. "Stratigraphic summary of Arkansas" (PDF). Arkansas Geological Commission Information Circular. 36: 19. Archived from the original (PDF) on 2016-12-21. Retrieved 2018-01-09.
  2. ^ a b Purdue, A.H. (1909). Slates of Arkansas. Geological Survey of Arkansas. pp. 30, 35.
  3. ^ Griswold, L.S. (1892). "Whetstones and the novaculites". Annual Report of the Geological Survey of Arkansas for 1890. 3.
  4. ^ a b c d e f g h i j k l Miser, Hugh D.; Purdue, A.H. (1929). "Geology of the De Queen and Caddo Gap quadrangles, Arkansas". U.S. Geological Survey Bulletin. 808: 40–42.
  5. ^ a b c d e f g Decker, Charles E. (1935). "Graptolites of the Sylvan Shale of Oklahoma and Polk Creek Shale of Arkansas". Journal of Paleontology. 9 (8).
  6. ^ a b c d e f g h i Decker, Charles E. (1936). "Some tentative correlations on the basis of graptolites of Oklahoma and Arkansas". Bulletin of the American Association of Petroleum Geologists. 20 (3): 301–311.