| Polk Creek Shale | |
|---|---|
| Stratigraphic range: Ordovician | |
| Type | Formation |
| Unit of | none |
| Sub-units | none |
| Underlies | Blaylock Sandstone |
| Overlies | Bigfork Chert |
| Thickness | 50 to 225 feet [1] |
| Lithology | |
| Primary | Shale |
| Location | |
| Region | Arkansas, Oklahoma |
| Country | United States |
| Type section | |
| Named for | Polk Creek, Montgomery County, Arkansas |
| Named by | Albert Homer Purdue [2] |
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.
Paleofauna
Graptolites
- N. velatus [4]
See also
References
- ^ 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.
- ^ a b Purdue, A.H. (1909). Slates of Arkansas. Geological Survey of Arkansas. pp. 30, 35.
- ^ Griswold, L.S. (1892). "Whetstones and the novaculites". Annual Report of the Geological Survey of Arkansas for 1890. 3.
- ^ 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.
- ^ 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).
- ^ 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.
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