Earth:Jackfork Sandstone
| Jackfork Sandstone Stratigraphic range: Pennsylvanian | |
|---|---|
| File:Quartz-rhqtz-83b.jpg Quartz from the Jackfork Sandstone | |
| Type | Formation |
| Underlies | Johns Valley Shale |
| Overlies | Stanley Shale |
| Thickness | 3,500 to 6,000 feet |
| Lithology | |
| Primary | Sandstone |
| Other | Shale, conglomerate |
| Location | |
| Region | Ouachita Mountains |
| Country | United States |
| Type section | |
| Named for | Jackfork Mountain, Pittsburg and Pushmataha Counties, Oklahoma[1] |
| Named by | J. A. Taff, 1902 |
The Jackfork Sandstone, also referred to as the Jackfork Group, is a geologic formation associated with the Ouachita Fold and Thrust Belt exposed in western Arkansas and southeastern Oklahoma.[2] It is named for Jackfork Mountain in Pittsburg and Pushmataha counties, Oklahoma.[2][3]
The Jackfork Sandstone is a thin- to massive-bedded, fine- to coarse-grained, brown, tan, or gray quartzitic sandstone with subordinate brown, silty sandstone and dark gray shale.[2] It outcrops from Pulaski County, Arkansas in the east to Atoka County, Oklahoma in the west, a distance of over 200 miles. It is highly weather-resistant, resulting in a continuous chain of prominent ridges, including Rich Mountain, the second highest natural point in the Ouachita Mountains.
Paleoflora
- Aphlebia
- A. parksii[4]
- Archaeocalamites
- A. stanleyensis[4]
- L. subclypeatum[4]
- Lepidostrobus
- L. peniculus[4]
- N. antecedens[4]
- Rhabdocarpos
- R. costatulus[4]
- Rhynchogonium
- R. choctavense[4]
- Sigillaria[4]
- Trigonocarpum
References
- ↑ Taff, J.A. (1902). "Description of the Atoka quadrangle". U.S. Geological Survey Geological Atlas of the United States 79: 4.
- ↑ 2.0 2.1 2.2 "Stratigraphic Summary of the Arkansas River Valley and Ouachita Mountains". Arkansas Geological Survey. Archived from the original on 2018-05-29. https://web.archive.org/web/20180529114957/http://www.geology.ar.gov/geology/strat_arkvalley_ouachita.htm.
- ↑ , p. 4, Wikidata Q63225784
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 White, David (1937). "Fossil plants from the Stanley Shale and Jackfork Sandstone in southeastern Oklahoma and western Arkansas". U.S. Geological Survey Professional Paper 186-C: 43–66. https://pubs.usgs.gov/pp/0186c/report.pdf.
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