| Jackfork Sandstone | |
| Type: | Formation |
| Age: | Pennsylvanian |
| Prilithology: | Sandstone |
| Otherlithology: | Shale, conglomerate |
| Namedfor: | Jackfork Mountain, Pittsburg and Pushmataha Counties, Oklahoma[1] |
| Namedby: | J. A. Taff, 1902 |
| Region: | Ouachita Mountains |
| Country: | United States |
| Underlies: | Johns Valley Shale |
| Overlies: | Stanley Shale |
| Thickness: | 3,500 to 6,000 feet |
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.
A. parksii[4]
A. stanleyensis[4]
C. inopinatus[4]
C. menae[4]
C. miseri[4]
L. subclypeatum[4]
L. peniculus[4]
N. antecedens[4]
R. costatulus[4]
R. choctavense[4]
T. gillhami[4]
T. vallisjohanni[4]