Jackfork Sandstone

Jackfork Sandstone
Stratigraphic range: Pennsylvanian
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]

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

A. parksii[3]
  • Archaeocalamites
A. stanleyensis[3]
C. inopinatus[3]
C. menae[3]
C. miseri[3]
L. subclypeatum[3]
L. peniculus[3]
N. antecedens[3]
  • Rhabdocarpos
R. costatulus[3]
  • Rhynchogonium
R. choctavense[3]
T. gillhami[3]
T. vallisjohanni[3]

References

  1. ↑ Taff, J.A. (1902). "Description of the Atoka quadrangle". U.S. Geological Survey Geological Atlas of the United States. 79: 4.
  2. 1 2 3 "Stratigraphic Summary of the Arkansas River Valley and Ouachita Mountains". Arkansas Geological Survey. Retrieved 2017-12-15.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 White, David (1937). "Fossil plants from the Stanley Shale and Jackfork Sandstone in southeastern Oklahoma and western Arkansas" (PDF). U.S. Geological Survey Professional Paper. 186-C: 43–66.


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