Atoka Formation

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Atoka Formation
Stratigraphic range: Pennsylvanian
TypeGeologic formation
UnderliesHartshorne Sandstone
OverliesBloyd Formation, Johns Valley Formation
RegionArkansas, Oklahoma
CountryUnited States
Type section
Named byJ.A. Taff[1]

Named after Atoka County, Oklahoma, the Atoka Formation is a geologic formation in central and western Arkansas, eastern Oklahoma, central and western Texas, and eastern New Mexico.[2] It is the surface rock of the Boston Mountains and dominates exposures in the Frontal Ouachita Mountains of the Arkansas River Valley.[2]


The Atoka Formation is a sequence of marine sandstones, siltstones, and shales, and may be as thick at 25,000 feet in the Ouachita Mountains.[2] The formation is conformable with the Bloyd Shale in the Boston Mountains and the Johns Valley Formation in the Ouachita Mountains.[2]


Trace Fossils[edit]

C. arkansanus[3]


  1. ^ Taff, J.A.; Adams, G.I. (1900). "Geology of the eastern Choctaw coal field". Twenty-First Annual Report of the United States Geological Survey, 1899-1900, Part 2, General Geology, Economic Geology, Alaska: 272, 273–274.
  2. ^ a b c d "Stratigraphic Summary of the Arkansas River Valley and Ouachita Mountains". Arkansas Geological Survey. Retrieved 2017-11-23.
  3. ^ Branson, Carl C. (May 1961). "New records of the Scyphomedusan Conostichus" (PDF). Oklahoma Geology Notes. 21 (5): 130–138. Retrieved 28 January 2018.