| Atoka Formation | |
|---|---|
| Stratigraphic range: Pennsylvanian | |
| Type | Geologic formation |
| Underlies | Hartshorne Sandstone |
| Overlies | Bloyd Formation, Johns Valley Formation |
| Lithology | |
| Primary | Sandstone |
| Other | Shale |
| Location | |
| Region | Arkansas, Oklahoma |
| Country | United States |
| Type section | |
| Named by | J.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]