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.

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.

This article about a specific stratigraphic formation in the United States is a stub.