The Atoka Formation (Pennsylvanian) of northwestern Arkansas is a complex succession of sandstone and shale units. Sandstone units in surface sections near the base of the formation in northern Crawford and southern Washington Counties may be correlated with units in the subsurface of the Arkoma Basin. The basal sandstone units of the Atoka Formation as recognized in the Arkoma Basin are correlated with thin, discontinuous sandstones within the Trace Creek Member of the Bloyd Formation in surface exposures to the north. Vertical grain size profiles, electric log profiles and the configuration of thickness trends suggest that lower Atoka sandstone units accumulated as linear coastal sand bodies that prograded southeastward.

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