The Paleozoic stratigraphic succession of the Ouachita Basin is dominated by deepwater siliciclastics, carbonates, and chert. Within the Carboniferous, the Stanley fan complex is a thick shale interval, with upper and lower sandstone sections, that was deposited during an overall sea level highstand. The overlying Jackfork Formation is predominantly a sandstone section, with no shelf equivalent. The Johns Valley Formation, a unit of turbidite sandstone, shales, and unusual boulder beds, overlies the Jackfork. The 6100-m-thick Atoka Formation succeeds the Johns Valley. This thick sandstone and shale interval is divisible into a central basin (or axial) fan complex, a series of slope (or intraslope basin) fans, and thick shelf margin deltaic complex.