The Cecil and Sells sandstones of the Atoka Formation (Pennsylvanian) were studied in the subsurface of eastern Crawford and western Franklin Counties. Sand of the Cecil sandstone was delivered to a high destructive, wave dominated delta southeast of Fort Smith and reworked laterally by longshore currents to form coastal barrier sands to the east. The Sells sandstone unit accumulated as a distributary channel system that bifurcates to the southeast and southwest. The interdistributary areas are characterized by immature sands interbedded with shales. These immature sands were deposited by crevasse splays and reworking of the distributary mouth bars by marine processes causing sand transport into the interdistributary areas.
Cardneaux, Chris A.
"Depositional Systems of the Sells and Cecil Sandstones, Atoka Formation (Pennsylvanian), Eastern Crawford and Western Franklin Counties, Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 32
, Article 10.
Available at: http://scholarworks.uark.edu/jaas/vol32/iss1/10