Two areas of Devonian sandstone development may be recognized in northern Arkansas. In northwestern Arkansas, the Clifty Formation comprises a massively bedded, super mature quartz arenite of Middle Devonian age overlain by thinner bedded, phosphatic quartz arenite and chert breccia of the Sylamore Sandstone Member, Chattanooga Shale (Upper Devonian). This sequence overlies Ordovician strata (Powell or Everton) and is succeeded by the Chattanooga Shale and strata of Lower Mississippian age. In north-central Arkansas, the Clifty Formation is absent and the Chattanooga Shale may develop sandstone at its base and top. Occasionally the Chattanooga Shale is absent and the entire interval may be Upper Devonian sandstone. These Upper Devonian sandstones are phosphatic, mature quartz arenites referred to the Sylamore Member except where they overlie the Chattanooga Shale. In these cases, the sandstone is recognized as an informal upper member of the Chattanooga. Reports of Lower Mississippian Sylamore Sandstone in north-central Arkansas are regarded as misidentification of the Bachelor Formation (Middle Kinderhookian)
Hall, Jeffery D. and Manger, Walter L.
"Devonian Sandstone Lithostratigraphy, Northern Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 31
, Article 16.
Available at: http://scholarworks.uark.edu/jaas/vol31/iss1/16