Surface and subsurface stratigraphic studies in northeastern Arkansas show the Calico Rock Sandstone (Middle Ordovician) to be a lobate sand body up to 200 ft thick. The environment of deposition is considered from a study of grain characteristics, ripple marks, subjacent and superjacent units and unpublished isopachous maps. The data indicate the Calico Rock Sandstone formed in a transgressing Everton sea as a barrier island and near shore sand complex. The quartz sand was derived from a northern source and was distributed by southwestward flowing longshore currents.
Suhm, Raymond W.
"Calico Rock Sandstone Member of the Everton Formation (Ordovician), Northern Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 29
, Article 24.
Available at: http://scholarworks.uark.edu/jaas/vol29/iss1/24