The Everton Formation is an intertonguing complex of sandstone, limestone, and dolomite exposed in northern Arkansas; it has produced gas shows in the subsurface. The Everton lithologies outcropping in bluffs along the west-east trending Buffalo and White Rivers can be divided into seven laterally persistent members. Previous investigators named 4 members but were unaware of their regional relations within the Everton. Three new informal members are defined.

The basal unit, the Sneeds Dolomite Member, disconformably overlies the Powell Dolomite (Canadian) and is laterally persistent. Members A and B consist of interbedded sequences of limestone and sandstone above the Sneeds. In the east, member A underlies a massive St. Peter-like sandstone known as the Calico Rock Sandstone Member, and, in the west, member B underlies the thick Newton Sandstone Member. Unnamed Everton dolomites include a medium crystalline dolomite facies, a late secondary replacement of limestone, exposed in the central part of the traverse, and a very finely crystalline dolomite facies with supratidal characteristics in the central and eastern parts of the traverse. Member C is a laterally persistent dolomitic sandstone-dolomite complex overlying the Newton sandstone n the west and the unnamed Everton dolomites in the central and eastern parts of the study area. The uppermost member, the Jasper, is also extensive and undergoes an eastward lithologic change from sandstone to limestone to dolomite.

The units of the Everton lack an abundant macrofauna except for the limestone facies of the Jasper Member. The meager fauna, lithologies, and vertical and lateral relations of the members record deposition on a shallow, broad shelf. The carbonate rocks accumulated in shallow subtidal, lagoonal, and supratidal environments, whereas the quartz sands were deposited in barrier-island, chenier-plain, and shallow-subtidal environments. The basinal area was on the south in the Ouachita geosyncline, and the intermittently exposed craton that acted as the source area for the terrigenous material lay on the north.

As a result of this study, the Everton can be correlated with equivalent deposits exposed in northeastern Oklahoma (Burgen Sandstone and lower and middle Tyner Formation). Tentative correlation with the Simpson Group of central and southern Oklahoma also is proposed.