Abstract. The Fayetteville black shale in northern Arkansas represents
     the maximum flooding interval and high stand systems tract of a regional
     transgression of the southern midcontinent, North America, that occurred
     during the Chesterian Series (Mississippian).  The informal lower and upper
     members of the formation both contain an abundant and diverse assemblage
     of ammonoid cephalopods that are typically crushed on bedding planes, but
     that be preserved as concretionary internal molds of testiferous, living
     chambers with crushed or uncrushed phragmocones.This material represents
     drifted shells that settled on to a sea floor of variable induration over   
     time,initially in life position, but later they fell over their sides. The
     base and top of the formation are time transgressive alang their present
     strike section. In the eastern portion of the Fayetteville Shale outcrop
     belt, basal strata contain an ammonoid assemblage equivalent to the
     Brigantian Stage, Visean Series (P2) identical to that of the underlying
     Batesville-Hindsville Formations.  The succeeding black shale contains an
     early Pendleian (E1a to early E1b) assemblage in its basal portion, while
     the bulk of the black shale facies is dominated by the ammonoid Tumulites
     varians and represents the middle Pendleian Stage (late E1b). In north
     central Arkansas, and E1c assemblage has been recovered from the top of the
     Fayetteville Shale, and E1c equivalents are found in the lower portion of
     the Pitkin Limestone, that confomably overlies the Fayetteville Shale and
     reflects aggradation and progradation of a carbonate shelf environment that
     characterized the late Mississippian Period throughout most of the southern
     midcontinent.