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In central and eastern Alabama, the 450-m-thick Upper Cretaceous (upper Santonian–uppermost Maastrichtian) section is composed of various paralic (barrier-shoreline) and hemipelagic (shelfal) facies associations. Based on outcrop and shallow-subsurface studies, the Upper Cretaceous section is divided into several stratigraphic break-bounded genetic packages of facies. The bounding stratigraphic breaks are either (1) low-relief surfaces characterized by thin conglomerates and facies discontinuities (probable parasequence boundaries or type-2 sequence boundaries), or (2) high-relief surfaces (probable type-1 sequence boundaries).

The basal (upper Santonian–lower Campanian) Eutaw Formation, bounded at the top and base by type-2 and type-1 sequence boundaries, respectively, consists of paralic facies arranged in two genetic packages that are separated by a low-relief break (probable maximum-flooding parasequence boundary). The overlying (lower Campanian) Mooreville-Blufftown interval encompasses shelfal and paralic facies arranged in four genetic packages. Low-relief breaks within the Mooreville-Blufftown interval are probable parasequence boundaries; the break between the Mooreville-Blufftown and the overlying Demopolis-Cusseta interval is a probable type-1 sequence boundary (age of boundary is approximately 80 Ma). In the upper Campanian Demopolis-Cusseta interval, shelfal and paralic facies occur in three genetic packages, bounded by low-relief (type-2) stratigraphic breaks. A probable type-2 sequence boundary occurs between the Demopolis-Cusseta interval and the overlying Ripley Formation. The Ripley Formation (lower and upper Maastrichtian) is composed of paralic facies, encompasses one probable type-1 sequence boundary, and has a type-1 sequence boundary with 67 m of relief at its top (age of boundary top is approximately 68 Ma). The overlying Prairie-Bluff–Providence interval (uppermost Maastrichtian) encompasses shelfal and paralic facies arranged in two genetic packages. A probable parasequence boundary occurs within the Prairie Bluff–Providence interval and a type-1 sequence boundary with considerable relief occurs at the top of the interval.

Review and analysis of study area biostratigraphy permits us to closely relate the genetic packages of facies and the stratigraphic breaks observed in this study to the current model of sequence stratigraphy that synthesizes previously documented global cycles of sea-level change in the Late Cretaceous.

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