ABSTRACT

Upper Cretaceous marine sedimentation in the inner Gulf Coastal Plain of Alabama spans the late Santonian to latest Maastrichtian (85 to 67 Ma) and encompasses 13 depositional sequences. The depositional sequences are separated by either type-1 (subaerial to submarine) or type-2 (mainly submarine) unconformities that delineate, and in some instances subdivide, formal stratigraphic map units in the region. The global pattern of third-order depositional sequences from 85 to 67 Ma is present within the Alabama marine section but is modified within some stratigraphic intervals. Modification in those intervals is the result of local and regional tectonic effects, which have produced several local depositional sequences. The depositional sequences in the study area are correlative with parts of the Niobrara, Claggett, and Bearpaw depositional cycles in the Western Interior Seaway of North America.