ABSTRACT

Investigation of modern facies relationships along the southwestern Louisiana shoreline demonstrates the complex interaction of "sediment supply" and "energy of coastal processes" (Bernard, 1965). Shallow water "wave energy" and proximity to suspended mud supply are qualitatively shown to be dominant variables.

Facies tracts show variation through a broad spectrum of geometries and sediment types. Mudflats, both intertidal and subaqueous, show highest rates of progradation, as compared to "normal" sand-rich beaches with low rates of progradation. An "intermediate" type of strandline, represented by a thin sand beach resting on eroded mudflat and marsh sediment, is shown to prograde at rates intermediate between those of mudflats and "normal" beaches, even though geometrical relationships would suggest retrogradation. Consideration of the interaction of various partially dependent sedimentary processes outlined in this paper can be used to characterize rates of progradation as well as to predict sediment type and geometry.