ABSTRACT

The Louisiana Chenier System is the product of a complex interaction of coastal, riverine, biologic, eolian, and storm processes. An important component of the Chenier System, the chenier ridge, has been described as an accumulation of sand and/or shell material winnowed from existing marsh and tidal flat deposits. According to most interpretations (Russell, 1940; Price, 1955; Bryne et. al., 1959; Gould and McFarlan, 1959), these ridges are correlative with changes in the flow direction of the Mississippi River from a westerly flow to an easterly flow. The extensive mudflat and marsh sediments that separate the chenier ridges have been thought by most workers to represent periods of progradation, influenced by a high sediment load from the Mississippi during periods of westerly discharge. These alternating periods of easterly and westerly flow represent the classical model that has been presented for genesis of the chenier plain over the past 3000 years.

While it is generally agreed that Mississippi River sedimentation has been a major factor in the development of coastal geomorphology of southwestern Louisiana, the "flip/flop" model presented above is overly simplified. Furthermore, the term "chenier ridge" has been indiscriminately applied to almost any morphologic unit within the system that shows noticeable relief as reflected in vegetative development. Therefore, little genetic significance should be ascribed to the term as it has been applied in most earlier reports.