Alluvial pedogenesis in Pleistocene and Holocene Mississippi River deposits: Effects of relative sea-level change

摘要

Comparison of Pleistocene and Holocene soils developed in Mississippi River meander-belt deposits in Louisiana illustrates the influence of relative sea-level change on pedogenesis. Holocene and Pleistocene meander belts have similar landscape morphologies, lithofacies, and soil characteristics, and probably formed under similar hydrologic regimes. The Pleistocene Avoyelles Prairie meander belt is now terraced, but it was originally graded to a lower relative sea-level position than the Holocene flood plain. Holocene alluvial soils are generally weakly expressed cumulative profiles with abundant redoximorphic features, and formed on an aggrading flood plain with a shallow fluctuating water table. The soil morphology varies with respect to landscape position and overbank lithofacies.