Systemic modification of coastal systems in the northern Gulf of Mexico is generated by rapid geomorphic change due to storms, relative sea level rise, significant reduction in sediment supply, and anthropogenic alteration. Policy makers, engineers, and scientists must understand the overall geologic evolution as well as small scale processes associated with past sea level cycles to make informed decisions when addressing current and future sea level rise. After the Last Glacial Maximum, sea level rose rapidly during marine isotope stage (MIS) 2 (approximately 29-14 ka) leading to a transgressive reworking of lithosomes. As sea level continued to rise, Holocene sediments underwent significant reworking and backstepping resulting in drowned paleovalley architecture. Coastal geomorphic evolution is partially preserved within the geologic record specifically within incised valleys and shelf deposits. This study synthesizes ~700 km of boomer geophysical data collected in 2021, 19 sediment cores, microfossil analyses, and radiocarbon dates to create a geomorphic evolutionary framework of the Pascagoula-Biloxi paleovalley and associated fill along the innershelf of the northern Gulf of Mexico. Sediment cores described within the footprint of the Pascagoula-Biloxi paleovalley consist of muddy bedding overlying muddy sand and sandy mud with Pleistocene clay around 450-500 cm downcore. One such core contained large wood chunks dated to ~11 ka cal yr BP resting on a Pleistocene clay basal facies. Preserved wood indicates either rapid burial or an anoxic system, in this case - likely a swamp. Along the edge of the Pascagoula-Biloxi paleovalley, a sediment core exhibits well preserved interbedded clay and peat layers also dated to ~11 ka cal yr BP. These similar ages indicate terrestrial/shoreline deposition, and these data provide constraints to reconstruct the immature paleo shoreline and associated features of the early Holocene.
