Soil-Landscape Relationships in the Rhode River Bathyscape of Chesapeake Bay.

The Rhode River subestuary on the western shore of Chesapeake Bay, MD is a drowned river valley that contains a diverse bathyscape of permanently submerged landforms and subaqueous soils. By conducting a bathymetric survey and comparing it to historic surveys we have shown landform stability over 82 years, indicating that soil surveys of this and similar environments may be of use to land and marine resource managers for generations to come. The soils within this bathyscape correlate well with 11 distinct types of delineated landforms, and this has allowed the development of new proposed soil series and associated soil-landscape relationships. Together, these form the foundation of a new subaqueous soil-landscape paradigm for Chesapeake Bay, which integrates an understanding of the soil forming factors at work in the Rhode River with over 100 pedon descriptions from throughout the bathyscape, and which should allow soil surveys to be quickly and easily conducted in similar subestuaries. Moving from the edge of the water to the center of the subestuary’s mouth, the Rhode River is predominantly framed by wave-cut platforms that are composed of scour-lag deposits over truncated subaerial soils that have been submerged and altered by sea level rise to form distinctive soils that record their Tertiary marine origin, subaerial pedogenic history, and more recent subaqueous pedogenesis. Wave-cut platforms grade into wave-built terraces as the water deepens, forming stratified sandy soils. These taper off in still deeper water, transitioning to finely-textured fluid soils that have filled the drowned valley. Where tidal marshes fringe the subestuary, some areas instead grade into submerged tidal marshes. In deeper water these transition into fluid soils with buried O horizons, and eventually to the fluid soils in the center of the subestuary. Hypersulfidic materials are concentrated in some of these soils, but monosulfidic and hyposulfidic materials are dominant.