Photo showing complex geomorphology of the Grand Bay marsh landscape

Photo showing the complex geomorphology of the marsh landscape of the Grand Bay National Wildlife Refuge/Grand Bay National Estuarine Research Reserve in coastal Alabama and Mississippi. (1) Geology—a tidal creek that at lower sea level than present served as a distributary channel of a river-delta system. (2) Hydrodynamics—wave erosion of the marsh edge. (3) Geochemistry/biogeochemistry—rich brown sediment exposed on the escarpment that either ends up back on the marsh or in the estuary. (4) Biology—patches of vegetation (bright green vs. dull brown) adapted to slightly different environmental conditions.