ABSTRACT

Bottom sediments within the lower Chesapeake Bay between the Potomac River and the Atlantic Ocean were analyzed for mud content, sand texture, organic content, and color. Parmetric distribution patterns indicate a complex dispersal model, in which sediments are derived from multiple sources. The bay region between the Potomac and York Rivers appears to be an effective mud trap, with the central basin constituting a uniformly-colored mud depocenter, while the marginal zones are composed of multicolored residual sand deposits. The baymouth sector south of the York River is a multicolored sand province that constitutes an effective mud-bypass area. A regional belt of highly organic sediments occurs throughout the lower bay which reflects a zone of high benthonic shell concentrations. San textures suggest a composite fabric of modern equilibrium sediments, and palimpsest sediments that reflect an earlier hydraulic regime. The palimpsest sediments may represent Pleistocene fluvial deposits of the ancestral Susquehanna drainage system, and early Holocene paralic deposits generated during the bay's inundation.