As part of a study of recent history of the Chesapeake Bay ecosystem, one- to eight- meter long sediment cores were obtained from the mesohaline section of the Chesapeake Bay between the mouths of the Potomac and Rhode Rivers. The sediments consist of three lithofacies: coarse-grained channel deposits, restricted-estuary sands and muds, and open-estuary muds. Water content, biogenic silica, magnetic susceptibility, trace metals, and nutrients (carbon, nitrogen, and their isotopes) were measured in the cores. Biogenic silica, trace-metal, and nutrient data provide a strong basis for discussing past primary productivity and water-column anoxia in the bay.