Cores from Delaware Bay tidal marshes separated by over 100 km reveal correlative transgressive overlap boundaries dated at 1.8 to 2.0 ka. Sedimentary fades at these boundaries that show strong marine influence abruptly (but conformably) overlie facies showing strong terrestrial influence. The transgressive overlap boundaries correlate with a transgression in wetland deposits of the New Jersey shore of Delaware Bay, further suggesting the occurrence of a significant regional sea-level movement. Because other mechanisms (rapid subsidence, autocompaction, rapid lateral erosion by tidal streams, and reduced sediment supply) are less likely, we propose that these transgressive facies transitions were produced by an acceleration in the rate of sea-level rise at 1.8 ka in the Delaware Bay.

Environmental rock-magnetic analyses were performed on sediments from all 17 sites drilled during Ocean Drilling Program Leg 155, Amazon Fan (Sites 930−946). In addition to the particles delivered to these sites via mass-wasting processes, rock-magnetic signals indicate the presence of authigenic magnetic-mineral phases. In particular, these phases include bacterial magnetite (Fe 3 O 4) and greigite (Fe 3 S 4).