BACKBARRIER DYNAMICS IN A GLACIATED ENVIRONMENT: THE EVOLUTION OF A SMALL SALTMARSH SYSTEM IN BOSTON HARBOR
A series of auger and vibracores along with an extensive ground-penetrating radar (GPR) survey of the upland regions provide a means for reconstructing both long- and short-term evolution of the marsh. Pervasive steeply dipping clinoforms in GPR profiles suggest that the marsh developed in a topographic low that formed between prograding delta lobes. Initial radiocarbon dating of basal peats demonstrates that the marsh is more than 3,000 years old and that these data might be used to construct a late-Holocene sea level curve for Boston Harbor. Stratigraphy indicates a change in marsh morphology from high to low marsh during the 20th century, and long-term accretion rates determined by Pb-210 will shed light on the ability of the marsh to maintain elevation with forecasted accelerated SLR. Sediment cores, aerial photographs and GPR data provide evidence of changes in the number and position of channels and tidal inlets linking the marsh to the open harbor. The recent changes in dominant marsh vegetation are likely to be a response to anthropogenic alterations, however it offers an insight into the ability of these small systems to respond to future acceleration in SLR.