RECONSTRUCTION OF LATE HOLOCENE RELATIVE SEA-LEVEL CHANGES FOR THE COASTAL PONDS OF RHODE ISLAND, USA

Author

F. Daniel Russell Jr., University of Rhode IslandFollow

Date of Award

2024

Degree Type

Thesis

Degree Name

Master of Science in Biological and Environmental Sciences (MSBES)

Department

Geosciences

First Advisor

Dawn Cardace

Abstract

Salt marsh peat deposits at many locations around the world, including the U. S. Atlantic and Gulf coasts, provide proxy data for reconstructing the history of changes in relative sea level (RSL). A geological database of index points has been established through sampling and analysis of salt marsh peat collected at many of those locations. However, spatial gaps in this database still exist in the available data for southern New England. A notable gap is the southern coast of Rhode Island, primarily due to the lack of precalculated tidal datums and the complexity of producing records in an active back barrier salt marsh setting. The primary goal of this research was to provide additional data to fill those gaps by establishing rates of sea-level rise in the salt marshes of the coastal ponds behind the barrier beach of southern Rhode Island. This project used basal-peat deposits, radiocarbon dating, and foraminifera that are indicators of local tide level. Exploratory/reconnaissance coring of the salt marshes of three ponds: Ninigret Pond, Quonochontaug Pond and Winnapaug Pond generally revealed very shallow peat deposits compared to those found around Narragansett Bay. Three locations were found that provided data sufficient to calculate usable rates of sea-level rise. The deepest peat deposit and oldest date was recovered at a salt marsh adjacent to Wildflower Road (WFN), Charlestown, RI. At 121 cm below the surface and a date of 1230 yrs. BP, the corresponding sedimentation rate and estimated rate of sea-level rise from the age/depth relationship was ~ 1 mm/yr. using the surface. This depth/age relationship and estimated rate of sea-level rise provides a frame of reference for sea level dynamics consistent with data of the same age and older in Narragansett Bay. Climate change, rising sea-level and storm waves have had an impact on the coastal salt marshes of Rhode Island and coastal communities of all the states along the U. S. Atlantic coast. The potential impacts from sea-level rise to salt marsh ecosystem services, coastal infrastructure, and coastal cultural resources, especially older indigenous cultural sites are likely to increase for decades if not centuries to come.

Recommended Citation

Russell, F. Daniel Jr., "RECONSTRUCTION OF LATE HOLOCENE RELATIVE SEA-LEVEL CHANGES FOR THE COASTAL PONDS OF RHODE ISLAND, USA" (2024). Open Access Master's Theses. Paper 2533.
https://digitalcommons.uri.edu/theses/2533