41 Environmental Records from Large Estuaries Along the Northeastern US Seaboard (Sponsored by Northeast Section SEPM)

Wednesday, 14 March 2001
8:15 AM - 12:30 PM

A 1000-YEAR RECORD OF INTENSE STORMS FROM EASTERN CONNECTICUT

Paper number: 41-8
Program: SYMPOSIA
Time: 8:15 AM – 12:30 PM

Authors

Abstract

This study attempts to extend the record of intense storms in Southern New England by analyzing historic and prehistoric storm-induced deposits at Barn Island Salt Marsh in Stonington, Connecticut. We visually described and performed loss-on-ignition analysis on sediment cores to identify sand and silt horizons within the marsh peat that we infer to be related to intense storms. Using cesium-137 analysis, we attribute the two uppermost sand layers to the hurricanes of 1938 and 1954. Although these uppermost layers are present in cores across much of the marsh, there seems to be more spatial variability in deeper layers. To sort out this variability, we took a network of 44 cores from the portions of the marsh most likely exposed to storm surge and wave energy during storms. Carbon-14, lead pollution, and pollen stratigraphic methods were applied to these cores in order to date the deeper sand layers.

Preliminary analysis indicates evidence for four intense storms between ~1450 A.D. and ~1000 A.D. (55-105 cm depth). The uppermost prehistoric sand layer at Barn Island (~55-60 cm) potentially correlates with an overwash deposit at Succotash Marsh in East Matunuck, Rhode Island dated to the 15th century A.D. An additional sand layer between 75 and 80 cm at Barn Island dates to the 14th or early 15th century A.D. and may correlate to an overwash deposit of approximately the same age at Succotash Marsh. Two other prehistoric sand/silt layers at Barn Island have been dated to the 13th century and the early 12th to late 11th centuries A.D. Finally, we analyzed the spatial variability of the sand layers to determine their three-dimensional geometry. The spatial location and geometry of these layers may be related to parameters such as wind direction of hurricanes, sediment source, and the morphological evolution of the marsh.