New radiocarbon dates from the inner Continental Shelf off southeastern Massachusetts and a local sea-level–rise curve for the past 12,000 yr

Abstract

New radiocarbon dates on shells and freshwater peat are used to draw a curve representing local sea-level rise for the past 12,000 yr. The samples were collected near the late Wisconsin glacial maximum where the Continental Shelf suffered the least and most rapid isostatic subsidence and rebound to the advance and retreat of the ice. Because the samples are from quiet-water embayments, they most likely have not been reworked or transported. For these reasons, the curve based on these data is believed to accurately represent sea-level rise in southeastern Massachusetts. Previously published radiocarbon dates from elsewhere on the inner shelf tend to reinforce the curve proposed here and suggest that the curve may be applicable for much of the inner Continental Shelf off the northeastern United States. The proposed sea-level–rise curve indicates that relative sea level was about 70 m below its present level 12,000 yr ago. From that time to about 10,000 yr ago, sea level rose at a rate of 1.7 m/100 yr. Between 10,000 and 6,000 yr ago, the rate of sea-level rise dropped gradually to about 0.3 m/100 yr and remained at that rate until about 2,000 yr ago. From then until now, the rate of sea-level rise has been about 0.01 m/100 yr.