Relative sea-level rise across the Eastern Border fault (Branford, Connecticut): evidence against seismotectonic movements

Abstract

Basal peat age–depth data from four salt-marsh sites located 500–1500 m south of the Eastern Border fault (EBF) near Branford, Connecticut, document an error envelope for the lower limit of relative mean high water (MHW) rise during the past 3300 yr. The long-term rate of relative lower-limit-MHW rise during the past 3000 yr (1.1 mm yr −1) corresponds with late Holocene rates of relative MHW rise found elsewhere in coastal Connecticut (0.9–1.2 mm yr −1). This result invalidates repeated claims that multiple seismotectonic lowering of a crustal block towards the south has occurred along a segment of the EBF near Branford shortly after 815 cal yr BC and during the past 1200 yr and calls for a non-tectonic interpretation of biostratigraphic evidence of local short-term sea-level variations.