Late Wisconsin and Holocene tectonic stability of the United States mid-Atlantic coastal region

Deposits that formed in the intertidal zone during sea-level rise 12,000 to 9,000 yr ago have undergone very little differential vertical deformation in the area between New York City and South Carolina. The lack of north-south vertical deformation contrasts with tide-gauge and with precise leveling measurements that have been used to indicate that considerable differential vertical movement is occurring along the coast. Probably, present rates of deformation cannot be extrapolated to early Holocene. Depths of dated in-place intertidal deposits and estimates that suggest the U.S. mid-Atlantic shelf was downwarped during Holocene glacio-isostatic adjustment are used to indicate that eustatic sea levels were not substantially below 30 m depth about 12,000 yr B.P.