Recession of the ice margin at a rate of 0.3 km/yr or more in coastal areas in central Maine between 13,000 and 12,700 yr B.P. resulted in a large-scale marine submergence of this region. Isostatic uplift brought the region above sea level by 12,100 yr B.P. Model calculations show the existence of an inland sea in the later stages of emergence. The chronology of these events is given by 14C dates on shells and seaweed from the Presumpscot Formation. Several criteria applied indicate age reliability of the shell dates within a few hundred years. 14C ages of the earliest grown organic material in kettles often lag behind the time of deglaciation.