Sea-level rise associated with global warming and adverse environmental implications in coastal areas have prompted interest in modeling the history of sea-level rise and its impact on deforestation during the pedogenic transformation of Ultisols (forest soils)to Histosols (coastal marshes). The modeling was based on data collected from sampling units along a marsh transect in Dorchester County, MD. In low-relief submerging environments, coastal marshes accrete vertically and migrate laterally over adjacent Ultisols to keep pace with sea-level rise. The marsh substrate is organic in nature overlying what once were upland forest soils. The history of sea-level rise was a two-step linear function, illustrating acceleration in the last two centuries. During the last 150 yr, the 210Pb-based rate of sea-level rise averaged 2.2 ± 0.4 mm yr –1. Before the last few hundred years, the long-term 14C-based rate of sea-level rise was 1.12 ± 0.2 mm yr –1. The rate of lateral migration of coastal marshes, which is also the rate of deforestation, showed similar acceleration following the history of sea-level rise. During the last 150 yr, the rate of deforestation averaged 3.29 ± 2.1 m yr-1. Before the last 150 yr, the long-term rate of deforestation averaged 0.19 ± 0.08 m yr-1. Modeled predictions of deforestation have shown that within a marsh ecosystem, where other controlling factors are at a steady state condition, slope of the adjacent upland controls the rate of deforestation. In the next century, the predicted rate of deforestation ranged from 2.5 to 10 m yr-1 averaging 6.3 ± 3.8 m yr-1. Assuming that the present rate of sea-level rise remains constant, the time needed to complete the pedogenic transformation of Ultisols to Histosols is 180 ± 35 yr. The most conservative future scenario of sea-level rise has reduced this time by 55%.