Tidal marshes are important for the ecosystem of the Chesapeake Bay. Their soils have the capacity to sequester large amounts of carbon as they accrete with sea level rise. The objective of this study is to quantify the factors controlling carbon sequestration in restored tidal marshes at Blackwater National Wildlife Refuge. Three marsh cells will be studied: a natural marsh, a marsh restored in 1983 using organic sediments, and a marsh restored in 2003 with coarse-textured sediments. The United State Geologic Survey has installed three sediment elevation tables (SETs) in each marsh cell. Transects will be laid out parallel to and perpendicular to each SET. Along each transect, four to five plots, 75 x 55 cm, will be marked at the surface with ground feldspar. This will be used to monitor accretion over the course of this long-term study. A core will be collected from each plot annually with a McCauley peat auger. Samples will be divided by horizon or 25-cm increments and analyzed for bulk density, organic carbon, and total nitrogen. A subset of samples will be analyzed for sulfides, particle size distribution, labile C and other nutrients. The results of this study will be used to make management decisions regarding the use of clean dredged sediments in restoring the tidal marshes of Blackwater National Wildlife Refuge.