ABSTRACT

The later Holocene sedimentary succession beginning about 2500 years B. P. in Broadkill Marsh, Sussex County, Delaware consists of tidal-creek clays and silts about 12 feet thick, overlain by 5 feet of interbedded thin peats and silty clay of salt marsh origin. The peats are formed of remains of marsh grasses Spartina, Disticlis, and Phragmites and of marine algae and pondweeds. The carbohydrate and protein amino acid residues are much lower in total amount than those of comparable peat deposits of freshwater marshes, which suggests that degradation of these components is more rapid in the tidal marine environment than in freshwater marshes. Polysaccharide residues are scarce to absent in much of the sediment-sequence just as in freshwater sediments, but small amounts o laminaran, starch and cellulose were found in peat about 2 feet below the present marsh surface.

Chlorophyll-derived pigments are lower and carotenoid pigments are much lower than in freshwater sediments of similar organic contents; which are further indications of the relatively unfavorable conditions for preservation of certain organic components in the tidal environment.