AbstractSurface sediments from 24 stations in the Raritan Bay‐lower New York Bay were analyzed seasonally for size‐grade distributions, percent volatiles and extractable hydrocarbons. Seasonal means of size‐grade fractions were not statistically different, although much inter‐ and intrastation variability occurred. Greater silt‐clay content tended to occur at the head of the bay (especially in winter) and decreased down the bay. During fall and winter, the occurrence of silt‐clay fractions tended to increase throughout the bay.Extractable hydrocarbons exhibited significant seasonal differences (p<0.05). Extractable hydrocarbon ranges were 1–1,273 μg/g dry sediment, with seasonal means of 160–327 μg/g dry sediment, depending on the bay region. Hydrocarbon content and percent volatiles generally increased with increased silt‐clay content. Best correlations of hydrocarbons with silt‐clay occurred in summer and fall. Throughout the seasons, hydrocarbon material appeared to move down the bay, with lowest values in fall‐winter and the h