GRAIN-SIZE TRENDS OF WASHOVER AND FLOOD-TIDAL-DELTA DEPOSITS ASSOCIATED WITH A RELICT ISLAND BREACH: CEDAR ISLAND, VIRGINIA, USA
Mean grain size of the surficial sediments ranges from 1.643 to 2.748Φ and shows a net landward fining trend from the lower foreshore (1.941Φ) to the distal washover fan/relict flood tidal delta (2.679Φ). This fining trend indicates that during overwash events, coarser particles are deposited first while finer particles are transported further landward. Sorting ranges from 0.408 to 0.784Φ. Sediments are moderately to moderately well sorted at the beach and on the distal portions of the washover fan/relict flood tidal delta but are well sorted to moderately well sorted along center portion of barrier island. Along island center, aeolian processes play larger role by reworking the surficial sediments, thus leading to better sorting. Skewness ranges from -0.434 to 0.196. Sediments are negatively skewed at the beach (-0.248 to -0.106) with positive skewness (0.157 to 0.010) dominating the island center then returning to negative skewness on the distal washover fan/relict flood tidal delta (-0.075 to -0.286). The negative skewness reflects waves reworking beach sand or washover deposits sourced from beach sand, whereas the positive skewness indicates exposure to aeolian processes and reworking along island center, which is slightly topographically higher where sands have an opportunity to dry out more often.