Northeastern Section - 36th Annual Meeting (March 12-14, 2001)

We sampled five beaches and their distributary rivers along the Connecticut coastline in order to study the provenance of the beach sediments. None of the sampled beaches had been replenished since 1966; thus the samples taken were thought to reflect the bedrock and surficial geology through which its paired river runs. The river-beach pairs sampled were: Housatonic River-Long Beach, Quinnipiac River-Rocky Beach, Thames River-Ocean Beach, Connecticut River-Guardhouse Point, and Hammonasset River-Hammonasset Beach. We determined the sorting, median grain size, heavy and light mineralogy, and percent calcium carbonate for each pair. The 3-phi grain size was used for mineralogical analysis. Median phi size for the rivers ranged from –1.4285 to 3.1429; median phi size for the beaches ranged from 0.00 to 1.0714. Beach sorting values were generally 0.6 greater than paired rivers. Carbonate content of beach samples decreased moving eastward along the coast. The most abundant heavy minerals in all samples were garnet, amphibole, and opaqueoxides. The river and beach samples generally reflect the lithology of their regions; however, the anomalously high abundance of garnet in the Guardhouse Point sample indicated unrecorded beach replenishment, and thus should not be used as a provenance indicator for Connecticut River sediments.