Origin and Age of Fluvioglacial Sediments on Staten Island NY and Implications for Meltwater Flow

Staten Island is less developed than the other boroughs of New York city, however outcrops of rock and surface sediment are limited, making interpretation of its geologic history challenging. When small areas of sediment are exposed, they can be used to improve our understanding of changes in sediment erosion and deposition over time. In this study of two small temporary outcrops, the beds of sediment were logged in the field and samples were collected for textural and compositional analyses. The results were interpreted in the context of previous work on similar exposures nearby. The sediments were found to be sands and gravels of fluvioglacial origin, containing reworked sediments of both the Pliocene Pensauken Formation, and older Triassic rocks of the Newark Basin. It is likely that they were deposited on an outwash plain during the Illinoian glaciation. They were deposited in a topographic low, directly overlying Cretaceous sedimentary rocks, but adjacent to sediments of the Pensauken Formation which had in turn been deposited as an earlier valley fill. This interpretation solves an apparent disagreement between previous studies, by illustrating how both the Pensauken Formation and later fluvioglacial sediments can be exposed over a small area.