The Sediment Sources of Atlantic Shore Beaches between Montauk Point and Democrat Point, Long Island New York USA

  • Peter Morgan

    Student thesis: Doctoral Thesis


    Speculation has arisen regarding the possibility of an additional offshore sediment source on the Atlantic inner shelf south of Long Island, New York, as a result of deficits in recent south shore budgetary estimates. In view of the importance of Long Island's inner shelf as a possible sediment source for other conflicting commercial uses in the future, the present study attempts to compare the known source at Montauk Point with sediments from buried palaeodrainage channels and nearby offshore and to examine the degree to which they may be linked to south shore beaches.

    Samples from each of these three environments were subjected to S.E.M. analysis using a checklist approach. Qualitative results comparing individual quartz grain surface feature variability with transport distance west of Montauk Point divided the south shore into three sections largely on the basis of mechanically derived and source textures: the distinctive glacial deposits formed in Ronkonkoma moraine at Montauk Point; Headlands section beaches, and Fire Island beaches. Surface feature variability plots and between sample variability plots revealed a more complex pattern of surface feature development than may be expected from what appears to be generally a single alongshore-trending wave dominated regime, which suggests an additional control such as an offshore source.

    Canonical variate analysis, as well as cluster and factor analyses confirmed qualitative findings and tentatively link offshore lobe deposits with onshore Fire island beaches, and distinguish them from Headlands beaches and Montauk Point. Strong supporting and complementary links between qualitative results, photographic evidence and subsequent statistical analysis suggest that the technique employed is a useful and valid sedimentological tool,
    Date of Award1990
    Original languageEnglish
    SponsorsPolytechnic of Wales

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